HomeMy WebLinkAboutCWMP Phase II Report (10 MB)_201401230911312117Report
Comprehensive Wastewater
Management Plan and Draft
Environmental Impact Report
Phase II –Alternatives and Site
Identification
Nantucket, Massachusetts
Volume I of II
Prepared for:
Nantucket Department of Public Works
Nantucket, Massachusetts
Prepared by:
Earth Tech, Inc.
196 Baker Avenue
Concord, Massachusetts 01742-2167
September 2003
27355
Comprehensive Wastewater Management Plan and
Draft Environmental Impact Report
Phase II –Alternatives and Site Identification
Nantucket, Massachusetts
Volume I of II
Prepared for:
Nantucket Department of Public Works
Nantucket, Massachusetts
Prepared by:
Earth Tech, Inc.
196 Baker Avenue
Concord, Massachusetts 01742-2167
September 2003
September 30, 2003
Dear Project Reviewer:
Enclosed please find one copy of the report entitled “Comprehensive Wastewater
Management Plan and Environmental Impact Report Phase II – Alternatives and Site
Identification and Draft Environmental Impact Report” (Phase II Report) completed in
accordance with the Massachusetts Department of Environmental Protection’s “Guide to
Wastewater Management Planning” dated January 1996. The review of the Comprehensive
Wastewater Management Plan (CWMP)/Environmental Impact Report (EIR) will be through
the submission of three documents including: (1) Phase I Report; (2) Phase II CWMP/Draft
EIR; and (3) Phase III CWMP/Final EIR.
This Phase II Report is consistent with the general requirements of the MEPA regulations
including being circulated per MEPA regulations at 301 CMR 11.16 (3). In addition, six (6)
copies will be available for public review at the Selectmen and Town Clerk’s Offices in the
Town Hall, Department of Public Works, Nantucket Land Council, Nantucket Planning and
Economic Development Commission and at the Antheneum (Public Library). The circulation
list is included in Section 7 of the Phase II Report.
A 30-day public comment period on the Phase II Report will be initiated by a notice of
availability fro review in the Environmental Monitor. Comments received will be considered
in determining the extent to which issues were adequately addressed. If you have comments,
please send them to:
Secretary of Environmental Affairs
251 Causeway Street
Boston, MA 02114
Attention: MEPA Unit
MEPA #12617
If you have questions regarding this project, please do not hesitate to contact the MEPA
office at 617-626-1000.
Very truly yours,
Earth Tech, Inc.
Thomas E. Parece, P.E.
Senior Project Director
Enclosures
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
TABLE OF CONTENTS
Section Page
LETTER OF TRANSMITTAL
EXECUTIVE SUMMARY................................................................................................................ES-1
LIST OF FIGURES .................................................................................................................................v
LIST OF TABLES..................................................................................................................................vi
1.0 INFORMATION UPDATE REQUEST OF THE PHASE I MEPA CERTIFICATE
A. NEEDS ANALYSIS DISCUSSION UPDATE..........................................................1-1
1. Introduction.............................................................................................................1-1
2. First Stage Analytical Approach - Rating Criteria Matrix ......................................1-1
3. Second Stage Analytical Approach - Soils, Groundwater
and Age/Lot Evaluation .........................................................................................1-3
4. Results of Needs Analysis ......................................................................................1-8
B. WASTEWATER FLOW UPDATE ...........................................................................1-26
C. DISPOSAL SITE ALTERNATIVES .........................................................................1-29
D. WATER SUPPLY ......................................................................................................1-29
E. PLANNING FOR GROWTH (EXECUTIVE ORDER #385)...................................1-29
2.0 IDENTIFY AND DISCUSS ALTERNATIVES FOR WASTEWATER DISPOSAL
A. INTRODUCTION ......................................................................................................2-1
B. OPTIMIZE OPERATION AND MAINTENANCE OF
EXISTING ON-SITE SYSTEMS...............................................................................2-1
1. Repair/Upgrade Existing On-Site Systems.............................................................2-2
2. Conventional Title 5 System...................................................................................2-4
C. WASTEWATER COLLECTION, TREATMENT AND
DISPOSAL ALTERNATIVES ..................................................................................2-6
1. Flow and Waste Reduction .....................................................................................2-6
2. Decentralized Facilities...........................................................................................2-12
3. Analysis of On-Site Alternatives ............................................................................2-34
4. Configurations and Alternative Sewer Systems......................................................2-37
5. Wastewater Treatment, Disposal, Reuse and Land Applications ...........................2-41
6. Existing Wastewater Infrastructure.........................................................................2-63
7. Existing Wastewater Treatment Facilities ..............................................................2-72
8. Potential Reuse Opportunities.................................................................................2-95
9. Residuals Disposal and Reuse ................................................................................2-98
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CWMP/DEIR – PHASE II REPORT
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D. WASTEWATER REUSE FOR ARTIFICIAL RECHARGE....................................2-107
1. General...................................................................................................................2-107
2. General Requirements for Wastewater Usage for Artificial Recharge..................2-107
3. Wastewater Treatment Levels and Technologies ..................................................2-110
4. Wastewater Recharge/Drinking Water Reuse Experience.....................................2-117
E. STORMWATER MANAGEMENT AND
GROUNDWATER RECHARGE INITIATIVES .....................................................2-124
F. SHORT LIST OF ALTERNATIVES........................................................................2-125
1. General...................................................................................................................2-125
2. Technical Considerations.......................................................................................2-127
3. Environmental Benefits .........................................................................................2-130
4. Economic Considerations ......................................................................................2-131
5. Water Balance Impacts ..........................................................................................2-132
3.0 SCREENING OF SITES FOR TREATMENT AND/OR DISPOSAL
A. CRITERIA DEVELOPMENT....................................................................................3-1
B. SITE IDENTIFICATION...........................................................................................3-12
1. General....................................................................................................................3-12
2. Surfside Wastewater Treatment Facility3-16 .........................................................3-16
3. FAA Site – Massasoit Bridge Road ........................................................................2-16
4. UMASS Site ...........................................................................................................3-17
5. Quidnet – No. 1 Site ...............................................................................................3-17
6. Quidnet – No. 2 Site ...............................................................................................3-17
7. Pocomo Road Site...................................................................................................3-17
8. Milestone Road – “Clear-Cut Site”.........................................................................3-17
9. Tom Nevers – Naval Station Site............................................................................3-18
10. Siasconset WWTF Site .........................................................................................3-18
11. Airport Site ...........................................................................................................3-18
12. Wauwinet Road Site .............................................................................................3-18
13. Wauwinet – Quidnet Roadways............................................................................3-18
14. State Forest Site ....................................................................................................3-18
15. Madaket – Warren’s Landing Area Roadways.....................................................3-19
D. PRELIMINARY SITE SCREENING...............................................................................3-19
1. Environmentally Sensitive Areas............................................................................3-19
2. Archaeological and Historical Resources...............................................................3-19
3. MCP Phase I Site Assessment ................................................................................3-20
4. Soil Suitability and Geologic Evaluation................................................................3-20
5. Sensitive Receptors.................................................................................................3-20
6. Hydrogeologic Evaluations.....................................................................................3-20
7. Historical Shoreline Analysis at Surfside WWTF..................................................3-22
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CWMP/DEIR – PHASE II REPORT
Section Page
E. IDENTIFICATION OF FEASIBLE SITES BASED
ON SCREENING ANALYSIS...................................................................................3-22
F. SUMMARY ......................................................................................................................3-25
4.0 EVALUATION OF SHORT LISTED ALTERNATIVES
A. ENVIRONMENTAL EVALUATION.......................................................................4-1
1. Introduction.............................................................................................................4-1
2. Evaluation ...............................................................................................................4-1
3. Recommendations based on Environmental Evaluation Criteria............................4-6
B. EVALUATION OF COSTS.......................................................................................4-10
1. Project Costs ...........................................................................................................4-10
2. Operation and Maintenance Costs ..........................................................................4-13
3. Wastewater Treatment Facilities Alternative Costs................................................4-14
4. Collection and Transmission Alternative Costs......................................................4-15
C. INSTITUTIONAL ARRANGEMENTS ....................................................................4-25
1. General....................................................................................................................4-25
2. Institutional and System Management Procedures .................................................4-27
D. RESIDUALS DISPOSAL ..........................................................................................4-30
E. LOCATION OF FACILITIES....................................................................................4-30
1. Madaket WWTF – FAA Site ..................................................................................4-30
2. Surfside WWTF Expansion....................................................................................4-31
3. Needs Areas ............................................................................................................4-31
F. PHASED CONSTRUCTION .....................................................................................4-32
G. FLEXIBILITY AND RELIABILITY.........................................................................4-32
H. IMPLEMENTATION CAPABILITY ........................................................................4-32
I. REGULATORY, DESIGN AND RELIABILITY REQUIREMENTS......................4-33
5.0 RECOMMENDED PLAN
A. DETAILED RECOMMENDED PLAN .....................................................................5-1
1. Introduction.............................................................................................................5-1
2. Study Areas.............................................................................................................5-1
3. Wastewater Treatment Facilities.............................................................................5-15
4. Existing Pump Stations...........................................................................................5-39
B. INSTITUTIONAL IMPACTS....................................................................................5-40
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CWMP/DEIR – PHASE II REPORT
Section Page
C. ENVIRONMENTAL IMPACTS................................................................................5-40
1. General....................................................................................................................5-40
2. Historical, Archaeological, Cultural, Conservation and Recreation.......................5-40
3. Wetlands, Flood Plains and Agricultural Lands .....................................................5-41
4. Zones of Contribution of Existing and proposed Water Supply Sources ...............5-41
5. Surface and Groundwater Resources Including Nantucket and
Madaket Harbor Watersheds..................................................................................5-41
6. Displacement of Households, Businesses and Services..........................................5-41
7. Noise Pollution, Air Pollution, Odor and Public health Issues Associated
with Construction and Operation...........................................................................5-41
8. Violation of Federal, State or Local Environmental and Land Use Statues or
Regulations and Plans Imposed by Such Statutes and Regulations.......................5-41
9. Changes if Development and Land Use Patterns
10. Pollution Stemming from Changes in Land Use ..................................................5-42
11. Damage to Sensitive Ecosystems..........................................................................5-42
12. Socioeconomic for Expansion ..............................................................................5-42
D. CAPITAL, OPERATION AND MAINTENANCE COSTS......................................5-42
1. Capital Costs...........................................................................................................5-42
2. Operation and Maintenance Costs ..........................................................................5-45
E. IMPLEMENTATION PLAN .....................................................................................5-46
6.0 DRAFT ENVIRONMENTAL IMPACT REPORT
A. PROJECT DESCRIPTION.........................................................................................6-1
1. General....................................................................................................................6-1
2. Summary.................................................................................................................6-1
3. Needs Areas ............................................................................................................6-1
4. Disposal Site Alternatives.......................................................................................6-2
5. Threshold Exceedances...........................................................................................6-2
B. WATER SUPPLY ......................................................................................................6-2
1. General....................................................................................................................6-2
2. Existing Conditions.................................................................................................6-2
3. Proposed Water Use................................................................................................6-2
C. EXECUTIVE ORDER 385/PLANNING FOR GROWTH........................................6-6
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CWMP/DEIR – PHASE II REPORT
Section Page
7.0 REVIEW OF PUBLIC PARTICIPATION PROGRAM
A. GENERAL..................................................................................................................7-1
B. PUBLIC MEETING ...................................................................................................7-2
C. RESPONSIVENESS SUMMARIES..........................................................................7-2
D. SUMMARY OF PUBLIC COMMENTS RECEIVED
DURING THE MEPA PROCESS..............................................................................7-3
E. CIRCULATION LIST................................................................................................7-4
8.0 SRF GRANT/LOAN ADMINISTRATION............................................................................8-1
LIST OF FIGURES
Figure Page
1-1 Typical Lot Configuration .......................................................................................................1-6
2-1 Conventional Title 5 System....................................................................................................2-5
2-2 Typical STEP System ..............................................................................................................2-14
2-3 Subsurface Cluster System ......................................................................................................2-15
2-4 Recirculating Sand Filter .........................................................................................................2-20
2-5 Amphidrome™ Process ...........................................................................................................2-22
2-6 Bioclere™ System ...................................................................................................................2-24
2-7 Cromaglass® System...............................................................................................................2-26
2-8 RUCK® System.......................................................................................................................2-29
2-9 Single Home FAST®...............................................................................................................2-30
2-10 Typical Grinder Pump Unit .....................................................................................................2-39
2-11 Surfside WWTF Flows and Precipitation................................................................................2-78
2-12 Watershed Sub-Basins ............................................................................................................2-140
3-1 Potential Wastewater Treatment and/or Disposal Sites ...........................................................3-13
3-2 Natural Resources and Environmentally Sensitive Areas........................................................3-15
5-1 Madaket Study Area ................................................................................................................5-3
5-2 Warren’s Landing Study Area.................................................................................................5-5
5-3 Monomoy Study Area..............................................................................................................5-6
5-4 Somerset Study Area................................................................................................................5-11
5-5 Shimmo Study Area.................................................................................................................5-13
5-6 Wastewater Treatment Facility Locations ...............................................................................5-16
5-7 Surfside WWTF Site Location.................................................................................................5-19
5-8 Surfside WWTF Process Layout .............................................................................................5-20
5-9 Siasconset WWTF Site Location .............................................................................................5-28
5-10 Siasconset WWTF Process Layout..........................................................................................5-29
5-11 Madaket WWTF Site Location................................................................................................5-34
5-12 Madaket WWTF Process Layout.............................................................................................5-35
5-13 Capital Improvement Program – FY 2004-2014 .....................................................................5-49
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CWMP/DEIR – PHASE II REPORT
LIST OF TABLES
Table Page
1-1 Rating Criteria Point Per Developed Lot .................................................................................1-4
1-2 Rating Criteria..........................................................................................................................1-9
1-3 Study Area Long Term Wastewater Disposal Option..............................................................1-27
1-4 Estimated Wastewater Flows by Study Area...........................................................................1-28
1-5 Estimated Wastewater Flows by Wastewater Treatment Facility............................................1-29
2-1 Summary of Monitoring Results Versus Treatment Requirements .........................................2-32
2-2 Summary of Water Quality Criteria For Class B Streams.......................................................2-44
2-3 Proposed Effluent Limitations.................................................................................................2-47
2-4 Class 1 Groundwater Permit Standards ...................................................................................2-48
2-5 Areas Required For Surface Application of Treated Effluent .................................................2-49
2-6 Areas Required For Subsurface Application of Treated Effluent............................................2-49
2-7 Wastewater Pumping Stations Survey Summary.....................................................................2-66
2-8 Massachusetts Groundwater Discharge Permit No. 1-200 Limits ...........................................2-74
2-9 Surfside WWTF Design Data ..................................................................................................2-75
2-10 Surfside WWTF Wastewater Flows (1999 through 2002)......................................................2-77
2-11 Surfside WWTF Performance – 1999......................................................................................2-80
2-12 Surfside WWTF Performance – 2000......................................................................................2-81
2-13 Surfside WWTF Performance – 2001......................................................................................2-82
2-14 Surfside WWTF Performance – 2002......................................................................................2-83
2-15 Surfside WWTF Serviceability Ratings...................................................................................2-84
2-16 Surfside WWTF Evaluation of Process Equipment – Headworks...........................................2-85
2-17 Surfside WWTF Evaluation of Process Equipment – Primary Clarifiers................................2-85
2-18 Surfside WWTF Evaluation of Process Equipment – Solids Handling Building....................2-87
2-19 Surfside WWTF Evaluation of Process Equipment – Sludge Management Building.............2-88
2-20 Surfside WWTF Evaluation of Process Equipment – Odor Control .......................................2-90
2-21 Surfside WWTF Evaluation of Process Equipment – CEPT Building....................................2-91
2-22 Surfside WWTF Evaluation of Process Equipment – Miscellaneous......................................2-92
2-23 Alternative Summary ..............................................................................................................2-126
2-24 Water Withdrawals .................................................................................................................2-133
2-25 Water Balance Impacts 2001 Annual......................................................................................2-134
2-26 Water Balance Impacts Summer 2001....................................................................................2-135
2-27 Water Balance Impacts 2025 Annual......................................................................................2-136
2-28 Water Balance Impacts Summer 2025....................................................................................2-137
3-1 Criteria Description..................................................................................................................3-2
3-2 Existing Conditions and Site Features .....................................................................................3-14
3-3 Results of Preliminary Screening.............................................................................................3-23
3-4 Wastewater Treatment and/or Disposal Sites ..........................................................................3-26
4-1 Innovative/Alternative System Evaluation ..............................................................................4-7
4-2 Connecting to the Existing System Evaluation........................................................................4-8
4-3 Communal System Evaluation.................................................................................................4-9
4-4 Surfside WWTF Alternatives - Estimated Construction Costs................................................4-14
4-5 Madaket Study Area Alternatives - Estimated Project Costs, Operation and
Maintenance Costs and Present Worth Costs ..........................................................................4-17
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CWMP/DEIR – PHASE II REPORT
Table Page
4-6 Monomoy Study Area Alternatives - Estimated Project Costs, Operation and
Maintenance Costs and Present Worth Costs ..........................................................................4-18
4-7 Somerset Study Area Alternatives - Estimated Project Costs, Operation and
Maintenance Costs and Present Worth Costs ..........................................................................4-20
4-8 Shimmo Study Area Alternatives - Estimated Project Costs, Operation and
Maintenance Costs and Present Worth Costs ..........................................................................4-22
4-9 Warren’s Landing Study Area Alternatives - Estimated Project Costs, Operation and
Maintenance Costs and Present Worth Costs ..........................................................................4-24
5-1 Summary of Recommended Plan.............................................................................................5-14
5-2 Typical WWTF Effluent Permit Requirements .......................................................................5-15
5-3 Surfside WWTF Design Criteria .............................................................................................5-24
5-4 Siasconset WWTF Design Criteria..........................................................................................5-31
5-5 Madaket WWTF Design Criteria.............................................................................................5-37
5-6 Summary of Estimated Project Costs.......................................................................................5-43
5-7 Bonding Scenarios ...................................................................................................................5-45
5-8 Estimated Operation and Maintenance Costs ..........................................................................5-46
6-1 Somerset Study Area Water Use Design Conditions...............................................................6-3
6-2 Shimmo Study Area Water Use Design Conditions ................................................................6-4
6-3 Monomoy Study Area Water Use Design Conditions.............................................................6-5
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
EXECUTIVE SUMMARY
In 1998, the Nantucket Department of Public Works retained Earth Tech, Inc. to prepare an Island-wide
Comprehensive Wastewater Management Plan/Environmental Impact Report (CWMP/EIR) to identify
areas within the Island with sub-surface wastewater disposal problems and to develop a plan to mitigate
or eliminate the problems. The Town established a special procedure for the review of this major and
complicated project. This special procedure is a three-phase process during which the scope of future
phases is based largely on the results of the preceding phase. The process consists of filing three
documents: (1) Phase I, Needs Analysis; (2) Phase II, Alternatives and Site Identification and Draft
Environment Impact Report; and (3) Phase III, Comprehensive Wastewater Management Plan and Final
Environmental Impact Report. The results of the Need Analysis and preliminary screening of alternatives
are included in this Document. This Document and further, more detailed analyses during the final Phase
will provide the basis for the design and ultimate construction of the approved plan.
This Document contains the results of extensive efforts by Earth Tech, Inc. and the Town of Nantucket to
evaluate the available options for improving the existing on-site wastewater disposal systems. In order to
obtain as much information as possible on the existing and projected land use, demographic conditions
and population, Earth Tech Inc., coordinated efforts with the Nantucket Planning and Economic
Development Commission (NP&EDC) and the Massachusetts Estuary Project (MEP). The goals of the
NP&EDC’s , “The Nantucket Comprehensive Plan”, coupled with the on-going Massachusetts Estuary
Project (MEP) have been utilized in evaluations and analyses for the community presented in this
Document and have been an integral force in the formation for the recommendations herein.
The MEP is currently gathering data in the Nantucket Harbor and Sesachacha Pond areas in order to
provide technical data relative to the maximum amount of nitrogen (nitrogen threshold) that each estuary
can tolerate without adversely changing its character and use. Madaket Harbor is also being studied but at
a later target date than the above-mentioned areas. MEP will set the target to be achieved in order to
protect and restore the health of the estuaries. Study areas affected by the MEP include Wauwinet,
Quidnet, Pocomo, and Polpis. Until the MEP data is completed, these areas will be recommended to stay
with their current on-site wastewater disposal systems but managed under the Septage Management Plan
currently under planning stages rather than an attempt a temporary solution and have to change when the
MEP data is in. Once the MEP data is complete, these areas will be further evaluated for long-term
recommendations. A recommended solution will be made for Madaket in this Report, which is based on
multiple criteria, in addition to the MEP.
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CWMP/DEIR – PHASE II REPORT
Other agencies utilized for information and considered herein are U.S. Soils Conservation Services, U.S.
Department of Agriculture, U.S. Coast Guard, local planning officials, the Nantucket Historic
Commission, the Natural Heritage Program, and local Town boards including Assessors, Building
Department, Board of Health, Public Works Department, Zoning Officials, and Nantucket Planning and
Economic Development Commission.
The Phase I, Needs Analysis was completed and filed with MEPA in August 2001. An Environmental
Notification Form (ENF) was filed with MEPA in October of 2001 as well. The Phase I Document
determined the areas on Island incapable of sustaining long-term with on-site wastewater disposal
systems throughout and beyond the 20-year planning period. There were ten Study Areas identified as
Needs Areas:
Madaket Shimmo
Monomoy Pocomo
Pocomo Polpis
Polpis Warrens Landing
Quidnet Wauwinet
See the map at the end of this Executive Summary for a description and the challenge and solution for
each of the ten identified Study Areas.
The scope of this Phase II CWMP/DEIR analyzed the selected alternatives in accordance with the revised
scope that was issued by the Secretary of EOEA and comments received on the Phase I CWMP/EIR
document. The MEPA Certificate, EOEA Number 12617, issued by the Secretary on November 16, 2001
asked for further clarification with regards to identification of Needs Areas and the methodology used in
order to ensure the rankings and rationale for the Study Areas is clear and appropriate. The Secretary
further clarified this “revised scope” in a letter dated May 17, 2002 where he states, “I hereby authorize
you to submit a single filing that combines the Phase II document and the requested information updates
and responses to comments received on the ENF and on the Phase I document”. The Response to
Comments can be found in Appendix A and Earth Tech update on the information request from the
MEPA Certificate issued November 16, 2001 can be found in its entirety in Section 1.
Page ES-2 Executive Summary
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
This Phase II CWMP/DEIR document contains the preliminary investigation into the viability of siting
wastewater treatment facility(s) and/or highly treated wastewater effluent disposal facilities in Nantucket.
Site selection, for both the wastewater treatment facilities (WWTFs), and the effluent disposal field(s) is
the most difficult to resolve. The screening criteria presented in this section were developed to assess the
viability of 14 sites identified within Nantucket as potential wastewater treatment facility and/or
wastewater disposal facility sites. The screening criteria used to evaluate these potential project sites was
based upon eleven environmental criteria. The environmental screening criteria were chosen based upon
review by the Project Proponent and upon comments received by the Proponent in the Secretary of the
Executive Office of Environmental Affairs Certificate on the ENF dated October 2001. It was determined
that by applying the screening criteria to the 14 identified sites a short list of selective potential sites
would be established for additional evaluation through field testing. The screening criteria chosen to
evaluate the potential project sites are: (1) wetlands; (2) soils; (3) drinking water supply - wellhead
protection areas (Zone I and Zone II); (4) fisheries (including shellfish areas); (5) waterbodies (distance
from surface water); (6) floodplains; (7) sensitive habitats; (8) park lands; (9) recreational resources;
(10) agricultural/historical interests; (11) shoreline change data; and (12) in or adjacent to an Area of
Critical Environmental Concern.
Wastewater treatment options were evaluated based on four levels of criteria. The first criteria, Technical
Factors, included flow and loading, land/site requirements, suitability for groundwater discharge, climate,
sludge disposal and ease of operation. The second criteria, Environmental Factors, included groundwater
and permitting impacts. The third criteria, Institutional Factors, included community acceptance,
regulatory and legal issues. The fourth criteria, Economic Factors, included construction cost and
operations cost. Various wastewater treatment technologies were evaluated based on the above criteria
and the Town of Nantucket’s goals regarding the operation and maintenance of the facilities.
The Phase II CWMP/DEIR document presents recommendations for wastewater management in the
above-mentioned ten identified areas of the Town of Nantucket where existing on-site wastewater
disposal systems are shown to be inadequate for long-term wastewater disposal. Specific
recommendations by Study Area have taken into account the appropriateness of utilizing: (1) innovative
alternative systems; (2) communal systems; and (3) local wastewater collection, treatment, and disposal
facilities. The Phase II CWMP/DEIR document evaluated the environmental impacts, technical design,
institutional factors, and project costs associated with each alternative and recommends the appropriate
solution to the wastewater disposal problems in the Town of Nantucket on a long term basis, with the
exception of those areas included in the MEP Study Areas.
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
The Phase II CWMP/DEIR document recommends that the Town of Nantucket upgrade the existing
Surfside Wastewater Treatment Facility, construct a new Madaket Wastewater Treatment Facility and
provide sanitary sewer via low pressure sewers and/or gravity sewers to five needs areas (Madaket,
Monomoy, Shimmo, Somerset and Warrens Landing), and to prepare a Septage Management Plan for the
remainder of the Island. It is the most environmentally sound and cost-effective alternative and insures
the sustainability of Nantucket’s water resources for centuries to come. The recommended plan is
estimated to be designed and constructed over a twelve-year period and has been divided into seven
construction phases. The construction phases were developed based on: (1) the need of an area to be
serviced; (2) funding constraints; and (3) minimizing construction related disruptions within the Town.
The capital cost of the recommended plan is estimated at $92.1 million and includes construction,
engineering (design and construction), legal, fiscal, administrative, and contingency costs for providing
sanitary sewerage to the five needs areas, and the construction of the Surfside WWTF upgrade and
Madaket WWTF.
The Town of Nantucket is also in the process of evaluating and mapping its existing wastewater and
stormwater infrastructure. This project has identified areas of the existing wastewater infrastructure that
need to be rehabilitated in order to eliminate excessive infiltration and inflow from the system and areas
of the existing stormwater infrastructure that needs be upgraded in order to eliminate street flooding and
eliminate pollution from being discharge into Nantucket Harbor. It is recommended that the Town of
Nantucket also implement the results of the Evaluation and Mapping Project. The capital cost of the
recommended plan is $83.3 million and includes construction, engineering (design and construction),
legal, fiscal, administrative, and contingency costs for rehabilitation of existing wastewater and
stormwater infrastructure.
The total O&M cost for the recommended plan identified in the Phase II CWMP/DEIR and Evaluation
and Mapping Project is estimated at an average of $2,730,000 per year. Costs are based upon present day,
competitively bid construction work prices and on an Engineering News Record (ENR) Construction Cost
Index of 6741 for September 2003.
The scope of the CWMP/FEIR Phase III document will present a final recommended plan and Final
Environmental Impact Report based on the comments received during the public comment period for the
CWMP/DEIR Phase II document. Appendix B contains the revised approved Scope of Work.
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Challenge:Evaluate alternatives for a 20-year solution to wastewater collection, treatment and disposal needs of the Town.Solution:An Island-wide study to maintain and/or improve environmental conditions while determining costs, benefits for long-term sustainability, protection of the sole source aquifer and public health, and preservation of Nantucket Harbor, Madaket Harbor, Polpis Harbor and Sesachacha Pond.MadaketChallenge• Small Dense Lots• Madaket Harbor Watershed• Private Water Supply & Wastewater DisposalSolution• Decentralize Wastewater TreatmentSomersetChallenge• Small Dense Lots• Private Water & Wastewater DisposalSolution• Connect into Existing Wastewater SystemPolpisChallenge• Nantucket Harbor Watershed• Degradation of Polpis Harbor• High Groundwater• Private Water Supply & Wastewater DisposalSolution• Septage Management PlanWauwinetChallenge• Small Dense Lots• Private Water Supply & Wastewater DisposalSolution• Septage Management PlanQuidnetChallenge• Topography• Small Dense Lots • Private Water & Wastewater DisposalSolution• Septage Management PlanTown WPZChallenge• Wellhead Protection Zone• Private Water Supply & Wastewater DisposalSolution• Septage Management PlanPocomoChallenge• Nantucket Harbor Watershed• High Groundwater• Private Water Supply & Wastewater DisposalSolution• Septage Management PlanMonomoyChallenge• Nantucket Harbor Watershed • Private Water Supply & Wastewater DisposalSolution• Connect into Existing Wastewater System ShimmoChallenge• Nantucket Harbor Watershed• Private Water Supply & Wastewater DisposalSolution• Connect into Existing Wastewater SystemWarrens LandingChallenge• Madaket Harbor Watershed• Small Dense Lots • Private Wastewater DisposalSolution• Decentralize Wastewater TreatmentArea of Wastewater Disposal NeedArea of Wastewater Disposal Need Based on Wellhead Overlay Protection ZoneArea of Wastewater Disposal Need Based on Harbor Watershed LinePrepared For: Town of Nantucket, Department of Public Works, 188Prepared For: Town of Nantucket, Department of Public Works, 188Madaket Road, Nantucket, MA 02554Madaket Road, Nantucket, MA 02554For Additional Information Contact: Mr. Jeffrey Willett, DirectoFor Additional Information Contact: Mr. Jeffrey Willett, Director, Department of Public Works, 508r, Department of Public Works, 508--228228--72447244Prepared By: Earth Tech, Inc., 196 Baker Avenue, Concord, MA 017Prepared By: Earth Tech, Inc., 196 Baker Avenue, Concord, MA 01742, Contact: Mr. Thomas Parece, P.E., 97842, Contact: Mr. Thomas Parece, P.E., 978--371371--41424142Date Prepared: June 2003Date Prepared: June 2003SiasconsetCurrently SeweredTownCurrently SeweredRemainder of IslandSeptage Management Plan
NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
1.0 INFORMATION UPDATE REQUEST OF THE
PHASE I MEPA CERTIFICATE
A. NEEDS ANALYSIS DISCUSSION UPDATE
1. Introduction
A Town wide Needs Analysis was performed to determine whether or not conventional
Title 5 on-site systems will be effective in disposing of wastewater within a given study
area throughout and beyond the 20 year planning period. A “Needs Area” is defined as a
Study Area where a majority of the developed or developable properties located within
the Study Area will not be able to utilize a conventional Title 5 septic system to
effectively dispose of wastewater throughout and beyond the 20-year planning period.
Data obtained from Board of Health records, Assessor’s files, and soil surveys of
Nantucket performed by the U.S. Department of Agriculture were used to ascertain
current land uses, associated soil and groundwater conditions, and to identify wastewater
disposal problem areas. The objective of the Needs Analysis was to determine the
specific Study Areas where conventional Title 5 wastewater disposal systems are
inadequate or conversely, where existing on-site wastewater disposal systems can remain
and be effective for wastewater disposal.
A comprehensive two stage approach was utilized in the analysis consisting of: (1) a
rating criteria matrix created to establish or eliminate a Study Area as a need area
(community provided data); and (2) an evaluation of each Study Area based only on
predominant soils classification, seasonally high groundwater level, and a combination of
system age and lot size (disposal system constraint data). This type of data is specifically
used when designing an on-site conventional Title 5 wastewater disposal system and is
used in this study to confirm or eliminate a Study Area as a need area as determined in
the First Stage Analytical Approach-Rating Criteria Matrix.
2. First Stage Analytical Approach - Rating Criteria Matrix
During the first stage, a rating criteria matrix was developed to evaluate the entire Island,
which was broken down into eighteen Study Areas. The matrix consists of four levels of
criteria that are assigned rating points. The information gathered in this first stage is the
“Community” information or data on file within the community such as Board of Health
Records (Title 5 reports, system repairs, system pumping records, percolation test
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information), Assessor records (lot size, age, density of properties, resale records,
locations to wetlands and surface water bodies) and Water Department records (aquifer
protection districts, proximity to wellheads, billing records for water use). The more
comprehensive data that exists on file in the community, the more detailed the first stage
analysis becomes and vice versa.
The highest rating is given to actual failures compiled from Board of Health records. The
second highest rating is given to categorical failures based on current Title 5 regulations.
The third highest rating is given to on-site systems that are at risk for
failure/noncompliance, which are on-site systems that: (1) have severe groundwater
limitations; (2) have severe soil limitations; (3) have on-site systems that were built
before 1978; (4) are constructed on a lot size of one-half acre or less; and/or (5) have two
or more septic tank pump-outs occurring within a calendar year. The fourth highest
criteria is given to on-site systems that have health/water quality issues associated with
on-site systems located: (1) in a Study Area with a density of on-site systems greater than
two per acre; (2) within 100 feet of a surface water body; wetland or stream; (3) located
within a 100 year flood plain; and (4) within a Zone II aquifer recharge area; and
(5) located within either the Nantucket Harbor Watershed or Nantucket Harbor
Watershed as defined by Chapter 99 of the Town By-Laws.
This “Community” data was compiled for each delineated Study Area and criteria points
were established based on the sum of this information from the matrix. For each study
area, the total criteria points were divided by the number of unsewered-developed lots.
This in effect “normalized” the criteria points on a per lot basis and formed a rating
number for each Study Area.
A “breakpoint” in the rating numbers is established from the tabulation of all of the Study
Area “rating numbers”. The “breakpoint” for Nantucket is 7.33 based on the First Stage
Analytical Approach-Rating Criteria Matrix.
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CWMP/DEIR – PHASE II REPORT
The breakpoint was established by listing the corresponding rating number for each Study
Area and calculating the difference between subsequent values. The largest differences
were then studied. After reviewing this data, the 7.33 breakpoint value was selected
because it best represented a threshold between specific conditions in Study Areas that
are currently sewered, and thus warranted the construction of sewers in the past in
Nantucket, and Study Areas that are currently unsewered.
All Study Areas with rating numbers that are greater than 7.33 were determined to be
“Need Areas”. The lower criteria point totals tend to reflect areas sustainable on current
on-site systems whereas the highest criteria point totals tend to reflect areas that require a
solution other than current on-site system. Refer to Table 1-1, Rating Criteria Points per
Developed Lots. The table shows, the differences in the points per developed lots and
that the breakpoint of 7.33 occurs in the Quidnet Study Area. As indicated in the
preceding paragraph, review of the differences helps to set the breakpoint. The larger
differences in points per developed lots represent a break in which one study area ranks
significantly higher than the preceding study area listed. This break was determined to be
significant in that, for example, Quidnet has more constraints in utilizing Conventional
Title 5 Systems for on-site wastewater disposal than areas such as Miacomet or Surfside
for example. The 7.33 break point was used to delineate the Study Areas into “No Need
Areas” and “Need Areas”. A second stage analytical approach was used to validate the
break point assumption. Refer to Table 3D-1 from the Phase I Report.
3. Second Stage Analytical Approach - Soils, Groundwater and Age/Lot Evaluation
During the second stage of the analysis, each Study Area was evaluated based on
predominant soil classification, groundwater levels, and a combination of system age and
lot size or in total “disposal system constraint data”. The three qualifying criteria are:
(1) 50 percent or more of the lots within the Study Area meeting the age/lot size criteria
(built before 1978 and a lot size of one-half acre or less); (2) 30 percent or more of the
Study Area having severe soils limitations (hardpan, bedrock, slope, flooding and
wetness); and (3) 20 percent or more of the Study Area having severe groundwater
limitations (seasonally high water table at the surface to 2 feet deep). If two of these
three criteria are met, then the Study Area is determined to be a need area.
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CWMP/DEIR – PHASE II REPORT
TABLE 1-1
TOWN OF NANTUCKET
CWMP/DEIR
RATING CRITERIA POINTS PER DEVELOPED LOT
Study Area
Points Per
Developed
Lot
Difference In
Points Per
Developed Lot
Miacomet 1.990 ---
Surfside 2.263 0.273
Tom Nevers Low-Density 3.238 0.974
Other 3.720 0.482
Shimmo 4.168 0.448
Tom Nevers High-Density 4.475 0.307
Siasconset 4.519 0.044
Town - WPZ 4.597 0.078
Town 5.077 0.480
Pocomo 5.111 0.034
Cisco 5.161 0.050
Monomoy 6.170 1.009
Quidnet 7.333 1.163
Somerset 7.404 0.070
Warren's Landing 8.088 0.685
Polpis 8.186 0.098
Madaket 8.400 0.214
Wauwinet 9.260 0.860
A thorough side by side comparison of the results of the above referenced two stage
evaluation methods is made to determine: (1) if a given Study Area shows consistent
need; and (2) areas where there is a conflict in need (e.g. areas that show a need in one
evaluation approach and no need in the other), which are then further evaluated in order
to identify the real need. This comparison identifies small Sub-Study Areas, which are
evaluated based on the second stage criteria, which include soils classification,
groundwater levels, and a combination of system age and lot size. Utilizing these two
steps provides a comprehensive approach to determine not only areas that require
something other than the current on-site system, but also those areas that can sustain with
their current on-site systems as a long-term wastewater solution.
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On-Site Wastewater Disposal System Age
On-site wastewater disposal systems built before 1978 have a very high likelihood of
failure due to the lack of design and construction controls placed on these systems prior
to this date. If a developed lot had an on-site wastewater disposal system that was built
before 1978, the system today would most likely fail a current Title 5 inspection. In
1978, Title 5 Regulations were promulgated by DEP and the local Boards of Health were
required to enforce these regulations. The significance of this date is that prior to 1978,
there were rules pertaining to the design and construction monitoring of on-site
wastewater disposal systems, but these requirements were significantly less stringent and
enforcement by the State Department of Public Health was ineffective.
Lot Size
Lot size will have a direct affect on whether or not a failed on-site wastewater disposal
system can be repaired to meet current Title 5 criteria. It is a reasonable assumption that
under less than ideal soil and groundwater conditions, all lots of one-half acre or less in
an area would, as a minimum, require a variance to Title 5 in order to repair the on-site
wastewater disposal system.
To better describe how lot size will affect the ability to repair an existing failed on-site
wastewater disposal system, consider the following scenario: a one-half acre lot with
typical dwelling, property line and structure setbacks along with Title 5 setbacks is shown
in Figure 1-1. If the soils and groundwater levels are not problematic there is about 9,150
square feet available for a soil absorption system. A typical soil absorption system
servicing a four-bedroom single-family residence generating 440 gallon per day of
wastewater being disposed into the ground with a percolation rate of 10 minutes per inch
will require about 2,500 square feet. If an on-site wastewater disposal system under the
same general conditions has to be mounded, due to high groundwater, the land area
required to build this system is about 4,400 square feet.
• If 30 percent of the one-half acre lot has severe soil limitations (hardpan,
bedrock, etc.) the useable land for a new on-site system is reduced to less than
2,500 square feet.
• If 20 percent of the one-half acre lot has severe groundwater limitations
(seasonally high groundwater level at the surface to 2 feet below grade) the
useable land for a new on-site system is reduced to less than 4,400 square feet.
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Combination Age and Lot Size Criteria
If 50 percent or more of the properties within a study area have an on-site system that
was built before 1978 and a lot of one-half acre or less, then the age/lot size criteria has
been met. The percentage was chosen as it represents that the majority of the study area
has a small lot size and an outdated on-site wastewater disposal system.
Severe Soils Criteria
If 30 percent or more of the soils within a study area classified as having severe
limitations (hardpan, bedrock, slope, high permeability sands, flooding and wetness) the
severe soils criteria has been met. The percentage represents the maximum amount of
severe soils that can be present on a lot and still construct a conventional Title 5 system.
Soil types were obtained from the Soil Survey Report by the U.S. Department of
Agriculture.
Severe Groundwater Criteria
If 20 percent or more of a study area is classified as having a “moderately shallow” to
“shallow” (high water table at the surface to 2 feet deep) seasonally high groundwater
level the severe groundwater criteria has been met. The percentage represents the
maximum amount of severe groundwater that can be present on a lot and still construct a
conventional Title 5 system. High groundwater levels were obtained from the Soil
Survey Report by the U.S. Department of Agriculture.
Need Determination
As per the Second Stage Analytical Approach, if two of the three criteria are met then the
study area qualifies as a “Need Area”. As previously discussed, the three criteria are: (1)
having 50 percent or more of the properties within the study area meeting the age/lot size
criteria (built before 1978 and a lot size of one-half acre or less); (2) having 30 percent or
more of the study area with severe soils limitations (hardpan, bedrock, slope, high
permeability sands, flooding and wetness); and (3) having 20 percent or more of the
study area with severe groundwater limitations (seasonally high water table at the surface
to 2 feet below grade).
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CWMP/DEIR – PHASE II REPORT
If this hypothetical one-half acre lot had an on-site wastewater disposal system that failed
and the property was developed before 1978 and the lot has either 30 percent severe soils
or 20 percent high groundwater, the existing system could not be repaired using a
conventional Title 5 system.
The options for a solution for this system would be either: (1) allowing variances to the
conventional Title 5 system; (2) on-site innovative-alternative systems;(3) communal
wastewater treatment and disposal; (4) local wastewater treatment and (5) regional
wastewater treatment. Of these alternatives, the recommended solution for each study
area with wastewater disposal needs will be presented in Phase II of the CWMP, based on
comprehensive technical, environmental, and financial considerations.
Refer to Table 1-2 for a summary of the results from the rating criteria matrix for the
entire Town from the Phase I Report on the next few pages. This shows all the criteria
used for evaluation and exactly how it applied to each of the eighteen Study Areas in
Town.
4. Results of Needs Analysis
The final results are summarized below for each study area.
Madaket
This study area is comprised of 394 acres of which approximately 232 acres are currently
developed. There are 435 developed lots located in this study area. The average age of
the residential units is 30 years. This study area is about 50 percent developed. About 22
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 30 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. water table varies from
the ground surface to two feet below grade). Approximately 435 systems fall within
3,600 feet of Madaket Harbor.
Between 1972 and 1999, there were 105 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 44
percent, based on 70 resales.
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TABLE 3D-2CWMP/EIRTOWN OF NANTUCKET, MASSACHUSETTSRATING CRITERIAYES NO 7.333CRITERIA NAME DESCRIPTION Madaket Warren's Landing Cisco Somerset Miacomet Surfside Tom Nevers Hi-DensityNumber Points Number Points Number Points Number Points Number Points Number Points Number PointsCRITERIA POINTS Total Number of Lots 864 99 204 206 127 419 350Actual Failure 4 Total Number of Developed Lots 435 68 143 161 101 281 255Imminent Failure 3 Total Number of Unsewered Developed Lots 435 68 143 161 101 281 255High Likelihood of Imminent Failure 2 Number of Resales since 3/31/95 70 19 27 30 15 44 26Health / Water Quality Issue 1 Number of Acres per Study Area 394 49 355 151 296 685 129Number of Net Acres for Developed Lots 232 26 143 103 197 363 63No. of Acres of Severe Groundwater Limitation 117 10 27 7 8 49 28Number of Acres of Severe Soil Limitation 86 26 178 96 149 112 61Actual Failure 3/31/95 to 1999 31 124 4 16 8 32 21 84 8 32 21 84 2 81972 to 3/31/95 74 296 2 8 10 40 8 32 6 24 27 108 0105 420 6 24 18 72 29 116 14 56 48 192 2 8Adjusted Total based on Developed/Unsewered Developed Ratio 420 24 72 116 56 192 8Imminent Failure System within Zone I Aquifer Recharge Area 9 27 0 6 18 1 3 0 11 33 0System within 50 feet of Private Drinking Water Well0000000System within 100 feet of Public Drinking Water Supply0000000Developed Lots with Less than 10,000 sq. ft. of area per Bedro 260 780 66 198 105 315 152 456 0 0 110 330269 807 66 198 111 333 153 459 0 0 11 33 110 330#High Likelihood of Imminent Failure Lots with Severe Groundwater Limitation 130 260#14 28#11 22#816836320 40#54 108#Systems Built before 1978 (Title 5) 281 562 1 2 43 86 13 26 15 30 72 144 2 4Lot Size less than or equal to 1/2 acre 246 492 62 124 34 68 100 200 2 4 52 104 97 194Lots with Severe Soil Limitation 95 190#36 72#72 144#103 206#51 102#46 92#121 242#Pumpouts Greater than 2 times per year0000000752 1,504 113 226 160 320 224 448 71 142 190 380 274 548#Health / Water Quality Issue2Density of Systems Greater Than 2 per Acre 435 435#68 68#000161 161#000000255 255#1System within 100 feet of Surface Water Body, Wetlands or Streams 0 0 7 7 8 8 3 3 3 3 0System located within 100 Year Flood Plain 53 53 0 660000System within Zone II Aquifer Recharge Area0000028280System within Harbor Watershed Line or 3,600' of Madaket Ha 435 435 34 3400000923 923 102 102 13 13 169 169 3 3 31 31 255 255Total Criteria Points for Study Area 3,654 550 738 1,192 201 636 1,141Rating Criteria Points Per Developed Lot 8.40 8.09 5.16 7.40 1.99 2.26 4.47RECOMMENDED AS A NEED AREA YES YES NO YES NO NO NO(Conventional Title 5 System Not Feasible for Majority of Study Area)
TABLE 3D-2 (Continued)CWMP/EIRTOWN OF NANTUCKET, MASSACHUSETTSRATING CRITERIACRITERIA NAME DESCRIPTIONom Nevers Lo-DensitySiasconset Quidnet Wauwinet Pocomo Polpis TownNumber Points Number Points Number Points Number Points Number Points Number Points Number PointsCRITERIA POINTS Total Number of Lots 195 1,049 77 68 140 100 4,741Actual Failure 4 Total Number of Developed Lots 122 664 45 50 81 59 3,943Imminent Failure 3 Total Number of Unsewered Developed Lots 122 127 45 50 81 59 890High Likelihood of Imminent Failure 2 Number of Resales since 3/31/95 48 27 9 3 11 10 108Health / Water Quality Issue 1 Number of Acres per Study Area 653 1,012 68 61 457 583 1,922Number of Net Acres for Developed Lots 374 349 45 51 297 395 1,333No. of Acres of Severe Groundwater Limitation 31 291 22 29 162 324 419Number of Acres of Severe Soil Limitation 286 479 19 9 163 371 1,076Actual Failure 3/31/95 to 1999 13 52 3 12 7 28 3 12 6 24 10 40 43 1721972 to 3/31/95 15 60 15 60 13 52 11 44 9 36 12 48 99 39628 112 18 72 20 80 14 56 15 60 22 88 142 568Adjusted Total based on Developed/Unsewered Developed Ratio 112 376 80 56 60 88 2,516Imminent Failure System within Zone I Aquifer Recharge Area 0 2 6 0 28 84 0 0 0System within 50 feet of Private Drinking Water Well0000000System within 100 feet of Public Drinking Water Supply0000000Developed Lots with Less than 10,000 sq. ft. of area per Bedroom 0 0 21 63 21 63 8 24 6 18 60 1800 0 2 6 21 63 49 147 8 24 6 18 60 180High Likelihood of Imminent Failure Lots with Severe Groundwater Limitation 6 126191 382#15 30#24 48#29 58#33 66#859 1,718Systems Built before 1978 (Title 5) 42 84 461 922 30 60 42 84 41 82 40 80 2,439 4,878Lot Size less than or equal to 1/2 acre 37 74 512 1,024 22 44 8 16 8 16 10 20 3,098 6,196Lots with Severe Soil Limitation 53 106#60 120#12 24#816829 58#38 76#498 996Pumpouts Greater than 2 times per year0000000138 276 1,224 2,448 79 158 82 164 107 214 121 242 6,894 13,788Health / Water Quality Issue2Density of Systems Greater Than 2 per Acre 0 00127 127#000000000000890 890System within 100 feet of Surface Water Body, Wetlands or Str5 5 29 29 28 28 33 33 27 27 60 60 447 447System located within 100 Year Flood Plain 2 2 1 1 1 1 13 13 8 8 16 16 65 65System within Zone II Aquifer Recharge Area 0 13 130000161161System within Harbor Watershed Line or 3,600' of Madaket Harbor 0 0 0 50 50 81 81 59 59 1,972 1,9727 7 170 170 29 29 96 96 116 116 135 135 3,535 3,535Total Criteria Points for Study Area 395 3,000 330 463 414 483 20,019Rating Criteria Points Per Developed Lot 3.24 4.52 7.33 9.26 5.11 8.19 5.08RECOMMENDED AS A NEED AREA NO NO YES YES NO YES NO(Conventional Title 5 System Not Feasible for Majority of Study Area)
TABLE 3D-2 (Continued)CWMP/EIRTOWN OF NANTUCKET, MASSACHUSETTSRATING CRITERIACRITERIA NAME DESCRIPTION Town - WPZ Shimmo Monomoy OtherNumber Points Number Points Number Points Number Points Number Points Number Points Number PointsCRITERIA POINTS Total Number of Lots 743 284 263 2,539 0 0 0Actual Failure 4 Total Number of Developed Lots 524 137 184 818 0 0 0Imminent Failure 3 Total Number of Unsewered Developed Lots 315 137 178 812 0 0 0High Likelihood of Imminent Failure 2 Number of Resales since 3/31/95 37 21 19 114Health / Water Quality Issue 1 Number of Acres per Study Area 744 881 276 21,863 0 0 0Number of Net Acres for Developed Lots 313 380 218 5,422 0 0 0No. of Acres of Severe Groundwater Limitation 7 171 44 5,263 0 0 0Number of Acres of Severe Soil Limitation 321 230 150 7,538 0 0 0Actual Failure 3/31/95 to 1999 23 92 9 36 17 68 60 240 0 0 01972 to 3/31/95 24 96 17 68 30 120 110 440 0 0 047 188 26 104 47 188 170 680 0 0 0 0 0 0Adjusted Total based on Developed/Unsewered Developed Ratio 313 104 194 685 0 0 0Imminent Failure System within Zone I Aquifer Recharge Area 0 0 0 10 30 0 0 0System within 50 feet of Private Drinking Water Well0000000System within 100 feet of Public Drinking Water Supply0000000Developed Lots with Less than 10,000 sq. ft. of area per Bedro 137 411 33 99 37 1110000137 411 33 99 37 111 10 30 0 0 0 0 0 0High Likelihood of Imminent Failure Lots with Severe Groundwater Limitation 5 10527 54#29 58#197 394#00000000Systems Built before 1978 (Title 5) 74 148 40 80 108 216 337 674 0 0 0Lot Size less than or equal to 1/2 acre 229 458 4 8 29 58 73 146 0 0 0Lots with Severe Soil Limitation 136 272#36 72#97 194#280 560#00000000Pumpouts Greater than 2 times per year0000000444 888 107 214 263 526 887 1,774 0 0 0 0 0 0Health / Water Quality Issue2Density of Systems Greater Than 2 per Acre 315 315#00000000000000000System within 100 feet of Surface Water Body, Wetlands or Str9 9 43 43 0 204 204 0 0 0System located within 100 Year Flood Plain 0 5 5 4 4 72 72 0 0 0System within Zone II Aquifer Recharge Area 473 473 3 3 116 116 117 117 0 0 0System within Harbor Watershed Line or 3,600' of Madaket Harbor 0 103 103 184 184 161 161 0 0 0797 797 154 154 304 304 554 554 0 0 0 0 0 0Total Criteria Points for Study Area 2,409 571 1,135 3,043 0 0 0Rating Criteria Points Per Developed Lot 4.60 4.17 6.17 3.72 0.00 0.00 0.00RECOMMENDED AS A NEED AREA NO NO NO NO NO NO NO(Conventional Title 5 System Not Feasible for Majority of Study Area)
NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
This study area has a criteria point rating of 8.40 per developed lot, which is above the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 46 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 22 percent have poor soils; and approximately 30
percent have high groundwater.
Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area. On-site innovative alternative systems, local or
satellite wastewater disposal systems are all presently viable alternatives for effectively
addressing the wastewater disposal needs in this study area. Of these alternatives, the
recommended solution for this study area will be presented in Phase II of the
CWMP/EIR, based on comprehensive technical, environmental, and financial
considerations.
Warren’s Landing
This study area is comprised of 49 acres of which approximately 26 acres are currently
developed. There are 68 developed lots located in this study area. The average age of
the residential units is 10 years. This study area is about 69 percent developed.
Approximately 53 percent of the soils in this study area are classified as severe (hardpan,
bedrock, slope, high permeability sands, flooding and wetness) and 221 percent of this
study area is classified as having moderate to severe groundwater levels (i.e. seasonally
high water table varies from the ground surface to two feet below grade). Approximately
34 systems fall within 3,600 feet of Madaket Harbor.
Between 1973 and 1999, there were 6 reported on-site wastewater disposal system repairs
or upgrades in this study area. Since the revised Title 5 regulations came into effect on
March 31, 1995, the failure rate in this study area has been approximately 21 percent,
based on 19 resales.
This study area has a criteria point rating of 8.08 per developed lot, which is above the
threshold of 7.33. The properties within this study area have the following
characteristics: no properties were developed before 1978 and had a lot size of one-half
acre or less; approximately 53 percent have poor soils; and approximately 21 percent
have high groundwater.
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Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area. On-site innovative alternative systems, local or
satellite wastewater disposal systems are all presently viable alternatives for effectively
addressing the wastewater disposal needs in this study area. Of these alternatives, the
recommended solution for this study area will be presented in Phase II of the
CWMP/EIR, based on comprehensive technical, environmental, and financial
considerations.
Cisco
This study area is comprised of 355 acres of which approximately 143 acres are currently
developed. There are 143 developed lots located in this study area. The average age of
the residential units is 19 years. This study area is about 70 percent developed. About 50
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 8 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. water table varies from
the ground surface to two feet below grade).
Between 1972 and 1999, there were 18 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 30
percent, based on 27 unsewered resales.
This study area has a criteria point rating of 5.16 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 9 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 50 percent have poor soils; and approximately 8
percent have high groundwater.
Conventional Title 5 septic systems are the recommended long-term wastewater disposal
solution for this study area. This study area should be maintained in accordance with the
Town’s Septage Management Plan.
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Somerset
This study area is comprised of 151 acres of which approximately 103 acres are currently
developed. There are 161 developed lots located in this study area. The average age of
the residential units is 12 years. This study area is about 78 percent developed. About 64
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 5 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. water table varies from
the ground surface to two feet below grade).
Between 1972 and 1999, there were 29 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 73
percent, based on 30 resales.
This study area has a criteria point rating of 7.40 per developed lot, which is above the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 1 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 64 percent have poor soils; and approximately 5
percent have high groundwater.
Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area. On-site innovative alternative systems, local or
satellite wastewater disposal systems are all presently viable alternatives for effectively
addressing the wastewater disposal needs in this study area. Of these alternatives, the
recommended solution for this study area will be presented in Phase II of the
CWMP/EIR, based on comprehensive technical, environmental, and financial
considerations.
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Miacomet
This study area is comprised of 296 acres of which approximately 197 acres are currently
developed. There are 101 developed lots located in this study area. The average age of
the residential units is 14 years. This study area is about 79 percent developed. About 51
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 3 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. water table varies from
the ground surface to two feet below grade).
Between 1972 and 1999, there were 14 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 53
percent, based on 15 resales.
This study area has a criteria point rating of 1.99 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 1 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 51 percent have poor soils; and approximately 3
percent have high groundwater.
Conventional Title 5 septic systems are the recommended long-term wastewater disposal
solution for this study area. This study area should be maintained in accordance with the
Town’s Septage Management Plan.
Surfside
This study area is comprised of 685 acres of which approximately 363 acres are currently
developed. There are 281 developed lots located in this study area. The average age of
the residential units is 19 years. This study area is about 67 percent developed. About 16
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 7 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. water table varies from
the ground surface to two feet below grade).
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Between 1972 and 1999, there were 48 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 48
percent, based on 44 resales.
This study area has a criteria point rating of 2.26 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 9 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 16 percent have poor soils; and approximately 7
percent have high groundwater.
Conventional Title 5 septic systems are the recommended long-term wastewater disposal
solution for this study area. This study area should be maintained in accordance with the
Town’s Septage Management Plan.
Tom Nevers – High Density
This study area is comprised of 129 acres of which approximately 63 acres are currently
developed. There are 255 developed lots located in this study area. The average age of
the residential units is 8 years. This study area is about 73 percent developed. About 47
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 21 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. water table varies from
the ground surface to two feet below grade).
Between 1972 and 1999, there were 2 reported on-site wastewater disposal system repairs
or upgrades in this study area. Since the revised Title 5 regulations came into effect on
March 31, 1995, the failure rate in this study area has been approximately 8 percent,
based on 26 resales.
This study area has a criteria point rating of 4.48 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 1 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 47 percent have poor soils; and approximately 21
percent have high groundwater.
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Conventional Title 5 septic systems are the recommended long-term wastewater disposal
solution for this study area. This study area should be maintained in accordance with the
Town’s Septage Management Plan.
Tom Nevers – Low Density
This study area is comprised of 653 acres of which approximately 374 acres are currently
developed. There are 122 developed lots located in this study area. The average age of
the residential units is 15 years. This study area is about 63percent developed. About 44
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 5 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. water table varies from
the ground surface to two feet below grade).
Between 1972 and 1999, there were 28 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 27
percent, based on 48 resales.
This study area has a criteria point rating of 3.24 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 3 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 44 percent have poor soils; and approximately 5
percent have high groundwater.
Conventional Title 5 septic systems are the recommended long-term wastewater disposal
solution for this study area. This study area should be maintained in accordance with the
Town’s Septage Management Plan.
Siasconset
This study area is comprised of 1,012 acres of which approximately 349 acres are
currently developed. There are 664 developed lots located in this study area of which
127 are currently unsewered. The average age of the residential units is 56 years. This
study area is about 63 percent developed with approximately 81 percent of the developed
lots connected to the existing wastewater collection system. About 47 percent of the soils
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in this study area are classified as severe (hardpan, bedrock, slope, high permeability
sands, flooding and wetness) and about 29 percent of this study area is classified as
having moderate to severe groundwater levels (i.e. water table varies from the ground
surface to two feet below grade).
Between 1972 and 1999, there were 18 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 11
percent, based on 27 resales of unsewered developed lots.
This study area has a criteria point rating of 4.52 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 53 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 47 percent have poor soils; and approximately 29
percent have high groundwater.
Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area since a majority of the study area is currently
provided with wastewater collection, treatment and disposal.
Quidnet
This study area is comprised of 68 acres of which approximately 45 acres are currently
developed. There are 45 developed lots located in this study area. The average age of
the residential units is 47 years. This study area is about 58 percent developed. About 28
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 32 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. seasonally high water
table varies from the ground surface to two feet below grade).
Between 1972 and 1999, there were 20 reported on-site wastewater disposal system
upgrades or repairs in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 78
percent, based on 9 resales.
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This study area has a criteria point rating of 7.33 per developed lot, which is at he
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 36 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 28 percent have poor soils; and approximately 32
percent have high groundwater.
Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area. On-site innovative alternative systems, local or
satellite wastewater disposal systems are all presently viable alternatives for effectively
addressing the wastewater disposal needs in this study area. Of these alternatives, the
recommended solution for this study area will be presented after the results of the
Massachusetts Estuary Project is completed and will be based on comprehensive
technical, environmental, and financial considerations.
Wauwinet
This study area is comprised of 61 acres of which approximately 51 acres are currently
developed. There are 50 developed lots located in this study area. The average age of
the residential units is 46 years. This study area is about 74 percent developed. About 15
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 47 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. seasonally high water
table varies from the ground surface to two feet below grade). Approximately 50 systems
are within the Harbor Watershed Line.
Between 1972 and 1999, there were 14 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 Regulations came into
effect on March 31, 1995, the failure rate in this study area is 100 percent, based on 3
resales.
This study area has a criteria point rating of 9.26 per developed lot, which is above the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 10 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 15 percent have poor soils; and approximately 47
percent have high groundwater.
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Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area. On-site innovative alternative systems, local or
satellite wastewater disposal systems are all presently viable alternatives for effectively
addressing the wastewater disposal needs in this study area. Of these alternatives, the
recommended solution for this study area will be presented after the results of the
Massachusetts Estuary Project is completed and will be based on comprehensive
technical, environmental, and financial considerations.
Pocomo
This study area is comprised of 457 acres of which approximately 297 acres are currently
developed. There are 81 developed lots located in this study area. The average age of
the residential units is 24 years. This study area is about 58 percent developed. About 36
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 35 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. water table varies from
the ground surface to two feet below grade). Approximately 81 systems are within the
Harbor Watershed Line.
Between 1972 and 1999, there were 15 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 55
percent, based on 11 resales.
This study area has a criteria point rating of 5.11 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 6 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 36 percent have poor soils; and approximately 35
percent have high groundwater.
Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area since the study area abuts the Town Harbor and is
entirely located within the Harbor Watershed Area. On-site innovative alternative
systems, local or satellite wastewater disposal systems are all presently viable alternatives
for effectively addressing the wastewater disposal needs in this study area. Of these
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alternatives, the recommended solution for this study area will be presented after the
results of the Massachusetts Estuary Project is completed and will be based on
comprehensive technical, environmental, and financial considerations.
Polpis
This study area is comprised of 583 acres of which approximately 395 acres are currently
developed. There are 59 developed lots located in this study area. The average age of
the residential units is 44 years. This study area is about 59 percent developed. About 64
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
high permeability sands, flooding and wetness) and about 56 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. water table varies from
the ground surface to two feet below grade). Approximately 59 systems are within the
Harbor Watershed Line.
Between 1972 and 1999, there were 22 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area is 100 percent, based on 10
resales.
This study area has a criteria point rating of 8.19 per developed lot, which is above the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 15 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 64 percent have poor soils; and approximately 56
percent have high groundwater.
Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area. On-site innovative alternative systems, local or
satellite wastewater disposal systems are all presently viable alternatives for effectively
addressing the wastewater disposal needs in this study area. Of these alternatives, the
recommended solution for this study area will be presented after the results of the
Massachusetts Estuary Project is completed and will be based on comprehensive
technical, environmental, and financial considerations.
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Town
This study area is comprised of 1,922 acres of which approximately 1,333 acres are
currently developed. There are 3,943 developed lots located in this study area of which
890 are currently unsewered. The average age of the residential units is 64 years. This
study area is about 83 percent developed with approximately 77 percent of the developed
lots connected to the existing wastewater collection system. About 56 percent of the soils
in this study area are classified as severe (hardpan, bedrock, slope, high permeability
sands, flooding and wetness) and about 22 percent of this study area is classified as
having moderate to severe groundwater levels (i.e. water table varies from the ground
surface to two feet below grade). Approximately 1972 systems are within the Harbor
Watershed Line.
Between 1972 and 1999, there were 142 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 40
percent, based on 108 resales of unsewered developed lots.
This study area has a criteria point rating of 5.08 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 47 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 56 percent have poor soils; and approximately 22
percent have high groundwater.
Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area since a majority of the study area is currently
provided with wastewater collection, treatment and disposal.
Town - WPZ
This study area is comprised of 744 acres of which approximately 313 acres are currently
developed. This area encompasses the Wellhead Protection Overlay Zone. There are
524 developed lots located in this study area of which 315 are currently unsewered. The
average age of the residential units is 15 years. This study area is about 71 percent
developed with approximately 40 percent of the developed lots connected to the existing
wastewater collection system. About 43 percent of the soils in this study area are
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classified as severe (hardpan, bedrock, slope, high permeability sands, flooding and
wetness) and about 1 percent of this study area is classified as having moderate to severe
groundwater levels (i.e. water table varies from the ground surface to two feet below
grade).
Between 1972 and 1999, there were 47 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 62
percent, based on 37 resales of unsewered developed lots.
This study area has a criteria point rating of 4.60 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 6 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 43 percent have poor soils; and approximately 1
percent have high groundwater.
Conventional Title 5 septic systems will be considered as the long-term wastewater
disposal solution for portions of this study area as this study area is located within the
Wellhead Protection Overlay Zone and approximately 40 percent is of the study area is
currently provided with wastewater collection, treatment and disposal. On-site
innovative alternative systems, local or satellite wastewater disposal systems are all
presently viable alternatives for effectively addressing the wastewater disposal needs in
this study area. Of these alternatives, the recommended solution for this study area will
be presented in Phase II of the CWMP/EIR, based on comprehensive technical,
environmental, and financial considerations. For those areas with on-site wastewater
disposal systems, they will continue to be the recommended long-term solution for this
study area. This study area should be maintained in accordance with the Town’s Septage
Management Plan.
Shimmo
This study area is comprised of 881 acres of which approximately 380 acres are currently
developed. There are 137 developed lots located in this study area. The average age of
the residential units is 21 years. This study area is about 48 percent developed. About 26
percent of the soils in this study area are classified as severe (hardpan, bedrock, slope,
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high permeability sands, flooding and wetness) and about 19 percent of this study area is
classified as having moderate to severe groundwater levels (i.e. seasonally high water
table varies from the ground surface to two feet below grade). Approximately 103
systems are located within the Harbor Watershed Line.
Between 1972 and 1999, there were 26 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 43
percent, based on 21 resales.
This study area has a criteria point rating of 4.17 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 1 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 26 percent have poor soils; and approximately 19
percent have high groundwater.
Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area since the study area abuts the Town Harbor and
approximately 75 percent is located within the Harbor Watershed Area. On-site
innovative alternative systems, local or satellite wastewater disposal systems are all
presently viable alternatives for effectively addressing the wastewater disposal needs in
this study area. Of these alternatives, the recommended solution for this study area will
be presented in Phase II of the CWMP/EIR, based on comprehensive technical,
environmental, and financial considerations.
Monomoy
This study area is comprised of 276 acres of which approximately 218 acres are currently
developed. There are 184 developed lots located in this study area of which 178 are
currently unsewered. The average age of the residential units is 29 years. This study area
is about 70 percent developed with approximately 3 percent of the developed lots
connected to the existing wastewater collection system. About 54 percent of the soils in
this study area are classified as severe (hardpan, bedrock, slope, high permeability sands,
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flooding and wetness) and about 16 percent of this study area is classified as having
moderate to severe groundwater levels (i.e. seasonally high water table varies from the
ground surface to two feet below grade). Approximately 184 systems are located within
the Harbor Watershed Line.
Between 1972 and 1999, there were 47 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 90
percent, based on 19 resales of unsewered developed lots.
This study area has a criteria point rating of 6.17 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 14 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 54 percent have poor soils; and approximately 16
percent have high groundwater.
Conventional Title 5 septic systems are not the recommended long-term wastewater
disposal solution for this study area since the study area abuts the Town Harbor and is
entirely located within the Harbor Watershed Area. On-site innovative alternative
systems, local or satellite wastewater disposal systems are all presently viable alternatives
for effectively addressing the wastewater disposal needs in this study area. Of these
alternatives, the recommended solution for this study area will be presented in Phase II of
the CWMP/EIR, based on comprehensive technical, environmental, and financial
considerations.
Remaining Island
This study area is comprised of 21,863 acres of which approximately 5,422 acres are
currently developed. There are 818 developed lots located in this study area of which
812 are currently unsewered. The average age of the residential units is 26 years. This
study area is about 32 percent developed with approximately 1 percent of the developed
lots connected to the existing wastewater collection system. About 35 percent of the soils
in this study area are classified as severe (hardpan, bedrock, slope, high permeability
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sands, flooding and wetness) and about 24 percent of this study area is classified as
having moderate to severe groundwater levels (i.e. seasonally high water table varies
from the ground surface to two feet below grade). Approximately 161 systems are located
within the Harbor Watershed Line.
Between 1972 and 1999, there were 170 reported on-site wastewater disposal system
repairs or upgrades in this study area. Since the revised Title 5 regulations came into
effect on March 31, 1995, the failure rate in this study area has been approximately 53
percent, based on 114 resales of unsewered developed lots.
This study area has a criteria point rating of 3.72 per developed lot, which is below the
threshold of 7.33. The properties within this study area have the following
characteristics: approximately 5 percent were developed before 1978 and have a lot size
of one-half acre or less; approximately 35 percent have poor soils; and approximately 24
percent have high groundwater.
Conventional Title 5 septic systems are the recommended long-term wastewater disposal
solution for this study area. This study area should be maintained in accordance with the
Town’s Septage Management Plan.
Of the eighteen studies areas, seven study areas have been identified as having a need or
are currently located within the existing service are, while the remaining study areas can
be maintained in accordance with the Town’s Septage Management Plan. Refer to Table
1-3 for a summary of the Needs Analysis.
B. WASTEWATER FLOW UPDATE
In the Phase I Report, wastewater flows were estimated for each study area for both the initial and
design years. The estimates are based on the number of developed lots and undeveloped parcels
within each study area based on the Assessor’s information. The design wastewater flow for each
study area was calculated from the undeveloped parcel and acreage data to determine the design
number of developed lots.
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TABLE 1-3
TOWN OF NANTUCKET
CWMP/DEIR
STUDY AREA LONG TERM WASTEWATER DISPOSAL OPTION
Long Term Wastewater Disposal Option
Study Area
On-site Innovative
Alternative Systems, Local or
Satellite WWTF
Septage
Management Plan
Miacomet X
Surfside X
Tom Nevers Low-Density X
Other X
Shimmo X
Tom Nevers High-Density X
Siasconset X
Town - WPZ X
Town X
Pocomo X
Cisco X
Monomoy X
Quidnet X
Somerset X
Warren's Landing X
Polpis X
Madaket X
Wauwinet X
The wastewater flow estimates have been expanded to include future flows from second
dwellings. Nantucket bylaws allow for a second dwelling to be built on buildable lots. The
wastewater flow estimates assumes that it is possible to build second dwellings on two thirds of
the current developed and undeveloped buildable lots. Refer to Table 1-4 for a summary of the
updated flows for each Need Area.
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TABLE 1-4
TOWN OF NANTUCKET
CWMP/DEIR
ESTIMATED WASTEWATER FLOWS BY STUDY AREA
Design Flows without
Second Dwellings (gpd)
Design Flows with
Second Dwellings (gpd)
Study Area Winter Summer Winter Summer
Madaket 101,715 175,730 169,516 293,007
Warrens Landing 16,465 28,480 27,497 47,562
Somerset 38,225 65,700 63,139 108,794
Siasconset 163,340 280,230 268,945 462,899
Quidnet 9,620 16,640 16,065 27,789
Wauwinet 11,250 19,250 18,439 31,685
Pocomo 20,980 36,185 34,862 60,198
Polpis 15,245 26,265 25,285 43,631
Town 883,710 1,470,245 1,378,766 2,326,559
Town-WPZ 147,920 237,115 215,845 354,606
Shimmo 34,300 59,225 57,107 98,675
Monomoy 42,295 72,740 69,936 120,551
Total Design Flows 1,485,065 2,487,805 2,345,402 3,975,955
Note:
1. Estimated Wastewater Flows do not include an allowance for infiltration/inflow.
The estimated design flows were then assigned to existing water treatment facilities or future
wastewater treatment facilities. The assigned flows were used to as design flows for the
evaluation of short listed alternatives. Refer to Table 1-5 for a summary of the updated flows by
wastewater treatment facility. The design flows for Quidnet, Wauminet, Pocomo, and Polpis will
be managed with a Septage Management Plan.
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TABLE 1-5
TOWN OF NANTUCKET
CWMP/DEIR
ESTIMATED WASTEWATER FLOWS BY
WASTEWATER TREATMENT FACILITY
Wastewater Treatment Facility
Flow – Design Summer (gpd)
Study Area
Flow – Design
Summer (gpd) Surfside Siasconset Madaket
Madaket 293,007 293,007
Warrens Landing 47,562 47,562
Somerset 108,794 108,794
Siasconset 210,175 210,175
Town 2,326,559 2,326,559
Town-WPZ 354,606 354,606
Shimmo 98,675 98,675
Monomoy 120,551 120,551
Total Design Flows 3,009,185 210,175 340,568
Notes:
1. The estimated wastewater flow for Siasconset has been adjusted based on the approved Facility
Plan dated December 1997 which calculated the future summer season sewered population being
75 percent of the future summer season total population.
2. Estimated Wastewater Flows do not include an allowance for infiltration/inflow.
C. DISPOSAL SITE ALTERNATIVES
The CWMP/DEIR Phase II Document in its entirety addresses this topic.
D. WATER SUPPLY
Section 6 of the CWMP/DEIR Phase II Document addresses this topic.
E. PLANNING FOR GROWTH (EXECUTIVE ORDER #385)
The CWMP/DEIR Phase II Document in its entirety addresses this topic.
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2.0 IDENTIFY AND DISCUSS ALTERNATIVES FOR WASTEWATER DISPOSAL
A. INTRODUCTION
A variety of wastewater alternatives were investigated to determine the appropriate wastewater
facilities that will meet the needs of Nantucket. The wastewater alternatives that were
investigated include: (a) the continued use of existing on-site wastewater disposal systems;
(b) replacement of existing wastewater disposal systems with Title 5 systems; (c) replacement of
existing wastewater disposal systems with on-site innovative/alternative options; (d) replacement
of existing wastewater disposal systems with cluster systems consisting of a pressure system and
communal subsurface disposal; and (e) replacement of existing wastewater disposal systems with
a conventional sewer collection system, either: (1) connection into the existing collection system;
(2) gravity sewers and pump station, (3) pressure sewers and grinder pumps, or (4) a combination
thereof. Each wastewater alternative is evaluated based on environmental and technical design
criteria and on site-specific data such as subsurface conditions, topography, and existing septic
system performance. This CWMP/DEIR Phase II document evaluates the environmental,
technical design and institutional cost associated with each alternative and recommends the
appropriate solution to the wastewater disposal problems for the Town of Nantucket in order to
reach a long-term solution to the wastewater needs of the Island.
B. OPTIMIZE OPERATION AND MAINTENANCE OF EXISTING ON-SITE SYSTEMS
One alternative to be considered is optimizing the performance of the existing on-site wastewater
disposal systems, which includes optimizing septage management plans, maintenance, and repair
and upgrade of current on-site systems. If this alternative were pursued Island-wide, all
developed lots currently not in a sewer service area, would remain dependent on their existing on-
site wastewater disposal systems. As documented in the Phase I CWMP/EIR Document, there
are substantial documented failures and disposal systems with eminent problems in Nantucket.
This alternative will look at each individual Study Area identified in the Phase I Document and
evaluate the potential for remaining on the current on-site wastewater disposal systems under a
Septage Management Plan. Assessments of various levels of compliance, including maximum
feasible compliance will be made. The potential effects on surface water quality, coordinating
efforts with the State Estuary Project in the Nantucket Harbor, Sesachacha Pond and Madaket
Harbor areas, will be discussed. Additional assessments will be made on groundwater quality and
the protection of the sole source aquifer, growth in the planning area as it relates to Executive
Order 385, land use limitations and socioeconomic factors such as residential and industrial
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development and public health issues. Economic and legal impacts to the Town and all
regulatory requirements of the State Department of Environmental Protection (DEP) and the
Federal Environmental Protection Agency (EPA) will be considered and discussed.
The Town of Nantucket has recently embarked on a study to develop a Septage Management Plan
(SMP) for the Island. The SMP will be completed in coordination with the final
recommendations of this Phase II CWMP/DEIR document in order to provide a long-term
solution to those areas on Island evaluated and recommended for this alternative.
1. Repair / Upgrade Existing On-Site Systems
One alternative for the areas of wastewater disposal need on the Island is continued use
of existing systems with emphasis on optimizing the performance of the existing on-site
wastewater disposal systems. This includes optimizing septage management plans,
maintenance, and repair and upgrade of on-site systems.
Failing on-site wastewater disposal systems contribute to the degradation of water quality
of groundwater, wetlands and surface water. The surface waters bordered by areas of
wastewater disposal need on the Island are: Tom Nevers Pond, Sesachacha Pond, The
Creeks, Miacomet Pond, Shimmo Creek, Hither Creek, Long Pond, No Bottom Pond, and
Reed Pond. The swamps and/or wetlands bordered by areas of wastewater disposal need
are: Pocomo Meadow, Squam Swamp, Rolgers Marsh, Millbrook Swamp, Brunt Swamp,
and Madaket Ditch. The harbors bordered by areas of wastewater disposal need on the
Island are: Nantucket Harbor, Madaket Harbor, and Polpis Harbor. These water bodies
and water ways are located adjacent, within, and downstream of the areas of wastewater
disposal need and are threatened by existing on-site wastewater disposal systems (both
properly operating as well as malfunctioning systems depending on the soils present and
groundwater table) which will eventually contribute to water quality degradation due to
contamination of groundwater.
As time passes, the non-conforming on-site wastewater disposal systems that do not meet
current Title 5 rules and regulations will become less adequate and will contribute to the
degradation of groundwater, wetlands and surface water. These sub-standard on-site
wastewater disposal systems combined with soils with severe limitations for subsurface
sewage disposal and high groundwater levels are a potential health hazard. With
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increased system age combined with these environmental issues, it is expected that
property owners will experience future operating nuisances and eventually failures. If the
water quality of surface water bodies continues to decline, Nantucket will potentially lose
a very important recreational resource. Declining water quality of Miacomet Pond,
Hither Creek, Long Pond, Nantucket Harbor, Madaket Harbor, and Polpis Harbor may
reach such unacceptable levels that swimming could be prohibited.
As more on-site wastewater disposal systems fail, individual property owners will be
required to upgrade their systems to a conventional or innovative/alternative Title 5
system. If this cannot be accomplished due to the physical site conditions, a tight tank
would be required and would only be approved by the DEP to eliminate a failed system.
The cost of frequently pumping these tight tanks will be a financial burden for the
property owners. Property owners would not be able to expand their homes and/or even
fully use their existing facilities. In this scenario, property values would decline.
With the increased potential of the degradation of both the water quality in the surface
water bodies and the drinking water supply from the sole source aquifer, Nantucket is
obligated to provide acceptable wastewater disposal for the areas of need. Continued use
or repair/upgrade of the existing on-site disposal systems in the areas of need is not
recommended as the wastewater disposal solution for the entire area of need due to the
likelihood that not all existing systems could be repaired or upgraded to conform to Title
5. Continued operation of poor or substandard disposal systems poses public health
hazards, environmental degradation and is a real threat to the sole source aquifer.
If it is recommended that the existing on-site wastewater disposal systems in specified
Study Areas will continue to be used, then, at a minimum, these systems need to be
operated and maintained under a septage management plan. The purpose of a septage
management plan is to maintain the operation of septic systems that will protect the
groundwater and reduce the expansion of the areas of wastewater disposal need, which
require structural solutions such as treatment facility and collection system. The
recommended septage management plan should include such items as recommended
septage pump-out frequencies and maintenance of on-site wastewater disposal systems.
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Public education concerning the importance of proper maintenance of on-site wastewater
disposal systems is a beneficial means of prolonging the life of these systems, and will be
included as part of the recommended septage management plan.
2. Conventional Title 5 System
This wastewater alternative entails replacing the existing on-site septic systems with Title
5 systems for wastewater management within the wastewater disposal need areas of the
Island. Under this option, the systems that do not meet the requirements of Title 5 would
be replaced with new Title 5 systems. The remaining septic systems would be upgraded
or replaced when it becomes necessary such as when the system fails.
The Massachusetts Environmental Code, 310 CMR 15.000, effective March 31, 1995
govern Title 5 systems. The standard components of a Title 5 system are a building
sewer, septic tank, distribution box, soil absorption system, and reserve area. Wastewater
exits the building through its building sewer and enters the septic tank where solids are
settled and retained. The septic tank effluent flows through the distribution box and to
the soil absorption system where it is distributed and treated prior to discharge to
appropriate subsurface soils. A schematic of this system is shown on Figure 2-1.
The Title 5 state code dictates certain requirements for the soil absorption system. For
instance, the minimum vertical separation distance from the bottom of the stone
underlying the soil absorption system to the top of the seasonally high groundwater table
is 4 feet in soils where the percolation rate is greater than 2 minutes per inch (mpi) and 5
feet in soils where the percolation rate is less than or equal to 2 mpi. In addition, there
must be at least 4 feet of naturally occurring pervious soil below the entire area of the soil
absorption system and the reserve area. Title 5 requires a reserve area to be located on
the property such that it can be used in case the primary soil absorption system fails. No
building, driveway or other physical improvement can be made to the reserve area; it
must remain in its pristine state. Setback requirements are also given in the Title 5 code,
which identifies the minimum horizontal separation required between the soil absorption
system and items such as a drinking water well, property lines and wetlands.
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In order to assess the suitability of replacing existing on-site wastewater disposal systems
with new Title 5 systems, several critical criteria need to be addressed. The most
common reasons that on-site septic systems fail (including Title 5 systems) is due to
overloading, poor construction, and poor maintenance. Assuming the systems are
properly constructed and maintained, the remaining issue to address is overloading of the
system. Several ways in which a soil absorption system can be overloaded are
(1) hydraulically overloading the soil, (2) pollutants clogging within the soil, and
(3) insufficient depth of naturally occurring pervious soil that results in improper
treatment of the effluent. Standard design practices should deal with each of these issues.
The most difficult condition to overcome is subsurface conditions including shallow
depth to groundwater and insufficient depth of naturally occurring pervious soil.
Variances from Title 5 code may be granted for septic systems that are unable to meet the
groundwater separation distance, depth to impervious layer, or other provisions of Title 5.
These systems are referred to as Title 5 Systems with Variances. In these cases, a
mounded system would be constructed. A mounded system is not a conventional Title 5
system. Mounded systems are sited in areas where there are slowly permeable soils,
shallow permeable soils over creviced or porous bedrock, or permeable soils with high
water tables.
C. WASTEWATER COLLECTION, TREATMENT AND DISPOSAL ALTERNATIVES
1. Flow and Waste Reduction
The entire Island relies on public and private water supply wells, which draw from a
groundwater supply or aquifer. There are two public water supply companies on the
Island; (1) Wannacomet Water Supply Company and (2) Siasconset Water Company.
There is also a small drinking water supply well servicing approximately 15 homes in the
Wauwinet area of the Island. The private drinking water wells on Island fall under the
jurisdiction of the Nantucket Board of Health.
The Town of Nantucket understands the significance of reducing its wastewater flows.
One of the ways to ensure this minimization is to implement water conservation measures
to reduce water use. In the development of the septage management plan, a significant
effort will be devoted to water conservation measures. At this point in time, any efforts
have been suggestive in nature due to the jurisdictional issues.
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Varieties of water conservation options have been presented by the DEP in the “1992
Water Conservation Standards for the Commonwealth of Massachusetts”. These options
are discussed below.
Public Education
Public education involves the dissemination of information and getting public support by
providing a basic understanding of sound water resources management. One of the three
main areas of emphasis that should be included in an educational program is explaining
to water users the various costs that are associated with providing water. These costs
include planning, engineering, construction, operation, maintenance, treatment,
wastewater facilities costs, piping, leak detection, infiltration/inflow reduction measures,
compliance costs, salaries and benefits, protection costs, training, and public education.
Other areas of emphasis include providing water system users with tangible evidence of
the cost savings and environmental benefits that can be attained through water
conservation. Materials for education programs may be sought from the Massachusetts
Water Works Association, the New England Water Works Association and other
organizations, and funded by local water and sewer revenues.
The “1992 Water Conservation Standards” makes the following suggestions for
developing a successful public education program: (1) the largest users should be targeted
early on to realize the greatest potential savings; (2) public education should reach to the
schools to get the children involved; (3) water bills should include a worksheet to enable
customers to track water use and conservation, and figure the dollar savings; (4) publicly
advertise water conservation successes (and failures) / public service announcements;
(5) joint advertising with hardware stores to promote household conservation devices;
and (6) provide information on landscaping, gardening, and lawn care practices that
promote water conservation.
The Wannacomet Water Supply Company has developed an aggressive public education
program through effective communication with its customers and partnerships with the
business and school communities on Island. The Annual Water Quality Report for 2001
and 2002 details the efforts the Wannacomet Water Supply Company has expended to
reach out to the community.
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In the Spring of 2001, Wannacomet Water Supply Company joined the Mid-Island
Partnership, which is a group of local businesses working together to improve the Island.
Wannacomet Water Supply Company also collaborates regularly with the Nantucket
Rotary Club.
Each year for the last three years, Wannacomet Water Supply Company participated in
the annual Cottage Hospital Health Fair providing information about water quality, the
sole source aquifer and water conservation.
Wannacomet Water Supply Company also participates in the education of the youth on
Island, working with the elementary, middle and high schools with various programs,
including the importance of water conservation. It has developed a “School-to-Career
Program” with the local high school to provide internships to seniors. In addition to the
Annual Water Quality Report, Wannacomet Water Supply Company distributes various
literature for public education on water quality and conservation.
Refer to Appendix C for copies.
Leak Detection and Repair
Leak detection and repair is intended to reduce the amount of water lost via leaks in the
water distribution system. This maintenance activity is considered most important in
older water systems. Leak detection programs can vary but should be carried out
regularly by the water suppliers.
Metering
Complete system metering lets customers know how much water they are using, provides
Nantucket with valuable knowledge of customer use patterns, assists in demand
management programs, and enables Nantucket to bill the customer accurately. With
accurate knowledge about current demand, Nantucket can more effectively identify
potential water savings, assist specific users to implement water saving measures,
determine unaccounted for water, and thereby provide the opportunity to reduce overall
system demand and plan efficiently for system growth. Metering costs should be
recovered through water rates, and include not only the costs for the metering equipment,
but also the costs associated with reading the meters regularly.
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In 2002, Wannacomet Water Supply Company transitioned from quarterly to monthly
billings for themselves as well as the Siasconset Water Company. This decision was
based on three objectives: (1) the need to obtain more accurate water accountability data;
(2) improve cash flow; and (3) have the ability to detect potential problems or leaks in the
customer’s service line and interior plumber sooner rather than later.
In 2002, Wannacomet Water Supply Company completed the implementation of the
Automated Meter Reading System. All water meters in the system are now read via a
mobile reading systems that is much more accurate than done manually. In order to
convert to this automated service, all accounts had to be reviewed and a new meter
installed.
Pricing
Full-cost pricing refers to price levels that recover all the direct and indirect costs
associated with providing water. For all sectors of water use, knowing the costs
associated with providing water and sewer services creates an appreciation of the
importance of conserving water and promotes greater understanding of the direct
relationship and environmental implications of individual water use and community
water resources, especially during seasonal or drought shortages. The pricing structure
for water should include the complete cost to run the system. These costs include
pumping, maintenance, electricity/fuel, treatment, distribution system operation and
maintenance, watershed/well site purchase/protection, capital replacement fund, capital
depreciation account, and debt service, purchase and installation of water conservation
retrofit equipment, public education program, staff and benefits, and leak detection and
repair.
The Nantucket Water Commission held a public informational hearing in 2001 to discuss
adopting new water rates, which had not been increased in over ten years. In 2002, the
commission adjusted the fees for meter and service installations. A basic rate is charged
for water, including the seasonal properties that shut off water for the winter, even if
there is zero usage. This charge covers annual operating expenses, debt service,
insurance costs, production and distribution system maintenance, billing and customer
support services.
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Residential Water Use
Residential water use from Massachusetts’ public water suppliers amounts to about 450
million gallons per day. Increasing efficiency of use and implementing conservation
measures can realize significant savings for consumers and suppliers, both in energy and
water costs. Residential users should be encouraged to use the following water saving
devices: low-flow showerheads, faucet aerators, toilet displacement devices and/or low-
flow toilets, toilet leak detection kits and moisture detectors on underground irrigation
systems.
Public Sector Water Use
Public municipal and state buildings and facilities should serve as demonstrations of
water saving techniques and concepts. The public should be aware that the state and
municipalities are not only doing their part, but also leading the way. Public facilities
(schools, hospitals, public offices, etc.) should be built or retrofitted with water
conservation devices such as faucet aerators, low flow shower heads, toilet displacement
devices or low-flow toilets, and self-closing faucets. Other public sector policies should
include charging contractors for using fire hydrants for pipe flushing and other
construction purposes.
Industrial, Commercial, and Institutional Water Use
The bulk of industrial, commercial, and institutional water use is for heating, cooling, and
processing, but often includes an appreciable sanitary and landscaping component.
Conservation measures must be tailored to reflect the type of water use and
characteristics of individual facilities. A reduction in facility water uses as well as a
reduction in pollutant discharge often accompany the implementation of source reduction
programs. Water conservation can be built into an industry’s strategy to comply with
sewer and discharge requirements and often results in monetary savings following short
payback periods. All industrial, commercial, and institutional water users should be
required to develop and implement a written water policy addressing at a minimum
demand management, leak detection and repair, a program of preventive maintenance,
and a program of employee education.
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They should also be required to perform water audits to determine the location and
amount of water used for heating, cooling processing, sanitary use, and outdoor use. This
information could then be used to determine areas to conserve water. Industrial,
commercial, and institutional users should also be required to install water saving
sanitary devices.
Industrial, Commercial, and Institutional Water Use is relatively small, accounting for
approximately five percent of the land use on Island. As previously mentioned,
Wannacomet has partnered with business groups on Island and the Rotary Club working
towards Island sustainability.
Water Supply System Management
The Nantucket Water Commission and more specifically the Wannacomet Water Supply
Company has taken advantage of many options for improving the efficiency of its
operations, educating the public and encouraging water conservation by consumers. The
public education to date developed by Wannacomet Water Supply Company provides a
framework for implementing these standards and establishing long-term priorities and
plans for system maintenance, source protection, and, as necessary, new source
development.
On April 12, 1999 at annual Town Meeting, Article 68, Nantucket adopted a set of
Conservation Bylaws, which were approved August 10, 1999 defining the public water
supply use restrictions on Island. Included in this bylaw under Chapter 114 are the
following:
• Authority;
• Purpose;
• Definitions;
• Declaration of a State of Water Supply Conservation;
• Restricted water uses;
• DEP and Public Notification of a State of Water Supply Conservation;
• Termination of Water Supply Conservation notice;
• State of Water Supply Emergency/DEP compliance; and
• Penalties.
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2. Decentralized Facilities
The Study Areas of wastewater disposal need identified in the Phase I Document are
currently relying on individual on-site wastewater disposal systems for wastewater
treatment and disposal. A majority of these systems are substandard, provide a low level
of treatment, and do not comply with the requirements of Title 5. The Phase I Document
identified eleven study areas that were determined to need some sort of upgraded
wastewater disposal, whether it be a sewage collection system, cluster systems serving a
limited number of homes, or on-site innovative/alternative disposal systems. This section
will discuss the option of providing each property that has an existing on-site wastewater
disposal system with an on-site or decentralized innovative/alternative wastewater
disposal system. The systems considered include (1) STEP/Cluster Systems; (2) Small-
scale Wastewater Treatment Plants; and (3) On-Site Innovative/Alternative Systems.
This alternative will be fully discussed and analyzed in those areas on Island affected
with an embayment included in the State Estuary Project. A coordination of efforts with
the Estuary Project will ensure long-term on-site wastewater disposal in compliance with
the final results or Total Maximum Daily Load (TMDL) of this project in the Nantucket
Harbor, Sesachacha Pond and Madaket Harbor areas.
A Title 5 system achieves only a nominal level of treatment in terms of Biochemical
Oxygen Demand (BOD5) and Total Nitrogen removal. Based on the compilation of
various studies and DEP data, typical effluent concentrations from a conventional Title 5
septic tank are as follows: the effluent BOD5 concentration is 170 mg/L; the effluent
Total Suspended Solids (TSS) concentration is 60 mg/L; and the effluent Total Nitrogen
concentration is 42 mg/L with the majority of this total being ammonia nitrogen.
Comparing these effluent concentrations with the influent concentrations noted during the
evaluation of Title 5, (BOD5 = 300 mg/L, TSS = 300 mg/L, and TN = 45 mg/L), the
conventional system can achieve about 43 percent removal of BOD5, about 80 percent
removal of TSS and only 6 percent removal of Total Nitrogen. These influent
concentrations to individual septic tanks were found to be higher than those of a medium
strength wastewater. According to “Wastewater Engineering: Treatment, Disposal,
Reuse” by Metcalf and Eddy, a medium strength wastewater has a Biochemical Oxygen
Demand (BOD5) of 220 milligrams per liter (mg/L), a Total Suspended Solids (TSS) of
220 mg/L, and a Total Nitrogen (TN) concentration of 40 mg/L. A typical wastewater
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treatment facility will remove 85 percent of the BOD5 and TSS and 60 to 80 percent of
the Total Nitrogen. These parameters are used in this section only to show the removal
efficiency of the Title 5 system. Title 5 systems do not adequately remove nutrients from
the wastewater before it enters the leaching field. From this it can be concluded that even
a properly installed and operating Title 5 septic system will still discharge levels of
pollutants which impact the quality of the receiving groundwater, in cases where the
groundwater enters the bottom of the soil absorption area.
STEP/Cluster Systems
One decentralized treatment alternative to a Title 5 system to consider is the Septic Tank
Effluent Pump (STEP) System which pumps septic tank effluent through a pressurized
sewer to a small-scale, off-site subsurface disposal cluster system or treatment facility.
This system consists of a septic tank that concentrates and collects the solids from the
wastewater and a pump, which pumps the septic tank effluent to a cluster subsurface
disposal system or treatment facility. Schematics of a typical STEP System and
Subsurface Cluster System are shown on Figure 2-2 and Figure 2-3, respectively.
Based on Title 5 requirements, a maximum flow of 10,000 gallons per day is allowed to
be discharged to a subsurface trench disposal system before a sewage treatment plant is
required. A treatment facility may or may not be required depending on the specific
wastewater flow from each of the individual need areas. The land area required for a
trench system for 10,000 gallons per day (about 45 residential/ commercial units) is about
17,800 square feet, assuming an optimal percolation rate of less than 5 minutes per inch
with Class I soils (sands, loamy sands) equaling 0.74 GPD/SF (based on Title 5
requirements).
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For the purpose of this calculation, it was assumed that each trench is 2 feet wide by 2
feet deep and 100 feet long, and that there is 6 feet between trenches. Title 5 also
requires space to be set aside for a reserve area in the event of system failure; however, it
allows the space between trenches to be used as the reserve. Therefore, the total area
required for 10,000 gallons per day is 17,800 square feet (approximately 0.4 acres),
which represents the minimum size of any one system based on the above assumptions.
This area only includes the area needed for the subsurface disposal system itself, and
does not include required setbacks from property lines, water bodies, buildings, slopes,
etc. The land area required due to setback limitations can only be determined when an
appropriate disposal area has been identified and designated, but an additional 50 percent
would not be excessive. Hence 0.6 acres would be appropriate. Although the foregoing
space requirements are needed to meet all of the setback limits of Title 5, it is quite
common for septic systems to be sited within smaller spaces and still function well.
STEP systems can be used to pump the effluent from individual residences through a
pressurized sewer to a small-scale treatment facility. As with a conventional Title 5
system, the septic tanks must be routinely pumped to remove solids.
Small-Scale Wastewater Treatment Plants
If more than 10,000 gallons per day is to be treated, a subsurface disposal system will no
longer be adequate and a treatment plant will be required. A typical plant consists of an
enclosed building which would include: anoxic pretreatment, primary settling and a
sludge storage tank; a flow equalization and pump chamber in order to normalize flow
over 24-hour periods; an aerobic biological process for organics reduction and
nitrification; a secondary clarifier; an anoxic denitrification process; sand filtration and
disinfection. The building would also typically include a laboratory, office and a utility
and equipment room. The amount of land required for the plant itself and related site
items varies with the capacity of the plant. The size of the disposal fields, however, is
based directly upon the flow and according to the “Guidelines for the Design,
Construction, Operation and Maintenance of Small Sewage Treatment Facilities with
Land Disposal,” January 1988 (as published by the Massachusetts Department of
Environmental Quality Engineering, Division of Water Pollution Control), a reserve area
tested and shown to be sufficient to replace the capacity of the original leaching area
would be required. Again, assuming an optimal percolation rate with good soils, open
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sand beds can treat 5.0 gallons per day/square feet and a subsurface trench system can
treat 2.5 gallons per day/square feet (based upon “Guidelines for the Design,
Construction, Operation and Maintenance of Small Sewage Treatment Facilities with
Land Disposal”). For the open sand bed alternative, this would consequently result in a
much smaller field of 2,000 square feet. Including 2,000 square feet for a reserve area,
the total land area required for the open sand bed alternative would be 4,000 square feet
(about 0.1 acre) for the equivalent wastewater flow of 10,000 gallons per day. Assuming
trenches that are 2 feet wide by 2 feet deep by 100 feet long and a 6 foot wide area
between trenches, a subsurface trench disposal system would occupy 5,000 square feet.
The area between the trenches can be used as the reserve area. Therefore, the total area
required for the equivalent 10,000 gallons per day flow utilizing a subsurface trench
system would be 5,000 square feet to over 100,000 square feet depending upon the
percolation rate of the soil.
On-Site Innovative/Alternative (I/A) Systems
Title 5 allows for the use of Innovative/Alternative (I/A) technologies with DEP
approval. Periodically, the DEP issues an updated memorandum entitled: “Title 5 I/A
Technologies Approved for use in 310 CMR 15.000 Massachusetts”. This memorandum
provides a description and status for a variety of innovative and alternative technologies.
A number of these I/A technologies provide enhanced wastewater treatment with
nitrogen reduction. Of these technologies, the on-site alternative systems that will be
evaluated for use in each of the areas or wastewater disposal need are the Recirculating
Sand Filter, Amphidrome™ Process, Bioclere™ System, Cromaglass®, RUCK® System,
and the Single Home FAST®.
According to Title 5, “alternative systems, when properly designed, constructed, operated
and maintained, may provide enhanced protection of public health, safety, welfare and
the environment.” I/A systems are recommended for use in areas where a conventional
Title 5 system cannot be sited. Title 5 details an approval process which proponents of
each respective innovative/alternative technology must adhere to in order to gain
approval of their alternative system. DEP approves the I/A technologies under four main
categories: Approval for Piloting; Provisional Approval; Certification for General Use;
and Approval for Remedial Use. These categories are described in the following
paragraphs:
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• Piloting Approval, which is addressed in 310 CMR 15.285, allows for controlled
field testing and technical demonstration of I/A technologies. Pilot systems can
only be built where the establishment to be serviced has access to a sewer system
or a conventional Title 5 system to which it can be connected if the alternative
system fails. If the I/A technology is approved for piloting it can be implemented
at a maximum of fifteen locations. A minimum of 18 months of environmental
monitoring must be performed at each facility. Piloting is considered successful
when at least 75 percent of the systems perform satisfactorily over 12 months.
• Provisional Approval, which is addressed in 310 CMR 15.286, provides for
broader field testing of the I/A technologies which appear to be technically
capable of providing equivalent levels of environmental protection as a
conventional Title 5 system. Under the provisional approval testing, it will be
determined if the technology is technically capable of providing this level of
treatment over a broader use than the pilot, and whether any further conditions
regarding operation, maintenance, or monitoring are necessary to ensure such
environmental protection. Provisional approval is contingent on successful
completion of the piloting program. Systems that have completed two (2) years
of general use in another state will also be considered for provisional approval.
A three (3) year performance evaluation must be performed on the first fifty (50)
systems. As with piloting, establishments to be serviced by provisional systems
must be capable of connecting to a sewer system or a conventional Title 5
system, if the alternative should fail.
• Certification for General Use, which is addressed in 310 CMR 15.288, facilitates
the use of I/A technologies which have shown that they provide the level of
environmental protection which is offered by a conventional Title 5 on-site
system. In order for an I/A technology to be Certified for General Use, it must
have a success rate during the provisional process of 90 percent. The DEP also
establishes nutrient removal credits for I/A technologies that are more effective
than a conventional Title 5 system in removing nitrates.
• Remedial Approval, which is addressed in 310 CMR 15.284, provides for rapid
approval of I/A technologies needed to upgrade currently failing or non-
conforming systems. In order for the technology to be considered for remedial
approval, it must have at least one year of general use in a state with climate
conditions similar to Massachusetts. Remedial approval is a “stopgap measure”.
It is not intended that the data collected for a remedial use approval will be used
to support an application for piloting, provisional or general certification.
Recirculating Sand Filter
The Recirculating Sand Filter (DEP approval March 1995) is an alternative treatment
system, which consists of a septic tank, a recirculation tank and pump, a sand filter with
underdrains, and a soil absorption system. The wastewater flows from the building
through its building sewer to a septic tank where solids are settled and retained. Effluent
from the septic tank flows by gravity and is collected in the recirculation pump chamber.
Within the recirculation pump chamber, the effluent from the septic tank and the effluent,
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which is returned from the sand filter, are mixed. This mixture is then periodically
pumped and evenly distributed over the sand filter bed surface. After percolating through
the sand filter, the effluent is collected by underdrains and either recirculated back by
gravity flow to the recirculation pump chamber or, if the chamber is full, discharged to a
soil absorption system. A typical schematic of this system is shown on Figure 2-4.
The Recirculating Sand Filter was issued a Certification for General Use and Remedial
Use Approval by DEP in March 1995. The Recirculating Sand Filter must meet
secondary treatment standards of 30 mg/L BOD5 and 30 mg/L TSS with a minimum
removal of 85 percent of the influent BOD5 and TSS. The effluent Total Nitrogen
concentration must not exceed 25 mg/L and the system shall remove a minimum of 40
percent of the influent total nitrogen concentration.
Generally, the Recirculating Sand Filter achieves a higher level of treatment compared to
a conventional Title 5 system. A variety of papers and studies have been written on
Recirculating Sand Filters showing very high levels of treatment. Some of these studies
show that typical BOD5 and TSS removals are greater than 90 and 85 percent,
respectively. Typical BOD5 and TSS effluent concentrations have been less than 15
mg/L. These studies also show that the Recirculating Sand Filter is capable of obtaining
high levels of Total Nitrogen removal of up to 75 percent. The effluent Total Nitrogen
concentration has been recorded to be as low as 10 mg/L. The Recirculating Sand Filter
is the I/A technology that is specifically covered in Title 5. The treatment capabilities of
all I/A technologies are compared to the Recirculating Sand Filter. In discussions with
DEP, the Recirculating Sand Filter does not always meet the effluent standards required,
however, due to DEP’s familiarity with the process and the majority of the data, which
they have reviewed, it is their opinion that the Recirculating Sand Filter is capable of
enhanced wastewater treatment compared to a conventional Title 5 system. DEP is
confident of the system’s treatment capabilities and ability to protect public health and
the environment.
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Amphidrome™ Process
The Amphidrome™ (DEP piloting approval June 1995) system is a fixed film,
sequencing batch biological filter. The Amphidrome™ primarily consists of an anoxic
equalization tank, the Amphidrome™ reactor/sand filter, and a clearwell. As with a
conventional Title 5 system, a soil absorption system is also required. Wastewater flows
from the building through its building sewer, combines with recycle flow from the
clearwell and enters the anoxic equalization tank. From the equalization tank, the
wastewater flows to the anoxic pretreatment/sludge storage area. The equalization tank
stores flow prior to treatment through the biological filter. The anoxic
pretreatment/sludge storage area settles solids, provides denitrification for the recycled
flow using the new flow as the carbon source, and stores and digests sludge.
A batch of wastewater flow is sent by gravity from the anoxic equalization tank, down
through the filter, to the clearwell. This flow of wastewater is then reversed by pumping
from the clearwell, up through the filter, back to the equalization tank. This cycle is
repeated several times until the required level of treatment is achieved. The cycles are
alternated between aerobic and anoxic modes. The wastewater flows through the filter to
the clearwell. The purpose of the clearwell is to provide storage for the flow to be
recycled or to be used as backwash. Once the degree of treatment is obtained, the effluent
is discharged to a soil absorption system. A schematic of this system is shown on Figure
2-5.
The Amphidrome™ Process was issued Piloting Approval by DEP in June 1995. It is
approved to be piloted as an equivalent technology to a Recirculating Sand Filter. The
Amphidrome™ Process must meet secondary treatment standards of 30 mg/L BOD5 and
30 mg/L TSS and a minimum of 85 percent of the influent BOD5 and TSS must be
removed. The system must also meet the nitrogen loading design standards as follows:
• For residential systems, the effluent total nitrogen concentration shall not exceed
19 mg/L and the system shall remove a minimum of 55 percent of the influent
total nitrogen concentration.
• For non-residential systems, the effluent total nitrogen concentration shall not
exceed 25 mg/L and the system shall remove a minimum of 40 percent of the
influent total nitrogen concentration.
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DEP requires that the influent and effluent parameters for this technology be monitored
monthly for the first year of operation. The proponent of this system is seeking to show
that the effluent total nitrogen concentration does not exceed 10 mg/L and that the system
removes a minimum of 76 percent of the influent Total Nitrogen. Therefore, the ultimate
goal of the Amphidrome™ Process is to achieve an effluent with a Total Nitrogen
concentration of less than 10 mg/L.
Bioclere™ System
The Bioclere™ (DEP general remedial and provisional approval March 1995) is
essentially a modified tricking filter, which can be added to a Title 5 system between the
septic tank and the soil absorption area. Wastewater flows from an establishment through
its building sewer, into a standard Title 5 septic tank in which primary settling occurs.
Effluent from the septic tank then flows by gravity to the baffled sump portion of the
Bioclere™. A dosing pump within this sump intermittently pumps the effluent up to the
top of the media bed for distribution. The wastewater trickles through this bed of highly
permeable plastic media and then mixes with the wastewater in the bottom of the
Bioclere™. This mixture is then recirculated to the top of the media bed in a continuous
cycle. Sloughed biomass and particles not removed through the septic tank or the filter
settle out in the base of the Bioclere™ unit from where a portion of the effluent sludge is
pumped back to the septic tank. The remaining portion of the effluent from the
Bioclere™ is discharged to a conventional leaching area. A schematic of this system is
shown on Figure 2-6.
The Bioclere™ was issued a Certification for General Use, Provisional Use Approval and
Remedial Use Approval by DEP in March 1995. The Bioclere™ must meet secondary
treatment standards of 30 mg/L BOD5 and 30 mg/L TSS with a minimum removal of 85
percent of the influent BOD5 and TSS. The system must also meet the nitrogen loading
design standards as follows:
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Figure 2-6
Bioclere™ System
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• For residential systems, the effluent total nitrogen concentration shall not exceed
19 mg/L and the system shall remove a minimum of 55 percent of the influent
total nitrogen concentration.
• For non-residential systems, the effluent total nitrogen concentration shall not
exceed 25 mg/L and the system shall remove a minimum of 40 percent of the
influent total nitrogen concentration.
A variety of papers and studies have been written on the Bioclere™ system showing high
levels of treatment. Some of these studies show that typical BOD5 and TSS removals are
about 85 and 70 percent, respectively. Typical BOD5 and TSS concentrations are about
50 and 70 mg/L, respectively. They also show that the Bioclere™ is capable of obtaining
high levels of Total Nitrogen removal of up to 25 percent above that of a conventional
Title 5 system. The effluent Total Nitrogen concentration has been recorded to be less
than 30 mg/L.
Cromaglass®
The Cromaglass® (DEP general piloting use approval September 1995) system is
composed of a fiberglass tank, which is separated into three chambers and operates as a
Sequencing Batch Reactor (SBR). Wastewater flows from the building through its
building sewer and enters into the first chamber of the Cromaglass® unit. Within the
first chamber, which is referred to as the “Solids Retention Section”, large inorganic
particles are retained. Wastewater, with smaller particles and broken organic solids, flow
through the grit screen into the second chamber. This chamber is referred to as the
“Aeration Section” where biological treatment by aeration occurs. New inflow is
continuously mixed with the existing activated sludge, which is maintained in this
chamber and aeration lasts for several hours. In this chamber, an anoxic period is also
provided for denitrification. After the anoxic period, a batch of treated wastewater is
transferred at preset intervals to the third chamber for clarification. This chamber is
called the “Clarification Section,” and is filled until the mixed liquor overflows the weir
back into the Aeration Section. The chamber is then isolated allowing solids separation
to occur by settling under quiescent conditions for about one hour. The sludge, which
collects at the bottom of the chamber, is either recycled by pump to the Aeration Section
or transferred to a sludge collection tank. After clarification, a batch of treated
wastewater effluent is discharged to the soil absorption system. A schematic of the
Cromaglass® system is shown on Figure 2-7.
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The Cromaglass® system was issued a Certificate for General Use and Piloting Approval
by DEP in September 1995. Under the General Use category, the Cromaglass® system
must meet the environmental protection requirements of a conventional Title 5 system. It
is also approved to be piloted as an equivalent technology to a Recirculating Sand Filter.
The Cromaglass® must meet secondary treatment standards of 30 mg/L BOD5 and 30
mg/L TSS and a minimum of 85 percent of the influent BOD5 and TSS must be removed.
The system must also meet the nitrogen loading design standards as follows:
• For residential systems, the effluent total nitrogen concentration shall not exceed
19 mg/L and the system shall remove a minimum of 55 percent of the influent
total nitrogen concentration.
• For non-residential systems, the effluent total nitrogen concentration shall not
exceed 25 mg/L and the system shall remove a minimum of 40 percent of the
influent total nitrogen concentration.
DEP requires that the influent and effluent parameters for this technology be monitored
monthly for the first year of operation. As with the Amphidrome™ Process, the
proponent of the Cromaglass® is seeking to show that the effluent Total Nitrogen
concentration does not exceed 10 mg/L and that the system removes a minimum of 76
percent of the influent Total Nitrogen.
RUCK® System
The RUCK® (DEP general use approval March 1995) system is referred to as a passive
nitrogen removal system. The components of the RUCK® system consist of two parallel
septic tanks, the nitrifying RUCK® filter, and a conventional subsurface leaching area.
One septic tank receives blackwater, which is the waste from toilets and drains equipped
with garbage grinders such as a kitchen sink; the other tank receives graywater, which is
the waste from showers, washing machines, dishwashers and other sinks, also called
washwater. These wastes must be separated at the source, therefore an establishment will
need to have the appropriate dual plumbing system or make plumbing changes to make
this possible. Blackwater flows from the establishment through the blackwater
designated building sewer to the blackwater septic tank where solids settle. The effluent
from this blackwater tank is then passed through the single pass aerobic RUCK® sand
filter. After the wastewater passes through this filter, it is collected at the bottom of the
filter, and is transferred to the graywater septic tank. Effluent from the RUCK® filter is
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combined with graywater from the establishment in the graywater septic tank. The
denitrified effluent from this tank is then transferred to a conventional soil absorption
system. A schematic of this system is shown on Figure 2-8.
The RUCK® System was issued a Certification for General Use Approval by DEP in
March 1995. The RUCK® must meet secondary treatment standards of 30 mg/L BOD5
and 30 mg/L TSS with a minimum removal of 85 percent of the influent BOD5 and TSS.
The effluent Total Nitrogen (TN) concentration must not exceed 19 mg/L and the system
shall remove a minimum of 55 percent of the influent TN concentration. The proponent
of the system has indicated that the RUCK® system has achieved between 60 to 85
percent removal of BOD5 and TSS and has achieved better than 55 percent removal of
Total Nitrogen. DEP requires sampling at three points in the process: the blackwater
effluent (septic tank effluent); graywater influent; and the distribution box (final effluent)
to the soil absorption system.
Single Home FAST®
The Single Home FAST® (DEP general, provisional and remedial use approval March
1995) system is a Fixed Activated Sludge Treatment (FAST) system. The FAST®
Process consists of two zones -- a primary settling zone and an aerobic biological zone.
The FAST® unit is essentially a fixed film media bed, which is inserted into a 1,500 to
2,000 gallon septic tank. A schematic of this system is shown on Figure 2-9.
The FAST® System was issued a Certification for General Use, Provisional Use
Approval and Remedial Use Approval by DEP in March 1995. The FAST® System
must meet secondary treatment standards of 30 mg/L BOD5 and 30 mg/L TSS with a
minimum removal of 85 percent of the influent BOD5 and TSS. The system must also
meet the nitrogen loading design standards.
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Figure 2-8
RUCK® System
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Figure 2-9
Single Home FAST®
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The proponent of this system is seeking to show that the effluent Total Nitrogen
concentration does not exceed 15 mg/L and that the system removes a minimum of 64
percent of the influent Total Nitrogen. Therefore the ultimate goal of the FAST® System
is to achieve an effluent with a Total Nitrogen concentration of less than 15 mg/L. DEP
has recognized that the FAST® unit is capable of 90 to 95 percent reduction in BOD5 and
TSS. The effluent concentrations of BOD5 and TSS are reported to be less than 30 mg/L.
It is also recognized that the unit can reduce the Total Nitrogen entering the system to 19
mg/L.
• For residential systems, the effluent total nitrogen concentration shall not exceed
19 mg/L and the system shall remove a minimum of 55 percent of the influent
total nitrogen concentration.
• For non-residential systems, the effluent total nitrogen concentration shall not
exceed 25 mg/L and the system shall remove a minimum of 40 percent of the
influent total nitrogen concentration.
Monitoring results for the six Innovative/Alternative (I/A) Technologies discussed above
were compiled and are summarized in Table 2-1. This Table shows the average effluent
concentrations and percent removals for several systems in operation for each I/A
technology. Also, shown on this Table is the DEP requirements and goals set for each
system. The monitoring results are variable in that not all technologies were sampled and
tested under the same conditions. Variable influent and effluent concentrations were
recorded depending on the source, day and time of day each sample was taken. Also,
different methods of sampling and testing were used for each technology. Although the
monitoring methods and results were different for each system and cannot be used to rank
the technologies, the results were helpful in evaluating the technologies in terms of
whether or not the technology achieved the effluent requirements set by DEP. In
summary, the monitoring results show that all of the technologies have the capability of
achieving enhanced treatment over that of a conventional Title 5 system. Of the systems
and monitoring results analyzed, the Recirculating Sand Filter, the Amphidrome™
Process, the Cromaglass® and the FAST® system achieved their respective DEP effluent
and removal requirements more frequently than the other technologies. These systems
achieve a higher degree of wastewater treatment than can be achieved by a Conventional
Title 5 system.
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NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 2-1 TOWN OF NANTUCKET CWMP/DEIR SUMMARY OF MONITORING RESULTS VERSUS TREATMENT REQUIREMENTS Average Monitoring Results DEP Treatment Requirements BOD5TSS Total NitrogenBOD5TSS TotalNitrogen EffluentPercentEffluentPercentEffluentPercentEffluentPercentEffluentPercentEffluentPercent ConcentrationRemovalConcentrationRemovalConcentrationRemoval ConcentrationRemovalConcentrationRemovalConcentration RemovalI/A TECHNOLOGY (mg/L)(%)(mg/L)(%)(mg/L)(%)(mg/L)(%)(mg/L)(%)(mg/L) (%) Recirculating Sand Filter 308530852540Colburn Street - Gloucester, MA 7.0 96.5 12.0 82.3 60.8 39.2 Langsford Street - Gloucester, MA 11.093.315.077.078.644.6Anne Arudel County - Maryland System A 4.0 98.1 8.0 88.9 22.0 59.3 System B 2.0 98.4 5.0 91.1 17.0 62.2 System C 8.0 97.8 10.0 89.721.070.4Chart House Restaurant - Chester, CT 4.0 99.1 7.0 96.5 11.9 73.5 Amphidrome Process 30853085 Residential --1955Stuart's Mall - Swansea, MA 9.2 95.0 9.9 68.5 14.5 67.5 Nonresidential -- 2540 Goal –10 76Bioclere 30853085 Residential --1955High Street - Gloucester, MA 29.0 78.4 33.0 62.3 26.9 39.8 Nonresidential -- 2540 Vale Court - Gloucester, MA 51.083.642.066.329.347.4 NSF Testing 13.0 82.417.063.822.320.5391 Atlantic Avenue - Cohasset. MA 7.3 87.6 8.9 64.0 12.3 11.1 Stop & Shop - Yarmouth, MA 112.0 81.1 86.0 50.4 43.7 35.3 Mercury Drive - S. Yarmouth, MA 50.0 63.9 79.0 63.5 24.0 21.7 Page 2-32 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 2-1 (cont) TOWN OF NANTUCKET CWMP/DEIR SUMMARY OF MONITORING RESULTS VERSUS TREATMENT REQUIREMENTS Average Monitoring Results DEP Treatment Requirements BOD5TSS Total NitrogenBOD5TSS TotalNitrogen EffluentPercentEffluentPercentEffluentPercentEffluentPercentEffluentPercentEffluentPercent ConcentrationRemovalConcentrationRemovalConcentrationRemoval ConcentrationRemovalConcentrationRemovalConcentration RemovalI/A TECHNOLOGY (mg/L)(%)(mg/L)(%)(mg/L)(%)(mg/L)(%)(mg/L)(%)(mg/L) (%) Cromaglass 30853085 Residential --1955Meadowbrook Christian School -- Milton, PA Nonresidential -- 2540 Phase I 11.1 92.1 19.2 86.2 12.9 29.7 Goal – 10 76 Phase II 7.5 95.8 11.9 93.1 4.7 78.7 NSF Testing 42.082.339.084.2 -- -- RUCK 30853085 Residential --1955Highway Inspection Facility -- Truckee, CA 9.7 80.9 -- -- 60.3 57.0 Porter's Orchard Lot No. 5 -- Colchester, VT 51.2 75.7156.048.2142.727.5Porter's Orchard 8 Home Composite 47.8 -- 63.1 -- 5.7 -- Single Home FAST 30853085 Residential --1955NSF Testing 9.0 93.87.096.49.373.2Nonresidential --2540Florida Keys -- Owners Demonstration 4.6 95.7 8.0 92.2 13.0 64.5 Goal – 15 64 140 Beach Street -- Cohasset, MA 20.1 -- 6.2 -- 12.2 -- Coonamesett Inn -- Falmouth, MA 14.8 -- 18.5 -- 6.6 -- Page 2-33 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
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I/A technologies can potentially overcome site and environmental constraints but at a
premium cost to the property owner. In remedial situations, I/A technologies with
nitrogen reduction allow for either a 50 percent reduction in leaching area; a two foot
reduction in the groundwater separation requirement; or a two foot reduction in the depth
of naturally occurring soil under the leach field. Since the treatment capabilities as well
as the cost of the I/A technologies are similar, one technology, Single Home FAST®
System, was selected in order to evaluate the wastewater disposal alternatives for the
areas of wastewater disposal needs. The costs of the I/A technologies are similar and all
are capable of achieving enhanced treatment over that of a conventional Title 5 system.
3. Analysis of On-site Alternatives
General
A brief on-site alternatives analysis to determine the optimal wastewater treatment and
disposal options for the areas of wastewater disposal needs is presented below. The
analysis considers each of the need areas as a single entity. To determine the optimal
wastewater treatment and disposal option for each need area, technical and environmental
factors were considered. The purpose of this evaluation is to determine which of the on-
site, cluster, and/or I/A options presented are feasible, if any, for the ten (10) wastewater
disposal Need Areas identified in Nantucket.
Conventional Title 5 Septic Systems
Conventional Title 5 septic systems would be a feasible option if all the existing
developed properties within the Need Areas are capable of siting a soil absorption system
according to Title 5 code. Without conducting site specific field investigations for each
property in each of the need areas, and based solely on the subsurface soil and
groundwater information gathered from Board of Health data, it is anticipated that some
of the identified need areas will not be able to meet Title 5 regulations for the soil
absorption system and pose a greater risk to the environment in other areas. Thus,
continued use of existing and use of conventional Title 5 septic systems are not
considered feasible for all of the need areas identified in the Phase I Document.
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Variances to Conventional Title 5 Septic Systems
Conventional Title 5 septic systems with a variance would also be a feasible option if all
of the existing developed properties within the need areas were capable of siting a soil
absorption system with either a variance from the Title 5 regulations or Town By-law.
The criteria used to determine whether variances to conventional Title 5 systems are
feasible for a need area are: lot size, soils, and groundwater. If the need area has an
average lot size of less than or equal to one-half acre but does not have either severe soil
or groundwater limitations, the area could potentially use variances to conventional Title
5 systems. If a need area has an average lot size less than or equal to one-half acre with
either severe soil or groundwater limitations, then variances to conventional Title 5
systems are not an option. Since all the properties within the need areas are not larger
than one-half acre in size, Title 5 systems with variances are a potential option for a
portion of each of the need areas, but not for all of each of the identified need areas.
Hence, this is not a feasible option for an entire need area. Each property would need to
be evaluated on a case-by-case basis in order to determine which properties could
effectively utilize Title 5 systems with variances. This option will be evaluated in those
Needs Areas recommended for long-term sustainable with on-site wastewater disposal
systems and managed under a Septage Management Plan.
STEP/Cluster Systems
STEP/Cluster systems would be a feasible option if a soil absorption system can be sited
within the area of wastewater disposal need or within close proximity to the need area.
The STEP/Cluster System consists of a septic tank effluent pump on each property and a
small scale, off-site subsurface cluster disposal system. The disposal system for this type
of facility is similar to a conventional Title 5 soil absorption system, except that it is
larger in scale and is located off-site from the wastewater source. As previously
discussed, at a minimum, approximately 0.4 acres are required for the disposal system,
assuming good soils and not including setback requirements from property lines, wells,
etc. If reasonable setback limits are included, 0.6 acres is typically required for the
disposal system.
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The disposal system could be located either on an undeveloped parcel in the need area, on
an undeveloped parcel just outside of the need area, or on a portion of an existing
developed parcel in the need area. The property would need to be either purchased by the
Town or an easement on the existing property would need to be obtained from the
property owner by the Town. It is unlikely that a property owner would be willing to sell
a portion of their property or grant an easement on their property to site a subsurface
disposal system. In addition, there would need to be enough area on the property with
adequate soils, depth to groundwater, depth of naturally occurring soil, and depth to ledge
to accommodate such a system. One of the major limiting factors in the Needs Areas is
insufficient land area so, thus STEP / Cluster systems are most likely not a viable option
for wastewater treatment and disposal in the identified areas of wastewater disposal need.
On-site Innovative Alternative Wastewater Treatment and Disposal Systems
On-site Innovative/Alternative (I/A) systems would be a feasible option if the existing
developed properties could accommodate innovative alternative systems (e.g.
recirculating sand filter, AmphidromeTM Process, BioclereTM System, Single Home
FAST, etc.) to effectively treat and dispose of wastewater. Like a conventional Title 5
system, these I/A systems require a soil absorption area. As previously mentioned, an
I/A system can potentially overcome site and environmental constraints but at a premium
cost to the property owner. In remedial situations, I/A technologies with nitrogen
reduction allow for either a 50 percent reduction in leaching area; a two foot reduction in
the groundwater separation requirement; or a two foot reduction in the depth of naturally
occurring soil under the leach field. If a property has either severe soil limitations or high
groundwater, the area could potentially use I/A wastewater treatment and disposal
systems. However, if a property has both severe soil limitations and high groundwater,
then I/A wastewater treatment and disposal systems are not an option. I/A systems will
be considered in those Needs Areas that can accommodate such systems and will be
offered as a recommendation if appropriate in order to comply with the recommendations
of the Estuary project. This option will also be included in the development of the
Island-wide septage management planning.
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4. Configurations and Alternative Sewer Systems
Gravity Sewer System
A gravity sewer system consists of sewer lines that allow residential, commercial, and
industrial customers to discharge into a sanitary system consisting of gravity pipes, which
flow downhill and are not pressurized. Gravity sewer systems operate by collecting the
wastewater via continuously sloped pipe, typically eight inches minimum diameter, and
transport the wastewater to local low points in the collection system. The design of a
gravity sewer system is dependent on the velocity of the wastewater within the pipes.
Minimum velocities are set to assure that suspended matter does not settle out in the
conduit, while maximum velocities are set to prevent erosion of pipe material. Extremely
flat or hilly terrain poses problems to gravity sewer installation since the gravity sewers
must continually slope downward. This results in the sewer becoming increasingly deep
or the need for a pump station. Pump stations are located at the local low points to
collect and pump the wastewater to the next high point in the collection system, where
the process continues.
Low Pressure Sewer System
A low-pressure sewer system has proven to be a viable alternative to gravity sewer
systems. A low-pressure sewer system includes small diameter pressure sewers fed by
individual grinder pumps at each source or can be configured so that the pump system
may also serve multiple sources. A pressure sewer system makes use of small diameter
piping, ranging in size from 1-¼ to 4 inches in diameter, buried at a shallow depth
following the profile of the ground. The pressure main and service pipe are generally
manufactured from polyvinyl chloride (PVC) or high density polyethylene (HDPE). The
pressure sewer mains and laterals are buried just below the depth of frost penetration
following the contour of the ground.
The pressure sewer system is separated into branches of sewers of different sizes
depending on the number of connections to each branch. Standard manholes are not
required in a pressure sewer system. Instead, flushing connections/drain manholes are
installed at the end of branches and where major changes in direction or size of pipe
occurs. Air relief/vacuum valve manholes are installed at high points in the system to
allow trapped air to escape. Each source will utilize a grinder pump for discharge of
sewerage into the main. Each grinder pump unit is equipped with a grinder pump, check
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valve, tank and all necessary controls. The units can be located outdoors close to each
source’s existing septic tank or cesspool so that the connection to the existing service
pipe exiting the building can be made easily. The units can also be located inside the
building. The grinder pump macerates the solids present in the wastewater to a slurry in
a manner that is similar to a kitchen sink garbage grinder and discharges wastewater to
the pressure sewer collection pipes. If a malfunction occurs, a high liquid level alarm is
activated. This alarm may be a light mounted on the outside of the building or an audible
alarm, which can be silenced by the customer. The customer will then notify the Town or
a Town approved technician or contractor to come and make the necessary repair. Figure
2-10 shows a schematic of a typical grinder pump unit.
A low-pressure sewer system collects and transports the wastewater from each customer
located in low points to the nearest gravity sewer. Each customer would provide the
service pipe from their building to the grinder pump, the grinder pump, and service pipe
to the property line. The Town would provide the service pipe and appurtenances from
the property line to the low-pressure sewer. Within the right-of-way, air relief manholes
with air and vacuum valves would be installed at all high points and terminal flushing
drain manholes would be installed at all low points. In addition, cleanouts would be
installed every 1,000 feet. As an option the Town may consider to purchase and install
the grinder pump units within the roadway right-of-way.
Vacuum Sewer System
Like the low-pressure sewer system, the vacuum sewer system is used where gravity
sewer systems are impractical and/or not economically feasible. The vacuum collection
system consists of three main components: (1) services, (2) collection mains, and (3) the
vacuum station. As with pressure sewers, the materials used for the collection mains and
service pipe are typically PVC or HDPE. The pipe diameter for the collection mains
range from a minimum of 4 to 10 inches. The service lines have a minimum diameter of
3 inches. The service lines consist of a vacuum valve, auxiliary vents, valve pit/sump or
buffer tank. The valve pit/sump accepts the waste from the customer. Included within
the valve pit is a vacuum valve, which provides the interface between the vacuum in the
collection piping and the atmospheric air in the building sewer, and a controller, which
regulates the vacuum cycle frequency.
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Figure 2-10
Typical Grinder Pump Unit
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When the vacuum valve is closed, system vacuum within the collection piping is
maintained; when it is open, the system vacuum evacuates the contents of the sump. An
auxiliary vent is installed on the customer’s service lateral and is necessary to provide the
volume of air that will follow the wastewater into the main. Buffer tanks are also used as
holding tanks to collect and regulate large flows such as those flows from apartment
buildings, schools and other large users, and are required when gravity flow switches to
vacuum flow.
Vacuum systems can be buried at a shallow depth due to the high velocity (15 to 18 feet
per second) of sewage, which keeps the lines from freezing. The collection mains can
follow the profile of the ground as long as there are small elevation changes. The
collection lines need to have a minimum slope of 0.2 percent toward the vacuum station.
Uphill liquid transport or temporary increases in elevation can be accomplished by the
insertion of lifts (vertical profile changes) along the sloped route to the station. These
lifts can consist of two 45-degree elbows connected by a straight piece of pipe and are
limited to a length of three feet. The collection mains are all connected to a vacuum
station located in the center of the service area. The vacuum created by the system pulls
sewage to the vacuum station and pumps it to its ultimate disposal point in the
downstream collection system. This station has a collection tank and a vacuum tank.
The wastewater is stored in the collection tank until a sufficient volume accumulates and
it is then evacuated. In addition to the collection and vacuum tanks, the vacuum station
includes: vacuum pumps to create the vacuum for wastewater transport; wastewater
pumps to transfer the wastewater which is pulled into the collection tank by the vacuum
pumps to the disposal point in the downstream collection system; controls; motor control
center; chart recorder; and a fault monitoring system to alert the operator of irregularities
such as low vacuum levels. Therefore, the vacuum station requires an electrical
connection, however, electrical connections at each user are not necessary. A standby
generator is required for this station so that the system can continue to operate in the
event of a power failure.
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5. Wastewater Treatment, Disposal, Reuse and Land Applications
As previously discussed, alternatives were presented for discharge of sewage from
Nantucket's need areas to various decentralized facilities. In this section, the alternative
of treating Nantucket's sewage at a new wastewater treatment facility, at the Siasconset
Wastewater Treatment Facility that is currently under construction, and/or at the Surfside
Wastewater Treatment Facility will be explored. The alternative will require a detailed
look at process requirements, cost impacts, land requirements, structure sizing, treatment
ability, as well as, looking into the existing treatment facilities and disposal systems
capacities.
In general, the new treatment facility alternative consists of providing an appropriate
level of sewerage treatment that would allow treated effluent discharge on the Island of
Nantucket. As such, the treatment technologies analyzed must be capable of producing
an effluent that meets DEP criteria. The following issues will be discussed in this
section: (1) Effluent discharge options; (2) Proposed effluent limitations; (3) Four general
treatment categories: suspended growth biological process, fixed film biological
processes, physical/chemical processes and natural systems processes; (4) Existing
Surfside and Siasconset wastewater treatment facilities; (5) Evaluation criteria; and
(6) Potential Reuse Opportunities.
The treatment categories and technologies described in this section do not represent all of
the treatment processes necessary only the central processes which accomplish most of
the treatment needed to meet proposed effluent limitations. It is assumed that all
treatment technologies will need preliminary screening of large objects, grit removal and
disinfection. The need for primary clarification will depend on the specific technology
involved, but it is assumed that many will require it. These issues will be addressed in
detail once the treatment technologies have been screened.
Effluent Discharge Options
Surface Water Discharges
The discharge of treated wastewater to surface waters is being evaluated as an option for
disposal in Nantucket. Surface waters also include wetland areas adjacent to streams and
waterbodies. This disposal option involves discharging highly treated effluent from a
treatment facility directly to a surface water body, stream or wetland system. For
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purposes of this discussion, the location of the discharge is considered independent of the
location of the treatment facility since the treated effluent could be transmitted along a
pipeline.
The discharges of pollutants to surface waters is regulated by DEP under the Surface
Water Discharge Permit Program (314 CMR 3.00) and the Massachusetts Clean Water
Act (MGL c.21, s.26-53). The point source discharge of pollutants is regulated by the
National Pollutant Discharge Elimination System (NPDES) permit program administered
by the EPA under Section 402 of the Clean Water Act. EPA is the lead agency in
NPDES permitting using compliance with water quality standards set under the DEP state
Surface Water Discharge Permit Program (314 CMR 3.00). The DEP cosigns the issued
permit, if it is determined that water quality standards will be met, a 401 Water Quality
Certificate is issued.
The Surface Water Discharge and NPDES Permit Program have been established to limit
or prohibit discharges of pollutants to surface waters to assure that surface water quality
standards of receiving waters are protected, maintained or attained. The antidegradation
provision of the Surface Water Quality Standards (314 CMR 4.04) requires that in all
cases existing uses shall be maintained and protected.
The Massachusetts Division of Marine Fisheries designates the following surface waters
and harbors in Nantucket as shellfish growing areas:
Polpis Harbor Sesachacha Pond
Nantucket Harbor West and East Nantucket Southeast Coastal
Head of the Harbor Madaket Harbor
Coskata Pond Northwest Coastal
Nantucket East Coastal Nantucket Northeast Coastal
Nantucket Southwest Coastal (Hummock Pond and Clark Cove)
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The effluent parameter of concern for a surface water discharge is phosphorus, which,
even at relatively low concentrations, can increase the growth of aquatic plants, and
produce algal blooms. Such conditions reduce the aesthetic and recreational utility of
receiving waters. Lakes, ponds, and small or slow moving streams are most sensitive to
increases in phosphorus and other nutrient loadings, due to their low flow through rates.
Table 2-2 outlines the minimum criteria for Class B waters, the anticipated designation of
receiving waters, as well as additional minimum criteria for surface waters.
Although EPA has stated that discharges to local surface waters should be considered,
they have expressed concerns that the local surface waters provide little or no dilution.
The larger surface waterbodies and streams in Nantucket include: Sesachacha Pond, Long
Pond, Tom Nevers Pond, Miacomet Pond, Coskata Pond, Hither Creek, and Gibbs Pond.
In addition, the larger harbors include: Nantucket Harbor, and Madaket Harbor. These
surface water bodies are either insufficient in size, predisposed to seasonal flooding,
suffering from poor water quality, used for recreational purposes or their locations limit
their use. The harbors are used for shellfish harvesting, which would represent an
incompatible use. In addition, it is doubtful that the U.S. Environmental Protection
Agency and/or Massachusetts Department of Environmental Protection would approve a
surface water discharge for Nantucket, as the waterways have already experienced
declining water quality due to elevated nutrient levels. As such a surface water discharge
to these ponds and harbors is not being considered further. The two existing wastewater
treatment facilities on the Island discharge to rapid infiltration basins.
As was previously stated in this Phase II Document, the stringent regulatory requirements
facing the surface water discharge and the unavailability of suitable surface waters on
Island preclude this disposal option as a reliable alternative and therefore a detailed
evaluation of this discharge option has not been developed for this document.
Additionally, as was previously discussed in the preceding section, the Massachusetts
Ocean Sanctuaries Act prohibits discharge of municipal wastewater off Nantucket. The
only purpose of presenting any type of surface water discharge in this document is to
address the opportunities and constraints associated with wastewater disposal.
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TABLE 2-2
TOWN OF NANTUCKET
CWMP/DEIR
SUMMARY OF WATER QUALITY CRITERIA FOR CLASS B STREAMS
CLASS B WATERS
(Minimum Criteria)
Description
Dissolved Oxygen Shall not be less than 6.0 mg/L in cold water fisheries and 5.0 mg/L in warm
water fisheries
Temperature Shall not exceed 68°F in cold water fisheries and 83°F in warm water fisheries
pH Shall be in a range of 6.5 through 8.3 standard units and not more than 0.5
units outside of the background range
Fecal Coliform Bacteria Shall not exceed the geometric mean of 200 organisms per 100 ml, not shall
mare than 10 percent of samples exceed 400 organisms per 100 ml
Solids Free from floating, suspended and settleable solids
Color and Turbidity Free from color and turbidity in concentrations or combinations that are
objectionable
Oil and Grease Free from oil , grease and petrochemicals that produce a visible film on the
surface of the water, impart an oily taste
Taste and Odor None in such concentrations or combinations that are aesthetically
objectionable
Additional Minimum Criteria
for All Surface Waters
All surface waters shall be free from pollutants in concentrations or
combinations that settle to form objectionable deposits, float as debris, scum or
other matter to form nuisances
Bottom Pollutants or
Alterations
All surface waters shall be free from pollutants in concentrations or
combinations, or from alterations that adversely effect the physical or chemical
nature of the bottom
Nutrients Shall not exceed site-specific limits necessary to control accelerated growth of
algae and other plants.
Radioactivity Free from radio-active substances in concentration or combinations that would
be harmful
Toxic Pollutants Free from pollutants in concentrations or combinations toxic to humans,
aquatic life or wildlife
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Groundwater Discharges
The discharge of treated wastewater to groundwater is being evaluated as an option for
disposal in Nantucket. This disposal option would involve the discharge of highly treated
effluent from a wastewater treatment facility into an infiltration bed designed to handle
the estimated discharge. For discussion purposes, the location of the discharge is
considered independent of the location of the treatment facility since the treated effluent
could be transmitted along a pipeline to the infiltration system.
The requirements for groundwater discharge of wastewater are outlined in the
Groundwater Discharge Permit Program (314 CMR 5.00 and 6.00). The principal
constituent of concern for groundwater discharges is nitrates, a primary component of
treated wastewater. Potential sites for use as a groundwater disposal site must be
comprised of sandy or gravely soils that exhibit medium infiltration rates. Sites that
contain poor soil permeability, high groundwater levels, and ledge, inhibit the downward
flow of water and are generally unacceptable. Soil properties can be amended by
excavating and amending the soils in the discharge area or mounding the infiltration beds.
This approach may be infeasible for larger systems designed for large wastewater flows
but may be appropriate for small systems.
The most difficult of these physical constraints to overcome is the shallow depth to
bedrock. Title 5 requires that 4 feet of naturally occurring pervious material be located
beneath the bottom of the leaching facility. In areas where bedrock is 4 feet or less from
the natural ground surface, a system cannot be installed in accordance with Title 5. Soils
with slight or moderate limitations for wastewater disposal are considered acceptable for
effluent beds. The groundwater discharge options within Nantucket are also restricted by
discharge standards that prohibit anti-degradation. The Nantucket County Soil Survey
Report by the U.S. Department of Agriculture indicates that soil classifications having
severe soil limitations to septic disposal represent approximately 14.2 percent and the soil
classifications having severe groundwater limitations to septic disposal represent
approximately 18.3 percent of the total land are of Nantucket.
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Proposed Effluent Limitations
Effluent limitations are dependent upon the method and location of treated effluent
discharge. As discussed above, there are two ultimate effluent discharge options: surface
water and groundwater discharge. A surface water discharge would involve discharging
treated effluent to a stream, pond, lake or wetland area. A groundwater discharge would
involve the discharge of treated effluent to the ground and percolation through the soil to
the groundwater. Groundwater discharge can be accomplished by discharging the treated
effluent to rapid infiltration sand basins; using spray irrigation or overland discharge; or
to subsurface disposal beds similar to Title 5 septic systems. Another groundwater
discharge method would be to utilize subsurface injection through wells.
A stream, pond or lake surface water discharge was determined to be infeasible in
Nantucket because of the more stringent effluent requirements associated with small,
intermittent low flow streams and primarily groundwater fed ponds. While a properly
sited system with highly treated effluent discharged to a surface water body through a
constructed wetland offers a high degree of treatment, it likely will not be able to meet
water quality requirements regarding metals where there is little or no dilution.
Accordingly, surface water discharges have been eliminated from further consideration.
For Nantucket, it was determined that groundwater discharge would be the most feasible
means of effluent discharge. The requirements for groundwater discharges can be found
in 314 CMR 5.00. According to these regulations, the minimum effluent limitations for a
Nantucket treatment facility are shown in Table 2-3.
Beneficial reuse of wastewater typically is associated with the application and reuse of
water for irrigation. In this context reuse also applies to discharging treated wastewater
into the ground to recharge the aquifer used for supplying drinking water. The
technology exists, through the use of micro-filtration and membrane technologies, if
necessary, to produce very clean effluent to meet most reuse needs.
Reuse of the wastewater effluent as seasonal irrigation at golf courses could reduce water
use at the course as well as minimize the summer loadings to adjacent waterbodies during
the critical spring-to-fall growing season.
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TABLE 2-3
TOWN OF NANTUCKET
CWMP/DEIR
PROPOSED EFFLUENT LIMITATIONS
Parameter
Open Beds
Proposed Limits (1)
Subsurface/Spray Irrigation
Proposed Limits (2)
Biochemical Oxygen Demand (BOD5) 30 mg/L 10 mg/L
Total Suspended solids (TSS) 30 mg/L 10 mg/L
Total Nitrogen 10 mg/L <10 mg/L
Fecal Coliform 200 mpn/100 ml 200 mpn/100 ml
Oil and Grease 15 mg/L 15 mg/L
(1) 314 CMR 5.00
(2) Proposed limits for subsurface disposal to prevent plugging of disposal area and to eliminate
the need for a reserve area.
Note: mg/L = milligrams per liter; mpn/100 ml = most probable number per 100 milliliters
This irrigation reuse is considered a secondary disposal option since a permanent effluent
disposal solution will still be required in the off months when the golf courses are not
operating. A more detailed discussion of Reuse follows in this section. DEP’s opinion is
that a properly planned and sited discharge that has received a high level of treatment can
be sited in a Zone II and still protect the environment and public health, although DEP
strongly recommends that discharges of highly treated wastewater to the groundwater
outside of a Zone II be considered first.
Based on the Interim Guidance on Reclaimed Water Use issued by DEP (Draft,
September 1, 1998), new discharges from wastewater treatment plants within aquifer
recharge areas (Zone IIs) must meet the discharge and treatment standards as shown in
Table 2-4. These standards apply to the reclaimed water at the point of discharge from
the treatment facility, unless otherwise noted. Siting a wastewater disposal site within a
Zone II is normally a prohibited use unless all other feasible alternatives have been
explored. The EPA New England Region has expressed concerns regarding the
groundwater discharge of wastewater within the Zone II. The concerns expressed by the
EPA include the reliability of the treatment facilities and adequacy of the water supply
monitoring programs for detecting potential health risks associated with contaminants in
the wastewater. Based on these concerns, EPA is not recommending discharge within a
Zone II as a preferred option.
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TABLE 2-4
TOWN OF NANTUCKET
CWMP/DEIR
CLASS 1 GROUNDWATER PERMIT STANDARDS
Parameter Standard
pH 6 to 9
BOD < 10 mg/L or < 30 mg/L
Turbidity < 2 NTU or < 5 NTU
Fecal Coliform median of 0 colonies/100 ml over continuous, running
7 day sampling periods, not to exceed 14/100 ml or
200 colonies/100 ml
TSS 5 mg/L or 10 mg/L
Total Nitrogen < 10 mg/L
Required Land Areas
The land area required for each alternative is the sum of the area required for the actual
treatment facility and the area required for effluent disposal. The land area required for
the actual facility is dependent upon the size of the treatment plant as well as the
treatment technology chosen. This is a highly variable parameter, thus it will be
discussed in general in the following subsection (Treatment Technologies and Evaluation
Criteria) as it relates to the specific technologies, which will be defined more precisely in
the screening process and subsequent detailed analyses of the prospective alternatives.
Land areas required for effluent disposal are dependent upon the soil characteristics of
the site and the method of disposal. Effluent disposal can be achieved through surface or
subsurface application. Table 2-5 and Table 2-6 include approximate land area
requirements for surface and subsurface disposal assuming a percolation rate of 5 to 10
minutes per inch and an application rate of 4 and 2.5 gallons per day/square feet,
respectively. These areas will have to be tailored to the specific facility and site once
screening is complete and soil characteristics have been determined.
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TABLE 2-5
TOWN OF NANTUCKET
CWMP/DEIR
AREAS REQUIRED FOR SURFACE APPLICATION
OF TREATED EFFLUENT
Surface Application (Open Sand Beds)
Application Rate: 4 gpd/ft2(1)
Average Daily
Flow
Leaching
Area
Reserve Area
Total Area
gpd ft2 Acres ft2 Acres ft2 Acres
200,000 50,000 1.15 50,000 1.15 100,000 2.30
400,000 100,000 2.30 100,000 2.30 200,000 4.59
600,000 150,000 3.44 150,000 3.44 300,000 6.89
800,000 200,000 4.59 200,000 4.59 400,000 9.18
1,000,000 250,000 5.74 250,000 5.74 500,000 11.48
(1) Based on recommendations in the “Guidelines for the Design, Construction, Operation,
and Maintenance of Small Sewage Treatment Facilities with Land Disposal.”
TABLE 2-6
TOWN OF NANTUCKET
CWMP/DEIR
AREAS REQUIRED FOR SUBSURFACE APPLICATION
OF TREATED EFFLUENT
Surface Application (Open Sand Beds)
Application Rate: 2.5 gpd/ft2(1)
Average Daily
Flow
Leaching
Area
Reserve Area
Total Area
gpd ft2 Acres ft2 Acres ft2 Acres
200,000 44,600 1.02 133,200 3.06 177,800 4.08
400,000 89,000 2.04 266,400 6.12 355,400 8.16
600,000 133,400 3.06 399,600 9.17 533,000 12.23
800,000 177,800 4.08 532,800 12.23 710,600 16.31
1,000,000 222,400 5.11 666,600 15.30 889,000 20.41
(1) Based on recommendations in the “Guidelines for the Design, Construction, Operation,
and Maintenance of Small Sewage Treatment Facilities with Land Disposal”.
(2) According to the “Guidelines,” the area between the leaching facilities can be used as the
reserve area.
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Treatment Technologies
In this section, a total of 14 treatment technologies will be described. These treatment
technologies to be discussed can be broken down into four broad categories as follows:
Suspended Growth Biological Processes
Conventional Activated Sludge/Extended Aeration
Pure Oxygen Activated Sludge
Sequencing Batch Reactors
Oxidation Ditch
A/O Systems
Fixed Film Biological Processes
Trickling Filters
Rotating Biological Contactors
Activated Biofilters
Physical/Chemical Processes
Chemical Coagulation
Granular Activated Carbon
Zimpro PACT
Natural Systems Processes
Aquaculture
Constructed Wetlands
Solar Aquatics™
The 14 wastewater treatment alternatives listed above are described in the following
paragraphs:
Suspended Growth Biological Treatment
Suspended growth treatment is a biological process that consists of microorganisms in
suspension feeding on organic pollutants in the wastewater. This process is
accomplished aerobically and therefore outside air is added. The added air serves two
purposes in that it provides microorganisms with their needed supply of oxygen and also
maintains the suspension of biomass. Within the suspended growth biological processes
category, a total of five alternatives will be considered. These treatment alternatives do
not need to be proceeded by primary treatment units in order to meet the proposed BOD5
and TSS effluent requirements. Suspended growth processes are capable of producing an
effluent that meets 10 mg/L BOD5, 10 mg/L TSS, 19 mg/L NO3 and 1 mg/L NH3.
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Conventional Activated Sludge/Extended Aeration
In the Conventional Activated Sludge (CAS) process, treatment is accomplished
by microorganisms in suspension. The process usually consists of a rectangular
shaped aeration tank and a final clarifier that separates out the biomass for either
wasting or recycling. Since in colder climates, an older sludge age is required to
achieve the required BOD5 effluent levels, extended aeration, which is a variation
of the activated sludge process, is commonly used. With extended aeration,
aeration time is up to 4 times longer than with the typical CAS system. Using
longer aeration times allows the facility to operate over a wider range of flows
and loads. However, such systems are usually limited to relatively low organic
loads and therefore are generally applicable to flows less than 1 MGD. Sludge
generated in the process is recycled and aerobically digested; therefore, very little
sludge is wasted compared to the typical CAS system. The extended aeration
system achieves better than secondary levels of treatment and can generally
reduce BOD5 and TSS to 10 mg/L, NO3 to 19 mg/L and NH3 to 1 mg/L. Some
biological nitrogen removal occurs as a consequence of periodic high waste load-
low oxygen and low wasteload-high oxygen cycles creating a suitable
environment for the appropriate bacteria. However, it is not anticipated that the
levels of total nitrogen removal required will be achieved without modification of
the normal extended aeration process or without additional treatment processes.
Although CAS/Extended Aeration Systems have been used successfully in this
country for over 70 years and it has been proven to be a flexible and reliable
process which produces year-round secondary treatment quality effluent, it has
been known to require relatively complex process monitoring and control, and
the process is subject to shock loadings and solids washout during flow surges.
Another drawback of the process is that it produces a sludge that is difficult to
thicken and dewater. Perhaps a more serious drawback to the use of this
treatment technology is that without added treatment units, the process cannot
reliably reduce nitrogen to required levels. This is an issue when considering
groundwater discharge. Climate is also an issue because extended aeration
cycles in cold weather hinder treatment performance. The use of extended
aeration may also have regulatory and legal implications because of its inability
to meet required effluent limitations.
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Construction and operation costs for CAS/Extended Aeration are usually not
especially high, although operation costs are higher than other treatment
processes because of the relatively complex operational requirements. Electric
power usage of Extended Aeration facilities tend to be high as a result of long
aeration times and therefore these facilities generally have higher operation costs.
Pure Oxygen Activated Sludge
Pure Oxygen Activated Sludge is a variation of CAS in which pure oxygen is
added to the aeration tank rather than air. Pure oxygen systems are used when it
is an advantage to keep aeration tank volumes and sizes small. Pure oxygen
activated sludge tanks are smaller (about one third (1/3) the volume) than CAS
tanks because more oxygen is available and therefore less time and volume are
needed to degrade organic pollutants. Due to the smaller footprint size, this
process is commonly used for treatment facilities with severe site constraints.
Like CAS/extended aeration systems, pure oxygen systems achieve better than
secondary levels of treatment and can generally reduce BOD5 and TSS to 10
mg/L, NO3 to 19 mg/L and NH3 to 1 mg/L. The pure oxygen process is not
capable, however, of reducing total nitrogen to required levels without additional
treatment processes.
Pure Oxygen Activated Sludge has many of the same benefits and drawbacks as
the CAS Process. The capital costs are about the same: the savings due to the
smaller tankage are comparable to the additional costs of the sophisticated
oxygen generation equipment. Additional drawbacks of Pure Oxygen Activated
Sludge are that it tends to cost more to operate than CAS due to the oxygen
required. The principle consideration, here and with CAS/extended aeration, is
the inability of the process to reliably reduce nutrients to required levels.
Sequencing Batch Reactors
Sequencing Batch Reactors (SBR's) are a variation of activated sludge biological
treatment. In the SBR process, the mixing, aeration and settling takes place in
one basin, not in separate basins typical of CAS processes. SBR's operate on a
fill-and-draw principle in which wastewater flows into a basin and is mixed and
aerated using mechanical and/or diffused aeration. When a basin is full, flow is
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diverted to a parallel basin while mixing and aeration continues in the full basin.
After a period of time, mixing and aeration is stopped and the tank contents are
allowed to settle. Excess sludge is removed from the bottom of the tank while
the treated effluent is decanted from the top. The SBR process achieves better
than secondary levels of treatment and can generally reduce BOD5 and TSS to 10
mg/L, NO3 to 19 mg/L and NH3 to 1 mg/L. An added advantage of the SBR
process is that nitrogen can be reduced to required levels without additional
equipment and tankage. If the SBR is run with an anoxic cycle, it can reduce
total nitrogen to 10 mg/L. If phosphorus removal is required, the SBR process
can be run with both an anaerobic cycle and anoxic cycle reducing the
phosphorous levels to about 1.5 mg/L.
The Sequencing Batch Reactor is used in relatively low flow, space-limited
applications. A particular advantage of the SBR is that it can handle shock and
variable flow and load. Another advantage of the SBR is that no secondary
clarifiers are required.
There may be some community acceptance issues as a result of the relatively
large tankage involved with the SBR process. The SBR combines the settling
and aeration steps into one tank that limits the size of the footprint of the facility.
SBR's can be built above-ground with exposed tank walls or can be constructed
at grade level depending on the terrain of the site. The above-ground tankage is a
possible aesthetic concern. Enclosing the above-ground tankage in a building is
an option; however, it would drive the cost of the SBR alternative up.
Oxidation Ditch
The oxidation ditch is a variation of the extended aeration process in which
oxygen is imparted to the wastewater through mechanical surface aerators. In the
other types of suspended growth systems described so far, the oxygen is usually
provided by diffused aeration. The oxidation ditch is characterized by its
distinctive "race track", oval shape. Like extended aeration, the oxidation ditch
achieves better than secondary levels of treatment and can generally reduce
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BOD5 and TSS to 10 mg/L, NO3 to 19 mg/L and NH3 to 1 mg/L. The oxidation
ditch is not capable, however, of reducing total nitrogen to required levels
without additional treatment processes.
An oxidation ditch is a special type of extended aeration process, and as a result,
its utilization will raise many of the criteria issues raised with CAS/extended
aeration. The only notable difference is the configuration used and community
acceptance issues that might surface as a result. The "race track" type
configuration employed takes up more space than typical extended aeration
layouts. The larger space required would cost more to purchase land and to
build, and the layout does not lend itself well to a building enclosure. Residents
in the area may find a large, unenclosed "race track" shape in their area unsightly.
Anaerobic/Anoxic/Oxic Systems
For the purposes of this report, Anaerobic/Anoxic/Oxic Systems are defined as
those processes that utilize a combination of anaerobic, anoxic and oxic (aerobic)
stages to reduce nitrogen and phosphorus. The removal of nitrogen occurs in a
two step process. The first step is done aerobically and involves the biological
oxidation of ammonia-nitrogen to nitrate-nitrogen. The second step is done in an
anoxic basin and reduces nitrate-nitrogen to nitrogen gas. The first step is known
as nitrification and the second step is known as denitrification.
Systems designed to remove nitrogen, A/O Systems, generally consist of an
anoxic stage followed by an aerobic stage, and a final clarifier that recycles
settled sludge to the anoxic zone. Nitrification occurs in the aerobic zone and
denitrification occurs in the anoxic zone. The anoxic zone is strategically placed
ahead of the aerobic zone in order to take advantage of influent organics that aid
in denitrification. The A/O System can generally reduce BOD5, TSS and Total
Nitrogen to 10 mg/L.
A variation of this process is the A2O2 process that consists of four sequential
stages: an anoxic stage, aerobic stage, anoxic stage, and aerobic stage. This A2O2
process can reduce BOD5 and TSS to 10 mg/L, and Total Nitrogen to about 4
mg/L.
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Systems designed to remove phosphorus and nitrogen, A2O Systems, utilize
anaerobic, anoxic and aerobic stages. Most biological wastewater treatment
processes can reduce phosphorus by 10 to 20 percent. Phosphorus is reduced in
wastewater treatment because it is an essential nutrient for biological cell growth.
Placing the anaerobic stage first followed by anoxic and aerobic stages can
enhance the amount of phosphorus removal. Placement of the anaerobic stage
first and following it with an aerobic stage causes a type of bacteria to
predominate, which takes up, more than the standard amount of phosphorus.
These bacteria accomplish the needed phosphorus reduction. Nitrogen is
removed in the anoxic-aerobic stages, as discussed in the previous paragraphs.
Typically A2/O systems can remove phosphorus to levels below 3 mg/L and
nitrogen to levels below 10 mg/L. Phosphorous removal, however, is typically
not required for groundwater disposal unless the location for the groundwater
discharge is in close proximity to a sensitive surface waterbody. The levels of
treatment obtained by all three of the Anaerobic/Anoxic/Oxic systems discussed
above are consistent with effluent limitations required for this study.
Many of the treatment technologies discussed in the previous paragraphs were
not able to meet proposed nutrient effluent discharge requirements. An A/O
system, with one of the above technologies as the aerobic component, will result
in proposed effluent requirements being met. The following treatment
technologies could serve as a component of the A/O system: extended aeration,
pure oxygen activated sludge, and oxidation ditch. Sequencing batch reactors
were not considered because they have the ability to meet nitrogen requirements
without the addition of an A/O system.
Of the treatment technologies available, extended aeration offers the most
benefits when used in conjunction with an A/O process. Pure oxygen activated
sludge tends to be more expensive than extended aeration due to the cost of
purchasing and generating the oxygen. The oxidation ditch tends to take up more
space, would be more costly to build and would be faced with community
acceptance issues as well.
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Fixed Film Biological Processes
Fixed Film Biological Processes are like suspended growth biological processes in that
they rely on microorganisms to accomplish reduction of organic pollutants. The
difference between the two is the medium in which the microorganisms thrive. With
suspended growth systems, the biological population is kept in suspension in a tank.
With fixed film processes, microorganisms grow on a surface and wastewater is applied
to the surface or the surface is applied to the wastewater. These treatment alternatives
need to be preceded by primary clarifiers in order to meet the required BOD5 and TSS
effluent requirements. Depending on the fixed film biological process implemented,
secondary treatment levels or better can be achieved. A total of three fixed film
biological processes will be considered.
Trickling Filters
With Trickling Filters, organic pollutant removal is accomplished by passing
wastewater over a collection of loosely packed media. Microorganisms grow on
the surface of the media and feed on the organic matter in the wastewater. With
time, the biological growth falls off the media and flows out of the trickling filter
tank with the treated wastewater. Air, needed by the microorganisms to degrade
organics, is entrained in the wastewater as it falls though the media. The typical
process also employs a secondary clarifier to separate biological matter from
treated wastewater. Trickling filters can accomplish secondary levels of
treatment and can generally reduce BOD5 and TSS to 30 mg/L. Trickling Filters
are not capable of consistently achieving BOD5 and TSS levels of 10 mg/L in
colder climates. In warmer climates a two stage Trickling Filter can generally
reduce BOD5 and TSS to 10 mg/L, NO3 to 19 mg/L and NH3 to 1 mg/L.
Nitrification (i.e., oxidation to convert ammonia into nitrate) is also possible, but
total nitrogen removal is not feasible using trickling filters.
Trickling Filters can’t remove nitrogen to required levels. The nature of the
Trickling Filter is such that it must be covered to perform properly. As such, it
will not be able to operate in Nantucket’s climate without this protection.
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Another option is to enclose the Trickling Filter in a building, however this is not
recommended due to the ventilation requirements of the filters. Covering of the
treatment process is assumed to be necessary for community acceptance,
however it will add to the construction cost of the facility.
Rotating Biological Contactors
Similar to Trickling Filters, Rotating Biological Contactors (RBC's) involve
growing bacteria on media. However, RBC's utilize large moving disks that
rotate through the wastewater rather than stationary media, which has
wastewater, passed over it. The rotating disk causes the microorganisms to be
exposed to cycles of air and wastewater (organics). The rotating action also
causes shear forces to slough off the bacterial growths. A final clarifier captures
the sloughed-off biological material. The principles involved are essentially the
same for RBC's and Trickling Filters. The advantage of RBC's is that they tend
to be more reliable and less susceptible to shock loading. Aerobic RBCs can
generally reduce BOD5 and TSS to 10 mg/L, NO3 to 19 mg/L and NH3 to 1
mg/L. A two stage RBC with both an anoxic and oxic stage combined with the
addition of methanol can economically reduce BOD5, TSS and Total Nitrogen to
10 mg/L. With the use of RBCs, sludge thickening is not required.
Wastewater treatment using rotating biological contactor technology is a
compact, relatively simple and reliable process that can easily be designed to
remove nitrogen. The nature of the RBC is such that it must be covered to
perform properly. Covering of the treatment process is also necessary for
community acceptance. Another option is to enclose the RBC in a building,
however this is not recommended due to access issues for operation and
maintenance and the high cost to provide proper lighting and ventilation.
Activated Biofilters
An Activated Biofilter (ABF) is a dual biological process that employs both
suspended growth and fixed film processes. In its typical arrangement, a fixed
film process (such as a trickling filter) is placed in series with a suspended
growth process (such as conventional activated sludge). The media used in the
ABF process is commonly redwood boards because the return activated sludge is
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mixed with the influent flow upstream of the trickling filter. The two systems are
usually combined in the Activated Biofilter arrangement in order to take
advantage of the strengths of each process. They are resistance to shock loads
and ease of maintenance for trickling filters and the flexibility and high-quality
effluents of conventional activated sludge. This type of system is capable of
nitrification, however removal of total nitrogen is not feasible with this process.
The ABF is capable of reducing BOD5 and TSS to 10 mg/L, NO3 to 19 mg/L and
NH3 to 1 mg/L.
The Activated Biofilter is a treatment technology, which utilizes both, suspended
growth and fixed film systems. These types of systems can not remove nitrogen
to required levels. While also taking advantage of the best features of suspended
growth and fixed film systems, Activated Biofilters also suffer similar criteria
problems for each type of system as described in the previous sections.
Physical/Chemical Processes
Physical/Chemical Processes are those processes that involve removal of pollutants solely
through the use of gravity settling and chemical addition and/or the addition of particles
that attract pollutants to surfaces. Biological activity is not intended to be the principal
pollutant-reduction mechanism in physical/chemical treatment. The following three
physical/ chemical alternatives will be discussed:
Chemical Coagulation
In general, particles in wastewater do not have an affinity for one another and do
not have a great tendency to agglomerate. Chemical coagulation involves the
addition of chemicals to increase particle affinity and therefore the tendency for
agglomeration. The overall process is usually accomplished in three steps:
coagulation, flocculation and sedimentation. In the coagulation step, chemicals
such as aluminum sulfate or iron salts are added to the wastewater and mixed
rapidly to destabilize solids. In the next step, flocculation, the destabilized solids
are mixed slowly to encourage agglomeration. In the last step, the destabilized,
agglomerated particles are settled out in a sedimentation tank. Chemical
coagulation can remove BOD5, TSS, insoluble organic nitrogen and phosphorus,
but is not effective in removing total nitrogen to the required levels.
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Chemical coagulation is not well suited to surges in flow and load, as chemical
dosages would constantly require adjustment to match influent conditions.
Complicated process control, large tankage and flow equalization would be
required.
Chemical coagulation can remove BOD5, TSS and phosphorus, but is not
effective in removing total nitrogen to the required levels. As such, treated
effluent will not be suitable for groundwater discharge that would raise
regulatory and legal issues. Other issues include the cost of the chemicals, and
the large quantity of chemical sludges produced.
Granular Activated Carbon
Treatment using granular activated carbon relies on the principle of adsorption.
Adsorption is a physical/chemical process by which materials accumulate on
surfaces. Since adsorption is a surface-active phenomenon, the larger the surface
the greater the tendency for adsorption to occur. Activated carbon is a popular
substance for adsorption because of its large surface area. Granular activated
carbon is typically not used in wastewater treatment because of the size and
amount of solids in the waste stream. It would not be effective in removing
nitrogen and phosphorus. It is better suited for removal of small particles and
residual organics. The Granular Activated Carbon process would not be very
effective without significant process addition and modification. The drawbacks
to the use of this process as a treatment technology are identical to chemical
coagulation. In addition there are additional operation and maintenance cost
issues due to the need to regenerate the carbon.
Zimpro PACT
Zimpro PACT is a patented process in which powdered activated carbon (PAC)
is added to the aeration tank of the conventional activated sludge process.
DuPont developed the process in the early 1970's, but Zimpro/Passavant
currently holds the patent. Once in the aeration tank, the bacteria and the PAC
work together to reduce organic material. The bacteria degrade most of the
organics and the PAC handles the remaining portion. In the conventional
arrangement, sludge and PAC are settled out in a clarifier and then returned to
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the aeration tank or wasted. When the PAC becomes spent, it must be replaced
or regenerated. Wastewater treatment facilities employing the PACT process can
achieve effluent BOD5 and TSS of 10 mg/L, but have not achieved effluent total
nitrogen and phosphorous concentrations to low levels that may be required for a
facility in Nantucket.
As with Granular Activated Carbon, Zimpro PACT is usually used for the
removal of small particles and residual organic matter. Zimpro PACT would not
be very effective without significant process addition and modification and the
drawbacks to its use as a treatment technology are identical to chemical
coagulation. Zimpro PACT is commonly used for industrial discharge; however,
it is generally more cost effective for industries to use some form of pretreatment
rather than the PACT process. The PACT process also creates more sludge and
operating costs due to the addition of PAC than the previously mentioned
technologies.
Natural Systems Processes
Natural Systems Processes involve utilization of naturally occurring plants and animals
for wastewater treatment. These types of systems consist of some tankage, but mostly
consist of large basins, ponds and wetlands. A total of three Natural Systems Processes
will be discussed.
Aquaculture
The Aquaculture process for treating wastewater generally consists of a series of
greenhouses and wetlands. Influent first passes through the headworks, where
grit and large objects are removed. From there, wastewater flows to a
greenhouse, which houses a series of solar tanks and solar ponds. Here, aquatic
and non-aquatic plants, bacteria and aquatic animals provide treatment. Next,
wastewater flows to clarifiers, sand filters and constructed wetlands. The
clarifiers separate biological solids from the water and the sand filters remove
residual solids prior to reaching the constructed wetland. The purpose of the
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constructed wetland is to accomplish the last phase of nitrogen removal.
Aquaculture treatment systems are capable of reducing BOD5 and TSS to
secondary treatment standards (30 mg/L). Nitrogen and phosphorus removals are
also reported to be feasible.
Constructed Treatment Wetlands
Constructed treatment wetlands are essentially man-made systems designed to
provide biological and chemical conditions that mimic natural wetlands systems.
However, unlike a traditional treatment facilities, these treatment wetland systems
offer many additional advantages, including longer service life, low O&M costs,
and a variety of aesthetic values. Treatment wetlands are comprised of rooted
vascular plants within shallow flooded or saturated soils that provide conditions
effective for wastewater treatment. The two types of treatment systems include
surface-flow wetland systems (SF) and subsurface-flow wetland systems (SSF).
The SF wetland systems consist of an excavated lined basin containing a shallow
substrate that supports emergent wetland vegetation. Treatment in the SF
wetland occurs primarily in the rhizomes of the plant material. The SSF wetland
systems use a bed of soil or gravel media for the growth of plants. Wastewater in
the SSF wetland systems flows by gravity horizontally through the media were
most of the treatment occurs from interaction with aquatic microorganisms.
Typical plants used in these treatment wetland systems include common reed
(Phragmites communis), cattail (Typha spp.) and bulrushes (Scirpus spp.).
Wetlands have been incorporated into wastewater treatment systems for more
than 25 years and have become a popular waste treatment alternative for
communities in both the U.S. and Europe. Recent estimates have identified
approximately 1,000 constructed wetlands are currently operating, ranging from
treatment for single-family homes to large-scale municipal systems. Cities and
towns such as Marion, MA, Minoa, NY, Iselin, PA; Arcata, CA; Orlando, FL;
PA; Monterey, VA and Columbia, MO have combined conventional treatment
technologies with treatment wetland systems to achieve discharge requirements.
The EPA issued a design manual (1988) formally recognizing constructed
wetland technology, and site-specific guidelines for their design have been
developed in many states. This Design Manual, “Constructed Wetlands and
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Aquatic Plant Systems for Municipal Wastewater Treatment Disposal” is
currently being updated by EPA to address the advances in technology and
understanding of these systems.
The effectiveness of these treatment wetland systems is based largely on the level
of pre-treatment, conservative estimates of constituent and hydraulic loading
rates, monitoring and operational strategies. Design parameters for the size of
these systems vary according to the treatment goals, estimated wastewater
volumes, effluent characteristics and hydraulic loading. General sizing for
approximately 1 MGD with a basin depth of 3 feet and a detention time of 6 days
would require approximately 6 acres.
Relatively elevated concentrations of trace metals can be found naturally
occurring in the streams and waterbodies in Nantucket. These metal
concentrations (i.e.: copper and lead) are found in groundwater within the
aquifer. Treatment wetlands can be effective at reducing metal concentrations.
Reduction of metals within the treatment wetlands can be accomplished through
immobilization in the surface soils or assimilation by plants and animals. The
reduction of metals is largely correlated to the inflow concentrations and
detention times. Specific performance data on the removal of trace metals from
treatment wetlands is limited.
Treatment wetlands systems are generally designed for the reduction of levels of
conventional pollutants including, nitrates, fecal coliform, Biological Oxygen
Demand (BOD) and Total Suspended Solids (TSS). The treatment wetland
systems should be viewed as a component in optimizing the overall wastewater
treatment process rather than a means to reduce trace metals. The use of these
wetland systems for this purpose is considered speculative. The applicability of
using treatment wetlands for wastewater disposal in Nantucket is viewed as a
final component in the treatment process prior to a direct discharge to surface
water or groundwater infiltration system. The option of discharging treated
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wastewater to surface waters/wetlands is not feasible in Nantucket due to the lack
of dilution potential offered by the low flow streams. However, the
implementation of a treatment wetland system could function as a buffer by
providing a “polishing” component in the treatment process.
In summary, the treatment wetland system could be used as part of a surface water
discharge in functioning to minimize the potential impacts to natural wetland
systems. Properly constructed treatment wetlands could control the quality and
quantity of the discharge, reduce channelized flow and assimilate nutrient levels.
The implementation of treatment wetland system as a component of the wastewater
plan would require site-specific characterization of the receiving waters and
development of discharge parameters.
Solar Aquatics™
The Solar Aquatics™ treatment process, a proprietary design, is characterized as
a natural system by its developer. It utilizes elements of natural wetland systems,
such as plants, subsurface wetland media and sand filtration with more
conventional treatment elements such as diffused aeration and settling tanks. The
Solar Aquatics™ process is housed in a greenhouse structure, which provides
light for photosynthesis of its plant life, the ability to grow plants year-round, as
well as provide an attractive appearance. Several Solar Aquatics™ facilities are
currently operating in the region. Solar Aquatic™ systems are capable of
reducing BOD5 and TSS to secondary treatment standards (30 mg/L). Designs
are available which are reported to reduce BOD5, TSS and Total Nitrogen to 10
mg/L. Phosphorus removals are also reported to be feasible.
6. Existing Wastewater Infrastructure
The Town is currently undertaking an evaluation and mapping program for the entire
collection system. The evaluation and program consists of the following: (1) visual
inspection to identify materials of construction, system configuration, depth of structure,
and identification of defects; (2) topographic survey to locate the existing manhole
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structures and obtain rim elevation; (3) creation of a system map compatible with the
Town’s existing GIS system; and (4) provide the Town with priorities for system repairs
and/or modifications. Nantucket’s existing wastewater Infrastructure is divided into two
service areas.
The first service area collects, transmits, treats and disposes of wastewater generated
from the Town area of the Island. The service area consists of approximately 34 miles of
sewer, 6 pumping stations, and a 2.24-mgd advanced primary wastewater treatment
facility (WWTF). The Surfside WWTF is located on South Shore Road in the Southwest
region of the Island. The facility is currently permitted to discharge 1.80 mgd of
advanced primary treated effluent during the summer months into 10 rapid infiltration
basins. The service area encompasses approximately 2,000 acres of land out of a total
30,580 acres on the Island. The Surfside WWTF serve approximately 4,000 residential
and commercial customers.
The second service area collects, transmits, and disposes of wastewater generated from
the Siasconset area of the Island. The service area consists of approximately 5 miles of
sewer, and a 0.12-mgd discharges raw wastewater into six infiltration basins. The
Siasconset WWTF is located on Low Beach Road in the Southeast region of the Island.
Over the last decade, the Town has been in the process of planning, design and permitting
an advanced wastewater treatment facility. The Siasconset WWTF is design for
advanced treatment of the wastewater with an average daily flow of 0.22-mgd and
discharge limits of 10 mg/L BOD5, 10 mg/L TSS and 5 mg/L Total N. Currently the
proposed facility is under construction and consists of the following components:
(1) Influent Flow Measurement; (2) Primary Clarifiers; (3) Sequencing Batch Reactors;
(4) Post Equalization; (6) Effluent Filtration; (6) Ultraviolet Disinfection; (7) Effluent
Flow Measurement; (8) Sludge Holding Tanks; (9) Scum Holding Tank; (10) Odor
Control System; and (11) Rehabilitation of the Existing Rapid Infiltration Basins. The
service area encompasses approximately 1,012 acres of land out of a total 30,580 acres on
the Island. The Siasconset WWTF will serve approximately 700 residential and
commercial customers.
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Collection System Tributary to the Surfside WWTF
The sewer collection system tributary to the Surfside WWTF consists of approximately
34 miles of sewer. The size of sewer pipes range from 4 to 30 inch in diameter. The
average pipe diameter in the system is 6 and 8 inches. The majority of the sewer system
flows by gravity and the most common pipe material is VC with oakum-mortar joints.
The manholes are generally round brick or concrete block construction with cast-iron
frames and covers. Most manholes are without steps and range between 2 to 17 feet in
depth, with an average depth between 6 and 8 feet.
The gravity sewers discharge to a pumping station on Sea Street where the sewage is
pumped through either of two force mains to the Surfside filter beds; a 20-inch ductile
force main installed in 1981, or a 20-inch cast-iron force main relined with 16-inch
polyethylene liner pipe installed in 1984. The total distance from the pumping station to
the ten slow sand filter beds on the south shore of the Island is about 17,800 feet. The
pumping station, the original force main, and original seven filter beds were built in
1929. Beginning at the pumping station, 5,300 feet of force main was repaired in 1959
and during the period repairs were in progress, an emergency force main bypass
discharging to the ocean at Brant Point was constructed and placed in service to permit
the repairs. The emergency bypass has been taken out of service.
Collection System Tributary to the Siasconset WWTF
The sewer collection system tributary to the Siasconset WWTF consists of approximately
5 miles of sewer. The size of sewer pipes range from 4 to 12 inch in diameter. The
average pipe diameter in the system is 6 and 8 inches. The sewer system flows by gravity
to the existing rapid infiltration basins and the most common pipe material is VC with
oakum-mortar joints. The manholes are generally round brick or concrete block
construction with cast-iron frames and covers. Most manholes are without steps and
range between 2 to 15 feet in depth, with an average depth between 6 and 8 feet.
Wastewater Pumping Stations
There are six pump stations located throughout the Town that convey the Town’s
wastewater to Surfside WWTF. The stations types consist of two submersible pump
stations, two suction lift pump stations, one air injection pump station and one custom
built station. Refer to Table 2-7 for a summary of the pumping stations.
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NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 2-7 TOWN OF NANTUCKET CWMP/DEIR WASTEWATER PUMPING STATIONS SURVEY SUMMARY ID Pump Station Type of Year Pumping System Station Alarms EmergencyGenerator Name Station Built UpgradeDesign CapacityNo.Miscellaneous HP (Y / N) (Y / N) Comments 1 AirportPump Station Submersible1989None300 GPM48’ TDH 1750 RPM 2ABSAF60-4 4 inch Discharge Y (Phone)N• Pump Run Times: 7,698 hours and 6,412 hours • Float controlled • Feeds Old South Road Pump Station • No flow measuring device • Control Panel needs to be replaced due to corrosion. • One pump overhauled 2Cato LanePump Station Ejector1964NoneUnknown2CompressorsNN• Feeds Surfside Pump Station • No Flow measuring device • Structure condition is poor due to corrosion • Station Access is unsuitable • High maintenance requirements 3 Old South Road (South Valley) Pump Station Suction Lift 1989 None 980 GPM 81’ TDH 1765 RPM 3Gorman RuppT6A3-B 12 3/8th inch impeller 40NY• DMT Corp. Generator: 100kW, 125kVa, 150 amps, 277/430 V, 3 ph, 60 Hz • Generator run time = 65 hours • Pump Run Times: 250 hours, 215 hours, and 223 hours • Structure condition good • Control Panel parts have been discontinued. • Town Maintained from 1989 to 1991 and 2001 to present. • Air bubbler controlled • Flow measurement device by Polysonics • Flow to station is much lower than design capacity. Page 2-66 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 2-7 (cont) TOWN OF NANTUCKET CWMP/DEIR WASTEWATER PUMPING STATIONS SURVEY SUMMARY ID Pump Station Type of Year Pumping System Station Alarms EmergencyGenerator Name Station Built UpgradeDesign CapacityNo.Miscellaneous HP (Y / N) (Y / N) Comments 4 Pine ValleyPump Station Submersible1989None458 GPM47’ TDH 1150 GPM 2ABSAFP/N-15 Y (Phone)N• Floats used for controls • 8” gravity in, 4” FM out • No flow data • Feeds Surfside Pump Station 5Sea StreetPump Station Custom Building 193019941800 GPM86’ TDH VFD 1900 GPM 78’ TDH VFD 3Worthington6MF17FR6 Westinghouse Motor 460V, 3ph, 60Hz, 1170 RPM Clow Yeomans GE Motor , 460V, 3ph, 60Hz, 1190 RPM, model#5k6404AS308 75 60 Y • Screen Motor: Underwriters Laboratories, FAB239175, 3 hp, 3ph, 1725 rpm, 230/408V • Grinder Motor = Underwriters Laboratories, SZ541361, 3 hp, 233V, 1725 rpm, 60 cycles, 3ph • Kohler Generator: 3ph, 60Hz, 277/480V, 230 kW, 288kVa, 346 Amps, 185 hrs 6SurfsidePump Station Suction Lift 1987 None 980 GPM 68’ TDH 1400 RPM 2Gorman RuppT5A3-B 40Y• Pump Run Times – 5,721 hours and 4,672 hours • Flow measurement device by Polysonics • Allen Bradley Control Panels, parts difficult to obtain • Generator only capable of running 1 pump. • Superior Generator: 75 kW, 93.75 kVa, 112 amps, 3ph, 60Hz, 277/480V Page 2-67 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
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CWMP/EIR – PHASE 2 REPORT
Pine Valley Pump Station
The Pine Valley Pump Station was constructed in 1989 and utilizes submersible
pumps as the mean to convey wastewater. The station is privately owned and
maintained. The station does not have a flow measurement device, on-site
emergency generator or capability of alarm transmission to the Surfside WWTF.
Wastewater flows from Pine Valley Pump Station are pumped into the collection
system that is tributary to the Surfside Road Pump Station.
Airport Pump Station
The Airport Pump Station was constructed in 1989 and utilizes submersible
pumps as the mean to convey wastewater. The Town has only maintained the
Airport Pump Station since early 2000 when it took control of the station from
the Nantucket Inn. The Airport Pump Station’s control panels are badly corroded
and are in need of replacement. The station does not have a flow measurement
device, on-site emergency generator or capability of alarm transmission to the
Surfside WWTF. Wastewater flows from Airport Pump Station are pumped into
the collection system that is tributary to the Old South Road Pump Station.
Kato Lane Pump Station
Kato Lane Pump Station is the only air injection station and is in poor condition
as its structure is in need of an upgrade. This ejector station also lacks suitable
access. The station does not have a flow measurement device, on-site emergency
generator or capability of alarm transmission to the Surfside WWTF.
Wastewater flows from Kato Lane Pump Station are pumped into the collection
system that is tributary to the Surfside Pump. The replacement of the Kato Lane
Pump Station included as part of the Siasconset WWTF project.
Old South Road Pump Station
Old South Road Pump Station (also known as South Valley Pump Station)
utilizes suction lift pumps as the mean to convey wastewater. The Town
maintained Old South Road Pump Station from 1989 to 1991. The South Valley
Subdivision Community took over the maintenance of the pump station from
1991 to 2001. In February of 2001, the Town took back the responsibility to
maintain the Old South Road Pump Station. Flow to this station is much lower
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than design capacity and therefore has created some operational problems. The
station does not have an on-site emergency generator or capability of alarm
transmission to the Surfside WWTF. Wastewater flows from Old South Road
Pump Station are pumped directly to the Surfside WWTF.
Surfside Road Pump Station
Surfside Road Pump Station utilizes suction lift pumps as the mean to convey
wastewater. The Surfside Road Pump Station is in need of a new generator since
the existing generator is capable of only running one pump, which reduces the
flexibility and redundancy of the station. Wastewater flows from Surfside Road
Pump Station are pumped directly to the Surfside WWTF.
Sea Street Pump Station
Sea Street Pump Station is the largest pump station located in a custom building
in the center of the downtown area. This is the oldest station dating back to
around 1930. The station has gone through two major upgrades, the most recent
in 1994. The Town is planning to replace the existing comminutor with a bar
screen. Currently the station has experienced a problem with excessive grease in
the collection system that accumulates in the station’s wetwell. In addition, the
Town has also experience problems with the variable frequency drives at Sea
Street. Wastewater flows from Sea Street Pump Station are pumped directly to
the Surfside WWTF utilizing either a 20-inch diameter force main or 16-inch
diameter force main.
The Sea Street pumping station was built in the 1930s and consists of a one-story
superstructure, 30 feet by 32-feet in plan partitioned into two sections comprising
of an 11-foot by 32-foot wet well extending below grade along the rear of the
building and a ground level control room with a below-grade dry well occupying
the remaining space on the street side.
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In the 1970s a headworks facility consisting of a comminutor and by-pass bar
rack was constructed to replace the manually cleaned screen cages. In addition,
an emergency generator was added to maintain operation of the station in the
event of a power outage. This equipment was installed in a new building located
directly behind the existing superstructure and was constructed adjacent to the
existing wetwell.
In the early 1990s, the pump station was upgraded to include the installation of a
channel grinding mechanism, chemical addition storage and feed equipment for
the force main and wetwell, activated carbon odor control system, ozone
generation and wetwell distribution equipment, separation of a large wetwell into
two compartments to facilitate cleaning, replacement of 2 pumps and the
additional of variable speed drives.
Portable Generator
For the three pump stations that do not have an on-site emergency generator, the
Town utilizes a portable generator during normal power failures. The portable
generator is currently stored at the Surfside WWTF. The portable generator is
covered with rust and requires some minor repairs.
Infiltration/Inflow
An infiltration/inflow (I/I) study was initiated on the Island of Nantucket in March of
1988. A previous study had been conducted in 1973. The objective of the I/I
investigation was to identify the portions of Nantucket’s wastewater collection system
that contribute excessive I/I to the local wastewater facility and to develop a list of cost
effective recommendations for the elimination or reduction of these I/I sources.
The sewer system in the Town of Nantucket was divided into seven Mini-systems, M1,
M2, M3, N1, N2, N3 and N4. Mini-system M1 was reported with excessive infiltration
with approximately 157,000 gpd. While mini-systems M1, M2, M3, N1 and N2 were
noted to incur 87 percent of the total inflow. In 1987 State Guidelines suggested that
mini-systems that account for at least 80 percent of the total system inflow must be
subjected to a Sewer Service Evaluation Survey (SSES).
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The SSES was performed to identify the specific locations of I/I sources, to quantify the
amount of I/I, to identify the method of rehabilitation to eliminate I/I, and to justify
rehabilitating each defined I/I source. Included in the SSES was flow isolation, manhole
inspections, private source inflow questionnaires, internal building inspections, smoke
testing, and dyed-water testing. The SSES was completed in 1989 and submitted to and
approved by the Massachusetts DEP in 1991. Final conclusions and recommendations
from the report include:
• Total removable design peak inflow amounted to 1.978 mgd, of which
approximately 1.68 mgd is attributable to private inflow sources;
• Approximately 160,000 gpd of infiltration was identified of which
approximately 20,000 gpd was found to be cost effective to be removed;
• Rehabilitate sewer lines and manholes identified in the cost-effective
analysis;
• Perform a testing and sealing program of identified leaking service
connections;
• Remove illegal connections to sewer system;
• Develop a regular maintenance program including flushing the sewer
lines to minimize the build up of debris and to maintain hydraulic
capacity; and
• Correct collapsed pipes and broken inverts, and remove heavy root
intrusion that contribute to heavy infiltration.
After the completion of the 1991 Town of Nantucket Infiltration/Inflow Analysis and
Sewer System Evaluation Survey, the Town has taken a number of steps to remove I/I
from its sewer system. Amongst the steps taken are the following:
• Removal of illegal connections;
• Removal of suspect catch basins;
• Purchased equipment to aid in locating and repairing broken lines and
potential I/I sources;
• Developed an Operation and Maintenance program that includes two full
time staff dedicated to the maintenance of the collection system;
• Manhole repairs and installation with an average of 10 manholes repaired
per year and 6 manholes replaced installed per year; and
• Replacement of the Washington Street Area interceptor that was
identified as a line that: (1) was a source of several surcharging events
per year; (2) was a source of significant infiltration;
(3) created a maintenance problem caused by a continual build-up of
debris; and (4) had various structure defects.
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CWMP/EIR – PHASE 2 REPORT
7. Existing Wastewater Treatment Facilities
Background
Earth Tech provided wastewater master planning services, including facilities planning
and EIR completion, for the Town of Nantucket. These services included the planning,
design and construction of the Surfside Wastewater Treatment Facility and the Siasconset
Wastewater Treatment Facility. The Surfside Wastewater Treatment Facility was
completed in 1991. Severe storms caused significant erosion that postponed construction
of the coastal Siasconset Wastewater Treatment Facility. Shortly thereafter, Earth Tech
evaluated short-term measures to be utilized as interim solutions for the Siasconset
wastewater disposal issue. The final result was only minor modifications being made to
the existing infiltration basins in 1991. In July 2002, an updated Coastal Erosion Report
was completed at the Surfside WWTF site. The Woods Hole Group completed this and
the former coastal erosion report done in July 1999 under subcontract with Earth Tech.
The reports summarize the fact that erosion is not an issue at this site. A copy of both
these erosion reports are included in Appendix D.
Surfside Wastewater Treatment Facility
The Surfside Wastewater Treatment Facility treats flow generated from the Center of
Nantucket and has a design capacity of 2.24 MGD. The Surfside Wastewater Treatment
Facility consists of a septage receiving tank, aerated grit chamber, three primary clarifiers
that utilize ferric chloride and polymer for enhanced treatment, ten rapid infiltration
basins, three aerated sludge holding tanks, one aerated septage equalization tank, and
process support systems. Sludge and septage are dewatered with belt filter presses and
can be mixed with wood chips in a portable mixer using aerated static pile method to
produce a product that meets DEP Standards for a Type I sludge or composted with
municipal solid waste. Currently, the Town transports the dewatered solids to the Town
landfill for co-composting in a privately operated facility. The facility has been in
operation since 1991 and underwent improvements in 1992 for odor control and
improved primary treatment.
A key element of the facility’s design is the odor control system, which treats odorous air
from the sludge dewatering area, grit dewatering area, sludge storage, septage
equalization, and the compost operation. The 4-stage odor control system utilizes a water
cooling chamber for the compost pile off gases, an acid wash chamber for ammonia
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odors, a sodium hypochlorite and sodium hydroxide scrubber for hydrogen sulfide, and
an activated carbon chamber for volatile organics. The process also includes chemical
addition to the sludge and septage holding tanks and to the sludge suction of the belt filter
press feed pumps as a back up to the air scrubbing system.
In addition, the Surfside Wastewater Treatment Facility is designed to receive an average
of 11,200 gallons per day of septage. The septage can be processed using several
methods: (1) Pumping to the Headworks; (2) Pumping to the Cyclone Grit Classifier; or
(3) Pumping to the Aerated Sludge Holding Tanks for Belt Press Dewatering.
The Nantucket Surfside WWTF provides primary settling for biochemical oxygen
demand (BOD5) removal and total suspended solids (TSS) removal. The Town’s
wastewater flows through a 12-inch Parshall flume where it is screened before continuing
through an aerated grit chamber, primary clarifiers with the final effluent discharged into
one of 10 rapid infiltration basins. Chemically enhanced primary treatment occurs during
the summer months by the addition of chemicals are various injection points.
Wastewater solids are stored in three aerated sludge holding tanks prior to dewatering
utilizing belt filter presses. Although the facility has the capability to stabilize the
dewatered wastewater sludge, using aerated static pile composting, the facility
discontinued composting operations in 1997 and the dewatered sludge is transported to an
on-island municipal solid waste composting facility that is privately operated. The
following is a summary of the unit process:
• One Aerated Grit Chamber with a dimension of 12 feet by 14 feet with sidewater
depth of 10 feet.
• One Septage Holding Tank with dimensions of 16.25 feet by 18 feet with a total
storage of approximately 19,700 gallons.
• Three Primary Clarifiers with dimensions of 81.5 feet by 18 feet with a side
water depth of 7 feet.
• Three Aerated Sludge Holding Tanks with varying dimensions of 16.25 feet by
18 feet for Tank No. 1 and Tank No. 2, and 13 feet by 25 feet for Tank No. 3.
• Two 1.0 meter Belt Filter Presses.
• Ten Rapid Infiltration Basins each 1.02 acres with a maximum loading depth of
2.5 feet.
• Multi-stage odor control system consisting of cooling chamber, acid wash
chamber, mist chambers followed by activated carbon chambers.
• Chemical storage and feed systems for chemically enhanced primary treatment.
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The Nantucket Surfside Wastewater Treatment Facility (WWTF) was designed in 1987
for expected conditions up to the summer of 2007 and is currently permitted to discharge
1.80 mgd. Although the Surfside WWTF is designed for 2.24-mgd, it currently has a
Class III Groundwater Discharge Permit issued by the Massachusetts DEP for only 1.80
mgd. Table 2-8 provides the limits imposed by the DEP Class III Groundwater
Discharge Permit issued March 4, 1992. A complete copy of the permit is included in
Appendix E. Over the last few summers, the facility has approached its permitted flow
limit. The DEP has refused the Town’s application to increase its discharge permit limits
to its capacity of 2.24 mgd.
TABLE 2-8
TOWN OF NANTUCKET
CWMP/DEIR
MASSACHUSETTS GROUNDWATER
DISCHARGE PERMIT No. 1-200 LIMITS
Effluent Discharge Limitation
Characteristics Units Average Daily Maximum Daily
Flow mgd 1.80 5.80
BOD5 mg/L 215 230
TSS mg/L 225 230
Oil & Grease mg/L 15.0
pH --- 6.5 – 8.5
The detailed design criteria for the existing Surfside WWTF is included in Table 2-9.
Peak flow on the Island is in the summer months between June and September and has
averaged 1.63 mgd as shown on Table 2-10 and Figure 2-11. The off-peak season on the
island records lower flows during the months of October through May, with an average
of 1.05 mgd. The quantity of wastewater into the wastewater system is influenced
heavily by the summer months, of which includes tourist season and an increase in the
residential population.
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CWMP/EIR – PHASE 2 REPORT
TABLE 2-9
TOWN OF NANTUCKET
CWMP/DEIR
SURFSIDE WWTF DESIGN DATA
Criteria
Initial Year
(1987)
Future Year
(2007)
Design Loading Data
Population 12,225 20,100
Flow (mgd)
Average Daily 1.6 2.24
Domestic 1.5946 2.2288
Septage 0.0054 0.0112
Peak Daily 4.8 6.68
Biochemical Oxygen Demand (lbs/day) 3,729 5,871
Domestic 3,387 5,264
Septage at 15,000 mg/L 293 607
Suspended Solids (lbs/day) 3,729 6,426
Domestic 3,056 5,025
Septage at 15,000 mg/L 673 1,401
Process Design Data
Aerated Grit Chamber
Number 1
Dimension, Each (feet) 12 x 14
Side Water Depth (feet) 10
Grit Screw Horsepower, Each ¾
Air Requirements, Each
Flow (cfm) 50 to 80
Pressure (psi) 9
Grit Washer
Number
12-inch Cyclone 1
10-inch Classifier 1
Horsepower ½
Aerated Septage Holding Tank
Number 1
Size, Each (feet) 16.25 x 18
Mixing Type Diffused Air
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CWMP/EIR – PHASE 2 REPORT
TABLE 2-9 (cont)
TOWN OF NANTUCKET
CWMP/DEIR
SURFSIDE WWTF DESIGN DATA
Criteria
Initial Year
(1987)
Future Year
(2007)
Air Requirements
SCFM Per 1,000 CF 30
Per Diffuser (scfm) 12
Total Storage, Each (gallons) 19,690
Primary Clarifiers
Number 3
Size, Each (feet) 81.5 x 18
Side Water Depth (feet) 7
Effective Surface Area, Each (square feet) 1,467
Volume, Each (gallons) 76,812
Overflow Rate (gpd/sq. ft.)
Average Daily Flow 364 509
Peak Daily Flow 2,576 1,518
Loading Rate (gpd/lf of weir) 16,667 23,336
BOD Removal (%) 60
Effluent SS (lbs/day) 1,492 2,570
Rapid Infiltration Basins
Number Provided 10
Average Loading Rate (gpd/sq. ft.) 4
Loading Depth (ft) 2.5
Basin Area (acres) 1.02
Aerated Sludge Holding Tanks
Number 3
Size, Ea. (ft)
Tanks 1 and 2 16.25 x 18
Tank 3 13 x 25
Depth, Ea. (ft) 9
Volume Ea. (cu. ft.)
Tanks 1 and 2 5,265
Tank 3 2,981
Total 8,246
Mixing Type Diffused Air
Air Requirements
SCFM per 1,000 CF 20
Per Diffuser (scfm) 12
Total Storage at 4 percent solids (gal) 61,680
Total Storage at 4 percent solids (days) 9.2 5.34
Belt Filter Presses
Number 2
Size, Ea. (meter) 1
Sludge Feed (lbs. D.S./wk) 15,662 26,990
Unit Capacity
Dry Solids (lbs/hr) 1,000
Liquid Feed (gpm at 4 percent D.S.) 50
Washwater Requirements
Flow (gpm) 65
Pressure (psi) 85
Unit Horsepower 7.5
Operations (hrs/wk/unit) 11.17 17.83
Sludge Cake, Min (% D.S.) 25
Polymer Required (lbs./ton D.S.) 5 to 10
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CWMP/EIR – PHASE 2 REPORT
TABLE 2-10
TOWN OF NANTUCKET
CWMP/DEIR
SURFSIDE WWTF WASTEWATER
FLOWS (1999 through 2002)
Average Flows (mgd)
Month 1999 2000 2001 2002
January 0.85 0.92 1.05 0.83
February 0.93 0.93 0.93 0.82
March 1.14 1.10 1.31 0.88
April 1.00 1.24 1.35 0.95
May 1.19 N/A 1.36 1.14
June 1.24 1.58 1.61 1.38
July 1.68 1.91 1.83 1.73
August 1.80 1.98 2.02 1.81
September 1.27 1.45 1.37 1.45
October 1.35 1.14 1.24 1.00
November 0.90 1.05 0.88 1.37
December 1.00 0.99 0.75 0.99
Annual Average 1.20 1.30 1.31 1.20
Peak Season Average 1.50 1.73 1.71 1.59
Off-Peak Season Average 1.05 1.05 1.11 1.00
Although the Town continues to experience a high growth rate, the Town’s efforts to
reduce infiltration/inflow is reflected in the fact that the average for the last four years is
only 1.25 mgd, considerable below the permit limit annual average of 1.80 mgd. The
average daily discharge flow in 1999 was 1.20 mgd with a maximum flow of 1.80 mgd.
The flow increased in 2000 with an average of 1.30 mgd with a maximum of 1.98 mgd.
The flow in 2001 increased yet again to an average of 1.31 mgd with a maximum of 2.02.
The average flow in 2002 dropped to 1.20 mgd with a maximum of 1.81 mgd.
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NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT FIGURE 2-11 TOWN OF NANTUCKET CWMP/DEIR SURFSIDE WWTF FLOWS AND PRECIPITATION 0.001.002.003.004.005.006.007.008.009.0010.00Jan-99Mar-99May-99Jul-99Sep-99Nov-99Jan-00Mar-00May-00Jul-00Sep-00Nov-00Jan-01Mar-01May-01Jul-01Sep-01Nov-01Jan-02Mar-02May-02Jul-02Sep-02Nov-02DateTotal Rainfall, in0.00.51.01.52.02.5Total Flow, mgdTotal RainfallTotal Flow Page 2-78 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
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CWMP/EIR – PHASE 2 REPORT
Refer to Table 2-11, Table 2-12, Table 2-13 and Table 2-14 for design loading data and
process design data for the calendar years 1999, 2000, 2001 and 2002, respectively. The
Nantucket Surfside Wastewater Treatment Facility is permitted to discharge an effluent
BOD5 of 215 mg/L. Over the last four years the facility’s maximum effluent BOD5 was
119 mg/L or approximately 55 percent of the permitted limit. The average effluent BOD5
in 1999 was 89 mg/L, the average effluent BOD5 in 2000 was 95 mg/L, and the average
effluent BOD5 in 2001 was 93 mg/L, and the average effluent BOD5 in 2002 was 101
mg/L.
The Nantucket Surfside Wastewater Treatment Facility is permitted to discharge an
effluent TSS of 225 mg/L. Over the last four years the facility’s maximum effluent TSS
was 34 mg/L or only 15 percent of the permitted limit. The average TSS discharge in
1999 was 34 mg/L, the average TSS effluent discharge in 2000 was 34 mg/L, the average
TSS effluent discharge in 2001 was 35 mg/L, and the average TSS effluent discharge in
2002 was 40 mg/L.
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NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-11 TOWN OF NANTUCKET CWMP/DEIR SURFSIDE WWTF PERFORMANCE - 1999 Influent Quality Effluent Quality Sludge Month Avg. Flow Total TSS (mg/L) Total Solids (mg/L)Gals. (x 1000 gal) Lbs (x 1000 lbs) Feed Cake Solids Solids Solids Oil & BOD TSS (mgd) Grease (mg/L) (mg/L)(mg/L) Temp.BOD pH(C) (mg/L)(%) (%) January .8515.817412219507.009.6994189925.914.62.029.7February.9319.9128969836.879.51196269619.113.12.729.5March1.1414.0126825906.929.5815049722.813.51.830.8April1.0029.4148965566.85 12.01024546123.613.61.728.6May1.197.4N/AN/AN/A6.89 17.9833594827.717.62.727.3June1.246.22602386506.79 19.4751853532.119.92.729.0July1.688.02182266876.78 22.6871747137.621.52.931.4August1.809.6N/AN/AN/A6.8123.5911651440.622.42.729.8September 1.27 7.8 233 282 652 6.75 21.5771545133.317.32.228.5October1.359.81771845506.8318.1592637328.113.02.328.5November.9041.51411193906.6915.1974541916.98.32.329.3December 1.0018.1118100 450 6.79 11.7984149113.89.32.929.0Total1 14.35321.2 184.1 Average1.2015.61721547466.8315.8893456326.815.32.429.3Minimum.856.2118823906.699.5591537313.88.31.727.3Maximum 1.8041.526028219507.00 23.51196294840.622.42.931.4 N/A- Not Available 1The average, minimum, maximum under total are based on the monthly values reported in this table. Page 2-80 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-12 TOWN OF NANTUCKET CWMP/DEIR SURFSIDE WWTF PERFORMANCE - 2000 Influent Quality Effluent Quality Sludge Month Avg. Flow (mgd) Oil & Grease BOD (mg/L) TSS (mg/L)Total Solids (mg/L) pHTemp.(C) BOD (mg/L)TSS (mg/L) Total Solids (mg/L)Gals. (x 1000 gal) Lbs (x 1000 lbs) Feed Solids (%) Cake Solids (%) January .9219.612810617826.89.5904249119.511.32.330.6February.9320.71271639176.98.11034348813.05.22.426.5March1.1017.310410714656.910.8844476721.312.12.131.2April1.2421.0N/AN/AN/A6.712.1895040928.616.93.031.0MayN/A15.8N/AN/AN/A6.815.6994744324.315.22.731.9June1.5811.01911136357.019.1751840628.223.93.126.9July1.918.72091857747.021.5981155240.228.12.428.4August1.9811.82573057237.121.4962048042.223.62.129.3September 1.45 37.1 153 76 615 6.9 20.5892760436.317.81.928.9October1.1420.0N/AN/AN/A7.018.5963058738.719.32.428.5November 1.05 23.0 N/AN/AN/A7.014.01103352627.016.61.629.3December.9923.6N/A N/A N/A 7.010.31133884122.215.72.829.0Total1 14.30229.4341.8 205.7Average1.3019.11671519877.016.4953454928.517.12.429.3Minimum .92 8.7 104 76 615 6.7 8.1 75 11 406 13.0 5.2 1.6 26.5 Maximum 1.98 37.1 257 305 1782 7.1 21.5 113 50 841 42.2 28.1 3.1 31.9 N/A- Not Available 1The average, minimum, maximum under total are based on the monthly values reported in this table. Page 2-81 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-13 TOWN OF NANTUCKET CWMP/DEIR SURFSIDE WWTF PERFORMANCE - 2001 Influent Quality Effluent Quality Sludge Month Avg. Flow (mgd) Oil & Grease BOD (mg/L) TSS (mg/L)Total Solids (mg/L) pHTemp.(C) BOD (mg/L)TSS (mg/L) Total Solids (mg/L)Gals. (x 1000 gal) Lbs (x 1000 lbs) Feed Solids (%) Cake Solids (%) January 1.0518.01459011167.068.610444116230.011.21.328.2February0.9322.8116883837.078.2933697323.415.53.027.0March1.3124.21331394977.028.5835268719.313.32.728.4April1.3514.9129994197.0811.01013938136.023.93.430.3May1.3618.41411665657.0816.4722642735.621.43.528.1June1.617.02512777427.13 19.6923947939.223.03.225.4July1.8310.02102158147.17 22.51032653537.626.13.327.2August2.028.62332256847.0122.8961745139.325.32.728.5September 1.3719.22092457576.8720.9811956431.415.92.428.0October 1.2413.71901906176.9319.2923350725.614.42.927.8November 0.8825.71661655816.9515.51294751821.014.11.929.5December 0.7521.0150 94 741 6.9712.41455464313.08.02.529.4Total1 15.70351.4 212.1Average1.3117.01731666607.0215.5993661129.317.72.728.2Minimum0.757.0116883836.878.2721738119.326.11.325.4Maximum 2.0225.725127711167.17 22.814554116239.38.03.530.3 1The average, minimum, maximum under total are based on the monthly values reported in this table. Page 2-82 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-14 TOWN OF NANTUCKET CWMP/DEIR SURFSIDE WWTF PERFORMANCE - 2002 Influent Quality Effluent Quality Sludge Month Avg. Flow (mgd) Oil & Grease BOD (mg/L) TSS (mg/L)Total Solids (mg/L) pHTemp.(C) BOD (mg/L)TSS (mg/L) Total Solids (mg/L)Gals. (x 1000 gal) Lbs (x 1000 lbs) Feed Solids (%) Cake Solids (%) January 0.83 29.5 120915607.09 9.20 1064650816.811.12.627.4February 0.82 21.01171586607.08 9.15 1077585112.49.15.126.8March 0.88 11.91201046586.82 10.65945555416.811.73.025.2April 0.95 22.8 113874416.6512.731164737924.816.13.528.9May 1.14 27.6 1451295416.6415.42913742633.316.84.530.4June 1.38 8.01721637196.83 18.73892754430.617.53.427.0July 1.73 9.62071937706.70 22.951202856036.428.73.427.4August 1.81 4.51761246656.71 23.041151849630.321.73.127.5September 1.45 9.11731475836.62 20.9861653821.916.33.127.1October 1.00 15.61531165336.70 18.12963748622.314.43.328.4November 1.37 38.0110995546.74 13.889451602N/A8.23.031.8December 0.99 18.8130 88 485 6.73 10.231114640911.512.25.532.7Total1 14.35257.1 183.8Average1.2017.91471275996.7516.01014053126.317.63.528.1Minimum0.824.5110874416.629.15861637911.58.22.625.2Maximum 1.8138.02071937707.09 23.041207585136.428.75.532.7 1The average, minimum, maximum under total are based on the monthly values reported in this table. Page 2-83 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
Evaluation of Process Equipment
The condition of all of the process equipment at the Surfside WWTF was evaluated. The
equipment evaluation is based on a site visits, discussions with the WWTF staff and
review of maintenance records. The serviceability rating is based on the following
qualitative rankings show in Table 2-15.
TABLE 2-15
TOWN OF NANTUCKET, MASSACHUSETTS
CWMP/DEIR
SURFSIDE WWTF SERVICEABILITY RATINGS
Rating Description
3 Good
2 Fair
1 Poor
0 Inoperative
Headworks
The Bar Rack, Parshall Flume and Aerated Grit Chamber are located in the
Headworks. An evaluation of the Headworks equipment found of a badly
corroded grit collector screw and retrievable aeration piping in need of
replacement, and the need for aluminum plates instead of the grating currently in
place. Currently a grating system is in place that allows odors to escape into the
air while using aluminum plates would contain the odors and allow the odorous
air stream to be treated in the existing odor control system. Table 2-16 shows the
summary of equipment in the Headworks.
Solids Handling Building
Grit Dewatering System, Grit Pump, Septage Pump, Primary Sludge Pumps, Belt
Filter Press Feed Pumps, Odor Control Equipment including Chemical Feed
System and Air Compressor are located in the Solids Handling Building. The
investigation of the Solids Handling Building concluded that the Cyclone
Dewatering System and grit and septage pumps are in need of rehabilitation or
replacement due to severe corrosion. Table 2-17 shows the summary of process
equipment in the Solids Handling Building.
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NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-16 TOWN OF NANTUCKET, MASSACHUSETTS CWMP/DEIR SURFSIDE WWTF EVALUATION OF PROCESS EQUIPMENT – HEADWORKS Description Qty Manufacturer Run Time (hrs) Serviceability Rating Nameplate Comments Flow Measuring Device 1 Sigma 950 3 - Primary measuring device is a 12” Parshall Flume Grit Pump 1 Hayward Gordon 2,092 2.5 3” Retrievable Piping 1 0 - Located in Grit Chamber - Used for Air Distribution - Out of Service - Needs Replacement - Manufactured by Schloss Grit Collector Screw 1 1 - Badly Corroded Floor Grates 1 - Needs aluminum plate to replace grating covered by plywood for odor containment. TABLE 2-17 TOWN OF NANTUCKET, MASSACHUSETTS CWMP/DEIR SURFSIDE WWTF EVALUATION OF PROCESS EQUIPMENT – PRIMARY CLARIFIERS Description Qty Manufacturer Run Time (hrs) Serviceability Rating Nameplate Comments Clarifier Drives 3 FMC Min: 57,205 Max: 86,000 2 MCC 2 - Exterior of cabinets beginning to corrode Page 2-85 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
Sludge Management Building
Belt filter presses and ancillary equipment, plant water system and emergency
generator are located in or near the Sludge Management Building. The location
of the plant water system in the Sludge Management Building creates an
unfavorable suction condition due to its significant distance from the water
supply. This condition has caused the pumps to periodically become air bound.
The belt filter presses are in very poor condition due to the significant amount of
corrosion in the control panels, the frame, and the ancillary mechanical
components. The air compressor is ongoing maintenance issue, and the tracking
system requires frequent maintenance.
The WWTF generator is adjacent to the sludge management building and also
faces minor corrosion of the base and frame. Do to the limited sludge storage
capacity, longer dewatering operations will be required in the short term when
the additional sludge from the Siasconset WWTF is processed at the facility.
Table 2-18 shows the summary of equipment in the Sludge Management
Building.
Odor Control System
The evaluation of process equipment pertaining to odor control identified the
same problem as other equipment. The air purification towers contain electrical
controls and fan motors that are severely corroded. The prechlorination pumps
are also corroding. Table 2-19 shows the summary of equipment for Odor
Control. At this time, the Nantucket WWTF does not use a SCADA system.
SCADA would be beneficial to this facility as a way of monitoring operations
and alarms at the WWTF as well as at the remote pump stations.
It is evident that the Nantucket WWTF has a corrosion problem with most of its
above ground equipment. The most likely cause of this problem is the salt water
blowing off the ocean. In process areas (such as the Sludge Management
Building) the presence of hydrogen sulfide is also contributing to the problems
with corrosion. In any means, it is necessary to rehabilitate or replace this
equipment.
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NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-18 TOWN OF NANTUCKET, MASSACHUSETTS CWMP/DEIR SURFSIDE WWTF EVALUATION OF PROCESS EQUIPMENT – SOLIDS HANDLING BUILDING Description Qty Manufacturer Run Time (hrs) Serviceability Rating Nameplate Comments Cyclone 1Krebs2,0921- Located in Grit Room - Supplied by Schloss - Corroded Inplant Pump 1 Hydromatic 1.5 5 hp - Heavily corroded Septage Pumps 1 Hayward Gordon Grit Rml: 2,092 Septage: 1,256 2.5 200 gpm@24’ 5 hp - Dual purpose pump - Variable speed - Used for grit and septage Sludge Pumps (Primary Sludge) 3Penn ValleyMin: 2,425 Max: 2,872 2.5 300 rpm 80 gpm - Double Disc Sludge Pumps (Belt Press Feed) 2US MotorMin: 2,897 Max: 12,903 2- Progressing Cavity - Variable speed De-Humidifier1Dryomatic2.5- Currently in use - Possible location for plant water Blowers (Aerated Sludge Holding) Min: 24,380 Max: 56,860 2.5 Page 2-87 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-19 TOWN OF NANTUCKET, MASSACHUSETTS CWMP/DEIR SURFSIDE WWTF EVALUATION OF PROCESS EQUIPMENT – SLUDGE MANAGEMENT BUILDING Description Qty Manufacturer Run Time (hrs) Serviceability Rating Nameplate Comments Plant Water Pumps 3 Systecon 1: 10,806 2: 6,320 3: 4,097 2 - Pumps periodically become air bound due to unfavorable suction conditions Polymer Feed System 2 Milton Roy/ Acrison 2 100 gph - 6,000 lb/yr Belt Filter Presses 2 Roedigger11.0meter- Control panels badly corroded - Air compresser for tracking system requires frequent maintenance - Frame and ancillary mechanical components corroded. Plant Generator 1 Kohler 777 2.5 92 hp - Some corrosion on base and frame Page 2-88 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
Table 2-20 shows the summary of Primary Clarifier equipment. Table 2-21
shows the summary of equipment in the CEPT Building. Table 2-22 shows the
summary of all miscellaneous equipment.
Siasconset Wastewater Treatment Facility
The existing Siasconset sewerage system, which dates back in part as far as 1914 and
serves the densely built up area of the village along the easterly end of the island. It
extends to Sankaty Head Lighthouse on the north, Front Street on the east, Ocean Avenue
on the south, and Burnell Street on the west. The system discharges all wastewater to
four rapid sand infiltration basins located off of Low Beach Road via a 12-inch diameter
gravity sewer. Currently, all wastewater flow from the Siasconset area passes through a
flow-metering manhole, abandoned screening chamber and a settling tank prior to
discharge at the basins. The flow metering equipment consists of a parshall flume and
level element retrofitted into a manhole.
The United State Coast Guard (USCG) also has existing wastewater disposal facilities in
the same area as the existing Town facilities. The USCG sewer infrastructure consists of
gravity sewer on USCG property, which services the main buildings off the end of Low
Beach Road, and the housing on Silver Street (cul-de-sac off of Low Beach Road). All
wastewater is discharge to two rapid sand infiltration basins via a 10-inch diameter
gravity sewer that runs from Low Beach Road cross-country to the basins.
The existing effluent beds noted above have been improved, however untreated
wastewater is still being discharged to the ground through the rapid infiltration basins due
to abandonment of the Siasconset WWTF project in 1990 because of coastal erosion
concerns.
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NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-20 TOWN OF NANTUCKET, MASSACHUSETTS CWMP/DEIR SURFSIDE WWTF EVALUATION OF PROCESS EQUIPMENT – ODOR CONTROL Description Qty Manufacturer Run Time (hrs) Serviceability Rating Nameplate Comments Hypochlorite Storage Tanks 2 3 - Tanks hold 3,000 gallons each - Delivery time is once every two weeks - 50 gpd used for scrubbers - 250 gpd used for prechlorination - Hypochlorite only used between 5/15-11/15 Scrubbers 2Quad2.5Chemtact - Consists of 50 hp compressed air system manufacturered by Sull Air Air Purification Towers 2 Calgon 2 - Vessels appear to be in good condition - Electrical controls and fan motors are severly corroded Mist Chamber Fans 2 Hartzell 2 Carbon Filtration Fans 2 New York Blowers 220hp- Odor control for Composting not in use - Odor control for sludge management system is in use Potassium Permanganate 2 - 25,000 lbs used per year Prechlorination Pumps 2 Hydroflo 1.5 20 gph - One pump for each scrubber - Exterior of pumps are corroding Page 2-90 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-21 TOWN OF NANTUCKET, MASSACHUSETTS CWMP/DEIR SURFSIDE WWTF EVALUATION OF PROCESS EQUIPMENT – CEPT BUILDING Description Qty Manufacturer Run Time (hrs) Serviceability Rating Nameplate Comments Cationic Polymer System 1 Acrison 2.5 - Not in Use Anionic Polymer System 1 Acrison 2.5 - Amount used for chemically enhanced primary treatment is 25 lbs/yr - Amount used for de-watering is 6,000 lbs/yr Polymer Pumps 3 Milton Roy 2.5 - One pump for each system and one for standby use Potassium Permanganate Tank 1 2.0 - 2,000 gallons of storage available - 0.5% solution is used - Venturi system used for mixing Aluminum Salt Tanks 2 Poly Processing 2.5 - Tank 1 capacity is 3,000 gallons - Tank 2 capacity is 1,000 gallons - Tank 1 stores Aluminum Salts - Tank 2 originally used to store Sodium Hydroxide, currently used to store Aluminum Salts - Approximately five deliveries per year (mid May, mid June, mid July, late August & late September) - Usage: 25,000 gallons/ year Aluminum Salt Pumps 3 Milton Roy 2.5 #1 & 2: 8.8 gph #3: 5.2 gph - Pump 3 was originally used for Sodium Hydroxide Page 2-91 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT TABLE 2-22 TOWN OF NANTUCKET, MASSACHUSETTS CWMP/DEIR SURFSIDE WWTF EVALUATION OF PROCESS EQUIPMENT – MISCELLANEOUS Description Qty Manufacturer Run Time (hrs) Serviceability Rating Nameplate Comments Compost Blowers 10 Dayton Min: 1,652 Max: 7,891 2 Model: 4C329 - Not In Use - High Pressure Direct Drive Blowers Screener 11.5- Was used for composting - Out Of Service Sludge Mixer 1 SSI 2 - Was used for composting - Not In Use SCADA- Not currently in place - Could be useful at this facility - Current alarm and indication panel uses relays and indicator lights. Page 2-92 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc
NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
As noted above severe storms caused significant erosion that postponed
construction of the coastal Siasconset Wastewater Treatment Facility and only
minor modifications being made to the existing infiltration basins in 1991.
Several years after the minor modifications, Earth Tech was engaged by the
Town of Nantucket to evaluate the alternatives for providing wastewater
treatment and disposal for the Siasconset area of the Island.
As part of the Plan, a Needs Analysis was conducted to investigate existing
conditions and to project future needs. Evaluations of topography, watersheds,
natural resources, surficial geology, soils, existing land use and populations
trends (sewered versus non-sewered, seasonal versus year round), water supply
systems and wastewater conveyance and treatment systems were conducted and
future wastewater flows were projected. It was concluded that in the year 2022, a
projected peak seasonal population of 3,500 individuals would require a facility
with a design average flow of about 220,000 gpd. It was also projected that the
facility would meet effluent limit concentrations of 10 mg/L for BOD5, TSS, and
Total Nitrogen.
Feasible options for regional wastewater treatment and disposal at the existing
Surfside Wastewater Treatment Facility were also evaluated. These options
included the investigation of force main routes, pumping station requirements,
environmental issues, and an analysis of existing versus projected wastewater
flows at the Surfside Wastewater Treatment Facility. One of the major elements
evaluated in the Facilities Plan was the alternative of treatment and disposal of
wastewater within the Siasconset Planning area versus the transport of
wastewater to the Surfside Wastewater Treatment Facility for treatment and
disposal. Significant issues included site availability within the planning area,
environmental impacts, and costs. The EIR addressed specific environmental
issues, including rare and endangered species, and coastal erosion. The EIR also
included detailed cost analyses of the treatment facility and sewering options.
On-site treatment and disposal was selected as the solution for the Siasconset.
Sequencing Batch Reactors (SBR) were selected as the secondary treatment
process for the facility. Multiple basins will be installed to allow the Operator
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NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
flexibility in the number of basins to be operated during each particular season.
It is anticipated that two or three larger volume basins will be operated during
summer months and one or two smaller volume basins operated during winter
months. The process has been designed not only to treat the projected future
summer flows and loadings, but also to adequately treat the initial winter low
flow and loadings.
The entire project includes construction of an influent pumping station,
wastewater treatment facility and infiltration basins. The influent pumping
station is located near the basins and will pump all of the wastewater to the new
wastewater treatment facility. The raw wastewater will pass through a channel
grinder prior to entering the pump station. Wastewater will then flow through the
following processes: influent metering structure, primary clarifiers, SBRs, post
equalization, effluent filters, UV disinfection system and an effluent metering
structure. All treated wastewater is then discharged to the infiltration basins.
The design includes a totally covered process in order to maximize odor control
at the facility. A biofilter system for treatment of the odorous air stream was
chosen due to the fact that it has a low profile (below grade organic bed) and
does not require any chemicals for operation.
The system has been designed to provide complete treatment without the use of
chemicals. This was a requirement of the Town because of the fact that the
facility is located on an island and will not be fully manned. The Siasconset
Wastewater Treatment Facility will be operated as a satellite facility to the
existing Surfside Wastewater Treatment Facility. A supplemental alkalinity
(sodium bicarbonate) chemical feed system has been included as a safety
measure for the secondary treatment process, but it is not anticipated that this
system will be needed for normal operation of the process.
The groundbreaking for this facility occurred in November 2002 with an
estimated completion date of July 2004.
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NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
8. Potential Reuse Opportunities
As discussed previously in this section, typically treated effluent is discharged
either to a surface water body or to the ground with percolation through the soil
to the groundwater. A third option, discussed in this section, is to reuse the
wastewater for non-potable needs. Some communities, throughout the United
State, have adopted policies on wastewater reuse in an effort to conserve valuable
water resources and provide a means for the disposal of treated effluent. A
properly developed wastewater reclamation program can provide valuable
benefits to both the municipality and the water/wastewater system users. Fee
structures can be developed whereby consumers pay a flat fee or no fee at all for
unlimited use of reclaimed wastewater for lawn irrigation and other non-potable
uses. If such a structure includes fees based on usage for potable water,
consumers can realize an economic benefit by using reclaimed wastewater for
irrigation purposes rather than potable water. Such a pricing scheme would also
encourage water conservation.
The agricultural, industrial, and commercial consumers can realize similar
economic benefits. With proper treatment, reclaimed wastewater demonstrates
few health risks, while providing the community with a solution to their
wastewater disposal problem.
The Water Environment Federation explored water reuse issues at their Annual
Conference and Exposition in October 1998. Specifically, water reuse
innovations and alternatives were presented as they applied to numerous Florida
communities. Such technologies include water reuse for landscaping,
agricultural uses, and fire protection. Following is a discussion of these
alternatives, and commercial/industrial water reuse applications as they may be
applied to the Town of Nantucket.
Landscaping
Reclaimed wastewater has been successfully used as irrigation water for
residential, commercial, and industrial applications. Reclaimed water has several
advantages over the use of potable water for irrigation. In St. Petersburg,
Florida, it was shown that the application of 1½ inches of reclaimed water per
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CWMP/EIR – PHASE 2 REPORT
week provided approximately 50 percent of the nitrogen, phosphorus, and
potassium requirements for horticultural and agricultural purposes. This resulted
in reduced fertilizing costs to the consumer. A study completed by St. Petersburg
indicated that when chloride levels in the reclaimed wastewater were kept below
400 mg/L, plants being irrigated with reclaimed water showed significantly more
growth than those plants irrigated with water from the city’s potable water
system.
Agricultural Uses
The City of Orlando, Florida has achieved success in wastewater reuse through
the implementation of Water Conserv II, a comprehensive program whereby
water is reused in agricultural irrigation systems and aquifer recharge. In areas
with a significant agricultural industry, wastewater reuse can substantially reduce
the amount of wastewater to be disposed of by traditional surface or subsurface
application procedures. Depending on demand, reclaimed wastewater can be
given to agricultural consumers free of charge or for a nominal fee, thereby
providing an incentive to farmers by decreasing costs and providing an
alternative for wastewater disposal. Benefits from the nutrient enriched
reclaimed wastewater are similar to those cited for wastewater reuse for
landscaping purposes.
Fire Protection
The use of reclaimed wastewater for fire protection involves unique construction,
permitting, and regulatory limitations. For such a system to be developed, the
Town of Nantucket would have to work closely with local, state, and federal
environmental and regulatory groups to develop a policy for the design of a
facility utilizing reclaimed wastewater in its fire protection system. Initial design
considerations would include delineating the potential uses of the facility for
which the fire protection system is being designed (food preparation, retail outlet,
industrial, etc.), examining construction constraints, and addressing regulatory
concerns (for example, would building occupants be required to sign an
agreement prohibiting them from salvaging certain items in the event of a fire).
Development of this alternative could require substantial investment of time and
resources, as this technology is relatively new.
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CWMP/EIR – PHASE 2 REPORT
Commercial/Industrial Uses
Commercial/Industrial consumers can use reclaimed wastewater for process
water and other non-potable applications within their facilities, and for irrigation
outside their facilities as described above. Commercial/Industrial consumers
could also prove instrumental in the implementation of reclaimed wastewater in
fire protection systems. The specific nature of any given industrial application
would require that the industrial water reuse program be tailored to meet the
specific needs of each facility.
Health concerns of the public will need to be addressed to promote acceptance of
a reclaimed wastewater system. St. Petersburg, Florida, has had no reported
cases of illness or disease resulting from the use of reclaimed water since the
inception of their reuse program in the 1970s. This fact is significant in that
homeowners have control over their use of reclaimed water, and many of the
residents of St. Petersburg are elderly and thus more susceptible to disease. The
specific health risks associated with the wastewater produced in the Town of
Nantucket would have to be studied and addressed as part of the development of
a wastewater reclamation program.
The drawbacks of reclaimed water use can be mitigated through careful planning.
If demand is anticipated to exceed supply, the Town may consider installing
metering devices and developing a rate structure so that usage can be monitored
and controlled. The Town would need to develop the rate structure in
conjunction with the potable water rate structure to ensure that incentives are still
present to encourage consumers to use reclaimed wastewater for their non-
potable water needs. Should the supply of reusable water exceed the demand, the
Town would have to implement other wastewater disposal alternatives to
supplement reuse activities. Consumers would have to be educated as to the
benefits and proper use of a reclaimed wastewater system. For example, use of
reclaimed water is not recommended for car washing, as the high mineral content
in the wastewater will leave a mineral deposit on vehicles. Such educational
objectives could be included in the water conservation plan.
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Finally, construction costs must be minimized. Installing a new reclaimed
wastewater distribution system in an area can be quite costly due to restoration
costs associated with installing the necessary piping. However, if construction is
coordinated with other projects, such as the construction of a wastewater
collection system, economic benefits could be realized. If such construction
activities can be coordinated, it may make economic sense to install dry lines in
areas of new development to accommodate the reclaimed water supply when it
becomes available.
9. Residuals Disposal and Reuse
In this section, technologies are reviewed for possible application in meeting the
Town of Nantucket’s sludge management needs if a new wastewater treatment
facility is constructed. A description of each technology option is presented,
focusing on the process, products and/or sidestreams, relative advantages and
disadvantages. Some of these, such as dewatered sludge landfilling, are
considered to be “disposal” technologies because sludge, as a waste material, is
being disposed. Others are often referred to as “beneficial-use” technologies
because they result in a product form of sludge that can be recycled for beneficial
purposes. For example, composting processes sludge into humus-like material
that contains plant nutrients and is an excellent soil conditioner. Some
technologies, such as incineration, have both disposal and beneficial aspects.
Ash, the end product of incineration, is usually disposed in a landfill. However,
heat produced during combustion can also be recovered and is sometimes used to
generate electricity. Methane recovery from sludge digestion will not be
considered since it would only be provided with anaerobic digestion facilities.
These facilities are typically not economical for smaller wastewater treatment
facilities with flows less than 5.0 MGD.
Incineration with Ash Landfilling
Incineration reduces sludge to ash and gases, decreasing the volume for disposal
by approximately 95 percent. Sludge ash is a sterile, inorganic, non-odorous
powdery material that is typically conditioned with water to minimize blow-away
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during handling and landfilling. Incineration exhaust gas contains pollutants,
which must be treated with emissions control equipment prior to release to the
atmosphere.
Federal and state regulations govern both ash handling and air pollution controls.
The ash must meet the standards set forth in the RCRA toxicity characteristic
leaching procedure (TCLP) prior to landfilling. Exhaust gases must meet Federal
New Source Performance Standards (NSPS), National Emissions Standards for
Hazardous Air Pollutants (NESHAP) and the 40 CFR Part 503 regulations with
respect to emissions of hazardous air pollutants, plume capacity and flue gas
temperature and oxygen content.
Advantages of incineration as a sludge management technology are that it is a
well-established and proven technology; the resultant ash is sterile and odor-free
and requires minimal landfill volume; large quantities can be processed and
disposed of on a continuous basis; and storage and transport requirements are
minimal.
Disadvantages are that: it is a relatively complex technology requiring skilled
operators; capital and operating costs, including costs for emission control, are
high; and two sidestreams are produced, ash and emissions, which require
additional treatment and handling. Odor production is often associated with the
use of this technology due to the relatively low temperature combustion practiced
at many existing incinerator facilities. However, combustion at high
temperatures will be required to comply with future emissions standards, which
should largely eliminate odor releases.
Heat-Drying with Distribution and Marketing
Heat-drying is a beneficial-use technology which uses heat from either flue gases
or steam heat exchangers to evaporate moisture from dewatered sludge and
produce an organic fertilizer/soil conditioner for distribution and marketing. A
sidestream of exhaust gases is also produced which must be treated by emissions
control equipment before discharge to the atmosphere.
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Both the heat-dried product and the emissions resulting from the process are
subject to federal and state regulations relating to land application of sludge. The
Federal NSPS, the NESHAP, 40 CRF Part 503 regulations, and state regulations
would regulate the release of exhaust gases from heat drying.
The main advantage of heat drying is that it produces a beneficial, marketable
product which is less bulky and potentially more valuable than compost because
of its higher nutrient content. Thus, transportation to more distant markets is
sometimes practical. In addition to local marketing of the product, it can be
distributed through brokers to large users such as citrus growers and tree farmers.
Heat-dried product can be used as a substitute for chemical fertilizers and has
numerous landscaping and horticultural applications.
Disadvantages are that it is a relatively complex and expensive technology that
requires skilled operators, strict emissions/odor control, and efficient
storage/handling/and marketing of a product with primarily a seasonal demand.
Another factor to consider is competition from heat-dried products produced
outside of the Town of Nantucket (e.g. Boston, New York City and possibly
some other communities that formerly relied on ocean dumping).
Composting with Distribution and Marketing
Composting is a beneficial-use technology, which accelerates the biological
decomposition of dewatered sludge through aeration and the addition of volatile
organic material to produce a humus-like soil conditioner for distribution and
marketing. The composting process generates two sidestreams which require
treatment: a liquid sidestream consisting of condensate and leachate and an
exhaust air sidestream which must be treated with odor control equipment.
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Compost can be marketed to various industries and users. Compost can be used
for the following:
Greenhouse, Nursery, and Turfgrass Use: To provide a growing medium
and soil amendment in a mix with other media for potting non-food chain
plants, for growing and transplanting nursery stock, and for soil
enhancement prior to new seeding and maintenance.
Golf Courses and Landscaping: To provide organic matter during
maintenance and fertilizing of the grasses, and as a soil amendment.
Landfills: As an amendment to soil used for final cover material and for
subsequent slope management.
Topsoil and Land Reclamation: As a soil amendment to improve the
growing ability, nutrient content, and water retention of poor, sandy,
gravel type soils.
The main advantages of composting are the relative simplicity of the technology,
the fact that it produces a beneficial and marketable product from sludge waste,
and that it can aid in meeting solid waste management needs by utilizing tree
trimmings and other yard wastes in the sludge composting process.
Disadvantages include potential difficulties with odor control, dependence on a
successful marketing and distribution program, and substantial storage/handling
requirements for a bulky product with a primarily seasonal demand. Additional
factors to consider include availability of suitable land for compost application
and competition for a limited market.
Alkaline Stabilization
Alkaline stabilization is a beneficial-use technology which uses exothermic (heat
producing) reactions resulting from mixing alkaline materials with dewatered
sludge to evaporate moisture and kill pathogens and odor-causing bacteria, while
fixating (chemically binding) metals to produce an organic soil conditioner/soil
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substitute. Alkaline-stabilized sludge can be used for agricultural, landscaping,
and land reclamation purposes. Alkaline stabilized sludge is different than
compost. The chief difference is that it has a much higher inert solids content
due to the chemicals added during processing.
The main advantages of alkaline stabilization are that it is a relatively simple
technology and that it produces a usable material without generating sidestreams.
Disadvantages are the need for a continuous supply of alkaline material,
substantial storage and handling requirements, and reliance on dependable outlets
for product distribution.
Agricultural or Non-Agricultural Land Application
Land application is a beneficial-use technology in which liquid or dewatered
sludge is applied directly to the land to promote agricultural or non-agricultural
plant growth. Land application can also be a sludge disposal technology, when
sludge is applied at higher than agronomic rates to dedicated sites. Land-applied
sludge is usually pretreated for pathogen reduction and stabilized by lime
conditioning or aerobic or anaerobic digestion. If the sludge is applied properly,
potential sidestream problems (i.e. odors, surface run-off, and leachate) can be
averted.
Advantages of land application are that it is a simple technology based on
beneficial-use and little capital investment is required. Disadvantages are that:
large usable land areas must be available; operation is weather- and season-
dependent, necessitating provisions for sludge storage; and careful application
and monitoring are required to control problems with odors, surface runoff, and
leachate.
Dewatered Sludge Landfilling (Monofilling)
Monofilling is the disposal of sludge by burial in a dedicated sanitary landfill.
Preprocessing typically consists of dewatering and may include anaerobic
digestion or chemical treatment for stabilization. Proper design and operation is
required to control leachate, volatile organics emissions, and methane gas
seepage. Landfilling of dewatered sludge is regulated by the RCRA toxicity
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characteristic leaching procedure (TCLP), 40 CFR Part 257 requirements for
landfills, and by state regulations governing landfilling. Sludge rarely fails the
TCLP test and so is usually classified as non-hazardous.
Advantages of monofilling include simple operation, minimal processing and low
costs. The overwhelming disadvantage is the need for suitable landfill sites to
place the dewatered sludge.
Co-Disposal
Co-disposal is the treatment and/or disposal of sludge in conjunction with
municipal solid waste (MSW). Possibilities include co-incineration, co-
composting, and landfill co-disposal. While co-incineration has been
successfully practiced in other countries, there are only two large-scale
operations in the United States – one located in the Western Connecticut region
at Stamford, the other in Duluth, Minnesota. Western Connecticut also has a
very small co-incinerator located in New Canaan. Typically, dry sludge solids
are burned at a rate of 1 dry pound for every 5 to 8 pounds of MSW; the
Stamford facility operates at a 1 to 20 ratio.
Advantages of co-incineration are the reduction in combined costs of incinerating
sludge and MSW separately and the process efficiency, which allows complete
burning of both materials without the use of auxiliary fossil fuels (and provides
an excess of heat for steam generation if desired). Disadvantages are the
dependence on a supply of MSW and coordination of sludge quantities with
MSW quantities during the co-incineration process.
Co-composting sewage sludge with MSW is a co-treatment technology which
has had limited acceptance in the United States in the past, but is beginning to
receive interest. The process requires presorting and pulverization of MSW
before mixing it with liquid sludge containing 5 to 12 percent solids. A 2 to 1
ratio of solid waste to sludge is the recommended minimum. Although beneficial
product results, the quality of the compost is inconsistent and generally inferior
to compost made from sewage sludge alone.
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The most common co-disposal practice is sanitary landfilling, which is
advantageous because of the complimentary absorption characteristics of the
solid waste and the soil conditioning characteristics of the sludge. Co-disposal
costs are typically lower than the costs of a dedicated sludge landfill due to the
economy of scale. Disadvantages of utilizing a co-disposal site include
operational problems associated with mixing refuse and sludge, increased
leachate and odor potential, and site capacity concerns.
The Town of Nantucket dewaters sludge at the Surfside Wastewater Treatment
Facility. Although the facility has the capability to compost the dewatered
sludge using the aerated static pile method, the Town is currently hauling it to a
Municipal solid waste composting facility located at the Department of Public
Works in Madaket. The municipal solid waste composting facility in a privately
owned and operated under a 25-year contract.
Contract Disposal Alternatives
An alternative to the Town of Nantucket disposing its own sludge is to have the
material transported to a private contract disposal facility. The sludge could be
transported in cake form, with a dump truck or a container truck using watertight
bodies. Dump trucks typically have a normal capacity of approximately 12 cubic
yards, though smaller and larger sizes are available. Container capacities
typically average approximately 30 cubic yards, though smaller and larger sizes
are also available. Containers can be custom made in different sizes, shapes, and
dumping configurations to suit the needs of a specific location.
The sludge could also be thickened and pumped into a tank truck in liquid form
for disposal at a facility, which accepts liquid sludge. The liquid sludge is
transported in tank trucks, which typically hold approximately 6,500 gallons
(though smaller and larger capacities are available).
Various facilities are available throughout the New England area. Wastestream
Environmental (WSE), with facilities located in Fitchburg, Upper Blackstone,
Mattabassett, and Hartford; New England Treatment Company (NETCO),
located in Woonsocket, Rhode Island; Waste Management, Inc. in Rochester,
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New Hampshire; and Naugatuck Treatment Company in Naugatuck, Connecticut
are all contract disposal facilities in the New England region. Costs at these
facilities depend on how the sludge is transported (in liquid or solid form), and
the sludge has to meet various criteria established by each facility. The cost will
be dependent on the specific characteristics of the sludge, but typically range
from $0.10 to $0.20 per gallon for liquid sludge and $90 to $100 per wet ton for
dewatered sludge. This fee typically covers the tipping fee at the facility but
does not cover the transportation costs from the Island.
Innovative Technologies
“Innovative technologies” is the generic term applied to a range of
unconventional sludge disposal technologies. In general, these technologies have
been demonstrated on a pilot scale or small facility basis, but have not seen
widespread use. End products range from a compost-like material to a concrete
aggregate substitute.
The following technologies are some of the more widely known, if not widely
practiced innovative technologies.
Aggregate Production
This type of process is available in various forms and is generally similar
to conventional incineration in that sludge volatiles are burned, leaving
only the inert fraction. In one of the process variations, sludge is burned
in a special furnace at very high temperatures to induce slag formation.
Instead of ash, liquid slag is removed from the bottom of the furnace and
dropped into a quenching medium, such as water, forming a stable,
fused, glassy solid, suitable for reuse as aggregate. This process is being
marketed by World Envirotech, and is used at a wastewater facility in
Monticello, New York.
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Earthworm Conversion, or Vermiculture
This is a stabilization process by which earthworms consume the organic
material in municipal wastewater sludge. The product of Vermiculture
(i.e., the worm castings) may be used as a soil conditioner, similar to
compost. This technology is still in the experimental stage. There are no
significant facilities in the United States.
Fuel from Sludge
The conversion of sludge solids to oil and char under pressure has been
proven technically feasible under laboratory conditions. However,
commercialization and scale-up have been estimated to be prohibitively
expensive.
Deep Well Oxidation
This process uses conventional oil well drilling technology to position an
annular reactor in a vertical position up to one mile below grade. The
process takes advantage of the great hydraulic head generated by the
liquid column, along with the application of head and oxygen, to oxidize
the sludge organics. A small prototype facility was constructed and
operated with mixed results in Longmont, Colorado early in the 1980’s.
Privatized facilities using modifications to the original concept are under
evaluation in Houston and Detroit. Chief disadvantages of the process
are corrosion or scaling of the reactor surfaces and generation of a side
stream with a high soluble organics content, which requires additional
treatment. The main advantages are the generation of a relatively inert
ash-like product, with low land area requirement.
As with the conventional technologies described previously, any
innovative technology would also be subject to corresponding federal
and state regulations governing processing and distribution. For
example, the aggregate production process would be regulated in a
manner similar to incineration, focusing on air quality impacts.
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Each of the innovative technologies described above has its unique
advantages. For example, the aggregate production process solves the
problem of ash disposal resulting from conventional incineration,
assuming a market for the aggregate material is found.
The major disadvantage of all innovative technologies is that they are
untried and unproven on a large scale in the United States. High costs
and operational problems are generally incurred in operating a facility
based upon a new unproven process.
A prime example of this is the difficulties experienced by the City of Los
Angeles with its innovative oil-based sludge drying system used at the
Hyperion treatment plant, which represented the first large-scale
adaptation of this technology for wastewater sludge in the U.S.
D. WASTEWATER REUSE FOR ARTIFICIAL RECHARGE
1. General
This section provides an overview of salient aspects, generally of a technical
nature, applicable to wastewater reuse for artificial recharge. Legal, institutional,
and economic aspects are not a part of this discussion. These aspects include (a)
desirable wastewater treatment levels, and (b) treatment technologies that
represent components of process train(s), which will produce effluent suitable for
artificial ground water recharge. This chapter also provides brief descriptions of
relevant representative projects currently in operation, which produce wastewater
effluents for artificial recharge or potable water reuse.
2. General Requirements For Wastewater Usage For Artificial Recharge
National Research Council’s report on Ground Water Recharge Using Waters of
Impaired Quality (1994) has extensively researched the aspects of wastewater
usage for artificial recharge. The following pertinent information is summarized
using the material presented in that report.
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Based on current information, wastewater used to recharge the ground water
must receive a sufficiently high degree of treatment (minimum secondary
treatment) prior to recharge so as to minimize the extent of any degradation of
native ground water quality, as well as to minimize the need for and extent of
additional treatment at the point of extraction. After proper treatment, the
wastewater is ready for recharge, either through surface spreading and infiltration
through the unsaturated zone or by direct injection into ground water. Recharge
by infiltration takes advantage of the natural treatment processes, such as
biodegradation of organic chemicals that occurs as water moves through soil.
The quality of the water prior to recharge is of interest in assessing the possible
risks associated with human exposures to chemical toxicants and pathogenic
microorganisms that might be present in the source water. Although one can
reasonably expect that such constituents will often be reduced during filtration
through the soil, as well as subsequently in the aquifer, a conservative approach
to risk assessment would assume that toxicants and microorganisms are not
completely removed and some are affected only minimally prior to subsequent
extraction and use. Thus when recharge water is withdrawn later for another
purpose, it may require some degree of post treatment, depending on its intended
use.
There are several operational issues that must be addressed on a site-specific
basis. These concerns are related to project sustainability, treatment needs,
public health impacts, and economic and institutional constraints. In the short-
term, project sustainability is controlled by operating and managing the system so
as to prevent or control clogging. Long-term sustainability is dependent on
finding the best combination of pretreatment, soil-aquifer treatment, and post
treatment for determining whether the wastewater used for recharge will exceed
the treatment and removal capacity of the soil-aquifer treatment system.
Constituents of concern in municipal wastewater include organic compounds,
nitrogen species, pathogenic organisms, and suspended solids. Treatment
processes are readily available and have been used successfully to treat municipal
wastewater effluent to levels acceptable for various recharge applications.
However, even when treated to a very high degree, disinfection of the effluent
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with chlorine results in the formation of disinfection by-products (DBPs) with the
residual organic compounds. These DBPs are of concern if the recovered ground
water is to be used for potable purposes. Raw municipal wastewater may include
contributions from domestic and industrial sources, infiltration and inflow from
the collection system, and, in the case of combined sewer systems, urban
stormwater runoff.
The occurrence and concentration of pathogenic microorganisms in raw
wastewater depend on a number of factors, and it is not possible to predict with
any degree of assurance what the general characteristics of a particular
wastewater will be with respect to infectious agents.
Healthy individuals do not normally excrete viruses for prolonged periods, and
the occurrence of viruses in municipal wastewater fluctuates widely. Viral
concentrations are generally highest during the summer and early autumn
months. Viruses as a group are generally more resistant to environmental
stresses than many of the bacteria, although some viruses persist for only a short
time in municipal wastewater.
Dissolved inorganic solids (total dissolved solids or salts, TDSs) are not altered
substantially in most wastewater treatment processes. In some cases, they may
increase as a result of evaporation in lagoons or storage reservoirs. Therefore,
unless wastewater treatment processes specifically intended to remove mineral
constituents are employed, the composition of dissolved minerals in treated
wastewater used for ground water recharge can be expected to be similar to the
composition in the raw wastewater.
Based on the information collected by numerous researchers, the following
treatments for the two types of ground water recharge methods are considered
desirable: (1) If the wastewater is indirectly discharged to the aquifer, the
wastewater should receive secondary treatment followed by
nitrification/denitrification, sand filtration, and disinfection; and (2) If the
wastewater is used for direct injection to the aquifer, the wastewater should
receive secondary treatment followed by sand filtration, a membrane process
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(such as micro-filtration/reverse osmosis, or similar treatment), and disinfection.
It is assumed that if a membrane process is used, nitrification/denitrification will
not be required because the membrane process will remove nitrogen compounds
present in the wastewater.
3. Wastewater Treatment Levels and Technologies
General
Wastewater treatment levels are generally classified as preliminary, primary,
secondary, tertiary, and advanced. The nature of each level of treatment is
discussed in the following sections.
Primary Treatment
The first step in treatment, sometimes referred to as preliminary
treatment, generally consists of the physical processes of screening, or
comminution, and grit removal.
Past this initial screening, primary treatment consists of physical
processes to remove settleable organic and inorganic solids by
sedimentation and floating materials by skimming. These also remove
some of the organic nitrogen, organic phosphorus, and heavy metals.
Primary treatment, together with preliminary treatment, typically
removes 50 to 60 percent of the suspended solids and 30 to 40 percent of
the organic matter. Primary treatment does not remove the soluble
constituents of the wastewater. Primary treatment has little effect on the
removal of most biological species present in wastewater. However,
some protozoa and parasite ova and cysts will settle out during primary
treatment, and some particulate-associated microorganisms may be
removed with settleable matter. Primary treatment does not reduce the
level of viruses in municipal wastewater.
While primary treatment by itself generally is not considered adequate
for ground water recharge applications, primary effluent has been
successfully used in soil-aquifer treatment systems at some spreading
sites where the extracted water is to be used for non-potable purposes.
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A disadvantage of using primary effluent is that infiltration basin
hydraulic loading rates may be lower because of higher suspended solids
and weaker biological activity on and in the soil of the infiltration
system. Also, too much organic carbon in the recharge water can have
adverse effects on processes that occur in the soil and aquifer systems.
In most cases, wastewater receives at least secondary treatment and
disinfection, and often tertiary treatment by filtration, prior to
augmentation of non-potable aquifers by surface spreading.
Secondary Treatment
Secondary treatment is intended to remove soluble and colloidal
biodegradable organic matter and suspended solids (SS). In some cases,
nitrogen and phosphorus also are removed. Treatment consists of an
aerobic biological process whereby microorganisms oxidize organic
matter in the wastewater. Several types of aerobic biological processes
are used for secondary treatment, including activated sludge, trickling
filters, rotating biological contactors (RBCs), and stabilization ponds.
Generally, primary treatment precedes the biological process; however,
some secondary processes are designed to operate without sedimentation;
e.g., stabilization ponds and aerated lagoons.
Tertiary Treatment
The treatment of wastewater beyond the secondary or biological stage is
sometimes called tertiary treatment. The term normally implies the
removal of nutrients such as phosphorus and nitrogen, and a high
percentage of suspended solids. However, the term tertiary treatment is
now being replaced in most cases by the term advanced wastewater
treatment, which refers to any physical, chemical, or biological treatment
used to accomplish a degree of treatment greater than that achieved by
secondary treatment.
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Advanced Wastewater Treatment
Advanced wastewater treatment processes are designed to remove suspended
solids and dissolved substances, either organic or inorganic in nature. Advanced
wastewater treatment processes generally are used when a high-quality reclaimed
water is necessary, such as for direct injection into potable aquifers. The major
advanced wastewater treatment processes associated with ground water recharge
are coagulation-sedimentation, filtration, nitrification-denitrification, phosphorus
removal, carbon adsorption, and reverse osmosis.
Coagulation-Sedimentation
Chemical coagulation with lime, alum, or ferric chloride followed by
sedimentation removes suspended solids, heavy metals, trace substances,
phosphorus, and turbidity. Viral inactivation under alkaline pH
conditions can be accomplished using lime as a coagulant, but pH values
of 11 to 12 are required before significant inactivation is obtained.
Filtration
Filtration is a common treatment process used to remove particulate
matter prior to disinfection. Filtration involves the passing of wastewater
through a bed of granular media, which retain the solids. Treatment of
biologically treated secondary effluent by chemical coagulation,
sedimentation, and filtration has been demonstrated to remove more than
99 percent of seeded poliovirus. This treatment chain reduces the
turbidity of the wastewater to very low levels, thereby enhancing the
efficiency of the subsequent disinfection process.
The primary purpose of the filtration step is not to remove viruses, but to
remove protozoa and helminth eggs and other suspended matter that may
contain adsorbed or enmeshed microorganisms, thereby making the
disinfection process more effective.
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Chemical coagulation and filtration, followed by disinfection, can
remove or inactivate 5 logs (99.999 percent) of seeded polio virus and
bacteria through these processes alone; and subsequent to conventional
biological secondary treatment, can produce effluent essentially free of
measurable levels of bacterial and viral pathogens.
Nitrification
Nitrification is the biological conversion of ammonia nitrogen
sequentially to nitrite nitrogen and nitrate nitrogen. Nitrification does
not remove significant amounts of nitrogen from the effluent: it merely
converts it to another form.
Denitrification
Denitrification removes nitrate nitrogen from the wastewater. As with
ammonia removal, denitrification is usually done biologically for most
municipal applications. In biological denitrification, nitrate nitrogen is
used by a variety of heterotrophic bacteria as the terminal electron
acceptor in the absence of dissolved oxygen (anaerobic conditions). In
the process, nitrate nitrogen is converted to nitrogen gas, which escapes
to the atmosphere. The bacteria in these processes require a
carbonaceous food source (e.g., carbonaceous BOD, methanol).
Phosphorus Removal
Phosphorus can be removed from wastewater by either chemical or
biological methods, or a combination of the two.
Carbon Adsorption
One of the most effective advanced wastewater treatment processes for
removing biodegradable and refractory organic constituents is the use of
granular activated carbon (GAC). GAC can reduce the levels of
synthetic organic chemicals in wastewater by 75 to 85 percent. The
basic mechanism of removal is by adsorption of the organic compounds
onto the carbon. Carbon adsorption preceded by conventional secondary
treatment and filtration can produce an effluent with a Biochemical
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Oxygen Demand (BOD) of 0.1 to 5.0 mg/L, Chemical Oxygen Demand
(COD) of 3 to 25 mg/L, and Total Organic Compound (TOC) of 1 to 6
mg/L.
Reverse Osmosis
Reverse Osmosis (RO) is used mainly as a wastewater treatment process
to remove suspended and dissolved solids (including microorganisms),
either organic or inorganic. Removal is accomplished by the passage of
wastewater through a semi-permeable membrane. The size, shape,
chemical characteristics, and concentration of the chemical species, as
well as the physical and chemical characteristics of the feed wastewater
and type of RO unit employed influence constituent removal. Because of
the nature of the RO process, feed wastewater must be of a fairly high
quality (low suspended solids content) to prevent membrane clogging
and deterioration.
Emerging Hybrid Technology
Membrane bioreactor (MBR) is an emerging technology, which
combines an activated sludge reactor with a membrane filtration unit.
The end result is an effluent that is similar to the one that is produced by
a process train consisting of a secondary treatment followed by tertiary
treatment and advanced treatment. MBR process essentially eliminates
the tertiary treatment step. The MBR effluent is considered suitable for
aquifer recharge.
Disinfection
The most important process for the destruction of microorganisms is disinfection.
Although the most common disinfectant is chlorine, ozone (O3) and ultraviolet
(UV) radiation are other prominent disinfectants used at wastewater treatment
plants. Other disinfectants, such as gamma radiation, bromine, iodine, and
hydrogen peroxide, have been considered for the disinfection of wastewater, but
are not generally used because of economical, technical, operational, or
disinfection efficiency considerations. Membrane processes (e.g., micro-
filtration, ultrafiltration, and reverse osmosis) have been shown to be effective in
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removing microorganisms, including viruses, from municipal wastewater, but
again are not commonly used. The strategy in the selection and use of
disinfectants for source waters prior to recharge should recognize the possibility
that the nature and quantities of the disinfection by-products (DBPs) that may be
formed are different from those in conventional water treatment. For example,
both chlorine and ozone react in wastewater with organic precursors, which are
likely to be greater in number and concentration than in freshwater sources of
drinking water, to form DBPs. Accordingly, treatment of water for potable
purposes is being modified to minimize the use of oxidizing disinfectants.
However, in the treatment of wastewater for non-potable purposes, the numbers
and concentration of DBPs are of less concern because long-term ingestion is not
an issue.
Chlorine
The efficiency of disinfection with chlorine depends on the water
temperature, pH, degree of mixing, time of contact, presence of
interfering substances, concentration and form of chlorinating species,
and the nature and concentration of the organisms to be destroyed. In
general, bacteria are less resistant to chlorine than viruses, which in turn
are less resistant than parasite ova and cysts.
The chlorine dosage required to disinfect a wastewater to any desired
level is greatly influenced by the constituents present in the wastewater.
Secondary effluent can be disinfected with chlorine to achieve very low
levels of coliform bacteria, although complete destruction of pathogenic
bacteria and viruses is unlikely to occur. Chlorination of secondary
effluent that has received further treatment to remove suspended matter
can produce wastewater that is essentially free of bacteria and viruses.
Chlorine, at the normal concentrations used in wastewater treatment,
may not destroy helminth eggs, Giardia lamblia, and Crypto sporidium
species.
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Ozone
Ozone is a powerful disinfecting agent and a powerful chemical oxidant
in both organic and inorganic reactions. Due to the instability of ozone,
it must be generated on site from air or oxygen carrier gas. Ozone
destroys bacteria and viruses by means of rapid oxidation of the protein
mass, and disinfection is achieved in a matter of minutes. Some
disadvantages are that the use of ozone is relatively expensive and
energy intensive, ozone systems are more complex to operate and
maintain than chlorine systems, and ozone does not maintain a residual
in water. Ozone is a highly effective disinfectant for advanced
wastewater treatment plant effluent, and it removes color and contributes
dissolved oxygen. It also breaks down recalcitrant organic compounds
into more biodegradable compounds, which is advantageous for ground
water recharge and soil-aquifer treatment.
Ultraviolet Radiation
Irradiation of wastewater with ultraviolet radiation for disinfection is
potentially a desirable alternative to chemical disinfection, owing to its
inactivating power for bacteria and viruses, affordable cost, and the
absence of chemical disinfection by-products. Exposure of
microorganisms to the appropriate amount of electromagnetic (EM)
radiation disrupts the cells’ genetic material and interferes with the
reproduction process. Some bacteria have repair enzyme systems that
are activated by similar EM energies, and thus these particular bacteria
may repopulate disinfected waters after disinfection when exposed to
light. UV disinfection for water and wastewater is the newest of the
disinfection technologies and therefore, valuable large-scale field
applications are still under study. However, the trend is toward more use
of UV disinfection.
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4. Wastewater Recharge/Drinking Water Reuse Experience In The U.S.A.
General
There are approximately 1,900 wastewater reuse projects currently operating
throughout the USA (approximately 34 states have such projects). Only a very
small number (probably less than 10) of those projects use direct wastewater
recharge into an aquifer. In most cases, the wastewater is used (after proper
treatment) for irrigation of urban landscapes and agricultural land or industrial
purposes.
Within the United States, wastewater reuse is most common in Florida,
California and Arizona. Prominent projects of wastewater reuse for drinking
water or ground water recharge are as follows:
Water Factory 21 in Orange County, California
The Orange County Water District (OCWD) has been injecting high
quality reclaimed water into selected coastal aquifers to establish a
saltwater intrusion barrier. Seawater intrusion was first observed in
municipal wells during the 1930s as a consequence of basin overdraft.
Over-drafting of the ground water continued into the 1950s. Over-
pumping of the ground water resulted in seawater intrusion as far as 3.5
miles inland from the Pacific Ocean by the 1960s.
OCWD began pilot studies in 1965 to determine the feasibility of
injecting effluent from an advanced wastewater treatment (AWT) facility
into potable water supply aquifers. Construction of an AWT facility,
known as Water Factory 21, began in 1972 in Fountain Valley, and
injection of the treated municipal wastewater into the ground began in
1976.
Water Factory 21 accepts activated-sludge secondary effluent from the
adjacent County Sanitation Districts of Orange County wastewater
treatment facility. The 15 MGD water reclamation plant processes
consist of: lime clarification for removal of suspended solids, heavy
metals, and dissolved minerals; re-carbonation for pH control; mixed-
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media filtration for removal of suspended solids; activated carbon
absorption for removal of dissolved organic compounds; reverse osmosis
for demineralization and removal of other constituents; and chlorination
for disinfection and algae control.
Prior to injection, the product water is blended 2:1 with deep well water
from an aquifer not subject to contamination. The blended water is
chlorinated in a blending reservoir before it is injected into the ground.
Depending on conditions, the injected water flows toward the ocean,
forming a seawater barrier; inland to augment the potable ground water
supply; or in both directions. On average, well over 50 percent of the
injected water flows inland. It is estimated that this injected water makes
up no more than 5 percent of the water supply for area residents who rely
on ground water.
County Sanitation Districts of Los Angeles County Ground Water
Recharge Projects
Since 1962, the Whittier Narrows Water Reclamation Plant (WRP) has
used reclaimed water along with surface water and storm water to
recharge ground water in the Montebello Forebay area of Los Angeles
County by surface spreading of the reclaimed water. The reclaimed
water makes up a portion of the potable water supply for the area
residents that rely on ground water. From 1962 until 1973, the Whittier
Narrows WRP was the sole provider of reclaimed water in the form of
disinfected secondary effluent for recharge. Some surplus effluent from
a third treatment plant, the Pomona WRP, is released to the San Jose
Wash, which ultimately flows to the San Gabriel River and becomes an
incidental source for recharge in the Montebello Forebay.
The WRPs start their wastewater treatment with primary and secondary
biological treatment. In 1978, all three WRPs added tertiary treatment
with mono- or dual-media filtration and chlorination/dechlorination to
their treatment regimes.
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After leaving the reclamation plants, the reclaimed water is conveyed to
one of several spreading areas (either specially prepared spreading
grounds or dry river channels or washes). In the process of ground water
recharge, the water percolated through an unsaturated zone of soil
ranging in average thickness from about 10 to 40 feet before reaching the
ground-water table. The usual spreading consists of five days of
flooding, during which water is piped into the basins and maintained at a
constant depth. The flow is then discontinued. The basins are then
allowed to drain and dry out for 16 days. This wet and dry cycle
maintains the proper conditions for the percolation process.
Denver’s Direct Potable Water Reuse Demonstration Project
In 1968, the Environmental Protection Agency (EPA) allowed Denver to
divert water from the Blue River on the west side of the Continental
Divide on the condition that it examine a range of alternatives to satisfy
projected future demands of a growing metropolitan area. The Direct
Potable Water Reuse Demonstration Project was designed to examine the
feasibility of converting secondary effluent from a wastewater treatment
plant to water of potable quality that could be piped directly into the
drinking water distribution system. In 1979, plans were developed for
the construction of a demonstration facility to examine the cost and
reliability of various treatment processes. The 1.0 MGD treatment plant
began operation in 1985, and during the first three years, many processes
were evaluated. Data from the evaluation period was used to select the
optimum treatment sequence, which was used to produce samples for a
two-year animal feeding health- effect study. Comprehensive analytical
studies defined the product water quality in relation to existing standards
and to Denver’s current potable supply. The project water exceeded the
quality of Denver’s drinking water for all chemical, physical, and
microbial parameters tested except for nitrogen, and alternative treatment
options were demonstrated for nitrogen removal. The final health-effect
study demonstrated no health effects associated with either water. The
raw water supply for the reuse plant was unchlorinated secondary
effluent (treated biologically) from the metropolitan Denver wastewater
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treatment facility. Advanced treatment included high-pH lime treatment,
single- or two-stage re-carbonation, pressure filtration, selective ion
exchange for ammonia removal, two-stage activated carbon adsorption,
ozonation, reverse osmosis, air stripping, and chlorine dioxide
disinfection. Side stream processes included a fluidized bed carbon
reactivation furnace, vacuum sludge filtration, and selective ion
exchange regenerant recovery.
San Diego’s Total Resource Recovery Project
San Diego, California imports virtually all of its water supply from other
parts of the state. New sources of imported water are not readily
available; the availability of existing supplies is diminishing. The city is
thus actively investigating advanced water treatment technologies for
reclaiming municipal wastewater that is presently being discharged to the
Pacific Ocean. Preliminary experiments were conducted at the bench-
scale (20,000 gallons per day) Aqua I facility in Mission Valley from
1981 to 1986. The pilot-scale (300,000 gallons per day secondary,
50,000 gallons per day advanced) treatment Aqua II Total Resource
Recovery facility operated at Mission Valley from 1984 through 1992.
The full-scale demonstration Aqua III facility (1.0 MGD secondary,
500,000 gallons per day advanced) was constructed in Pasqual Valley
and began full-time operation in October 1994.
The Aqua II pilot facility uses channels containing water hyacinths for
secondary treatment followed by a 50,000 gal/day advanced treatment
system designed to upgrade the secondary effluent water to a quality
equivalent to raw water for potable reuse. A technical advisory
committee in conjunction with the city selected the tertiary and advanced
process trains in 1985. Tertiary treatment to produce a low-turbidity
water suitable for reverse osmosis feedwater was provided by a package
water treatment plant, with ferric chloride coagulation, flocculation,
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sedimentation, and multimedia filtration. The system included
ultraviolet light disinfection, cartridge filtration, chemical pretreatment,
reverse osmosis using thin-film composite membranes, aeration tower
decarbonation, and carbon adsorption. The final process train produces
water that meets U.S. drinking water standards.
Tampa Water Resource Recovery Project
The Tampa Water Resource Recovery Project was developed to satisfy
the future water demands of both the City of Tampa and the West Coast
Regional Water Supply Authority. The proposed project involves the
supplemental treatment of the Hookers Point Advanced Wastewater
Treatment (AWT) Facility effluent to achieve acceptable quality for
augmentation of the Hillsborough River raw water supply. In 1993, a
pilot plant was designed, constructed, and operated to evaluate
supplemental treatment requirements, performance, reliability, and
quality.
Source water for the pilot plant was withdrawn downstream from AWT
Facility denitrification filters prior to chlorination. The pilot plant
facility evaluated four unit process trains, all of which included
preaeration, lime treatment and recarbonation, and gravity filtration,
followed by either (1) ozone disinfection, (2) reverse osmosis and ozone
disinfection, (3) ultrafiltration and ozone disinfection, or (4) granular
activated carbon (GAC) adsorption and ozone disinfection. The process
train including GAC adsorption and ozone disinfection was selected for
design.
The City of Tampa’s industrial base is mostly food oriented. Inputs to
the wastewater system were confirmed by a “vulnerability analysis.”
Tampa has an active pretreatment program, and there has been no
interference with the plant’s biological process since startup in 1978.
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The design of the advanced treatment plant allows for rejection of water
at any level of treatment and diversion back to the main plant. The use
of a bypass canal for storage and mixing provides a large storage
capacity and constant dilution of product water with canal and river
water. Water can be diluted from the aquifer when river water is not
available. Flood control gates allow the canal to be flushed if a problem
is detected. Canal water can be drawn through a “linear well field” along
the canal to provide further ground water dilution. Five miles of canal
and river provide additional natural treatment prior to the intake for the
drinking water treatment plant.
Public Health Issues of Wastewater Effluent Recharge
The following material is derived from the information provided in the National
Research Council’s Report on Ground Water Recharge Using Waters of Impaired
Quality (1994).
A major consideration in the use of wastewater effluent for artificial recharge is
the possible presence of chemicals in the effluent that may be hazardous to
human health. At the present time, according to the National Research Councils
Committee Report on Ground Water Recharge Using Waters of Impaired
Quality, on the basis of available information, there is no indication that the
health risks from using reclaimed wastewater are greater than those from using
existing water supplies or that the concentrations of chemicals, with several
exceptions, or microorganisms are higher than those established in drinking
water standards set by the EPA.
Studies have been made of the chemical and microbiological characteristics of
recovered water, although they are limited in number and scope. Several studies
have shown that the recovered water can meet drinking water standards, even
when the recharge source is treated municipal wastewater. Such findings lead
some experts to the conclusion that these extracted waters are as acceptable as
water supplied from traditional sources. Other experts strongly disagree; saying
that water originating from an impaired source is inherently more risky. For
instance, disinfection of the recharge waters may develop a different mix of
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disinfection by-products (DPBs), often unidentified, from those found in
conventional water supplies. Also, the characterizations of the organic material
and the full range of microbiological constituents are incomplete. In addition,
source waters of impaired quality and recharge water withdrawn from the aquifer
at the point of use may contain some contaminants at higher concentrations than
are likely to be present in conventional water supplies. And throughout the
whole process, there is increased reliance on technology and management,
leaving open the door for errors. Thus, the question arises whether drinking
water standards developed for conventional water supply systems are sufficiently
protective of human health when ground water is recharged with waters of
impaired quality. There is a substantial amount of uncertainty principally related
to the presence of synthetic organic chemicals, inorganic chemicals, disinfection
by-products, and pathogenic organisms.
The assessment of health risks associated with recharge using wastewater
effluent is far from definitive because there are limited chemical and
toxicological data and inherent limitations in the available toxicological and
epidemiological methods. The limited data and extrapolation methodologies
used in toxicological assessments provide a source of limitations and
uncertainties in the overall risk characterization.
Similarly, epidemiological studies suffer from the need for very long time
periods required, because cancers have latency periods of 15 year or more.
Also, such studies require large populations to uncover the generally low risks
associated with low concentrations of toxicants. Past studies of the possible
adverse health effects from reclaimed water have tended to be limited in terms of
toxicological characterization and have focused only on those chemicals for
which drinking water standards exist.
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Summary and Conclusions
Many communities currently use water sources of varying quality, including
sources that receive significant upstream discharges of wastewater. In this sense,
cities upstream of drinking water intakes are already providing water reclamation
in their wastewater treatment facilities; for they treat the water, then release it
into the raw water supply used by downstream communities.
A small but growing number of communities include the use of highly treated
wastewater to augment water supply. Projects currently operating in the United
States generally produce reclaimed water that meets or exceeds the quality of the
raw waters those systems would use otherwise, as measured by current standards
established by the Safe Drinking Water Act. Current potable reuse projects and
studies have demonstrated that technology exists to produce reclaimed water of
excellent measurable quality and to ensure system reliability.
Assessment of health risks associated with recharge using wastewater effluent is
far from definitive because there are limited chemical and toxicological data and
inherent limitations in the available toxicological and epidemiological methods.
E. STORMWATER MANAGEMENT AND GROUNDWATER RECHARGE
INITIATIVES
The implementation of infiltration measures as part of stormwater management will
increase the annual recharge to groundwater. One method of improving the groundwater
infiltration may be creating improvements to developed subdivisions were stormwater
management was never applied. Some of the recharge potential in these subdivisions
could be restored by retrofitting the existing drainage systems to encourage infiltration.
The incorporation of infiltration trenches and basins, dry wells and water quality swales
are some of the measures that could be utilized. This stormwater management initiative
would be a large undertaking and potentially expensive to accomplish.
The Town began addressing its drainage and stormwater in 1999 with a project consisting
of an evaluation and mapping of limited areas of wastewater and drainage infrastructure
on Island. There have been numerous amendments to the original contract, adding
additional phases and the complete wastewater infrastructure area to the project.
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Extensive inspections have been performed on approximately 3,300 wastewater and
drainage manholes, drainage catch basins and drainage out-flow structures in Town.
Since 1999, additional work has been done not only inspections but also topographical
surveys, GIS mapping, and database developing for the Town. The most recent work
completed provides the Town with detailed horizontal and, more importantly, vertical
elevations of the entire wastewater and drainage infrastructures and an evaluation of the
14 outfalls that discharge into Nantucket Harbor. Work to be completed includes
individual catch basin watershed analysis and pipe system analysis.
F. SHORT LIST OF ALTERNATIVES
1. General
The CWMP/EIR Phase I and Phase II Documents identified a variety of
alternative wastewater disposal options to be evaluated for each area of
wastewater disposal need. These alternatives, which include (1) the continued
use of existing on-site wastewater disposal systems; (2) replacement of existing
wastewater disposal systems with Title 5 systems; (3) replacement of existing
wastewater disposal systems with on-site innovative/alternative (I/A) systems;
(4) replacement of existing wastewater disposal systems with cluster systems
consisting of a pressure system and communal subsurface disposal; (5)
replacement of the existing wastewater disposal system with a conventional
sewer collection system by, either: (a) connection into the existing collection
system at Surfside or Siasconset, (b) gravity sewers and pump station(s), (c)
pressure sewers and grinder pumps, or (d) a combination thereof.
Section 4.0 of this Phase II CWMP/DEIR Document evaluates the costs
associated with each of the short-listed alternatives and plan selection and
Section 5.0 will detail the final recommended plan.
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The CWMP/EIR Phase I Document determined study areas where conventional
Title 5 wastewater disposal systems are inadequate for long-term sustainability
and study areas where existing on-site systems can remain and be effective for
wastewater disposal. The Phase II Document has evaluated the alternatives listed
above for each of the identified Need Areas. The alternatives that will be further
evaluated for each of the areas of wastewater disposal need are shown in Table 2-
23.
TABLE 2-23
TOWN OF NANTUCKET
CWMP/EIR
ALTERNATIVE SUMMARY
Study Area On-Site I/A Communal Local
1-Madaket X X
2-Warren’s Landing X X
3-Cisco X
4-Somerset X X
5-Miacomet X
6-Surfside
7-Tom Nevers Low Density X
7H-Tom Nevers High Density X
8-Siasconset X
9-Quidnet X X X X
10-Wauwinet X X X X
11-Pocomo X X X X
12-Polpis X X X X
13-Town X
14-Town-WPZ X
15-Shimmo X X
16-Monomoy X X
17-Remainder of Island X
Note: Bold indicates a Need Area
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The continued use of existing on-site disposal systems was evaluated for all
Study Areas on Island. This was evaluated based on existing on-site systems and
with replacement title 5 systems. Local wastewater treatment and disposal
systems were evaluated for all areas of need since this is a viable alternative.
Communal wastewater treatment and disposal systems was evaluated only for
those areas of need in which there is a site or sites available for treated
wastewater effluent disposal within that specific Study Area. Innovative
Alternative wastewater treatment and disposal systems were evaluated for those
areas of need, which meet the severe soil limitations and high groundwater
criteria necessary for proper operation and maintenance.
An analytical approach was utilized to assess the viability of each alternative for
each of the individual Study Areas. The alternatives were evaluated based on
technical considerations, environmental benefits, and economic feasibility. A
screening process was used, which rejected options that do not meet the physical
constraints of the planning area, such as climate, soils, and topography. Options
were rejected if they were not compatible with air and water quality. Only
options that which appear to provide the greatest environmental, technical,
financial and institutional benefits have been short-listed. Other factors used in
the screening process include reliability, complexity, ease of implementation as
well as capital and operating costs.
2. Technical Considerations
On-Site Wastewater Disposal
On-site wastewater disposal was evaluated based on the ability of existing
systems to perform to current Title 5 standards. This includes optimizing
Septage Management Plans, maintenance and repair and upgrade of on-site
systems.
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Innovative/Alternative Wastewater Treatment and Disposal Systems
I/A treatment was evaluated based on the ability of the process to perform under
existing conditions. The review consists of answering “Yes” or “No” to the
following three questions: (1) Is a majority of the lot sizes within the Study Area
greater than one-third acre; (2) Do suitable soils exist for more than 70 percent of
the Study Area?; and (3) Do suitable groundwater conditions exist for more than
80 percent of the Study Area?
Is a majority of the lot sizes within the Study Area greater than one-third
acre?
Lot size has a direct effect on whether or not a failed on-site wastewater disposal
system can be repaired to meet Title 5 criteria with the use of I/A technologies.
It is assumed that under ideal soil and groundwater conditions, all lots of one-
third acre or less with an on-site wastewater disposal system would, as a
minimum, require a variance to Title 5 in order to be repaired. A one-third acre
lot size is the absolute minimum lot size, which is feasible for an upgrade of an
existing on-site wastewater disposal system.
Another contributing factor utilized in the screening process were the results of
the effect of the water balance in each of the 14 drainage sub-basins on the
Island, which is included in this section.
Based on all these factors, a short list of alternatives has been developed to meet
Nantucket’s long-term wastewater needs. Refer to Table 2-23 for the short-list of
alternatives.
Do suitable soils exist for more than 70 percent of the study area?
If 30 percent or less of the soils within a study area were classified as having
severe limitations (hardpan, bedrock, slope, flooding and wetness) the severe
soils criteria has been met. Soil types were obtained from the Nantucket County
Soil Survey Report by the U.S. Department of Agriculture.
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If the question is answered “Yes”, then I/A treatment is considered a feasible
alternative for existing areas of wastewater disposal need. If the question is
answered “No”, then the evaluation would continue and the next question which
must be answered “Yes” in order for I/A treatment to be considered a feasible
alternative for existing areas of wastewater disposal need.
Do suitable groundwater conditions exist for more than 80 percent of the
study area?
If 20 percent or less of a study area is classified as having a moderately shallow
to shallow (high water table at the surface to 2 feet deep) seasonally high
groundwater level, the severe groundwater criterion has been met. The U.S.
Department of Agriculture obtained high groundwater levels from the Nantucket
County Soil Survey Report.
If the question is answered “Yes”, then I/A technologies are considered a feasible
alternative for existing areas of wastewater disposal need. If the question is
answered “No” and the previous question was answered “No” then I/A
technologies are not considered a feasible alternative for existing areas of
wastewater disposal need.
If it is determined that the alternative is technically feasible then the alternative
will be reviewed for environmental benefits and economic considerations.
Local Wastewater Collection, Transmission, Treatment and Disposal System
The local wastewater collection, transmission, treatment and disposal system
alternative was evaluated based on the availability of site(s) for wastewater
treatment facilities and treated wastewater effluent disposal sites located within
the Town of Nantucket. The evaluation consists of answering “Yes” or “No” to
the following four questions: (1) Is there available capacity in either the
Siasconset Wastewater Treatment Facility or the Surfside Wastewater Treatment
Facility for additional flows from Needs Areas; (2) If capacity is available, is it
technically, economically and/or politically feasible to direct flow to either of
these WWTFs; (3) If necessary, are sites available for the construction of
wastewater treatment facilities?; and (4) Are sites available for treated
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wastewater effluent disposal via groundwater discharge?. All questions must be
answered “Yes” in order for local wastewater collection, transmission, treatment
and disposal system alternative to be considered a feasible alternative for two or
more designated areas of wastewater disposal need.
If it is determined that this alternative is technically feasible then this alternative
will be reviewed for environmental benefits and economic considerations.
Communal Wastewater Collection, Transmission, Treatment and Disposal
System
The communal wastewater collection, transmission, treatment and disposal
system alternative was evaluated based on the availability of site(s) for a
wastewater treatment facilities and treated wastewater effluent disposal sites
located within a given area of need. The evaluation consists of answering “Yes”
or “No” to the following two questions: (1) Is a site available for construction of
a wastewater treatment facility?; and (2) Is a site available for treated wastewater
effluent disposal via groundwater discharge?. Both questions must be answered
“Yes” in order for the communal wastewater collection, transmission, treatment
and disposal system alternative to be considered a feasible alternative for a
designated area of wastewater disposal need.
If it is determined that this alternative is technically feasible then this alternative
will be reviewed for environmental benefits and economic considerations.
3. Environmental Benefits
Each technically feasible alternative was further evaluated for its ability to meet
the following environmental goals: maintain stream flows, recharge Zone II
aquifers, and reduce pollutant loadings to preserve aquatic habitats. The
evaluation consisted of answering “Yes” or “No” to the following three
questions: (1) Does the alternative maintain stream flows?, (2) Does the
alternative recharge a Zone II aquifer area?, and (3) Does the alternative reduce
pollutant loadings?.
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Does the alternative maintain stream flows?
This question would be answered “Yes” if the treated wastewater effluent from
the alternative discharges into a location that would maintain stream flows within
the Town of Nantucket. A “Yes” answer would be indicative of an
environmental benefit. This question would be answered “No” if the effluent
from the alternative discharges into a location that would not maintain stream
flows within the Town of Nantucket. A “No” answer would indicate that the
alternative has no environmental benefit in maintaining stream flows.
Does the alternative recharge a Zone II aquifer area?
This question would be answered “Yes” if the treated wastewater effluent from
the alternative discharges into a Zone II aquifer, and therefore results in an
environmental benefit. Likewise, this question would be answered “No” if the
treated wastewater effluent from the alternative does not discharge into a Zone II
aquifer area and therefore would not result in an environmental benefit as
recharge.
Does the alternative reduce pollutant loadings?
This question would be answered “Yes” if the treated wastewater effluent from
the alternative reduces pollutant loadings to a higher degree than a conventional
Title 5 system. Since all of the alternatives being considered will reduce
pollutant loadings to a higher degree than a conventional Title 5 system, this
question will be answered “Yes” for all of the alternatives. Therefore, all of the
alternatives will reduce pollutant loadings and are environmentally beneficial.
4. Economic Considerations
All technically feasible and environmentally beneficial alternatives were further
evaluated with regard to estimated project costs and estimated annual operation
and maintenance costs. The estimated project costs include costs for
construction, engineering services, fiscal, legal, administrative, land acquisitions,
easements and police details. The estimated operation and maintenance costs
were converted to a present worth value based on the interest rate of 7 percent
and the expected life cycle of the alternative. Capital construction and operation
and maintenance costs were computed for each feasible alternative by designated
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NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
area of need. The total present worth value (capital construction and operation
and maintenance) for each feasible alternative was divided by the number of
users serviced in order to normalize the costs on a per user basis.
5. Water Balance Impacts
Water balance can be described as replacing whatever groundwater is removed
via potable sources and the elimination of groundwater recharge through the use
of on-site wastewater disposal systems with groundwater recharge by means of
treated effluent discharge into the ground.
Maintenance of water balance within the drainage sub-basins was a consideration
in the evaluation of alternatives. The cause and effects of alternative wastewater
treatment on the water balance in each sub-basin was reviewed for impacts.
Efforts to recharge the groundwater in any need areas whose water balance has
been affected by alternative wastewater treatment and disposal takes precedence.
Refer to Table 2-24 through Table 2-28 for the Island-wide effects on the water
balance. Section 4.0 of this report details the alternatives reviewed for each need
area and the effect, if any, on the water balance in the drainage sub-basin.
Background
The Commonwealth of Massachusetts Watershed Initiative is a collaborative
effort of state and federal agencies, conservation organizations, municipal
officials and other interested parties working towards protecting and restoring
natural resources and ecosystems on a watershed basis. Because watersheds are
defined by natural hydrology, they represent the most logical basis for managing
water resources.
The primary goals of the Watershed Initiative are to:
• Improve water quality;
• Restore natural flows to rivers;
• Protect and restore sensitive habitats;
• Improve public access and balance resource use;
• Improve local abilities to protect water resources; and
• Promote shared responsibility for watershed protection and management.
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NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT Page 2-133 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc TABLE 2-24 TOWN OF NANTUCKET CWMP/DEIR WATER WITHDRAWALS Name Subbasin Registered Volume (MGD)1 Permitted Volume (MGD)1 Days2 Actual Pumpage 12001 (MGD) Volume Distributed20013 (MGD) Summer Useage 20014 (MGD) Volume DistributedSummer 2001 (MGD) Estimated Useage 20255 (MGD) Volume Distributed2025 (MGD) Estimated Summer Useage 2025 4,5 (MGD) Volume DistributedSummer 2025 (MGD) Over Usage Volume6(MGD) Wannacomet Water Company (3 Wells) 0.610 0.62 365 0.71 Harbor 0.125 0.13 0.44 0.44 0.20 0.20 0.71 0.71 0.00 Harbor 0.674 0.67 0.85 0.85 1.08 1.08 1.36 1.36 0.00 Ocean 0.458 0.46 1.05 0.146 1.050.740.741.691.690.00Siasconset Water Department (4 wells) 0.110 0.00 365 0.21 Ocean 0.030 0.03 0.050.050.050.050.080.080.00 Ocean 0.030 0.03 0.050.050.050.050.080.080.00 Ocean 0.000 0.00 0.000.000.000.000.000.000.00 Ocean 0.140 0.14 0.330.330.220.220.520.520.00Miacomet Golf Course Miacomet 0 210 0.000 0.00 0.00 0.00 0.146 0.00 0.248 0.00 0.00 Wauwinet HouseHarborN/AN/A N/A0.0020.000.01300.00200.01300.00Surfside Beach Ocean N/A N/A N/A0.0000.00000.00000000.00Westender Restaurant Madaket N/A N/AN/A 0.00040.0004 0.001100.000400.00110Nantucket Golf Club Ocean 0 0.19 2400.10470.090.1800.1900.3200.00Nantucket Conservation Foundation Ocean 2.42003651.88000.941.88000.9400002.52Ocean View Farm Long 0.420 0 150 0.0800 0.040.160.080.420.210.840.420.46Sankaty Head Golf Course Ocean 0.13001830.14000.000.2400.1300.2200.18 TOTAL 3.690 0.956 3.664 2.526 5.243 3.794 3.230 2.552 6.103 4.879 4.081 Notes: 1. Listing from DEP printout entitled “Actual Water Use – 2001”. DEP lists withdrawals over the permitted period. Actual Usage numbers were adjusted for the whole year. 2. Days reflect approved number of days of operation. 3. Volume distributed reflects the volume of water, which flows to surface water or groundwater. Agricultural lands are calculated to have a 50% consumption rate and a 50% recharge rate. Golf courses, commercial, and industrial withdrawal are calculated to have a 100% loss. Industrial losses are assumed to be 100% since they discharge to the municipal WWTF and are included in the municipal collection calculations. 4. Summer usage assumes that the days of operation include July and August. 5. Estimated Usage is the registered or permitted withdrawal amount adjusted for the whole year. 6. Water Withdrawal Registrations issued before the Water Management Act include a clause which allows the Withdrawal Volume to exceed the Registered Volume by 100,000 gallons per day of operation. In subsequent tables, future water withdrawals are based on maximum permitted amount. Over usage volumes are shown here to illustrate a possible worst case scenario.
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT Page 2-134 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc TABLE 2-25 TOWN OF NANTUCKET CWMP/DEIR WATER BALANCE IMPACTS- 2001 ANNUAL Subbasin (-) Amount Withdrawn (mgd) (-) Amount Distributed (mgd) (-) Amount Collected (mgd) (+) Amount Discharged (mgd) Water Balance Impact (mgd) Groundwater Recharge (mgd) Capaum 0.00 0.000.000.000.000.00Harbor 0.800.570.770.00-1.01-0.21Hummock 0.000.060.090.00-0.02-0.02Long 0.080.040.000.00-0.040.04Madaket 0.000.000.000.000.000.00Maxcy 0.000.000.000.000.000.00Miacomet 0.000.210.290.00-0.08-0.08Ocean 2.781.500.651.80-0.130.86Sesachacha 0.000.000.000.000.000.00Tom Nevers 0.000.000.000.000.000.00Washing 0.000.000.000.000.000.00Total 3.66 2.386 1.80 1.80 -1.28 0.59
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT Page 2-135 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc TABLE 2-26 TOWN OF NANTUCKET CWMP/DEIR WATER BALANCE IMPACTS- 2001 SUMMER Subbasin (-) Amount Withdrawn (mgd) (-) Amount Distributed (mgd) (-) Amount Collected (mgd) (+) Amount Discharged (mgd) Water Balance Impact (mgd) Groundwater Recharge (mgd) Capaum 0.00 0.00 0.00 0.000.000.00Harbor 1.30 1.05 1.060.00-1.32-0.01Hummock 0.00 0.12 0.120.000.000.00Long 0.16 0.08 0.000.00-0.080.08Madaket 0.00 0.00 0.000.000.000.00Maxcy 0.00 0.00 0.000.000.000.00Miacomet 0.00 0.40 0.400.000.000.00Ocean 3.78 1.82 0.892.47-0.380.93Sesachacha 0.00 0.00 0.000.000.000.00Tom Nevers 0.00 0.00 0.000.000.000.00Washing 0.000.000.000.000.000.00Total 5.24 3.4682.472.47-1.780.99
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT Page 2-136 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc TABLE 2-27 TOWN OF NANTUCKET CWMP/DEIR WATER BALANCE IMPACTS- 2025 ANNUAL Subbasin (-) Amount Withdrawn (mgd) (-) Amount Distributed (mgd) (-) Amount Collected (mgd) (+) Amount Discharged (mgd) Water Balance Impact (mgd) Groundwater Recharge (mgd) Capaum 0.000.0000.000.000.000.00Harbor1.29 1.051 1.150.00 -1.39 -0.10Hummock0.000.1200.090.000.030.03Long0.42 0.000 0.10 0.00 -0.52 -0.10Madaket0.000.0000.110.00-0.11-0.11Maxcy0.000.0000.000.000.000.00Miacomet0.150.3970.330.00-0.080.07Ocean1.38 0.879 0.912.711.30-0.03Sesachacha0.000.0000.010.00-0.01-0.01Tom Nevers0.000.0000.000.000.000.00Washing 0.000.0000.000.000.000.00Total 3.23 2.4482.712.71-0.78-0.26
NANTUCKET, MASSACHUSETTS CWMP/EIR – PHASE 2 REPORT Page 2-137 Alternatives For Wastewater Disposal L:\work\27355\PROJ\Report\Phase II\Section 2.doc TABLE 2-28 TOWN OF NANTUCKET CWMP/DEIR WATER BALANCE IMPACTS- 2025 SUMMER Subbasin (-) Amount Withdrawn (mgd) (-) Amount Distributed (mgd) (-) Amount Collected (mgd) (+) Amount Discharged (mgd) Water Balance Impact (mgd) Groundwater Recharge (mgd) Capaum 0.000.000.000.000.000.00Harbor2.091.851.580.00-1.820.27Hummock0.000.150.130.000.020.02Long0.840.590.140.00-0.400.44Madaket0.000.180.150.000.020.03Maxcy0.000.000.000.000.000.00Miacomet0.250.530.460.00-0.170.08Ocean2.931.461.253.721.010.21Sesachacha0.000.010.010.000.000.00Tom Nevers0.000.000.000.000.000.00Washing 0.000.000.000.000.000.00Total 6.10 4.7693.723.72-1.341.05
NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
A significant change in the Commonwealth’s approach to managing the state’s water
resources occurred in 1993 with the adoption of the Watershed Initiative, a strategy to
implement integrated, watershed-based resource management by establishing
collaborative efforts among individuals, groups, municipalities and agencies with local,
regional, state and federal agencies in each watershed. The watershed is the primary
focus for coordinating and resolving resource management issues such as water supply
shortages, stream flows, fisheries and wildlife protection and wastewater assimilation.
The 1996 update of the Massachusetts Water Supply Policy Statement recommends that
action be coordinated with the watershed approach to strengthen local capability to
develop and implement water resource management programs. In addition, the 1996
statement advocates that: (1) communities recognize the interconnection of groundwaters
and surface waters in water supply management and planning; (2) local and regional
integration of planning and management of water supplies and wastewater treatment; (3)
aggressive implementation of water conservation measures; (4) watershed protection to
ensure both ground and surface water quality are protected and improved;
(5) reduce the need for out of basin resources (“keep it local”); and (6) the updating of
local zoning bylaws to protect and preserve the natural resources capacity while seeking
to provide adequate water supply and wastewater treatment.
It is these principles that form the foundation of the Commonwealth of Massachusetts
Watershed Initiative, which support the “watershed approach” to environmental planning
and decision making in order to guarantee the citizens and inhabitants of the
Commonwealth sufficient quantity and quality of water resources for the long-term.
An initiative of this CWMP/EIR is to evaluate the potential positive effects of the
disposal of highly treated wastewater effluent, as groundwater recharge, within the
various watershed subbasins on Nantucket, in offsetting groundwater withdrawals as
water supply and/or the replacement of on-site wastewater disposal facilities with sewers.
The primary focus of the evaluation centers on areas of Town that are currently sewered
or are a designated “Needs Area” where there is a potential for sewers. The result of the
water balance analysis is a definitive identification of the watershed subbasins where the
volume of groundwater removed as water supply is greater than, equal to or less than the
volume of groundwater recharge through wastewater disposal. Potential discharge sites
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NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
for the disposal of highly treated wastewater effluent will be given a priority within
stressed watershed subbasins. The watershed subbasins and Study Areas where sewers
exist or may exist in the future are shown on Figure 2-12.
The water balance is calculated by sub basin. The sub basins are delineated by Horsely,
Witen, Hegemann Entitled Water Resources Protection Plan, Nantucket Massachusetts,
Nantucket Land Counsel, January 1990.
The water balance is calculated using the following formula:
Water Balance = (–) Amount withdrawn (+) Amount distributed
(–) Amount collected
The groundwater recharge is calculated by the following formula:
Groundwater Recharge = (+) Amount distributed (–) Amount collected
Amount Withdrawn
The total amount of water withdrawn from each subbasin is the sum of the water
withdrawn from the municipal water supply sources and all non-municipal water
withdrawals by commercial/industrial entities that are required to report such data to the
DEP. The municipal withdrawal volume data is from the Department of Environmental
Protection’s 2001 Public Water Supply Annual Statistical Report. The non-municipal
withdrawal volume data is from the DEP’s 2001 Actual Water Withdrawal Report.
Additional water withdrawals from small capacity private wells that may be located
within certain watersheds are assumed to be negligible.
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SURFSIDE
WWTF
CAPAUM
HARBOR
TOM
NEVERS
OCEAN
OCEAN
OCEAN
12
11
4125
6
3
9
8
7
1013
1
2
14
SIASCONSET
WWTF
LONG
HUMMOCK
MIACOMET
SESACHACHA
MADAKET
WASHING
MAXCY
SURFSIDE
WWTF
CAPAUM
HARBOR
TOM
NEVERS
OCEAN
OCEAN
OCEAN
12
11
4125
6
3
9
8
7
1013
1
2
14
SIASCONSET
WWTF
LONG
HUMMOCK
MIACOMET
SESACHACHA
MADAKET
WASHING
MAXCY
* Source: MassGIS, Town of Nantucket Mapsheet developed by Horsley, Witten, Hegemann
Entitled Water Resources Protection Plan, Nantucket, Massachusetts Nantucket Land Council, January 1990.
SEPTEMBER 2003l:\work\27355\gis\maps\sites_figure2-12.mxd0 5,5002,750 Feet
FIGURE 2-12
AREAS OF WASTEWATER
DISPOSAL NEED AND
WATERSHED SUBBASIN
BOUNDARIES
NANTUCKET, MASSACHUSETTS
Existing Wastewater Service Area
Area of Wastewater Disposal Need
Based on Harbor Watershed Line
Area of Wastewater Disposal Need
Area of Wastewater Disposal Need Based
on Wellhead Overlay Protection Zone
Watershed Boundary*
LEGEND:
Wastewater Treatment Facility
Private Water Supply
Public Water Supply
Potential Site Boundary
14 Potential Wastewater Sites
Wetlands
Ponds
Roads
NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
The actual municipal withdrawal volumes, non-municipal withdrawal volumes and the
DEP registered and/or permitted withdrawal volumes for the year 2001 along with the
projected 2025 volumes of withdrawal from these sources are shown in Table 2-24. Each
registered and/or permitted water supply source was placed in its respective subbasin
based on its longitude and latitude and confirmed with the data included in the DEP
Water Management Act permit for each source.
The summer withdrawals for 2001 and estimated summer withdrawals for 2025 are
shown in Table 2-24. The summer withdrawals for 2001 are the average of the water
withdrawals on the Island for the months of July and August. The non-municipal
withdrawals for 2001 are the actual withdrawals from DEP and assume that the days of
operation include the moths of July and August. The 2025 summer non municipal
withdrawals are the maximum permitted amount and assume that the days of operation
include the months of July and August.
The projected water withdrawal from existing municipal water supply sources in 2025 is
based on the analysis performed for the Comprehensive Wastewater Management Plan.
It is projected that the average daily withdrawal volume will increase by approximately 2
percent each year from 2002 to 2025. It is assumed in this analysis that the increase in
withdrawal volume will be shared equally by all existing water supply sources and that
no new water supply sources will be developed before 2025. The estimate of 2025 non-
municipal withdrawals is assumed to be the maximum permitted amount.
Amount Distributed
The amount distributed is the volume of water dispersed throughout the entire water
system. The amount distributed is calculated by using the water use quantities for the
entire Island. The Island withdrawal quantities are then distributed across the area of
water service in each sub basin.
The current amount of municipal water distributed in Nantucket was reported to DEP in
the 2001 Public Water Supply Annual Statistical Report. The amount of water
distributed over each subbasin is estimated from the recorded volume of water reported to
DEP, as metered, to each category of municipal water customer. The difference between
the volume of water delivered through the municipal water system infrastructure and the
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NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
amount of water withdrawn at each supply source is unaccounted-for-water. The
unaccounted-for-water component is distributed proportionally across the entire area of
Town serviced by the municipal water system. Non-municipal withdrawals are added to
the amount distributed in their respective subbasins. The water balance assumes that
agricultural resources recharge the sub basins by 50 percent of their irrigation rate.1
Amount Collected
The amount of water collected is calculated by using the estimated quantity of
wastewater delivered to the municipal sewer system. The amount collected the
calculated quantity of wastewater pumped accepted at the Surfside WWTF in 2001 and
the estimated amount of wastewater accepted at Surfside WWTF in 2025. The total
collections are then distributed over the sewered area of the sub basins.
The annual total uses the discharge quantity from 2001, and the summer total uses the
average 2001 discharge quantity for the months of July and August. This data is taken
from the Phase I report. The 2025 total annual discharge assumes that the wastewater
treatment plants discharge the estimated flow for the design year as calculated in the
Phase I report. The 2025 summer discharge is proportional to 2001 summer discharge.
The 2025 collection area includes the Needs Areas.
Summary
The baseline water balance impact analysis for the calendar year 2001 is presented in
Table 2-25 and Table 2-26. The result of this analysis shows that water withdrawals
exceed groundwater recharge in five of the eleven subbasins located within the
Nantucket. These subbasins and the effective negative recharge are summarized as
follows:
• Harbor
• Ocean
• Miacomet
• Long
• Hummock
1 Viessmaen, Jr., Warren, Hammer, Mark J., Water Supply and Pollution Control, Fifth Edition, HarperCollins
College Publishers, 1993, pg. 32.
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NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
The major cause of negative recharge in these subbasins is the municipal water supply.
The Town’s existing groundwater supply sources are located within the subbasins with
the most impact, Harbor and Ocean. The effect of collecting potential recharge through
the existing sewer system is minimal with respect to the withdrawal of groundwater
supply from the municipal water supply system.
The projected water balance impact analysis for the calendar year 2025 is presented in
Table 2-27 and Table 2-28. The result of this analysis shows that water withdrawals
continue to exceed groundwater recharge in five of the eleven subbasins identified. Some
of the sub basins have changed due to proposed water withdrawal changes. The
projected effective negative recharge by subbasin for the calendar year 2025 are
summarized as follows:
• Harbor
• Long
• Madaket
• Miacomet
• Sesachacha
If it is assumed that the recommended town-wide wastewater management plan will
include sewering as a long-term solution for wastewater disposal in the identified Needs
Areas, then the amount of potential recharge from on-site wastewater disposal systems
will be reduced accordingly. As is the case presently, the effect of collecting potential
recharge through a proposed sewer system for the identified Needs Areas is minimal with
respect to the withdrawal of groundwater supply from the municipal water supply system.
The primary goal of the Commonwealth of Massachusetts Watershed Initiative is to keep
water local thereby maintaining more constant stream flows and recharging aquifer areas.
The identified potential subsurface wastewater disposal sites, located throughout the
Island of Nantucket will be evaluated for their ability to receive highly treated wastewater
effluent from existing and/or potential wastewater treatment facilities.
The result of the water balance analyses confirms that in certain watershed subbasins the
volume of groundwater removed as water supply is greater than the volume of
groundwater recharge through on-site wastewater disposal systems. Potential subsurface
wastewater disposal sites for highly treated wastewater effluent will be given a priority
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NANTUCKET, MASSACHUSETTS
CWMP/EIR – PHASE 2 REPORT
within the five identified stressed watershed subbasins for the design year of 2025.
Recharge from stormwater will be considered for the Harbor subbasin during the
evaluation and mapping project and recharge from a wastewater treatment facility will be
considered for the Long and Madaket subbasins.
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
3.0 SCREENING OF SITES FOR TREATMENT AND/OR DISPOSAL
A. CRITERIA DEVELOPMENT
The screening criteria presented in this section was developed to assess the viability of 14 sites
identified within Nantucket as potential wastewater treatment facility and/or wastewater disposal
facility sites. The screening criteria used to evaluate these potential project sites was based upon
eleven environmental criteria. The environmental screening criteria were chosen based upon
review by the Project Proponent and upon comments received by the Proponent in the Secretary
of the Executive Office of Environmental Affairs Certificate on the ENF dated October 2001. It
was determined that by applying the screening criteria to the 14 identified sites a short list of
selective potential sites would be established for additional evaluation through field testing. The
screening criteria chosen to evaluate the potential project sites are: (1) wetlands; (2) soils;
(3) drinking water supply - wellhead protection areas (Zone I and Zone II); (4) fisheries
(including shellfish areas); (5) waterbodies (distance from surface water); (6) floodplains;
(7) sensitive habitats; (8) park lands; (9) recreational resources; (10) agricultural/historical
interests; (11) shoreline change data; and (12) in or adjacent to an Area of Critical Environmental
Concern. A description of each screening criteria is given below and presented on Table 3-1.
The criteria was also developed with respect to whether or not there was an existing
“Opportunity” or environmental “Constraint” for the site to be utilized for a treatment facility
and/or disposal facility for Nantucket’s wastewater.
The designation of an “Opportunity” within the screening criteria reflects the positive aspects of
the environment that could be used in a beneficial manner in siting treatment and/or disposal
facilities. Similarly, the designation of environmental “Constraints” within the screening criteria
reflects aspects of the site and environment that would not be beneficial in siting these facilities.
The “Constraints” are identified as “Minimal”, “Moderate”, and “Severe” depending on the
extent and nature of the obstacles to developing each site. All sites were potentially located to
avoid directly impacting any of the screening criteria.
Page 3-1 Screening of Sites
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TABLE 3-1 TOWN OF NANTUCKET CWMP/DEIR CRITIERIA DESCRIPTION Page 3-2 Screening of Sites Screening Criteria Facility Surface water Discharge Groundwater Discharge Wetlands (a)Opportunity-N/A No Constraint-if greater than 200 feet from wetlands Minimal Constraint-if within 200 feet of wetlands Moderate Constraint-if within 100 feet of wetlands Severe Constraint-if within wetland Opportunity if wetlands present adjacent to Site No constraint if within 200 feet of wetlands Minimal constraint if between 200 and 400 feet from wetlands Moderate constraint if between 400 and 1000 feet from wetlands Severe constraint if greater than 1000 feet from wetlands Opportunity - N/A No constraint if greater than 1000 feet from wetland Minimal constraint if between 400 and 1000 feet from wetlands Moderate constraint if between 100 and 400 feet from wetland Severe constraint if within 100 ft of wetland Soils Opportunity-N/A No Constraint-based on mapped soil type Minimal Constraint- based on mapped soil type Moderate Constraint- based on mapped soil type Severe Constraint-if within known documented hazardous soil area No opportunity, minimal, or moderate constraint based on mapped soil type Severe constraint if within known hazardous area Opportunity if mapped within sand/gravel deposits No constraint - N/A Minimal constraint - N/A Moderate constraint - if mapped within till/bedrock Severe constraint if mapped within known hazardous area Drinking Water Supply Opportunity - N/A No constraint if outside Zone II Minimal constraint if within Zone II Moderate constraint - N/A Severe constraint - N/A Opportunity - N/A No constraint if greater than 1000 feet from Zone II Minimal constraint - N/A Moderate constraint if within Zone II and greater than 1000 feet from public well Severe constraint if within Zone II and within 1000 feet from public well Opportunity - N/A No constraint if greater than 1000 feet from Zone II Minimal constraint - N/A Moderate constraint if within Zone II and greater than 1000 feet from public well Severe constraint if within Zone II and within 1000 feet from public well Fisheries and Shell Fish Beds Opportunity-N/A No constraint if facility is downstream or greater than 1000 feet of fish stocking area Minimal constraint if facility is located within 400 feet from fish stocking area Moderate constraint if facility is located within 200 feet fish stocking area Severe constraint if facility is located directly in fish stocking area Opportunity - N/A No constraint if discharge is downstream or greater than 1000 feet of fish stocking area Minimal constraint if discharge within 400 feet from fish stocking area Moderate constraint if discharge within 200 feet fish stocking area Severe constraint if discharge directly into fish stocking area Opportunity - N/A No constraint if discharge downstream or greater than 1000 feet of fish stocking area Minimal constraint if discharge within 400 feet from fish stocking area Moderate constraint if discharge within 200 feet fish stocking area Severe constraint -N/A Waterbodies (a)Opportunity-N/A No Constraint-if greater than 200 feet from water body Minimal Constraint-if within 200 feet of water body Moderate Constraint-if within 100 feet of water body Severe Constraint-if within wetland Opportunity if adjacent waterbody present No constraint if within 200 feet of waterbody Minimal constraint if between 200 and 400 feet from waterbody Moderate constraint if greater than 400 feet from waterbody Severe constraint if greater than 1000 feet from waterbody Opportunity - N/A No constraint if greater than 1000 feet from waterbody Minimal constraint if between 200 and 1000 feet from waterbody Moderate constraint if within 200 feet from waterbody Severe constraint - N/A Floodplains (a)Opportunity - N/A No constraint if outside of floodplain Minimal constraint -N/A Moderate constraint - if within floodplain Severe constraint N/A Opportunity - N/A No constraint if outside of floodplain Minimal constraint -N/A Moderate constraint - N/A Severe constraint if within floodplain Opportunity - N/A No constraint if outside of floodplain Minimal constraint -N/A Moderate constraint - N/A Severe constraint if within floodplain Sensitive Habitat (a)Opportunity - N/A No constraint if outside of sensitive habitat Minimal constraint - N/A Moderate constraint if within sensitive habitat and greater than 100 feet from wetland Severe constraint if within sensitive habitat and within 100 feet from wetland Opportunity - N/A No constraint if greater than 200 feet from sensitive habitat Minimal constraint if within 200 feet of sensitive habitat Moderate constraint if within sensitive habitat and greater than 100 feet from wetland Severe constraint if within sensitive habitat and within 100 feet from wetland Opportunity- N/A No constraint if greater than 200 feet from sensitive habitat Minimal constraint if within 200 feet of sensitive habitat Moderate constraint if within sensitive habitat and greater than 100 feet from wetland Severe constraint if within sensitive habitat and within 100 feet from wetland Park Lands Opportunity - N/A No constraint if greater than 200 feet from park lands Minimal constraint if abutting park lands Moderate constraint - N/A Severe constraint if within park lands Opportunity - N/A No constraint if greater than 200 feet from park lands Minimal constraint if abutting park lands Moderate constraint if within park lands Severe constraint - N/A Opportunity- N/A No constraint if greater than 200 feet from park lands Minimal constraint if within 200 feet of park lands Moderate constraint if within park lands Severe constraint - N/A Recreation Resources Opportunity - N/A No constraint if greater than 200 feet from recreation resource Minimal constraint if within 200 feet of recreation resource Moderate constraint if within recreation resource area Severe constraint - N/A Opportunity - N/A No constraint if greater than 200 feet from recreation resource(b)Minimal constraint if within 200 feet of recreation resource Moderate constraint if within recreation resource Severe constraint - N/A Opportunity - N/A No constraint if greater than 200 feet from recreation resource Minimal constraint if within 200 feet of recreation resource Moderate constraint if within recreation resource Severe constraint - N/A Agricultural/Historic Interests Opportunity - N/A No constraint if greater than 200 feet from historic interest Minimal constraint if within 200 feet of historic interest Moderate constraint if directly abutting historic interest Severe constraint if within historic interest Opportunity - N/A No constraint if greater than 200 feet from historic interest Minimal constraint if within 200 feet of historic interest Moderate constraint if directly abutting historic interest Severe constraint if within historic interest Opportunity - N/A No constraint if greater than 200 feet from historic interest Minimal constraint if within 200 feet of historic interest Moderate constraint if directly abutting historic interest Severe constraint if within historic interest Shoreline Change Data Opportunity - N/A No constraint outside of area of documented erosion Minimal constraint if within 200 feet of documented erosion Moderate constraint if directly abutting documented erosion Severe constraint if within area of documented erosion Opportunity - N/A No constraint outside of area of documented erosion Minimal constraint if within 200 feet of documented erosion Moderate constraint if directly abutting documented erosion Severe constraint if within area of documented erosion Opportunity - N/A No constraint outside of area of documented erosion Minimal constraint if within 200 feet of documented erosion Moderate constraint if directly abutting documented erosion Severe constraint if within area of documented erosion Area of Critical Environmental Concern (ACEC)(a)Opportunity - N/A No constraint if outside of ACEC Minimal constraint -N/A Moderate constraint - N/A Severe constraint if within ACEC Opportunity - N/A No constraint if outside of ACEC Minimal constraint -N/A Moderate constraint – N/A Severe constraint if within ACEC (a)Opportunity - N/A No constraint if outside of ACEC Minimal constraint -N/A Moderate constraint – N/A(a)Severe constraint if within ACEC (a)Nantucket and Madaket Harbor Watersheds Opportunity - N/A No constraint if outside of Watershed Delineation Minimal constraint -N/A Moderate constraint - N/A Severe constraint-N/A Opportunity - N/A No constraint if outside of Watershed Delineation Minimal constraint -N/A Moderate constraint - N/A Severe constraint-N/A Opportunity - N/A No constraint if outside of Watershed Delineation Minimal constraint -N/A Moderate constraint - N/A Severe constraint-N/A (a) Based on available information, potential sites were located to avoid directly impacting wetlands, floodplains, ACEC (Site specific), sensitive habitat (Site specific) and waterbodies and are at least 100 feet removed. 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NANTUCKET, MASSACHUSETTS
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For those sites large enough to locate a facility or groundwater discharge site outside of any
environmental criteria onsite, either a “No Constraint” or “Opportunity” rating was given due to
the overall site size and availability of land outside of any environmental constraints.
• “Opportunity”: the positive attributes associated with the criteria that could be a
benefit to siting the facility (positive).
• “Constraint”: the nature of the obstacles associated with the criteria that could
negatively affect the siting of the facility.
1. “No Constraint”: the criteria does not have any positive attributes or impose any
obstacles to the siting of the facility (neutral).
2. Minimal Constraint”: the criteria imposes the lowest degree of obstacles in the
siting the facility.
3. Moderate Constraint”: the criteria imposes average obstacles to the siting the
facility.
4. Severe Constraint”: the criteria does impose extremely difficult obstacles to
overcome in the siting the facility.
For the purposes of this report, it is presumed that treated effluent from any proposed facilities
will be discharged to land, as the Massachusetts Ocean Sanctuaries Act prohibits ocean discharge
of municipal wastewater off Nantucket. Although the Ocean Sanctuaries Act permits
municipalities to apply for a waiver from its requirements, the Department of Environmental
Protection would most likely deny the consideration of ocean discharge as an option, as it did
during the Siasconset Facilities Planning Process. The Island is designated a Sole Source
Aquifer, by the Environmental Protection Agency under the auspices of the Safe Drinking Water
Act (Section 1424e) and gives the EPA the authority to review and restrict federal funding for
projects that represent threats to the aquifer. Although “Surface Water Discharge” is defined in
Table 3-1, any surface water discharges have been eliminated from consideration due to stringent
regulatory requirements and the lack of suitable surface waters located on the Island. The surface
fresh water bodies on Island are derived entirely from precipitation. Approximately 57 percent of
the precipitation is returned to the atmosphere by evaporation and transpiration by plants.
Significant amounts of this precipitation infiltrates the permeable sandy soils and recharge the
underground aquifer. A limited amount results in surface water runoff directly into the Island’s
few streams ponds, and wetland areas. A perfunctory review of these streams, ponds and wetland
areas located on Island identifies them as unsuitable for any treated effluent discharge due to not
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only their size but locations as well. The water resources for the Town are unique in that the
fragile ecosystem survives on a system whereby fresh groundwater floats on top of salt water due
to the density difference between salt and fresh. Surface water flow and the runoff from the land
area is directly related to the topography of the Island’s land area. Water moves from the higher
to the lower elevations, which in Nantucket’s case, is from center Island towards the shoreline.
Ultimately this groundwater movement discharges to the ponds, wetland areas, and harbors or
eventually in some areas to the open ocean.
At times of high groundwater, typically the spring months, many of these surface water bodies
are flooded by the natural cause of events. For this reason alone, these surface water bodies
cannot handle additional flow in the form of treated effluent.
Wetlands
The wetlands screening criteria is considered an important factor in siting both the treatment
facilities and effluent disposal facilities. It was determined that “No Opportunities” exist for
constructing treatment facilities or effluent disposal facilities in wetlands. These facilities would
need to be constructed in upland areas to avoid filling or alternation of wetlands. The wetland
related “Constraints” are based on distances from the wetland. The wetland screening criteria is
developed with the assumption that the potential facilities will be greater than 100 feet away from
wetland areas.
The wetlands criteria for surface water discharge facilities is considered more constrained the
further removed from the wetland, since the discharge of the treated effluent ideally should be
directly into the receiving water body. Those sites located within 100 feet of a wetland are
considered to present “Minimal Development Constraints” because the proximity of the treatment
facility and the length of the treated wastewater effluent discharge piping is minimized. Sites
located distant (greater than 400 feet) from the wetland/surface water would pose “Moderate” and
“Severe Constraints” since access to the discharge point is restricted.
Soils
Soil type is considered to have a greater influence on the selection of an effluent
disposal/groundwater discharge site than on the selection of a treatment facility site due to the
variable infiltration properties of soils. However, soil type is not as critical in selecting a
treatment facility or surface water disposal site since construction is predominantly above ground.
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The only “Constraint” associated with soil type for the construction of treatment facilities or
surface water discharge facilities is the presence of known hazardous materials on site. The soil
properties and the presence of hazardous material on site is considered primary to the selection of
potential groundwater discharge sites.
To ensure proper function of an effluent disposal facility, a suitable site must have a soil
permeability high enough to allow percolation of the effluent into the soil profile at a rate that
will properly treat the effluent. Suitable soil types were determined by review of the Nantucket
County Soil Survey Reports, developed by the U.S. Department of Agriculture's Soil
Conservation Service. Soil types with slight or moderate limitations for sewage disposal will be
considered to present “No Constraint” (slight) or “Minimal Constraint” (moderate) with regards
to locating a subsurface effluent disposal/groundwater discharge system. Soil types with severe
limitations for sewage disposal or soils mapped within hazardous areas will be considered to
present “Severe Constraints” with regards to locating a subsurface effluent disposal/groundwater
discharge system.
The soils within the Town of Nantucket are generally of four types. These soil types are listed
below in descending order of the soil’s suitability for potential groundwater discharge of treated
effluent.
• Soil Type 1: Sand and Gravel Deposits – 0 to 50 feet deep
• Soil Type 2: End Moraines
• Soil Type 3: Till or Bedrock
• Soil Type 4: Landfill
Sites located within areas, which are comprised of Soil Type 1, are considered to provide the
greatest “Opportunity”. Soil Types 2, 3 and 4 are not considered suitable for effluent disposal,
therefore, sites with these soil types are considered to have “Severe Constraints”.
Floodplains
Construction within 100-year floodplains is constrained by regulatory restrictions on development
within floodplain areas for protection of flood storage and for protection of the constructed
facility to flood hazards. This criteria was considered to present “Moderate Developmental
Constraints” with regard to siting of treatment facilities if located within a floodplain, and “No
Constraint” if located outside of a floodplain.
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Potential groundwater discharge sites located within the 100-year floodplain are restricted from
being located in velocity zones and floodways in accordance with DEP regulations (310 CMR
15.213(2)). A facility in the 100-year flood plain would also be more susceptible to flooding
during major storm events. Therefore, the floodplain site selection criterion was considered to
present “Severe Developmental Constraints” for groundwater disposal facilities if the potential
site is located within the floodplain. If the disposal site is outside the floodplain then “No
Constraints” are present to development of a groundwater discharge facility. The 100-year flood
plain was identified through review of the Federal Emergency Management Agency (FEMA)
Flood Insurance Rate Maps for Nantucket, Community-Panel Numbers 250230 0001-0020. Sites
with insufficient buildable area outside the flood plain were deemed unacceptable and were
eliminated from consideration.
Surface water discharge facilities located within a floodplain are a concern since the discharge
flow would represent additional flow that would have to be accommodated during the 100-year
flood event. Most of the primary streams in Nantucket are associated with a floodplain.
Therefore, potential flooding impacts could be buffered by the capability of the stream to handle
slight increases in flow. Therefore, surface water discharges within a floodplain were eliminated
from the evaluation as previously stated. If the disposal site is outside the floodplain then “No
Constraints” are present to development
Waterbodies (Distance from Surface Water)
Although surface water discharges have been eliminated from consideration as previously
mentioned, the following information regarding surface water discharges describe the usual
process for evaluation and is for discussion purposes only.
Proximity to waterbodies is considered a factor in the siting of surface water and groundwater
discharge locations. The location and construction of treatment facilities should not impact
waterbodies if the facility is located greater than 100 feet from the waterbodies. The screening
criteria for waterbodies is not considered to present “Developmental Constraints” on treatment
facility sites regardless of the location outside the resource.
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Surface water discharge sites are required to be located proximate to a surface waterbody.
Therefore, this site selection criteria is accorded substantial weight in the surface water discharge
site selection process when being considered. Those sites located proximate to surface
waterbodies are considered to present an “Opportunity” for development. Those sites, which are
not located proximate to a waterbody, are considered to present extensive “Developmental
Constraints” regarding the surface water discharge site selection process.
Groundwater discharge sites should be located a sufficient distance from a surface water to ensure
the facility does not affect the water quality of the surface water. The proposed subsurface
disposal of effluent may result in the creation of a groundwater “mound” beneath the disposal
field. The system should be sited such that the outer edges of the mound do not significantly
influence the hydrology or water quality of the adjacent surface water body. Therefore, it was
conservatively assumed that a groundwater discharge effluent bed should be at least 500 feet from
a surface water body to provide an adequate margin of safety to ensure preservation of surface
water quality. Potential groundwater discharge sites located at least 500 feet from a surface water
body are considered to present an “Opportunity” for development. If within 500 feet, the site is
considered to present “Moderate Constraints” for groundwater disposal.
Drinking Water Supply - Wellhead Protection Areas (Zone I and II)
The Town of Nantucket has an overlay district, the Public Wellhead Recharge District, designed
to protect the Town’s groundwater resource to ensure a safe and healthy public water supply
(Nantucket Code Section 139-12B). Siting a wastewater treatment facility or an effluent disposal
discharge in this overlay district is strictly prohibited. For this siting study, only sites with
suitable area outside of the public wellhead protection district will be considered viable options.
Treatment facility sites, without an associated discharge on site, located in Zone II areas are not
scrutinized the same as treatment facility sites with a groundwater discharge since the potential
impacts to drinking water quality are minimal. Due to the importance of the Zone II resource
areas, treatment facility sites located in Zone II areas are considered to present “Minor
Developmental Constraints” while those located outside these areas are considered to present “No
Constraints”.
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The proximity of surface water and groundwater discharge sites to public drinking water supplies
is a significant criterion in the screening process due to the stringent regulatory restrictions which
apply to siting these facilities within Zone I and II areas. This criterion is not given the same
significance with respect to the siting of the treatment facilities since construction of a treatment
facility does not necessarily include an effluent discharge. The screening criteria were developed
to coincide with the requirements of the Nantucket Code (Zoning Overlay District),
Massachusetts Drinking Water Regulations and the designation of Zone I (for wells with a yield
of greater than 100,000 gpd, the Zone I is assumed to be 400 feet in radius) and Zone II
(contributes to the well under severe pumping and recharge conditions).
Siting an effluent discharge is prohibited within a Zone I area. The location of a surface water or
groundwater discharge within a Zone II area and greater than 1,000 feet from a public well is
considered a “Moderate Constraint”. In order to conservatively protect the Zone II areas, which
are nitrogen sensitive, more stringent nitrogen discharge limitations have been established by
DEP. Discussions with regulatory agencies regarding this matter suggest that an effluent
discharge should not be considered unless all alternative options have been exhausted and a
risk/benefit analysis has been performed. Current DEP policy allows for a wastewater discharge
within Zone II’s. Due to the higher levels of treatment and public concerns placed on siting
wastewater discharge facilities within Zone II’s, a “Severe Constraint” is identified for a
discharge within 1,000 feet of a drinking water supply well within the Zone II. Location of a
facility outside of the Zone II is viewed as having “No Constraint” for either a treatment facility
or a discharge facility. Zone II areas were determined from the MASS GIS database and Town
maps entitled “Public Wellhead District, Siasconset,” prepared by Horsely, Witten and
Heggemann, Inc. for the Siasconset Wellfield and “Public Wellhead Recharge District: Town” for
the Wannacomet Wellfield.
Fisheries (Including shellfish beds)
The proximity of the potential facility site to fisheries resources, which includes shellfish beds,
and adjacent waterbodies is a factor in siting surface water and groundwater discharge facilities.
It was assumed that the location and construction of treatment facilities would not impact
fisheries, if the facility is located greater than 100 feet from the waterbodies supporting the
fisheries. The screening criteria for fisheries is considered to present “No Constraints” to
development on treatment facility sites regardless of the location outside the resource.
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Surface water discharge facilities pose the greatest threat to the fishery resources since the
discharge of treated wastewater is directly into the waterbodies, which support the fisheries.
Therefore, this criteria is considered to present a “Moderate Developmental Constraints” for a
facility if it is located within 100 feet of a fish stocking area. If a site is located downstream or
greater than 1,000 feet from a fish stocking area the site is considered to present “No Constraint”
for the facility.
While groundwater discharges may impact fisheries, there is less risk of impact because the
discharge is not directly into the surface water body, which contains the fisheries. Therefore, the
criteria is only considered to present a “Minimal Constraint” for sites located within 400 feet of
the fish stocking areas, and “No Constraint” for sites located greater than 1,000 feet from fish
stocking areas. It was considered to be a “Moderate Constraint” if the facility site was located
within 200 feet of the fisheries.
Sensitive Habitats
Sensitive habitats considered in the screening criteria include Estimated Habitats of Rare
Wildlife, Certified Vernal Pools, Priority Sites of Rare Species Habitats and Exemplary Natural
Communities, and Areas of Critical Environmental Concern. These habitats are sensitive to
changes in the environment and are protected in both DEP Wetland Protection and Surface Water
Quality Regulations. These regulations impose restrictions on development of any kind within
the boundaries of these mapped habitats, and thus, for sites located within sensitive habitats, there
is a “Severe Constraint” to development. Therefore, the “Constraints” to treatment facilities,
surface water and groundwater disposal facilities is viewed to be equally restricted. The criteria
identifies a “Severe Constraint” for those sites located within a sensitive habitat area, a “Minimal
Constraint” if outside of, but abutting a sensitive habitat area, and “No Constraint” for those sites
located a sufficient distance outside of a sensitive habitat area. Other sensitive habitats include
park lands, recreational resources, and historical interests.
Park Lands and Recreational Resources
Land developed for recreational use or as park lands should be avoided in siting treatment
facilities and disposal facilities (groundwater or surface water). If the existing land use of the
potential site involves park or conservation lands or other recreational resources, construction of a
treatment facility and/or disposal facility would represent an incompatible use conflict.
Therefore, the presence of a park, conservation, or recreation land poses a “Severe Constraint” to
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development of a treatment facility. If the potential treatment facility site is located on property
directly abutting the resources, then a “Minimal Development Constraint” exists on the site. If
located greater than 200 feet from theses resource areas, the criteria is considered to present “No
“Constraints” to development.
Groundwater and surface water discharge facilities do not impact these resources to the same
extent the buildings and above ground structures associated with a treatment facility would.
Therefore, these wastewater disposal facilities are only considered to present “Moderate
Developmental Constraints” for sites located within the resource areas, and “Minimal
Constraints” if the sites are located outside the resource areas and “No Constraints” to
development if located greater than 200 feet from these resource areas.
Agricultural/Historical Interests
The proximity of the potential facilities (wastewater treatment facility and/or wastewater disposal
facility) to historic resources is a factor that will be considered in siting the facilities. The
Massachusetts Historical Commission State Register of Historic Places 2001 was consulted to
determine the existence of historic resources within Nantucket. In addition to the presence of
historic resources, the Massachusetts Historical Commission (MHC) has commented that there
are many areas throughout the Island that could contain archaeological resources. The
Massachusetts Historical Commission has noted that Nantucket has one of the highest densities of
known archaeological sites in the Commonwealth.
In screening the potential project sites, it is considered desirable to select sites that do not impact
these resources. The Massachusetts Historical Commission (MHC) is the jurisdiction notified of
details regarding proposed projects in designated historic areas as well as the Nantucket Historic
District Commission (NHDC). The MHC will then determine whether State Register properties
exist within a project’s area of potential impact. If it is determined that the proposed project will
have an adverse effect, the applicant will be required to present a comprehensive analysis of
alternatives. By eliminating these sites, the project will preserve the resources and avoid potential
administrative and regulatory burdens associated with development in these areas. Since the
developmental regulatory “Constraints” associated with these resources apply with equal force to
either treatment facilities or disposal facilities, independent of any specific characteristics
associated with the facilities, this screening criterion is considered to present the same
“Constraints” for each facility. The criterion presents a “Severe Constraint” for those sites
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located within a historic resource area, a “Moderate Constraint” if directly abutting the site, a
“Minor Constraint” if within 200 feet a historic resource area and “No Constraint” for those sites
located greater than 200 feet outside of these resource areas.
Shoreline Change Data
The proximity of the potential or existing facilities to the Nantucket shoreline is a factor
considered. The purpose of this parameter is to quantify the changes in shoreline position using
the most accurate data sources and compilation procedures available and to characterize any areas
of erosion and accretion. This criteria was utilized specifically for the current Surfside Facility.
An “Historical Shoreline Change Analysis for the Surfside, Nantucket Coastline”, which is an
evaluation of the existing and potential erosion at the Surfside disposal bed area was conducted in
1999 and again in 2002 in order to determine the useful disposal area available at this specific
site. The Woods Hole Group performed both studies, which looked at shoreline changes from
1846 to 2002. Refer to Appendix D for the complete reports.
In screening the potential for this type of site, it was considered desirable to select sites that are
not affected with shoreline changes due to historical erosion. The criteria presents a “Moderate to
Severe Constraint” for those sites located within an area of erosion and “No Constraint” for those
sites outside of any erosion areas.
Nantucket and Madaket Harbor Watersheds
The proximity of the potential or existing facilities to the Nantucket Harbor Watershed, as
described in a technical report entitled, “Nantucket Water Resource Management Plan,” 1990, by
Horsley, Whitten & Hegemenn, Inc. and as delineated on a map entitled “Nantucket Harbor
Watershed,” Nantucket GIS, dated January, 1999 and the Madaket Harbor Watershed area, of
which the Horsley, Whitten & Hegemenn, Inc. plan was the principal source and was adopted by
reference at the 2003 Town Meeting, are both factors that have been considered.
This site development criteria presents a unique environmental/sensitive receptor for each site
based on the siting of a wastewater treatment facility and/or treated wastewater disposal facility.
The designation of an “Opportunity” within the screening criteria reflects the positive aspects of
the existing land use that could be used in a beneficial manner in the siting of any facilities.
Similarly, the designation of environmental/sensitive receptor “Constraints” within the screening
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criteria reflect aspects of the site that would not be beneficial in the siting of these facilities. The
siting of any facilities within these designated areas will be evaluated using the most stringent
criteria and efforts will be made to avoid or minimize direct impacts to the screening criteria.
Evaluations will be made depending on the nature and extent of any obstacles in the potential
development of the site(s). In the context of the direct goals of this Project, the removal of
problem and failing on-site wastewater disposal systems within any designated watershed area(s)
to new wastewater treatment facilities, designed to treat and dispose of a highly treated
wastewater effluent that is located within the boundaries of these designated areas, would be rated
as an “Opportunity” as an environmental benefit would be achieved.
B. SITE IDENTIFICATION
1. General
The following section provides a description of the 14 sites identified as potential
locations for local or centralized treatment facilities and/or groundwater treated effluent
disposal locations. Refer to Figure 3-1 for site locations. The identification of sites in
this section includes both properties and sites within larger parcels. Existing conditions
and site features for each site are presented in Table 3-2, with respect to the screening
criteria. Information used in the description of the sites was obtained from MassGIS data
layers, Nantucket Master Plan, Nantucket Assessor records and USGS topographic maps.
The information used to characterize the environmental conditions of these sites is
viewed as conservative and appropriate for planning and screening purposes. Most of the
sites screened in this analysis have been visited in the field and information gathered
during these inspections is reflected in the details of the site. The information was
supplemented by a field reconnaissance of the potential site locations with the existing
conditions as represented on Figure 3-2.
The discussion describes the sites in terms of their location, the primary land use
associated with the sites, and the significant site features and conditions. The search for
potential sites involved a variety of previously described environmental parameters and
also parcel size. Size is important to the type of facility proposed such as: (1) Centralized
Treatment – undeveloped land of generally five acres or larger; and (2) Satellite
Treatment-undeveloped land of generally one to two acres located within identified Need
Area neighborhoods. The existing conditions for all 14 potential project sites were
characterized based on the screening criteria previously outlined.
Page 3-12 Screening of Sites
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SURFSIDE
WWTF
12
11
4125
6
3
9
8
7
1013
1
2
14
SIASCONSET
WWTFSURFSIDE
WWTF
12
11
4125
6
3
9
8
7
1013
1
2
14
SIASCONSET
WWTF
* Source: MassGIS, Town of Nantucket Mapsheet developed by Horsley, Witten, Hegemann
Entitled Water Resources Protection Plan, Nantucket, Massachusetts Nantucket Land Council, January 1990.
SEPTEMBER 2003l:\work\27355\gis\maps\sites_figure3-2.mxd0 5,5002,750 Feet
* Wastewater disposal within existing roadways will be
considered if no other viable groundwater disposal sites
are identified.
Surfside WWTF
SITE NAMEID
Madaket - Warren's Landing Roadways
Wauwinet - Quidnet Area Roadways*
State Forest
Milestone Road - Clearcut Site
FAA Site
UMASS - Pocomo Site
Quidnet #1 Site
Quidnet #2 Site
Pocomo Road Site
Tom Nevers - Naval Site
Siasconset WWTF
Airport
Wauwinet Road Site*
1
2
3
4
5
6
7
8
9
10
11
12
13
14
FIGURE 3-1
POTENTIAL WASTEWATER
TREATMENT AND/OR
DISPOSAL SITES
NANTUCKET, MASSACHUSETTS
LEGEND:
Public Water Supply
Wastewater Treatment Facility
Potential Site Boundary
Nantucket and Madaket Harbor
Watershed Boundaries*
Parcels
Ponds
Wetlands
TABLE 3-2 TOWN OF NANTUCKET CWMP/DEIR EXISITNG CONDITIONS AND SITE FEATURES Site Map/Parcel Wetlands SoilsDrinking Water Fisheries Supply And Shell Fish Beds WaterbodiesFloodplainsSensitive Habitat Park Lands Recreation Resources Agricultural/ Historic Interests Shoreline Change Data Nantucket and Madaket Harbor Watersheds 1. Surfside WWTF 87-87* No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby Ocean Nearby Outside of Flood Plain No Sensitive Habitat Nearby None Located Within or Proximate None Located Within or Proximate None Documented Step 1 Review No Erosion Data Reported Outside of Harbor Watershed Delineations 2. FAA Site 63-9 No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby Ocean Nearby Outside of Flood Plain No Sensitive Habitat Nearby None Located Within or Proximate None Located Within or Proximate None Documented Step 1 Review No Erosion Data Reported Portions Within Harbor Watershed Delineations 3. UMass Site 26-1 Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby Ocean Nearby Portions Within Flood Plain Sensitive Habitat Nearby None Located Within or Proximate None Located Within or Proximate None Documented Cursory Review No Erosion Data Reported Within Nantucket Harbor Watershed Delineation 4. Quidnet Area-1 21-36 No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby No Waterbodies Nearby Outside of Flood Plain No Sensitive Habitat Nearby None Located Within or Proximate None Located Within or Proximate None Documented Cursory Review No Erosion Data Reported Outside of Harbor Watershed Delineations 5. Quidnet Area-2 21-53 No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby No Waterbodies Nearby Outside of Flood Plain No Sensitive Habitat Nearby None Located Within or Proximate None Located Within or Proximate None Documented Cursory Review No Erosion Data Reported Outside of Harbor Watershed Delineations 6. Pocomo Area 14-72 No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby No Waterbodies Nearby Outside of Flood Plain Sensitive Habitat Nearby None Located Within or Proximate None Located Within or Proximate None Documented Cursory Review No Erosion Data Reported Outside of Harbor Watershed Delineations 7. Milestone Road 70-2 No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby No Waterbodies Nearby Outside of Flood Plain Within Sensitive Habitat Within or Proximate Conservation Land Potential Within No Erosion Data Reported Outside of Harbor Watershed Delineations 8. Tom Nevers Site 91-6 No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby Ocean Nearby Outside of Flood Plain No Sensitive Habitat Nearby None Located Within or Proximate Proximate to Park None Documented Cursory Review No Erosion Data Reported Outside of Harbor Watershed Delineations 9. Siasconset WWTF 74-52* No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby Ocean Nearby Outside of Flood Plain No Sensitive Habitat Nearby None Located Within or Proximate None Located Within or Proximate None Documented Cursory Review No Erosion Data Reported Outside of Harbor Watershed Delineations 10. Airport Site No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby No Waterbodies Nearby Outside of Flood Plain Sensitive Habitat Nearby None Located Within or Proximate None Located Within or Proximate None Documented Cursory Review No Erosion Data Reported Outside of Harbor Watershed Delineations 11. Wauwinet Road Area 14-29 Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby No Waterbodies Nearby Outside of Flood Plain Within Sensitive Habitat None Located Within or Proximate None Located Within or Proximate None Documented Cursory Review No Erosion Data Reported Outside of Harbor Watershed Delineations 12. Wauwinet-Quidnet Roadways No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby Wetlands and Ocean Nearby Portions Within Flood Plain Within Sensitive Habitat None Located Within or Proximate None Located Within or Proximate None Documented Cursory Review No Erosion Data Reported Portions Within Harbor Watershed Delineations 13. State Forest Sites No Wetlands Onsite Sand and Gravel Deposits Within Zone II No Fish Stocking Nearby No Waterbodies Nearby Outside of Flood Plain Within Sensitive Habitat Within or Proximate Within or Proximate Potential Within No Erosion Data Reported Outside of Harbor Watershed Delineations 14. Madaket-Warren’s Landing Roadways No Wetlands Onsite Sand and Gravel Deposits Outside of Zone II No Fish Stocking Nearby Wetlands and Ocean Nearby Portions Within Flood Plain Within Sensitive Habitat None Located Within or Proximate None Located Within or Proximate None Documented Cursory Review No Erosion Data Reported Portions Within Harbor Watershed Delineations *-Multiple Parcels Notes: “Proximate to wetlands” is defined as within 400 feet, but greater than 100 feet “Removed from wetlands” is defined as greater than 400 feet “Proximate to stream/waterbody” is defined as within 200 feet Page 3-14 Screening of Sites L:\work\27355\PROJ\Report\Phase II\Figures\Section 3\Screening Criteria Tables.doc
12
3
GP
WELL
DIONIS
BEACH
DUG
WELLS
#1-4
MADAKET
BEACH
WAUWINET
HOUSE
SURFSIDE
BEACH
THE
CHILDRENS
HOUSE
WESTENDER
RESTAURANT
STATE FOREST
WELL #3MIACOMET GOLF
COURSE WELLS
MILESTONE RD WELL # 2
MILESTONE RD
WELL # 1
NANTUCKET
WATER
12
3
GP
WELL
DIONIS
BEACH
DUG
WELLS
#1-4
MADAKET
BEACH
WAUWINET
HOUSE
SURFSIDE
BEACH
THE
CHILDRENS
HOUSE
WESTENDER
RESTAURANT
STATE FOREST
WELL #3MIACOMET GOLF
COURSE WELLS
MILESTONE RD WELL # 2
MILESTONE RD
WELL # 1
NANTUCKET
WATER
* Source: MassGIS, Town of Nantucket Mapsheet developed by Horsley, Witten, Hegemann
Entitled Water Resources Protection Plan, Nantucket, Massachusetts Nantucket Land Council, January 1990.
SEPTEMBER 2003l:\work\27355\gis\maps\cwmp_figure3-2.mxd0 5,5002,750 Feet
FIGURE 3-2
COMPREHENSIVE WASTEWATER
MANAGEMENT PLAN
NATURAL RESOURCES
AND ENVIRONMENTALLY
SENSITIVE AREAS
NANTUCKET, MASSACHUSETTS
Zone II Area Boundary
LEGEND:
Public Water Supply Wells
NHESP 2003 Massachusetts
Certified Vernal Pools
Sand and Gravel Deposits
Depth of Deposit, 0-50 Feet
400 Foot Buffer Around Public Water
Supply Locations
Till or Bedrock
End Moraines
Wetlands
Water Bodies
Landfill
Streams, Canals, Shore
NHESP 2003 Priority Habitats for
State-Protected Rare Species
NHESP 2003 Estimated Habitats for
Rare Wildlife: For Use with the MA
Wetlands Protection Act Regulations
(310 CMR 10)
NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
1. Surfside Wastewater Treatment Facility- Assessor Map 87 and Multiple Parcels
This site is located on the southern tip of the Island directly east of Miacomet Pond and
municipally owned. The site is the current location of the Town’s main Wastewater
Treatment Facility as well as nine open sand beds for discharge of the wastewater treated
at this location. The Surfside Wastewater Treatment Facility currently treats flow from
the center of Nantucket and has a design capacity of 2.24 MGD (the current DEP
permitted flow is 1.8 MGD). The Surfside Wastewater Treatment Facility consists of a
septage receiving tank, aerated grit chamber, three primary clarifiers that utilize ferric
chloride and polymer for enhanced treatment, ten rapid infiltration basins, three aerated
sludge holding tanks, one aerated septage equalization tank, and process support systems.
Sludge and septage are dewatered with belt filter presses and can be mixed with wood
chips in a portable mixer using aerated static pile method to produce a product that meets
DEP Standards for a Type I sludge or composted with municipal solid waste.
The Town is currently working on a Preliminary Design Report for the upgrade and
expansion of this Facility in order to handle additional flows based on the results of the
Phase I CWMP/EIR. A hydrogeologic evaluation of the facility and discharge beds has
been completed for this site and is included in Appendix F.
2. FAA Site - Massasoit Bridge Road - Assessor Map 63 and Parcel 9
This site is located east of Long Pond and west of Hummock Pond in the southwest
corner of the Island, south of the Town department of Public Works and currently owned
by the Federal Government. The site consists of a large open area, approximately 100
acres in size where the Federal Aviation Administration has maintained a tower with the
land area covered in steel mesh to aid in the tower’s reception. The site is large enough
to accommodate buffers to the remote residential parcels in the area. The site
immediately abuts land under the Nantucket Conservation Foundation. Evaluations at
this site for soils and groundwater have been positive for the discharge of highly treated
effluent and for the location of a package wastewater treatment facility.
A hydrogeologic evaluation of this site for the design and construction of a wastewater
treatment facility and discharge beds for highly treated effluent has been completed and
is included in Appendix G.
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3. UMASS Site - Assessor Map 26, Parcel 1
This site is located on Polpis Road west of Polpis Harbor abutting Folgers Marsh. This
site consists of approximately 100 acres and owned by the University of Massachusetts,
Boston Campus. The school maintains the site and buildings located within the property.
The property consists of large wetland areas on the westerly side, dry upland areas to the
south and borders Polpis Harbor to the north.
4. Quidnet-No. 1 Site - Assessor Map 21, Parcel 53
This site is located within the village of Quidnet on Polpis Road northwest of Sesachacha
Pond. This site consists of approximately five acres and is privately owned. The current
land use for this parcel is identified in Town Assessor records as Accessory Land with
Improvement. The property is fairly level and dry.
5. Quidnet-No. 2 Site - Assessor Map 21, Parcel 36
This site is located within the village of Quidnet on Polpis Road northwest of Sesachacha
Pond. This site consists of approximately 13 acres and is privately owned. The current
land use for this parcel is identified in Town Assessor records as Vacant Residential. The
property is fairly level and dry.
6. Pocomo Road Site - Assessor Map 14, Parcel 72
This site is located off of the Wauwinet Road area on Pocomo Road just south of the
Wauwinet Study Area. This site consists of approximately six acres and is privately
owned. The current land use for this parcel is identified in Town Assessor records as
Vacant Residential. The property is fairly level and dry.
7. Milestone Road - “Clear-cut Site” - Assessor Map 70, Parcel 2
This site is located directly on Milestone Road and is sometimes referred to as the “Clear-
Cut” land. This site consists of approximately 223 acres and is owned and maintained by
the Nantucket Conservation Foundation. The current land use for this parcel is identified
in Town Assessor records as Tax Exempt. The property is level and dry.
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
8. Tom Nevers - Naval Station Site - Assessor Map 91, Parcel 6
This site is located in the village of Tom Nevers in the southeast shore of the Island just
east of the village of Siasconset. This site consists of approximately six acres and is
privately owned. The current land use for this parcel is identified in Town Assessor
records as Vacant Residential. The property is fairly level and dry.
9. Siasconset WWTF Site - Assessor Map 74, Parcel 52
This site is located within the village of Siasconset on property formerly under the
jurisdiction of the United States Coast Guard. The new wastewater treatment facility is
presently under construction at this site, with a design capacity of 0.22-mgd. There are 4
open sand beds located across the street on Low Beach road where the treated effluent is
discharged.
10. Airport Site - Assessor Map 78, Parcel 3
This site is located on Town-owned property adjacent to the Nantucket Municipal
Airport. The site consists of approximately 42 acres of undeveloped land and is fairly
level and dry.
11. Wauwinet Road Site - Assessor Map14, Parcel 29
This site is located in the northeastern portion of the Island in the direction of the village
of Pocomo. The site consists of approximately four acres and is privately owned. The
current land use for this parcel as identified by Town Assessor records is Vacant
Residential.
12. Wauwinet - Quidnet Area Roadways
This site includes the unpaved roadways in the villages of Wauwinet and Quidnet
adjacent to the identified areas of need.
13. State Forest Site - Assessor Map 68, Parcel 70
This site is the Sate Forest parcel located near the center of the Island off of Old South
Road. The site consists of approximately 39 acres of undeveloped land and is under the
state’s jurisdiction.
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
14. Madaket - Warren’s Landing Area Roadways
This site includes the unpaved roadways in the villages of Madaket and Warrens Landing
adjacent to the identified areas of need.
C. PRELIMINARY SITE SCREENING
1. Environmentally Sensitive Areas
Environmentally sensitive areas such as wetlands, flood plains, depth to groundwater,
wellhead recharge/Zone Is/Zone IIs, surface waters, sensitive habitats and existing land
use on each of the above sites was assessed. Any wetland/flood plains on site will be
delineated according to appropriate federal and state guidelines. The functional value of
the wetland as well as the potential to avoid or minimize impacts on, wetlands was
determined. Wellhead recharge/Zone I/Zone II areas were delineated. The proximity of
each site to these areas and the impacts of siting wastewater facilities was assessed. The
characteristics of the groundwater at each site has been described. The effect, if any, on
the groundwater at each site has been described. The effect of the project on groundwater
quality has been assessed. Based upon groundwater investigations at the site, the surface
waters potentially receiving flow from land application on the site have been identified.
Each surface water body has been described in terms of existing conditions, use, and
water quality issues. Impacts on surface waters from the wastewater discharge have been
assessed to determine the level of treatment necessary at each site. Any area potentially
affected by the activity, including downstream surface waters receiving groundwater
from the site(s), has been surveyed for the presence of sensitive natural resources and
receptors. This was accomplished by: (1) review of resource maps; (2) discussion with
state, local and federal agency personnel; (3) field reconnaissance; and (4) review of
readily available information. With the utilization of windshield surveys, existing maps,
and discussions with appropriate local planning officials, and the availability of the
EOEA Build-Out Analysis, the current and future land use at each site has been assessed.
1. Archaeological and Historical Resources
A review of existing information and the potential for significant historic and
archaeological resources has been evaluated. The Massachusetts Historical
Atlas/Register was reviewed for pertinent information on each identified site. A copy of
the Project Notification Form (PNF) filed with MHC, which includes the Step 1
archaeological survey for the two short-listed sites is included in Appendix H.
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
2. MCP Phase I Site Assessment
A review of the Massachusetts Bureau of Waste Site Cleanup has been performed in
order to determine the location of any hazardous materials on any of the identified sites.
A complete listing can be found in Appendix I and at http://www.state.ma.us/cgi-
bin/dep/wscreport.cgi.
3. Soil Suitability and Geologic Evaluation
Soil permeability and geologic conditions have been assessed at each site using existing
data and maps such as the USDA Soil Conservation Services surficial geology maps and
soil survey reports. Local Board of Health records were also used where applicable.
Additionally, field testing was performed at each site to determine the ability of the soil at
to allow percolation of wastewater effluent into the soil at a rate to properly treat the
effluent. Depth to groundwater and site specific soil conditions have been assessed
through field testing.
4. Sensitive Receptors
Sensitive receptors, which include the location of developed residential areas, schools,
hospitals, nursing homes and commercial/industrial parcels within 500 feet of each site
has been delineated. The potential impacts of odors, noise, traffic and visual aesthetics of
construction and operation of any wastewater facilities to be located on each identified
site in relation to the identified sensitive receptors have been assessed.
5. Hydrogeologic Evaluations
FAA Site
The following is a summary of the hydrogeological results of the FAA Site. Refer to
Appendix G for the complete hydrogeological report as well as all tables and figures cited
in this summary.
The high groundwater conditions described in Section 3 and listed in Table 3-2 were used
for all of the model simulations to predict the groundwater mound under discharge
conditions. The proposed discharge area is approximately 340,000 square feet as shown
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
in Figure 2-1. The proposed discharge rate is 351,000 gallons per day. The simulated
groundwater mound at this discharge rate is shown in Figure 4-1.
The maximum groundwater mound is approximately 1.8 feet. The highest water table
elevation beneath the discharge area is predicted to be approximately 5.8 feet. The lowest
ground elevation at the site is currently about 17 feet. The groundwater modeling
indicates that the proposed discharge can be easily accommodated at the site and still
maintain the required separation distance of four feet from the top of the mound.
The three-dimensional groundwater flow model was coupled with a particle tracking
model called PATH3D (Zheng, 1991) in order to illustrate the potential movement of
groundwater over time and to predict the ultimate discharge of effluent-impacted
groundwater generated at the site. Four particles were seeded at each of the 130 nodes
representing the discharge area. The particles were tracked forward for a period of 30
years. The results of the particle tracking analysis are shown in Figure 4-2. The model
predicts that approximately 76 percent of the effluent-impacted groundwater will
discharge to the ocean. The remainder will discharge to Long Pond.
SURFSIDE WWTF
The following is a summary from the hydrogeological report on the Surfside WWTF Site.
Refer to Appendix F for the complete hydrogeological report as well as all tables and
figures cited in this summary.
The high groundwater condition described Section 2 and listed in Table 2-1 was used for
all of the model simulations to predict the groundwater mound under discharge
conditions. The initial model runs indicated that the existing bed configuration would not
be able to accommodate significantly greater flows while still maintaining a four-foot
separation between the top of the mound and the bottom of the beds. Since there is
sufficient land area for the construction of additional beds at the site, it was decided to
use those potential beds in the maximum discharge simulation.
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NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
6. Historical Shoreline Analysis at Surfside Wastewater Treatment Facility
The Woods Hole Group performed historical shoreline analyses in the vicinity of the
Surfside wastewater Treatment Facility in 1999 and again in 2002. The completed
reports and maps can be accessed in Appendix D.
D. IDENTIFICATION OF FEASIBLE SITES BASED ON SCREENING ANALYSIS
The screening criteria previously presented was applied to the 14 sites identified above. The
preliminary screening of sites involved applying the 12 environmental criteria: (1) wetlands;
(2) soils; (3) drinking water supply - wellhead protection areas (Zone I and Zone II); (4) fisheries
(including shellfish areas); (5) waterbodies (distance from surface water); (6) floodplains;
(7) sensitive habitats; (8) park lands; (9) recreational resources; (10) agricultural/historical
interests; (11) shoreline change data; and (12) in or adjacent to an Area of Critical Environmental
Concern. Each site was screened with respect to the potential for construction of a treatment
facility and/or location of a groundwater discharge site.
As previously mentioned, the designation of an “Opportunity” within the screening criteria
reflects the positive aspects of the environment that could be viewed as a benefit in siting these
facilities. Similarly, the designation of environmental “Constraints” within the screening criteria
reflects aspects of the site and environment that would pose limitations in siting the treatment
and/or disposal facilities. The “Constraints” are identified as “Minimal”, “Moderate”, and
“Severe” depending on the extent and nature of the obstacles to developing each site.
The feasible site or sites to accommodate the recommended wastewater facilities were identified
upon the completion of the detailed screening described in the previous tasks. The results of this
preliminary screening are presented in Table 3-3. This Table presents a rating of each site based
on the application of the screening criteria. The sum of the opportunities and various
“Constraints” are reflected in a rating of low, moderate or high potential for siting of a facility or
disposal site. The rationale for the ratings is as follows:
High Potential = predominately “Opportunities” and “No Constraints”; may have a
“Minimal” or “Moderate Constraint”.
Moderate Potential = characterized by more than 1 “Moderate” and 1 “Minimal
Constraint”.
Low Potential = presence of a least one “Severe Constraint” plus a minimal, “Moderate”
or additional “Severe Constraint”.
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TABLE 3-3 TOWN OF NANTUCKET CWMP/DEIR RESULTS OF PRELIMINARY SCREENING Site No. Site Name Wetlands Soils Drinking Water Supply Fisheries Waterbodies Floodplains Sensitive Habitat Park Lands Recreation Resources Agricultural/ Historic Interests Shoreline Change Data Nantucket and Madaket Harbor Watersheds Rating 1 Surfside WWTF, 87-87* Treatment Facility No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint 2 FAA Site, 63-9 Treatment Facility No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint 3 UMass Site, 26-1 Treatment Facility No Constraint No Constraint No Constraint No Constraint Minimal Minimal Minimal No Constraint No Constraint No Constraint No Constraint Minimal Groundwater Discharge No Constraint No Constraint No Constraint No Constraint Minimal Minimal Minimal No Constraint No Constraint No Constraint No Constraint Minimal 4 Quidnet Area, 21-36 Treatment Facility No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint 5 Quidnet Area, 21-53 Treatment Facility No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint 6 Pocomo Area, 14-72 Treatment Facility No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint 7 -2 Milestone Road, 70 Treatment Facility No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Minimal Severe Severe No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Minimal Severe Severe No Constraint No Constraint 8 Tom Nevers-US Navy,91-6 Treatment Facility No Constraint No Constraint No Constraint No Constraint No ConstraintNo Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharges No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint 9 Siasconset WWTF, 74-52* Treatment Facility No Constraint No Constraint No Constraint No Constraint No ConstraintNo Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint High potential alternative Moderate potential alternative Low potential alternative Page 3-24 Screening of Sites L:\work\27355\PROJ\Report\Phase II\Figures\Section 3\Screening Criteria Tables.doc
TABLE 3-3 (cont) TOWN OF NANTUCKET CWMP/DEIR RESULTS OF PRELIMINARY SCREENING Site No. Site Name Wetlands Soils Drinking Water Supply Fisheries Waterbodies Floodplains Sensitive Habitat Park Lands Recreation Resources Agricultural/ Historic Interests Shoreline Change Data Nantucket and Madaket Harbor Watersheds Rating 10 Airport-78-1, 78-2, 78-3 Treatment Facility No Constraint No Constraint No Constraint No Constraint No ConstraintNo Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint 11 Wauwinet Area, 14-29 Treatment Facility Minimal No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge Minimal No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint 12 Wauwinet –Quidnet Roadways Treatment Facility No Constraint No Constraint No Constraint No Constraint Minimal Minimal No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint Minimal Minimal No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint 13 State Forest Sites-Multiple Parcels Treatment Facility No Constraint No Constraint No Constraint No Constraint No ConstraintNo ConstraintSevereSevereSevereMinimal No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint SevereSevereSevere Minimal No Constraint No Constraint 14 Madaket-Warren’s Landing Roadways Treatment Facility No Constraint No Constraint No Constraint No Constraint No Constraint Minimal No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint Groundwater Discharge No Constraint No Constraint No Constraint No Constraint No Constraint Minimal No Constraint No Constraint No Constraint No Constraint No Constraint No Constraint High potential alternative Moderate potential alternative Low potential alternative Page 3-24 Screening of Sites L:\work\27355\PROJ\Report\Phase II\Figures\Section 3\Screening Criteria Tables.doc
NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
The rating for each potential site, presented in the preliminary screening table, only considers
the environmental factors that can influence the siting of a wastewater treatment and/or
disposal facility. Engineering design considerations, constructability and/or political decisions
may also influence final site selection.
As stated previously, all 14 sites identified as potential wastewater treatment and/or
groundwater discharge sites are situated on a parcel of land or contiguous parcels of land that
have an area greater than that needed for siting of these type facilities. In most cases, this
allowed for the potential treatment facilities and/or groundwater discharge site(s) to be sited
with the maximum available buffer from any of the 11-screening criterion. This enabled more
potential sites to rate either a “No Constraint” or “Opportunity” designation due mainly to the
overall area of the parcel(s) and availability of usable land within the parcel(s), which
minimizes or eliminates potential environmental and/or other constraints.
E. SUMMARY
The Study Areas on Island rated as Need Areas, namely Wauwinet, Quidnet, Pocomo, Polpis,
which are included in the study being completed by The Massachusetts Estuaries Project (MEP),
will be evaluated further when the results of the Study are complete. At this point in time, we are
recommending that these areas be managed under the Island’s Septage Management Plan. The
MEP is in the process of addressing the issue of nitrogen loading in the Nantucket Harbor and
Sesachacha Pond areas on Island and will develop the maximum amount of nitrogen (nitrogen
threshold) that each estuary can tolerate without adversely changing its character or present use.
When this final data is released from the MEP, a thorough evaluation of the MEP data will be
made and a final recommendation will follow for these Study Areas.
Based on the preliminary screening criteria for those Needs Areas outside of the above-
referenced, two of the 14 proposed groundwater disposal sites and proposed wastewater treatment
facility sites rated favorably and are recommended for use as wastewater treatment facilities as
well as groundwater disposal of the treated effluent: (1) Surfside Wastewater Treatment Facility;
and (2) FAA Site.
Detailed evaluations including field-testing, of these two short list of favorable sites have been
completed and are included in Appendices E and F. The number of wastewater treatment and/or
groundwater disposal sites considered for detailed evaluation have been predicated on the land
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CWMP/DEIR – PHASE II REPORT
area required by the recommended wastewater management plan to support the treatment and
disposal of wastewater in Nantucket. The detailed evaluation considers technical feasibility,
economic viability and the most efficient use of the identified sites for the recommended
wastewater management plan. Table 3-4 summarizes the sites considered the most favorable for
siting of a wastewater treatment facility and/or groundwater disposal facility Island-wide with
those in the MEP Study Areas, identified in Table 3-4 with Italics, being delayed from further
review.
TABLE 3-4
TOWN OF NANTUCKET
CWMP/DEIR
WASTEWATER TREATMENT AND/OR DISPOSAL SITES
Site
Number
Site
Description
Groundwater
Disposal
Wastewater
Treatment
Facility
1 Surfside WWTF
87-87*
X X
2 FAA Site
63-9
X X
3 UMass
26-1
X X
4 Quidnet Area
21-36
X X
5 Quidnet Area
21-53
X X
6 Pocomo Area
14-72
X X
7 Milestone Road
70-2
8 Tom Nevers-US Navy
91-6
X
9 Siasconset WWTF
74-52
X X
10 Airport
78-1*
X
11 Wauwinet Area
14-29
X X
12 Wauwinet-Quidnet Roadways X
13 State Forest Site X
14 Madaket-Warrens Landing Roadways X
*Multiple Parcels
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4.0 EVALUATION OF SHORT LISTED ALTERNATIVES
AND PLAN SELECTION
A. ENVIRONMENTAL EVALUATION
1. Introduction
The three alternatives (Innovative/Alternative systems, connecting to the existing system,
and communal systems) for the five Need Areas, whose evaluations were completed with
this Report, were screened for direct and indirect impact. The direct and indirect impacts
of the short listed alternatives were screened for building a new Madaket wastewater
treatment facility at the FAA site, expanding the existing Surfside wastewater treatment
facility, and providing sewer service to Madaket, Warren’s Landing, Somerset, Shimmo,
and Monomoy.
2. Evaluation
General
The alternatives were evaluated for the following direct impacts: (a) Historical,
Archaeological, Cultural, Conservation and Recreation; (b) Wetlands, Flood Plains, and
Agricultural Lands; (c) Zones of Contribution of Existing and Proposed Water Supply
Sources; (d) Surface and Groundwater Resources Including Nantucket and Madaket
Harbor Watersheds; (e) Displacements of Households, Businesses and Services; (f) Noise
or Air Pollution or Odor and Public Health Issues Associated with Construction and
Operation; (g) Violation of Federal, State or Local Environmental and Land Use Statutes.
In addition, the alternatives were evaluated for the following indirect impacts:
(a) Changes in Development and Land Use Patterns; (b) Pollution Stemming from
Changes in Land; (c) Damage to Sensitive Ecosystems; and (d) Socioeconomic Pressures
for Expansion.
The following is a summary of each of the evaluation criteria.
Direct Impacts
Historical, Archaeological, Cultural, Conservation and Recreation
There are no known impacts to historical, archeological, cultural, conservation or
recreational resources for any of the alternatives. A Step I Historical and
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Archeological Survey was conducted for the FAA site and the proposed
expansion area of the Surfside Wastewater Treatment Facility. The survey
showed that there would be no impacts on those sites. Refer to Appendix H for a
copy of the Project Notification Form filed with the Massachusetts Historical
Commission on these two sites.
While there are no known impacts, connecting the Madaket Needs Area and the
Warren’s Landing Needs Area to the existing wastewater treatment facility
would have the most potential for impact. Due to the considerable distance, if
sewers were installed from these Needs Areas to the existing wastewater
infrastructure, it would make the Island more vulnerable to impacts to historical
and archeological impacts.
It is possible that there would be impacts associated with the installation of I/A
systems in all of the areas of need, but the individual property owners would
install the systems and would be required to review the impact on the installation
of the systems on any Historical, Archaeological, Cultural, Conservation and
Recreation resources.
Wetlands, Flood Plains, and Agricultural Lands
There is a potential for temporary impacts to wetlands from each of the
alternatives. All three alternatives potentially impact the 100-foot wetland buffer
zone. The impacts would be temporary and associated with the construction of
sewer infrastructure. Any impacts would be mitigated by erosion control during
construction. The Conservation Commission and the DEP will review all erosion
control measures during the Notice of Intent process.
Zones of Contribution of Existing and Proposed Water Supply Sources
None of the treatment alternatives will impact the Zones of Contribution. The
contribution zones for the water supply sources do not fall into the areas of any
of the alternatives.
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Surface and Groundwater Resources Including Nantucket and Madaket
Harbor Watersheds
The I/A systems would have a negative impact in all of the proposed sewered
areas. While the I/A systems provide a higher level of treatment than current on-
site wastewater disposal systems, the I/A systems do not provide the same level
of treatment as an advanced wastewater treatment facility. Since some of the
areas have close proximities to the Nantucket and Madaket Harbor Watersheds it
will be required that any wastewater treatment system achieve a high level of
treatment.
Communal systems in Somerset, Shimmo and Monomoy would have negative
impact on water resources because of the constraints on available land and high
volume of wetland areas. There are no available parcels of land in these areas
that would provide for the required buffer zones around water resources.
Displacements of Households, Businesses and Services
Communal systems in the Somerset, Shimmo and Monomoy areas would have a
severe constraint regarding displacement of households, businesses and services.
There are currently no available land parcels in these areas that would meet the
requirements for communal systems. If communal system were required in these
areas, then parcels would have to be taken by Eminent Domain and would
displace residential property owners.
Noise Pollution, Air Pollution, Odor and Public Health Issues Associated
with Construction and Operation
There will be some temporary construction noise associated with all of the
alternatives. Limiting the hours and the days of construction will mitigate the
construction noise impacts. There may be additional noise impacts associated
with expanding the Surfside Wastewater Treatment Facility due to the additional
treatment processes. Additionally, the residential areas are so dense in Somerset,
Shimmo and Monomoy that communal systems would cause impacts associated
with noise pollution, air pollution, and odor issues. Any impacts associated with
these alternatives will be mitigated in the final design.
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Violation of Federal, State or Local Environmental and Land Use Statutes
or Regulations and Plans Imposed by Such Statutes and Regulations
None of the alternatives would violate any of the Federal, State or Local
Environment and/or Land Use Statutes or Regulations and plans imposed by any
of the statutes and regulations.
Indirect Impacts
Changes in Development and Land Use Patterns
Connecting the proposed sewer infrastructure to the existing wastewater
treatment facility would impact land use and development patterns in Madaket
and Warren’s Landing. These areas are not in close proximity to the existing
facility. A connection would have to be across open space and several buildable
parcels. An expansion of this magnitude would open up these areas and the areas
along the way to significant development.
Building a communal system on the FAA site would have positive impact to the
Madaket and Warren’s Landing area. The parcel has the potential for high
density development with the current zoning and land use. This kind of
development would cause a long-term negative change in development and land
use patterns.
Communal systems in Somerset, Shimmo and Madaket would have a negative
impact to the areas in regards to land use patterns. Currently, there are no parcels
available for development of a communal system in these area, the Town would
have to change the land use of several parcels in order to accommodate a
communal system.
Pollution Stemming from Changes in Land Use
Connecting the proposed sewer infrastructure to the existing wastewater
treatment facility would impact land use and development patterns in Madaket
and Warren’s Landing. These changes in development and land use would cause
noise pollution, impacts to historical and cultural resources, impacts to water
resources, and impacts to Long Pond and Madaket Harbor Watershed.
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Building a communal system on the FAA site would have positive impact to land
use in the Madaket and Warren’s Landing area. New, high density development
on this site would have a negative environmental impact on Long Pond and
Madaket Harbor Watershed.
Land Use patterns would have to be changed for communal systems in Somerset,
Shimmo. Communal systems in dense residential areas could have negative
impact on noise pollution, odor pollution and the water resources, such as
wetlands.
Damage to Sensitive Ecosystems
I/A systems would negatively impact the sensitive ecosystems of all of the
proposed sewer expansion areas. I/A systems do not treat wastewater to as high
of a level of treatment as wastewater treatment facilities. The wastewater
effluent from I/A systems has the potential to negatively impact wetlands, and
harbor watershed areas.
Connecting Madaket and Warren’s Landing to the existing wastewater treatment
facility at Surfside would include construction along a significant distance. This
construction would go through an increased amount of wetland buffer zone areas.
There are currently no available parcels in Somerset, Shimmo and Monomoy for
communal systems. If a communal system was built on one of the available
parcels, it would negatively impact sensitive ecosystems, such as wetlands and
harbor watersheds because of the poor soils and shallow depth to groundwater.
Socioeconomic Pressures for Expansion
Socioeconomics would not be affected by I/A systems or communal systems
because these systems would be designed to treat only the exiting systems.
Connecting Madaket and Warren’s Landing to the exiting facilities may affect
Socioeconomics. The expansion could cause increased development and
negatively impact the socioeconomics in regard to several factors associated with
development, such as increased budget need for items such as school systems,
maintenance of roadways, fire protection and other Town services.
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3. Recommendations Based on Environmental Evaluation Criteria
Table 4-1 summarizes the evaluation of the environmental criteria with regards to
Innovative/Alternative Systems for the five Need Areas. The evaluation indicates that
Innovative/Alternative Systems for all of the Study Areas have an equal number of
impacts and therefore is not considered a high potential alternative.
Innovative/Alternative System would not impact the existing Surfside WWTF nor require
the construction of the Madaket WWTF and therefore is not applicable to this evaluation.
Table 4-2 summarizes the evaluation of the environmental criteria with regards to
Connection to the Existing System for the five Need Areas and Surfside WWTF
Expansion. The evaluation indicates that a Connection to the Existing System for
Mononoy, Somerset, and Shimmo Study Areas has the least impacts and therefore is
considered the highest potential alternative. Connection to the Existing System would
not require the construction of the Madaket WWTF and therefore is not applicable to this
evaluation.
Table 4-3 summarizes the evaluation of the environmental criteria with regards to the
Communal System for the five Need Areas, Surfside WWTF Expansion, and Madaket
WWTF Construction. The evaluation indicates that a Communal System for Madaket
and Warren’s Landing Study Areas has the least impact and therefore is considered the
highest potential alternative.
The analysis of impacts indicates that the best alternative for wastewater disposal
problems in the Madaket and Warren’s Landing Study Areas is to construct a communal
WWTF at the FAA site, and the best alternative for wastewater disposal problems in the
Somerset, Shimmo and Monomoy Study Areas is to connect to the existing Surfside
WWTF.
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NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 4-1 TOWN OF NANTUCKET CWMP/DEIR INNOVATIVE/ALTERNATIVE SYSTEM EVALUATION DirectImpacts IndirectImpacts Description Historical, Archaeological, Cultural, Conservation and Recreation Wetlands, Flood Plains, and Agricultural Lands Zones of Contribution of Water Supply Sources Surface and Groundwater Resources Displacements of Households, Businesses and Services Construction and Operation Pollution Violation of Land Use Statutes Changes In Land Use Patterns Pollution Stemming from Changes in Land Damage to Sensitive Ecosystems Socioeconomic Pressures for Expansion Madaket WWTF at FAA Site N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Surfside WWTF Expansion N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Madaket Monomoy Shimmo Somerset Warren’s Landing High potential alternative, no impact Moderate potential alternative, minimal constraints Low potential alternative, severe constraints Page 4-7 Evaluation of Short Listed Alternatives L:\work\27355\PROJ\Report\Phase II\Section 4.doc
NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 4-2 TOWN OF NANTUCKET CWMP/DEIR CONNECTING TO THE EXISTING SYSTEM EVALUATION DirectImpacts IndirectImpacts Description Historical, Archaeological, Cultural, Conservation and Recreation Wetlands, Flood Plains, and Agricultural Lands Zones of Contribution of Water Supply Sources Surface and Groundwater Resources Displacements of Households, Businesses and Services Construction and Operation Pollution Violation of Land Use Changes In Land Use Patterns Pollution Stemming from Changes in Land Damage to Sensitive Ecosystems Socioeconomic Pressures for Expansion Madaket WWTF at FAA Site N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Surfside WWTF Expansion Madaket Monomoy Shimmo Somerset Warren’s Landing High potential alternative, no impact Moderate potential alternative, minimal constraints Low potential alternative, severe constraints Page 4-8 Evaluation of Short Listed Alternatives L:\work\27355\PROJ\Report\Phase II\Section 4.doc
NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 4-3 TOWN OF NANTUCKET CWMP/DEIR COMMUNAL SYSTEM EVALUATION DirectImpacts IndirectImpacts Description Historical, Archaeological, Cultural, Conservation and Recreation Wetlands, Flood Plains, and Agricultural Lands Zones of Contribution of Water Supply Sources Surface and Groundwater Resources Displacements of Households, Businesses and Services Construction and Operation Pollution Violation of Land Use Changes In Land Use Patterns Pollution Stemming from Changes in Land Damage to Sensitive Ecosystems Socioeconomic Pressures for Expansion Madaket WWTF at FAA Site Surfside WWTF Expansion Madaket Monomoy Shimmo Somerset Warren’s Landing High potential alternative, no impact Moderate potential alternative, minimal constraints Low potential alternative, severe constraints Page 4-9 Evaluation of Short Listed Alternatives L:\work\27355\PROJ\Report\Phase II\Section 4.doc
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B. EVALUATION OF COSTS
1. Project Costs
Cost estimates have been prepared for the various alternatives for the areas of wastewater
disposal need. The presentation of costs is preliminary in nature and contains
construction, construction contingencies, administrative, legal, design engineering, and
construction engineering. Construction costs are based upon present day, competitively
bid construction work prices and on an Engineering News Record (ENR) Construction
Cost Index of 6741 for September 2003. We recommend that budget costs be updated
periodically prior to each construction phase.
Costing of Off-Site Wastewater Disposal Alternatives
For the areas of wastewater disposal need where off-site wastewater disposal alternatives
are being considered, the project costs for conventional gravity sewers with pumping
stations versus low-pressure sewers were estimated. The estimated project costs are
based on the following:
• Collector and Interceptor Sewers and appurtenances are estimated to be
$275 per linear foot for pipes ranging in size from 8 inches to 12 inches;
• Pumping Stations are estimated to be $750,000 per pumping station;
• Force Mains and appurtenances are estimated to be $200 per linear foot
for pipes ranging in size from 3 inches to 6 inches;
• Low Pressure Sewers and appurtenances are estimated to be $175 per
linear foot for pipes ranging in size from 1-1/2 inches to 3 inches;
• Low Pressure Sewer Pumping System estimated at $12,500 each and
includes the purchase and installation of the pumping unit, control panel,
piping and abandonment of the existing on-site wastewater disposal
system;
• Design Engineering is estimated to be ten (10) percent of Construction
Cost;
• Construction Engineering is estimated to be ten (10) percent of
Construction Cost;
• Administrative, Fiscal and Legal Costs are estimated to be five (5)
percent of Construction Cost;
• Land Takings for pumping stations are estimated at $250,000 per acre
and that ½ acre of land is required for each pumping station. The cost
estimates assumes that no other Land Takings and/or Easement are
required;
• Sub-Total of Project Cost includes all items listed above;
• Contingency is estimated to be twenty (20) percent of the Construction
Cost; and
• Total Estimate Project Cost includes Sub-Total Project Cost plus
Contingency.
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Costing of On-Site Innovative/Alternative Systems
Since the treatment capabilities as well as the costs of the innovative/alternative (I/A)
technologies are similar, one on-site I/A technology, FAST® System, was selected in
order to evaluate the wastewater disposal alternatives for the areas of wastewater disposal
need. The Single Home FAST® System can accommodate flows up to 440 gallons per
day (gpd). The site conditions on each property play a major role in the costing of I/A
systems. It has been assumed that each property has enough usable land to accommodate
its existing septic tank, a FAST® system, pump chamber, necessary piping, distribution
box, and a rectangular leaching area. The areas of wastewater disposal need where I/A
systems are being considered have either 30 percent or more of the study area with severe
soil limitations (hardpan, bedrock, slope, flooding and wetness) or 20 percent or more of
the study area with severe groundwater limitations (seasonally high water table at the
surface to 2 feet deep). These site conditions contribute to the construction cost of the
I/A system. For the areas of wastewater disposal need where on-site I/A systems are
being considered, the construction costs of two different FAST® systems have been
estimated. The effluent loading rates, leaching area requirements, and I/A system credits
are based on the requirements/provisions of Title 5. These systems are described in the
following paragraphs.
Case 1: Single Home FAST® System
Design Flow of 440 gpd, Poor Soils, Suitable Depth to Groundwater
This system includes the existing septic tank, a Single Home FAST® System,
piping, distribution box and leaching trenches. It has been assumed that the
poor soils within the study area have a percolation rate of 60 minutes per inch
(mpi), which as per Title 5, require an effluent loading rate of 0.15 gpd/SF. It
has been assumed that the effective leaching area of each trench includes the
bottom of the trench (2 feet) and a maximum of 2 feet of each sidewall.
Therefore each trench provides 6 SF of leaching area per linear foot of trench.
Title 5 allows a credit of a 50 percent reduction in leaching area with the use of
an I/A system. Based on these requirements, each system requires 245 linear
feet of leaching trench. Therefore, this system includes a 72-foot by 36-foot
leaching area consisting of four 62-foot long leaching trenches with a distance
of 6 feet between trenches. The area between the trenches is the designated
reserve area.
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Case 2: Single Home FAST® System
Design Flow of 440 gpd, Suitable Soils, Poor Depth to Groundwater
These systems include the existing septic tank, a Single Home FAST® System,
a pump and pump chamber, piping, distribution box and mounded leaching
trenches. It has been assumed that the suitable soils within the study area have
a percolation rate of 10 mpi, which as per Title 5, require an effluent loading
rate of 0.60 gpd/SF. It has been assumed that the effective leaching area of
each trench includes the bottom of the trench (2 feet) and a maximum of 2 feet
of each sidewall. Therefore each trench provides 6 SF of leaching area per
linear foot of trench. Since this system is located in an area with shallow depth
to groundwater, the leaching area needs to be raised in order to meet Title 5
requirements. A pump chamber is required to pump the FAST® System
effluent to the elevated leaching trenches. Title 5 allows a credit of a 2-foot
reduction in depth to groundwater with the use of an I/A system. This system
requires a 2-foot mound to provide adequate separation between the bottom of
the leaching area and groundwater. Based on these requirements, each system
requires 123 linear feet of leaching trench. Therefore, this system includes a
41-foot by 36 foot leaching area consisting of four 31-foot long leaching
trenches with a distance of 6 feet between trenches. The area between the
trenches is the designated reserve area.
The estimated construction costs for the FAST® systems are estimated at $50,000 each.
The estimated construction cost is based on the following:
• Single Home FAST® System requires a 2,000 gallon tank and/or pump
chamber;
• Single Home FAST® System requires 4 days for installation;
• Filter fabric and washed stone are used within leaching trenches;
• Site will be loam and seeded after construction of I/A system;
• Contractor’s payroll burden is approximately 50 percent of labor cost;
• Contractor’s overhead and profit is approximately 15 percent of material,
equipment and labor cost; and
• Construction contingency is approximately 20 percent of the total
construction cost.
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2. Operation and Maintenance Costs
Operation and Maintenance Costs for Off-Site Wastewater Alternative
The annual operation and maintenance (O&M) costs for the design year has been
estimated and is assumed to be approximately the same for each alternative. The costs
include estimated manpower, electrical power, supplies, equipment and maintenance for
the gravity sewers, pump stations, force mains, wastewater treatment facilities and
groundwater disposal sites. In order to maximize the life of the system, particularly the
pumping stations and wastewater treatment facilities, a comprehensive O&M program is
recommended. This will require a full time operating staff that will perform daily,
weekly and monthly tasks in order to achieve this goal. Therefore, the largest factor in
the O&M costs for each of the alternatives is labor. It has been assumed that other Town
resources will be used to aid in the operation of the system including billing, and sharing
of equipment and manpower during emergencies. The O&M costs are based on the
following:
• Operating Staff
o Staff for WWTFs, pumping stations and wastewater
infrastructure has been estimated to include: 1 superintendent, 1
administrative assistant, 1 clerical staff, 1 laboratory technician,
4 operators and 4 laborers
o Staff for Septage Management Plan has been estimated to
include: 1 superintendent, 1 administrative assistant
o Staffing Cost estimated at an average of $27.50 per hour per
person including benefits
• Power Cost estimated at $0.15 per kilowatt hour with each system/pump
operating for 6 hours per day
• Yearly cost for supplies, spare parts, lubrication and calibration of
measurement
o Wastewater Treatment Facilities estimated at $52,500 per year
o Pumping Stations estimated at $10,000 per station
• Compliance Monitoring and Testing
o Wastewater Treatment Facilities Management Plan at $40,000
per year
o Pumping Stations at $5,000 per station
o Septage Management Plan at $1,000 per week.
• Maintenance Contract including yearly inspection, supplies, spare parts,
and lubrication for Low Pressure System Pumping Unit estimated at
$500 per unit
• O&M costs include items such as chemicals, telephone, postage, permit
fees, legal, accounting, insurance, taxes and assessments, principal and
interest on loans, and fuel
• Present Worth Cost based on 20 years at 7 percent interest (10.594).
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Operation and Maintenance Costs for On-Site Innovative/Alternative Systems
Operation and maintenance of the FAST® System includes septic tank pumping, blower
maintenance, periodic inspections, and electrical costs. Depending on the approval and
permit issued by DEP, water quality testing may also be required. Septic tank pumping
should be performed on a regular basis such as once every two to three years. The cost of
this service is about $200 per pump-out. Yearly maintenance service contracts may be
obtained through the manufacturer’s representative of the FAST® System. The service
contract includes the four service visits, which are required by DEP. The estimated costs
of the service contracts for the Single Home FAST® System is estimated $500 per year.
Water quality testing is required on a quarterly basis and is estimated at $250 per year.
Annual electrical cost for a Single Home FAST® System is estimated at about $25 a
month or approximately $300 per year. Therefore the total annual operation and
maintenance cost for a Single Home FAST® System is estimated $1,150.
3. Wastewater Treatment Facilities Alternative Costs
An estimated construction cost was developed for two of the alternatives for the Surfside
WWTF. Table 4-4 presents the estimated construction cost for the Surfside WWTF.
TABLE 4-4
TOWN OF NANTUCKET
CWMP/DEIR
SURFSIDE WWTF ALTERNATIVES
ESTIMATED CONSTRUCTION COSTS
Alternative
Number
Description
Estimated
Construction
Cost
1 Modified Ludzack Ettinger $24,000,000
2 Sequencing Batch Reactors (SBRs); $22,500,000
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Cost comparisons for the Surfside facility were calculated for Modified Ludzack Ettinger (MLE)
process and Sequencing Batch Reactors (SBRS). Costs for these two processes are very similar.
The detailed cost comparison is calculated in the Surfside Preliminary Design Report. Trickling
filters and Rotating Biological Contactors were not considered because they require chemical
addition, which is not consistent with the Town’s goals for minimal use of hazardous chemicals.
In addition, both RBCs and Trickling Filters require a downstream process for nitrogen removal.
The cost comparisons for the treatment alternatives for Madaket were based on the Facilities Plan
for the Siasconset Wastewater Treatment Facility. The comparisons for the Siasconset Facility
detailed that SBRs were the most cost effective alternative. The Town decided to use the same
treatment process in Madaket because operation and maintenance costs are cheaper for the Town
if the same treatments processes are used.
4. Collection and Transmission Alternatives Costs
Various alternatives were evaluated for addressing the areas of wastewater disposal need
in the Town of Nantucket. The three alternatives are: (a) Convention Gravity Sewer with
Pumping Stations and Force Mains and connection to the existing system; (b) Low
Pressure Sewers with connection to the existing system; and (c) Innovative/Alternative
Systems with on-site disposal. An estimated project cost, estimated operation and
maintenance cost, and present worth cost was developed for each of these alternatives for
the five needs areas (Madaket, Monomoy, Somerset, Shimmo, and Warren’s Landing)
identified in Phase I. The present worth analysis for the collection and transmission
alternatives is based on the cost to both the Town and the individual homeowner.
Madaket Study Area
Alternative No. 1 consists of the installation of approximately 38,150 l.f. of gravity
sewers, 16,320 l.f. of force mains and 6 pumping stations. All gravity sewers and force
mains would be located in existing roadways while each of the pumping stations would
required the purchase of land. The approximate 293,007 gpd of wastewater generated in
the Madaket Study Area would be transported and treated at the proposed Madaket
Wastewater Treatment Facility.
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Alternative No. 2 consists of the installation of approximately 39,930 l.f. of low pressure
sewers. All low-pressure sewers would be located within existing roadways. The
approximate 293,007 gpd of wastewater generated in the Madaket Study Area would be
transported and treated at the proposed Madaket Wastewater Treatment Facility.
Alternative No. 3 consists of the installation of approximately 549 innovative/alternative
systems. The approximate 293,007 gpd of wastewater generated in the Madaket Study
Area would be treated and disposed locally.
Table 4-5 presents the estimated project cost, operation and maintenance cost and present
worth for each of the three alternatives for this study area.
Monomoy Study Area
Alternative No. 1 consists of the installation of approximately 19,830 l.f. of gravity
sewers, 9,500 l.f. of force mains and 5 pumping stations. All gravity sewers and force
mains would be located in existing roadways while each of the pumping stations would
required the purchase of land. The approximate 120,551 gpd of wastewater generated in
the Monomoy Study Area would be transported and treated at the proposed Monomoy
Wastewater Treatment Facility.
Alternative No. 2 consists of the installation of approximately 19,270 l.f. of low pressure
sewers. All low-pressure sewers would be located within existing roadways. The
approximate 120,551 gpd of wastewater generated in the Monomoy Study Area would be
transported and treated at the proposed Monomoy Wastewater Treatment Facility.
Alternative No. 3 consists of the installation of approximately 227 innovative/alternative
systems. The approximate 120,551 gpd of wastewater generated in the Monomoy Study
Area would be treated and disposed locally.
Table 4-6 presents the estimated project cost, operation and maintenance cost and present
worth for each of the three alternatives for this study area.
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NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 4-5 TOWN OF NANTUCKET CWMP/DEIR MADAKET STUDY AREA ALTERNATIVES ESTIMATED PROJECT COSTS, OPERATION AND MAINTENANCE COSTS AND PRESENT WORTH COSTS Alternative Number Description Quantity Unit Unit Price Extended Total Estimated Project Cost Estimated O&M Cost Present Worth Cost 1 Gravity SewersGravity Sewer38,150L.F$275$10,491,250Pumping Station6Each$750,000$4,500,000Force Main16,320L.F$200$3,264,000Land Acquisition6Each$125,000$750,000 $19,005,250$189,200$21,009,6352 Low Pressure Sewer Low Pressure Sewer 39,930L.F $175$6,987,750 Grinder Pumps and Appurtenances 549Each$10,000$5,490,000$12,477,750$278,281$15,425,8623Innovative/Alternative549Each$50,000$27,450,000$27,450,000$631,350$34,138,522 Page 4-17 Evaluation of Short Listed Alternatives L:\work\27355\PROJ\Report\Phase II\Section 4.doc
NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 4-6 TOWN OF NANTUCKET CWMP/DEIR MONOMOY STUDY AREA ALTERNATIVES ESTIMATED PROJECT COSTS, OPERATION AND MAINTENANCE COSTS AND PRESENT WORTH COSTS Alternative Number Description Quantity Unit Unit Price Extended Total Estimated Project Cost Estimated O&M Cost Present Worth Cost 1 Gravity SewersGravity Sewer19,830L.F$275$5,453,250Pumping Station5Each$750,000$3,750,000Force Main9,500L.F$200$1,900,000Land Acquisition5Each$125,000$625,000 $11,728,250$167,200$13,499,5672 Low Pressure Sewer Low Pressure Sewer 19,270L.F $175$3,372,250 Grinder Pumps and Appurtenances 227Each$10,000$2,270,000$5,642,250$115,325$6,864,0013Innovative/Alternative227Each$50,000$11,350,000$11,350,000$261,050$14,115,564 Page 4-18 Evaluation of Short Listed Alternatives L:\work\27355\PROJ\Report\Phase II\Section 4.doc
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CWMP/DEIR – PHASE II REPORT
Somerset Study Area
Alternative No. 1 consists of the installation of approximately 19,970 l.f. of gravity
sewers, 7,115 l.f. of force mains and 3 pumping stations. All gravity sewers and force
mains would be located in existing roadways while each of the pumping stations would
required the purchase of land. The approximate 108,794 gpd of wastewater generated in
the Somerset Study Area would be transported and treated at the proposed Somerset
Wastewater Treatment Facility.
Alternative No. 2 consists of the installation of approximately 19,970 l.f. of low pressure
sewers. All low-pressure sewers would be located within existing roadways. The
approximate 108,794 gpd of wastewater generated in the Somerset Study Area would be
transported and treated at the proposed Somerset Wastewater Treatment Facility.
Alternative No. 3 consists of the installation of approximately 205 innovative/alternative
systems. The approximate 108,794 gpd of wastewater generated in the Somerset Study
Area would be treated and disposed locally.
Table 4-7 presents the estimated project cost, operation and maintenance cost and present
worth for each of the three alternatives for this study area.
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NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 4-7 TOWN OF NANTUCKET CWMP/DEIR SOMERSET STUDY AREA ALTERNATIVES ESTIMATED PROJECT COSTS, OPERATION AND MAINTENANCE COSTS AND PRESENT WORTH COSTS Alternative Number Description Quantity Unit Unit Price Extended Total Estimated Project Cost Estimated O&M Cost Present Worth Cost 1 Gravity SewersGravity Sewer19,970L.F$275$5,491,750Pumping Station3Each$750,000$2,250,000Force Main7,115L.F$200$1,423,000Land Acquisition3Each$125,000$375,000$9,539,750$123,200$10,844,9312 Low Pressure Sewer Low Pressure Sewer 19,970L.F $175$3,494,750 Grinder Pumps and Appurtenances 205Each$10,000$2,050,000$5,544,750$104,391$6,650,6693Innovative/Alternative205Each$50,000$10,250,000$10,250,000$235,750$12,747,536 Page 4-20 Evaluation of Short Listed Alternatives L:\work\27355\PROJ\Report\Phase II\Section 4.doc
NANTUCKET, MASSACHUSETTS
CWMP/DEIR – PHASE II REPORT
Shimmo Study Area
Alternative No. 1 consists of the installation of approximately 26,315 l.f. of gravity
sewers, 5,000 l.f. of force mains and 5 pumping stations. All gravity sewers and force
mains would be located in existing roadways while each of the pumping stations would
required the purchase of land. The approximate 98,675 gpd of wastewater generated in
the Shimmo Study Area would be transported and treated at the proposed Shimmo
Wastewater Treatment Facility.
Alternative No. 2 consists of the installation of approximately 26,315 l.f. of low pressure
sewers. All low-pressure sewers would be located within existing roadways. The
approximate 98,675 gpd of wastewater generated in the Shimmo Study Area would be
transported and treated at the proposed Shimmo Wastewater Treatment Facility.
Alternative No. 3 consists of the installation of approximately 185 innovative/alternative
systems. The approximate 98,675 gpd of wastewater generated in the Shimmo Study
Area would be treated and disposed locally.
Table 4-8 presents the estimated project cost, operation and maintenance cost and present
worth for each of the three alternatives for this study area.
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NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 4-8 TOWN OF NANTUCKET CWMP/DEIR SHIMMO STUDY AREA ALTERNATIVES ESTIMATED PROJECT COSTS, OPERATION AND MAINTENANCE COSTS AND PRESENT WORTH COSTS Alternative Number Description Quantity Unit Unit Price Extended Total Estimated Project Cost Estimated O&M Cost Present Worth Cost 1 Gravity SewersGravity Sewer26,315L.F$275$7,236,625Pumping Station5Each$750,000$3,750,000Force Main5,000L.F$200$1,000,000Land Acquisition5Each$125,000$625,000 $12,611,625$167,200$14,382,9422 Low Pressure Sewer Low Pressure Sewer 26,315L.F $175$4,605,125 Grinder Pumps and Appurtenances 185Each$10,000$1,850,000$6,455,125$94,992$7,461,4703Innovative/Alternative185Each$50,000$9,250,000$9,250,000$212,750$11,503,874 Page 4-22 Evaluation of Short Listed Alternatives L:\work\27355\PROJ\Report\Phase II\Section 4.doc
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Warren’s Landing Study Area
Alternative No. 1 consists of the installation of approximately 7,400 l.f. of gravity sewers,
3,925 l.f. of force mains and 2 pumping stations. All gravity sewers and force mains
would be located in existing roadways while each of the pumping stations would required
the purchase of land. The approximate 47,562 gpd of wastewater generated in the
Warren’s Landing Study Area would be transported and treated at the proposed Warren’s
Landing Wastewater Treatment Facility.
Alternative No. 2 consists of the installation of approximately 8,000 l.f. of low pressure
sewers. All low-pressure sewers would be located within existing roadways. The
approximate 47,562 gpd of wastewater generated in the Warren’s Landing Study Area
would be transported and treated at the proposed Warren’s Landing Wastewater
Treatment Facility.
Alternative No. 3 consists of the installation of approximately 89 innovative/alternative
systems. The approximate 47,562 gpd of wastewater generated in the Warren’s Landing
Study Area would be treated and disposed locally.
Table 4-9 presents the estimated project cost, operation and maintenance cost and present
worth for each of the three alternatives for this study area.
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NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 4-9 TOWN OF NANTUCKET CWMP/DEIR WARREN’S LANDING STUDY AREA ALTERNATIVES ESTIMATED PROJECT COSTS, OPERATION AND MAINTENANCE COSTS AND PRESENT WORTH COSTS Alternative Number Description Quantity Unit Unit Price Extended Total Estimated Project Cost Estimated O&M Cost Present Worth Cost 1 Gravity SewersGravity Sewer7,400L.F$275$2,035,000Pumping Station2Each$750,000$1,500,000Force Main3,925L.F$200$785,000Land Acquisition2Each$125,000$250,000$4,570,000$101,200$5,642,1132 Low Pressure Sewer Low Pressure Sewer 8,000L.F $175$1,400,000 Grinder Pumps and Appurtenances 89Each$10,000$890,000$2,290,000$45,258$2,769,4593Innovative/Alternative89Each$50,000$4,450,000$4,450,000$102,350$5,534,296 Page 4-24 Evaluation of Short Listed Alternatives L:\work\27355\PROJ\Report\Phase II\Section 4.doc
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5. Recommendations Based on Evaluation of Cost
The evaluation of costs indicates that the best alternative for wastewater disposal
problems for each of the Study Areas is the installation of a Low Pressure Sewer System
and to use Sequencing Batch Reactors for the Expansion of the Surfside WWTF
Expansion and new Madaket WWTF.
C. INSTITUTIONAL ARRANGEMENTS
1. General
The Town of Nantucket Department of Public Works is presently governed by its Board
of Selectmen. The Town presently owns and operates two municipal sewer systems, one
that currently collects, treats and disposes of wastewater at the Surfside Wastewater
Treatment Facility and another smaller collection system located in Siasconset. At
present, the Siasconset WWTF is undergoing a major upgrade with the design and
construction of a state of the art wastewater treatment facility. The Town is also, in the
process of undertaking a Preliminary Design Report to upgrade and expand its Surfside
Wastewater Treatment Facility. All areas presently not connected to either of these two
systems rely on individual on-site wastewater disposal systems, which are under the
jurisdiction of the local Board of Health under state Title 5 rules and regulations at “310
CMR 15.000 - The State Environmental Code, Title 5: Standard Requirements for the
Siting, Construction, Inspection, Upgrade and Expansion of On-Site Sewage Treatment
and Disposal Systems and for the Transport and Disposal of Septage, Effective 3/31/95.”
Historically the Town of Nantucket Board of Health has adopted requirements for design
and construction of on-site systems that augmented the state requirements.
In early 1997, the Nantucket Planning and Economic Development Commission retained
Earth Tech, Inc. to prepare a Facilities Plan for Wastewater Disposal and Treatment for
the Village of Siasconset. The report entitled “Siasconset Facilities Plan for Wastewater
Treatment and Disposal,” Nantucket Massachusetts, dated December 31, 1997,
(Siasconset Facilities Plan) detailed a solution for the Siasconset Wastewater Infiltration
Beds and the lack of wastewater treatment achieved by the infiltration beds. The
facilities plan report met the requirements of the Administrative Consent Order between
the Town of Nantucket and the Department of Environmental Protection.
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In early 1998, the Nantucket Department of Public Works retained Earth Tech, Inc. to
prepare an Island-wide Comprehensive Wastewater Management Plan/Environmental
Impact Report (CWMP/EIR). In general, the objective of a CWMP/EIR is to identify areas
within the Town with subsurface wastewater disposal problems and to develop a plan to
mitigate or eliminate the problems. The wastewater treatment solutions presented in the
Siasconset Facilities Plan are considered in this CWMP/EIR.
The Town of Nantucket established a special procedure for review of this major and
complicated project. The special procedure consists of a three phase review of the
CWMP/EIR Document. The Document has been delineated into three phases, where the
scope of future phases is based in part on the results of the preceding phase. The first
phase, Phase I, included the Needs Analysis. This Report, Phase II contains the
Alternatives and Site Identification and Draft Environmental Impact Report (DEIR) and
Phase III will include the Final Environmental Impact Report (FEIR). The scope of the
Island-wide CWMP/EIR is twofold: (1) to determine the areas on the Island with
wastewater disposal problems that cannot be solved with a conventional Title 5 wastewater
disposal system; and (2) evaluate and make recommendations on the most viable solution
for wastewater disposal in each study area based on environmental, technical, and
economic considerations. With the filing of this Phase II Report, both of these scope items
have been determined and a recommended plan has been established.
The currently recommended plan for new and expanded wastewater collection,
transmission and treatment facilities are being evaluated, and will be proposed to be
designed and constructed under the guidance and direction of the Town of Nantucket
Department of Public Works and Board of Selectmen.
In order to manage and operate the proposed wastewater collection, transmission and
treatment facilities, the Town will need to implement institutional and system management
procedures, which are briefly described in the following paragraphs.
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2. Institutional and System Management Procedures
Establishment of Sewer and Septic Overlay Districts
In order to legally identify the boundaries of and set policy relating to, sewer and septic
overlays need to be delineated. This will allow the Town to distinguish which properties
have the right to hook into the municipal sewers system and, also, those that will be
managed under the Town’s Septage Management Program. This will involve acceptance
at the Town’s level as well as the filing of special legislation for enactment and
enforcement.
Review of the Current Sewer Use Rules and Regulations
A thorough review of the current Sewer Use Rules and Regulations needs to be
completed in order to set the minimum requirements for all users of the Town’s
wastewater collection, transmission and treatment facilities. This will enable the Town to
continue to comply with all applicable state and federal laws as well as the requirements
of the receiving treatment facilities. Included in these regulations will be the provisions
for sewer connections and extensions, building sewers, infiltration/inflow, construction
requirements, regulation of wastewater discharges, pretreatment of industrial wastewater,
permit applications and issuance, reporting requirements, compliance monitoring,
enforcement proceedings, service charges and fees. The main purpose of these
regulations is to prevent the introduction of undesirable pollutants and to provide
standard requirements for all users discharging into the sewer system. These regulations
must be in accordance with those of the receiving treatment facilities accepting
Nantucket’s wastewater. The rules and regulations will be administered by the Director
of Public Works.
Cost Recovery Plan
Cost Recovery Program will need to be developed in order to recover the capital costs of
new and expanded wastewater collection, transmission and treatment facilities.
Nantucket will need to address the problem of how to equitably apportion the capital
costs among its system’s users. The cost recovery for the planning, design, construction
and implementation of Nantucket’s wastewater facilities and the cost(s) of capital outlay
could potentially be by a combination of property taxes and betterments. An equitable
means of recovering these costs could be: to recover the cost of any portion of the project
that provides a general benefit to the entire community through municipal property taxes;
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and to recover the cost of public improvements which are of specific benefit to a
particular area in the community by betterments. Nantucket must arrive at a financing
solution that is fair, equitable and politically acceptable. A cost recovery plan will be
formulated, reviewed, and adopted by the Town prior to the start of construction of the
Project.
Review of Current Sewer User Charge System
A review of the current sewer user charge system will need to be completed and,
reviewed and any changes adopted by the Town which meets the requirements of the
state regulations in order to recover the costs required to operate, maintain and replace
the wastewater collection, transmission and treatment facilities.
Sewer System Expansion Control Policy
A Sewer System Expansion Control Policy will need to be developed, along with special
legislation, and adopted by the Board of Selectmen that deals with issues concerning the
expansion of the sewer collection system outside of the finalized “Needs Areas”
approved in the CWMP/EIR. The expansion of the sewer service areas within Town will
need to be controlled in order for the Town to stay within its allotted flow allowances at
the receiving wastewater treatment facilities. This policy should address issues such as:
• The number of service connections allotted to large parcels of
undeveloped land that have frontage on a sewer line in a designated area;
• Connections to force mains;
• Sewer service to back lots which do not have frontage on a street that has
sewers;
• The possibility of establishments not in a designated sewer service area
connecting into a gravity main that services a designated sewer area;
• Sewer system extension outside the “Needs Areas” as identified and
approved in the CWMP/EIR;
• Title 5 failures outside of the designated sewer areas;
• Policy to service the first floor of a structure by gravity and exceptions to
this rule;
• Connections to interceptors outside of the designated service area; and
• Establishment of “Low Flow Sewer Systems”.
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This policy should address the above issues and, when implemented, will prioritize the
concerns for the Town to include in any future expansion plans for the sewer system if
there is adequate capacities remaining within their wastewater flow allowances at the
receiving wastewater treatment facilities.
Review of Sewerage System Staffing and Operations Plan
A review of the current and projected Sewerage System Staffing and Operations Plan will
need to be completed. This plan will review and estimate the current and proposed tasks,
responsibilities and staffing requirements for each aspect of the operation and
maintenance of the current and proposed wastewater collection, transmission and
treatment facilities. The relative merits to Town staff versus contract operations should
be evaluated.
Review of Current System Construction Standards
In order to maintain consistency Island-wide, there should be a review and discussion on
construction standards for the Town. Included in this review would be facility design
(for spare part redundancy and general O & M) and manhole design.
Septage Management Plan
Proactive in its approach to the CWMP/EIR, the Town of Nantucket has already begun
the process of developing a Septage Management Plan for the areas of Town not included
in the current and proposed municipal sewer service area. The goal of this Septage
Management Plan (SMP) is to protect and maintain public health, ensure protection of
surface and groundwater quality, provide sustainability of the Island’s single-source
aquifer, maintain water resources as recreational, aesthetic and economic assets, improve
the environment and prevent its deterioration, preserve and retain local control of on-site
wastewater disposal systems without regulatory intervention and to protect private
investments with regards to residential property values that is not only accepted locally
but in accordance with all regulatory requirements. The successful long-term
sustainability of on-site wastewater disposal systems is dependent on proper operation
and maintenance in order to prevent adverse health and environmental impacts. It is the
intent of this SMP to operate in conjunction with the Town’s municipal wastewater
collection systems in the proper collection and disposal of septage on Nantucket.
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The Town must develop a form of government to regulate and oversee the Septage
Management Plan. This organizational body may be the current Board of Health or
entity working under the jurisdiction of the Board of Public Works or some other form of
government, elected, appointed or otherwise (separate from general Town government).
This SMP management entity chosen by Nantucket will be responsible for administering
the institutional requirements set forth in the final approved SMP that is now being
evaluated.
Water Conservation Program
It is recommended that an overall water conservation program be implemented in order to
reduce the amount of water consumed and discharged into both the existing on-site
wastewater disposal systems and the proposed wastewater collection, transmission and
treatment facilities. The Town will be limited as to how much wastewater it can send to
the receiving wastewater treatment facilities. Not only will the implementation of water
conservation devices and programs result in lower operational costs to each user, but it
will also result in reserve capacity at the receiving treatment facilities should future areas
of Need arise in Town. This is presently being undertaken by the Wannacomet Water
Company. It is recommended that the Department of Public Works, in conjunction with
the Water Company work to promote a public education program in order to achieve
maximum benefit.
D. RESIDUALS DISPOSAL
The Town leases the property for the Municipal Compost facility. A private contractor operates
the facility. According to the facility operator, the composting facility can handle the proposed
additional residuals disposal. The recommended plan is to continue this operation. No other
alternatives were reviewed because this alternative is already established and permitted.
E. LOCATION OF FACILITIES
1. Madaket WWTF – FAA Site
The Madaket facility is proposed on the current FAA site. The facility will be at least
1,000 feet away from residential areas and located outside of any environmentally
sensitive areas. This will minimize any potential aesthetic issues with the facility.
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The hydrogeological study for the site will help to situate the disposal beds on the site in
the area of least consequence. In addition, the wastewater effluent will be treated to a
much higher degree than the current Title 5 systems. This will minimize any impacts to
Long Pond or Madaket Harbor.
The wastewater treatment facility will be designed to meet the guidelines of the
Nantucket Historic District Commission (NHDC) as detailed in, “Building with
Nantucket in Mind.” The guidelines detail strict design requirements, such as building
color, building outline, and the use of native species in landscaping. The final design will
be reviewed by the NHDC during their building permit process.
2. Surfside WWTF Expansion
The proposed Surfside WWTF project will be an expansion of the existing facility. Since
the site has been previously disturbed and is currently used and permitted for wastewater
treatment, the project will have minimal effect on the area.
The design will be similar to the existing facility and will be designed to meet the
guidelines of the Nantucket Historic District Commission (NHDC) as detailed in,
“Building with Nantucket in Mind.” The guidelines detail strict design requirements,
such as building color, building outline, and the use of native species in landscaping. The
final design will be reviewed by NHDC during their building permit process.
3. Needs Areas
Madaket, Monomoy, Somerset, Shimmo, and Warren’s Landing Study Areas will receive
sewer expansion. The sewer lines will be constructed in existing roadways. This will
minimize aesthetic problems. No new pumping stations in these areas are proposed.
This new infrastructure will be located outside of environmental sensitive areas, since it
will primarily be in previously disturbed locations. Removing theses areas from their
failing Title 5 systems and putting them on a sewer system will remove many pollutants
in these areas from the Nantucket and Madaket Harbors.
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G. PHASED CONSTRUCTION
A phased construction will be used for the construction of the selected alternative. A phased
construction will allow the Town to spread out the cost of design, construction, and
implementation of the selected alternative through several fiscal years. In addition, the selected
capital improvement will be reviewed with the town departments and committees, such as the
Department of Public Works, Board of Selectmen and Finance Committee to determine the
financial impacts of the recommended plans along with any other improvement projects such as
roadway improvements and school. The Town is also in the process of determining the financing
methods necessary to implement the recommendations detailed herein.
H. FLEXIBILITY AND RELIABILITY
The wastewater treatment alternatives will be design to be flexible and reliable so that any
unforeseen circumstances can be dealt with in a timely manner. All infrastructure and wastewater
treatment will be designed in accordance with the New England Interstate Water Pollution
Control Commission’s “Guide for the Design of Wastewater Treatment Works.” The guide
details how to number and arrange units so that the componet parts of plants are arranged for the
greatest operating convenience, flexibility, and economy and for the installation of future units.
The design and layout of the treatment facilities will include provisions for future expansion or
future upgrades.
In addition, the facilities will be similarly designed so that the operation and maintenance of the
facilities on the Island will be standardized. All three of the wastewater treatment facilities on the
Island will utilize SBRs and be standardized on other unit processes, such as pumping equipment.
The standardized design will maximize efficiency and the ability to minimize the impacts from
unforeseen equipment problems.
I. IMPLEMENTATION CAPABILITY
Each of the recommended alternatives will be reviewed by the applicable federal, state and local
governmental units for ability to implement via appropriate permitting agencies. As part of the
MEPA process, Nantucket is required to provide the Secretary of Environmental Affairs and the
public with a 30-day public review period, during which comments are solicited by the Secretary,
reviewed and applied appropriately in the MEPA Certificate. In addition to the MEPA process all
of the plans and specifications for this project will be reviewed through the SRF program and will
be subject to all required permitting regulations.
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The Town of Nantucket is prepared to bear its local share of the cost of the selected alternatives
through local appropriations, Town Meeting action and through the user tax base. Currently the
Town has one WWTF in operation and one WWTF under construction both of which fall under
the Department of Public Works jurisdiction. Other recommended institutional arrangements are
discussed in this Report and will be in place before any plan is implemented.
J. REGULATORY, DESIGN AND RELIABILITY REQUIREMENTS
As part of the MEPA process, Nantucket is required to file an EIR. The Secretary issued a
Certificate containing a scope which provides a description of alternatives to be considered in the
EIR, environmental impacts to be analyzed, and techniques to be used in the analysis. EIRs are
subject to 30 days of agency and public comment after publication in the Environmental Monitor.
This project is also subject to the rules and regulations of the State Revolving Fund (SRF). Plans
and Specifications will be reviewed and approved by the Department of Environmental Protection
and the project will be evaluated and subject to all required permitting regulations.
All of the recommended plans in this Report have been formally approved on the federal, state
and local level. This plan will not implement any new technologies which have not already been
approved by MEPA and the SRF program. The Town of Nantucket has worked closely with the
DEP and MEPA in this process.
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5.0 RECOMMENDED PLAN
A. DETAILED RECOMMENDED PLAN
1. Introduction
In previous sections of this Report, each study area determined by the Phase I Report to
be a Need Area was looked at in terms of possible solutions for wastewater need. This
Section of the Report highlights the recommended plan for each study area as well as
associated institutional impacts, environmental impacts, capital costs, and operation and
maintenance costs.
2. Study Areas
In Phase I of the CWMP, the Island was delineated into eighteen (18) study areas based
on geographic location. All of these areas were analyzed for the need for wastewater
disposal beyond the use of Conventional Title 5 on-site wastewater disposal systems.
Once an area was determined to be a Needs Area, several alternatives were analyzed in
order to determine a solution for each area’s needs. The four options analyzed for each
area were: (1) Conventional Gravity Sewers with Pump Stations and Forcemains; (2)
Low Pressure Sewers; (3) I/A systems; and (4) On-Site Wastewater Disposal Systems
with the implementation of a Septage Management Plan (SMP).
Each Needs Area was first evaluated for the possibility of connecting to an existing
collection system to be treated at either the Siasconset Wastewater Treatment Facility or
the Surfside Wastewater Treatment Facility. This was not a feasible option for Madaket,
Warren’s Landing, Polpis, Pocomo, Wauwinet, and Quidnet due to their distance from
either Wastewater Treatment Facility. The costs incurred with attempting to tie these
areas into existing facilities due to the length of pipe needed to connect these areas as
well as operation and maintenance costs would be prohibitive.
The next options evaluated were constructing a local treatment facility or
communal/cluster treatment for each study. Land availability and the abundance of
wetlands, harbor watersheds proximity, and other water bodies pose as major obstacles
on the Island and therefore local and communal treatment became difficult scenarios for
numerous study areas. Constructing a local treatment facility combined with ground
water discharge of treated effluent necessitates acres of land, which combined with the
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above mentioned water and wetland issues, eliminates this option in many areas on Island
With the establishment of a SMP to be implemented by the Town, on-site Conventional
Title 5 wastewater disposal systems become a sensible solution for many areas that lack
efficient land area or susceptibility to incur excessive costs.
Study Area 1 – Madaket
The Madaket Area was deemed unable for long-term sustainability with the
current on-site wastewater disposal systems in the Phase I Report or simply a
Needs Area. The recommended plan consists of the installation of 39,930 linear
feet of low-pressure sewer with sizes ranging from 1-1/4 to 4 inch diameter pipe.
Approximately 1,400 linear feet of the total 39,930 will be used for connection to
a future satellite wastewater treatment facility. All low-pressure sewers will be
located in the roadways and end at the new satellite wastewater treatment plant
in-plant pump station. Refer to Figure 5-1 for the proposed Madaket Collection
System.
A parcel located in close proximity of the Madaket Study Area will be able to
accommodate the construction of this package wastewater treatment plant as well
as groundwater discharge, therefore making this the most feasible option. The
Federal Aviation Administration currently owns the parcel where the new
Madaket Wastewater Treatment facility is proposed to be located.
Study Area 2 – Warren’s Landing
The Warren’s Landing Study Area was deemed unable for long-term
sustainability with the current on-site wastewater disposal systems in the Phase I
Report or simply a Needs Area.. The recommended plan consists of installation
of 8,000 linear feet of low-pressure sewer with sizes ranging from 1-1/4 to 4 inch
diameter
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pipe. All low-pressure sewers will be located in the roadways and connected to
the Madaket collection system via Madaket Road. Refer to Figure 5-2 for the
proposed Warren’s Landing Collection System.
The Madaket collection system will discharge wastewater to a satellite
wastewater treatment facility, the proposed Madaket Wastewater Treatment
Facility. A parcel located in close proximity to the Madaket Study Area will be
able to accommodate the construction of this package wastewater treatment plant
as well as groundwater discharge, therefore making this the most feasible option.
The Federal Aviation Administration currently owns the parcel where the new
Madaket Wastewater Treatment facility is proposed to be located.
Study Area 3 – Cisco
The Cisco Study Area was determined in the Phase I Report as long-term
sustainable with the current on-site wastewater disposal systems or simply not an
area of need. Therefore, the recommended plan is for continued use of
Conventional Title 5 and other in place on-site wastewater disposal systems with
oversight from the Town under a Septage Management Plan.
Study Area 4 – Somerset
The Somerset Study Area was deemed unable for long-term sustainability with
the current on-site wastewater disposal systems in the Phase I Report or simply a
Needs Area. The recommended plan consists of the installation of 12,850 linear
feet of gravity sewer with sizes ranging from 4 to 8 inch diameter pipe and 7,115
linear feet of low-pressure sewer. Refer to Figure 5-3 for the proposed Somerset
Collection System.
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Of the 12,850 linear feet of gravity sewer, 1,000 linear feet will be used to
connect to the Town’s existing gravity sewer via Bartlett Road to Surfside Road,
which will convey the wastewater to the Sea Street Pump Station located in the
Town Area of Nantucket. The Sea Street Pump Station will pump the
wastewater flow to the Surfside Wastewater Treatment Facility for treatment and
disposal. All sewers will be located in the roadways.
Study Area 5 – Miacomet
The Miacomet Area was determined in the Phase I Report as long-term
sustainable with the current on-site wastewater disposal systems or simply not an
area of need. Therefore, the recommended plan is for the continued use of
Conventional Title 5 and other on-site wastewater disposal systems with
oversight from the Town under a Septage Management Plan.
Study Area 6 – Surfside
The Surfside Study Area was determined in the Phase I as long-term sustainable
with the current on-site wastewater disposal systems or simply not an area of
need. Therefore, the recommended plan is for the continued use of Conventional
Title 5 and other on-site wastewater disposal systems with oversight from the
Town under a Septage Management Plan.
Study Area 7 – Tom Nevers – Low Density
The Tom Nevers-Low Density Study Area was determined in the Phase I Report
as long-term sustainable with the current on-site wastewater disposal systems or
simply not an area of need. Therefore, the recommended plan is for the
continued use of Conventional Title 5 and other on-site wastewater disposal
systems with oversight from the Town under a Septage Management Plan.
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Study Area 7H – Tom Nevers-High Density
The Tom Nevers-High Density Study Area was determined in the Phase I Report
as long-term sustainable with the current on-site wastewater disposal systems or
simply not an area of need. Therefore, the recommended plan is for the
continued use of Conventional Title 5 and other on-site wastewater disposal
systems with oversight from the Town under a Septage Management Plan.
Study Area 8 – Siasconset
The Siasconset Study Area was deemed unable for long-term sustainability with
the current on-site wastewater disposal systems in the Phase I Report or simply a
Needs Area. However, the Siasconset Area is currently being addressed with the
design and construction of the Siasconset Wastewater Treatment Facility due to
be finished construction in spring of 2004. The facility is located in the
Siasconset area on United States Coastguard property. The recommended plan is
for all unsewered lots to be connected to the Siasconset collection system.
Study Area 9 – Quidnet
The Quidnet Study Area was deemed unable for long-term sustainability with the
current on-site wastewater disposal systems in the Phase I Report or simply a
Needs Area. The Quidnet Area ranks high in terms of requiring attention due its
location in proximity to Sesachacha Pond and the number of failing on site
wastewater disposal systems. Sesachacha Pond is currently listed on the State’s
303(d) list for having high Nitrogen levels. However, due to the MEP, the
recommended plan consists of maintaining Conventional Title 5 systems along
with other on-site wastewater disposal systems. The Town, with the auspices of
the Septage Management Plan will monitor all systems and at the completion of
the MEP, will be reevaluated for a long-term wastewater solution in accordance
with the guidelines of the MEP. Refer to the Executive Summary for an
explanation of the MEP.
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Study Area 10 – Wauwinet
The Wauwinet Area was deemed unable for long-term sustainability with the
current on-site wastewater disposal systems in the Phase I Report or simply a
Needs Area. However, due to the MEP, the recommended plan for the Wauwinet
Study Area consists of maintaining Conventional Title 5 systems along with
other on-site wastewater disposal systems. The Town, with the auspices of the
Septage Management Plan will monitor all systems and at the completion of the
MEP, will be reevaluated for a long-term wastewater solution in accordance with
the guidelines of the MEP. Refer to the Executive Summary for an explanation
of the MEP.
Study Area 11 – Pocomo
The Pocomo Study Area is a Needs Area based on the Nantucket Harbor
Watershed delineation. However, the recommended plan for the Pocomo Study
Area consists of maintaining Conventional Title 5 systems along with other on-
site wastewater disposal systems. The Town, under the auspices of the Septage
Management Plan will monitor all systems and at the completion of the MEP,
will be reevaluated for a long-term wastewater solution in accordance with the
guidelines of the MEP. Refer to the Executive Summary for an explanation of
the MEP.
Study Area 12 – Polpis
The Polpis Study Area was deemed unable for long-term sustainability with the
current on-site wastewater disposal systems in the Phase I Report due not only to
its proximity in relation to the Nantucket Harbor Watershed delineation, but,
also, based on qualifying criteria as detailed in the Phase I Report. However, due
to the MEP, the recommended plan for the Polpis Study Area consists of
maintaining Title 5 systems along with other on-site wastewater disposal
systems. The Town under the auspices of the Septage Management Plan will
monitor all systems and
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at the completion of the MEP, will be reevaluated for a long-term wastewater
solution in accordance with the guidelines of the MEP and at the completion of
the MEP, will be reevaluated. Refer to the Executive Summary for an
explanation of the MEP.
Study Area 13 – Town
The Town was deemed unable for long-term sustainability with the current on-
site wastewater disposal systems in the Phase I Report due not only to its
proximity in relation to the Nantucket Harbor Watershed delineation, but, also,
based on qualifying criteria as detailed in the Phase I Report. The majority of the
Town Area’s properties are already connected to Town sewer. Gravity sewers
and pump stations collect and convey the wastewater to the Surfside Wastewater
Treatment Facility for treatment and disposal. The recommended plan is for the
remaining unsewered lots to be connected to the existing collection system.
Study Area 14 – Town WPZ
The Town Wellhead Protection Zone (WPZ) is a Needs Area based on vicinity to
the Town well water. The majority of the WPZ is connected via gravity sewers
to the existing Surfside Collection System to be treated at the Surfside
Wastewater Treatment Facility. The remaining Town WPZ Study Area is
serviced through on-site wastewater treatment systems. The Town Septage
Management Plan will monitor these unsewered parcels.
Study Area 15 – Shimmo
The Shimmo Study Area is a Needs Area based on the Nantucket Harbor
Watershed delineation. The recommended plan consists of the installation of
26,315 linear feet of low pressure sewer with sizes ranging from 1-1/4 to 4 inch
diameter pipe. The Shimmo collection system will tie in directly to the gravity
sewer in the Monomoy Study Area via Polpis Road. Figure 5-4 provides a layout
for the proposed Shimmo Collection System.
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Both the Monomoy and Shimmo collection systems will discharge to the existing
Town collection system at Milestone Road, which will convey the wastewater to
the Sea Street Pump Station. The Sea Street Pump Station will pump the
wastewater flows to the Surfside Wastewater Treatment Facility for treatment
and disposal.
Study Area 16 – Monomoy
The Monomoy Area is a Needs Area based on the Nantucket Harbor Watershed
delineation. Currently, there are approximately three-percent of the developed
lots connected to the collection system that conveys wastewater to the Surfside
Wastewater Treatment Facility. The recommended plan consists of connecting
the remaining Monomoy Study Area to the same collection system via 14,540
linear feet of low pressure sewer with sizes ranging from 1-1/4 to 4 inch diameter
pipe. The collection system also includes 4,730 linear feet of 8-inch gravity
sewer that will travel down Polpis Road to Milestone Road, thereby connecting
the Monomoy and Shimmo Collection Systems to the Town Collection System.
This whole system would connect to the Sea Street Pump Station to be conveyed
for treatment and disposal at the Surfside wastewater Treatment Facility. All
sewers will be located in the roadways. Refer to Figure 5-5 for the proposed
layout of the Monomoy Collection System.
Study Area 17 – Remaining Island
The Remaining Island Area was determined in the Phase I Report as long-term
sustainable with the current on-site wastewater disposal systems or simply not an
area of need. Therefore, the recommended plan is for the continued use of
Conventional Title 5 and other on-site wastewater disposal systems with
oversight from the Town under a Septage Management Plan.
Refer to Table 5-1 for a summary of the recommend plan.
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NANTUCKET, MASSACHUSETTS CWMP/DEIR – PHASE II REPORT TABLE 5-1 TOWN OF NANTUCKET CWMP/EIR SUMMARY OF RECOMMENDED PLAN Study Area Recommended Plan Study Area Recommended Plan Study Area Recommended Plan Madaket • Needs Area Based on Matrix • 39,930 LF Low Pressure Sewer • Treatment at Madaket WWTF Tom Nevers –Low Density • Not Needs Area • Continued Use of On-Site Systems • Monitored by Septage Management Plan Polpis• Needs Area Based on Matrix • Continued Use of On-Site Systems • Monitored by Septage Management Plan • To Be Reevaluated After Completion of The Massachusetts Estuaries Project Warren’s Landing • Needs Area Based on Matrix • 8,000 LF Low Pressure Sewer • Connection to Madaket Collection System • Treatment at Madaket WWTF Tom Nevers –High Density • Not Needs Area • Continued Use of On-Site Systems • Monitored by Septage Management Plan Town• Needs Area Based on Matrix • Connect All Unsewered Lots to Town Collection System • Treatment at Surfside WWTF Cisco • Not Needs Area • Continued Use of On-Site Systems • Monitored by Septage Management Plan 8 Siasconset• Needs Area Based on Matrix • Connect All Unsewered Lots to Siasconset Collection System • Treatment at Siasconset WWTF (Currently Under Construction) Town WellheadProtection Zone • Needs Area Based on Well Protection Zone • Connect All Unsewered Lots to Town Collection System • Treatment at Surfside WWTF Somerset • Needs Area Based on Matrix • 12,850 LF Gravity Sewer • 7,115 LF Low Pressure Sewer • Connection to Town Collection System • Treatment at Surfside WWTF Quidnet• Needs Area Based on Matrix • Continued Use of On-Site Systems • Monitored by Septage Management Plan • To Be Reevaluated After Completion of The Massachusetts Estuaries Project Shimmo• Needs Area Based on Harbor Watershed • 26,315 LF of Low Pressure Sewer • Connection to Monomoy Collection System • Treatment at Surfside WWTF Miacomet • Not Needs Area • Continued Use of On-Site Systems • Monitored by Septage Management Plan Wauwinet• Needs Area Based on Matrix • Continued Use of On-Site Systems • Monitored by Septage Management Plan • To Be Reevaluated After Completion of The Massachusetts Estuaries Project Monomoy• Needs Area Based on Matrix • 14,540 LF of Low Pressure Sewer • 4,730 LF of Gravity Sewer • Connection to Town Collection System • Treatment at Surfside WWTF Surfside • Not Needs Area • Continued Use of On-Site Systems • Monitored by Septage Management Plan Pocomo • Needs Area Based on Harbor Watershed • Continued Use of On-Site Systems • Monitored by Septage Management Plan • To Be Reevaluated After Completion of The Massachusetts Estuaries Project Remaining Island• Not Needs Area • Continued Use of On-Site Systems • Monitored by Septage Management Plan Page 5-14 Recommended Plan L:\work\27355\PROJ\Report\Phase II\Section 5.doc
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3. Wastewater Treatment Facilities
The Island of Nantucket currently operates one wastewater treatment facility, the Surfside
Wastewater Treatment Facility (WWTF). The Island’s second wastewater treatment
facility is currently being constructed in the Siasconset Area. The recommended plan
includes the construction of a third wastewater treatment facility in the Madaket Area of
the Island. Figure 5-6 shows the three wastewater treatment facilities’ locations on the
Island of Nantucket. Table 5-2 shows the Typical WWTF Effluent Requirements.
Surfside WWTF
The Surfside WWTF, located on South Shore Road in the Southwest region of the Island
is currently permitted to discharge 1.80 mgd of advanced primary treated effluent during
the summer months into 10 rapid infiltration basins. The service area encompasses
approximately 2,000 acres of land out of a total 30,580 acres on the Island. The Surfside
WWTF serves approximately 4,000 residential and commercial customers. The Surfside
WWTF was built in 1991 and is in dire need of rehabilitation.
TABLE 5-2
TOWN OF NANTUCKET
CWMP/DEIR
TYPICAL WWTF EFFLUENT PERMIT REQUIREMENTS
Effluent Permit Parameter
Monthly
Average
Weekly
Average
Daily
Maximum
BOD5 (mg/L) 10 15 20
TSS (mg/L) 10 15 20
Settleable Solids (ml/L) 0.1 -- 0.3
Fecal Coliform Bacteria (#/100ml) -- -- 200
Total Residual Chlorine (mg/L) < 1.0 -- 1
Toxicity - LC50 (% survival) -- -- > 50
pH -- -- 6.0 to 8.5
Total Nitrogen 10 -- --
NO3 < 10 -- --
Total Phosphorous -- -- --
Oil and Grease 15 -- --
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The Town of Nantucket has already begun the next step of upgrading and expanding the
existing Surfside WWTF. Earth Tech was selected to prepare a Preliminary Design
Report (PDR) to identify and develop the necessary upgrades at the WWTF. The PDR
includes expanding and improving the headworks, providing secondary treatment for the
removal of BOD, TSS and nitrogen, expansion of the effluent disposal beds, sludge
processing improvements, septage receiving improvements, and odor control. The PDR
is being developed with the following project goals in mind that have been identified by
the Town:
• Maximize Use of the Existing Site;
• Low Maintenance;
• Operation Without the Use or a Limited Use of Chemicals;
• Capture and Treat Odors;
• Meet High Discharge Limits; and
• Community Acceptance.
The Town requested that the PDR include a cost-effective review of alternatives for
providing secondary treatment with biological processes, furnishing expanded sludge
dewatering capabilities, and improving the existing odor control facilities. As such, the
following alternatives were evaluated:
• Biological Unit Process Alternatives included: (a) Modified Ludzack
Ettinger; (b) Sequencing Batch Reactors (SBRs); (c) Trickling Filters;
and (d) Rotating Biological Contactors.
• Sludge Processing Alternatives included: (a) High performance Belt
Filter Presses, (b) Centrifuges; and (c) Rotary Presses.
• Odor Control Alternatives included: (a) Packed bed scrubbers; (b) Mist
chamber scrubbers; and (c) Bio-Filters.
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Of these alternatives, SBRs were selected for providing biological secondary treatment,
Centrifuges were selected for providing sludge dewatering, and Packed Bed Scrubbers
were selected to provide odor control. A recommended plan, including these selected
alternatives, was presented in the PDR, and is discussed below and shown on Figure 5-7
and Figure 5-8:
Grit Removal
It is recommended that the existing aerated grit chamber be expanded to provide
for a new aerated grit chamber. An additional chamber would allow for
operational flexibility, particularly for maintenance. In addition, it is
recommended that a building be constructed adjacent to the aerated grit chamber.
The new building will be provided with automated grit processing equipment. In
addition, the recommendation is for the building to serve as a new septage
receiving area. Providing housing around the septage receiving area will prevent
the escape of odors. Finally, it is recommended that the aerated grit chambers be
covered with aluminum plates and that new ductwork be provided for odor
control.
Primary Clarification
The existing rectangular clarifiers have the necessary capacity to handle the
design flow, therefore it is recommended that they be kept in service for primary
clarification prior to secondary treatment. In addition, it is recommended that the
sludge removal equipment, including mechanical drives and pumps, be
refurbished and that aluminum covers with ducts for odor control be provided.
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Solids Handling Building
It is recommended that the Solids Handling Building be modified by relocating
the sludge holding tanks. The existing pipe gallery, which is currently severely
congested, could then be expanded into what is now the sludge holding tank area.
Biological Unit Processes
Of the four alternatives evaluated (SBRs, MLE Process, RBCs, and Trickling
Filters), SBR's are the recommended alternative for providing secondary
treatment. Both RBCs and Trickling Filters are not recommended because they
require chemical addition, which is not consistent with the Town’s goals for
minimal use of hazardous chemicals. In addition, both RBCs and Trickling
Filters require a downstream process for nitrogen removal.
In the evaluation, it was determined that the MLE Process, is a suitable
alternative capable of providing the same level of treatment and operation
flexibility at approximately the same cost as SBRs. SBRs are recommended
because the Siasconset WWTF (currently under construction) is a SBR facility
and the proposed Madaket WWTF is anticipated to be an SBR facility.
Therefore, SBRs are recommended because it is anticipated that there will be an
overall cost savings to the Town and a simplification of operation realized by
providing essentially the same treatment process and process equipment at all
three facilities.
Effluent Disinfection
Disinfection of the WWTF effluent through the use of an ultraviolet (UV) system
using medium-pressure quartz vapor lamps is the recommended method of
effluent disinfection. The ultraviolet process is capable of destroying all types of
pathogens in clear liquids without the addition of chemicals or heat. UV
disinfection is consistent with the Town’s goals for minimal use of hazardous
chemicals. Most other disinfection alternatives require the use of chemicals.
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Effluent Disposal Bed Expansion
The current means of disposing of the treated effluent is through groundwater
infiltration by rapid infiltration basins. In order to expand the facility to treat and
dispose of the 3.5 MGD future design wastewater flow, an analysis was needed
to determine the required infiltration basin capacity. For this determination, a
preliminary groundwater model was developed. The model indicated that the
existing bed configuration would not be able to accommodate the significantly
greater flows being proposed. Since there is sufficient land area for the
construction of additional beds at the site, it was decided to use those potential
beds in the maximum discharge simulation. Model runs to evaluate the use of
additional beds, found that the expanded 3.5 MGD flow could be disposed of
through the construction of 5 additional disposal beds. Although additional
model simulations are required in order optimized disposal bed configurations,
the site is capable of handling the additional discharge being proposed.
Sludge and Septage Dewatering and Disposal
Of the three alternatives evaluated, belt filter presses, centrifuges, and rotary
presses, the recommended alternative for sludge dewatering is centrifuges. An
annual cost evaluation, presented in the PDR determined that BFP’s and
centrifuges are close in cost and that rotary presses are more expensive.
Centrifuges are recommended for sludge dewatering because they require less
space than belt filter presses and reduce the quantity of odorous air required to be
processed in the odor control system.
The sludge dewatering facilities at Surfside will need to have capacity to dewater
primary sludge, waste sludge from the SBR’s and primary and waste sludge that
is hauled from the Siasconset WWTF. In addition, it is recommended that the
centrifuges be sized such that they could handle sludge from the planned
Madaket WWTF, in an emergency situation. In this manner, the sludge
dewatering facilities at Madaket could be smaller because there would be no need
for a redundant backup. If dewatering equipment at that Madaket facility needed
to be repaired, the sludge could be hauled to the Surfside WWTF. It is
recommended that the existing Compost Shelter be enclosed and modified to
house the centrifuges. In addition, it is recommended that the layout be designed
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such that the trucks used to haul the dewatered sludge, could park and load
within the renovated sludge building. In this manner, odorous air could be
contained and therefore minimize odor problems at the facility.
As was previously discussed, it is recommended that a new building be
constructed to house both the grit processing equipment and septage receiving.
Having the septage hauling trucks park and unload septage within an enclosed
building will allow for capturing the odorous air and therefore reduce odor
problems at the facility.
Odor Control
A packed media scrubber system is recommended to “scrub” odorous air
generated at the WWTF. Although the biofilter alternative does not require
hazardous chemical, the volume of air requiring treatment makes the biofilter
cost prohibitive.
Building Renovations
There are several building renovations being recommended. As previously
discussed, it is recommended that the sludge holding tanks be relocated so that
the pipe gallery in the existing Solids Handling Building could be expanded to
relieve congestion. It is recommended that the existing Compost Shelter be
enclosed and used as a Sludge Handling Building. It is recommended that the
existing Sludge Management Building be renovated to use part of the building as
a laboratory and part of the building as a maintenance building. In this manner, a
much needed enclosed maintenance work area will be provided and the
Administrative Building that now houses the Laboratory could become more of a
true Administration Building. Finally, it is recommended that the existing Bulk
Material Shelter be enclosed and used for large equipment maintenance and bulk
storage. This would provide a much needed area, out of the elements, for storage
and maintenance. Table 5-3 shows the Surfside WWTF and Design Criteria.
TABLE 5-3
TOWN OF NANTUCKET
CWMP/DEIR
SURFSIDE WWTF DESIGN CRITERIA
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Description
Future Design
Summer 2025
A. Flows and Loadings
Residential Flow (mgd) 3.5
BOD5 Concentration (mg/l) 300
TSS Concentration (mg/l) 200
TKN Concentration (mg/l) 40
NH4-N Concentration (mg/l) 25
Total P Concentration (mg/l) 10
WWTF Design Flow Average Day, Peak Month (mgd) 3.500
WWTF Max. Day, Peak Month (mgd) 5.250
Design Flow Peaking Factor 2.20
WWTF Design Instantaneous Maximum Flow (mgd) 7.700
B. Primary Treatment
No. of Units 3
Type Rectangular
Length Each (ft.) 81.5
Width Each (ft.) 18
Sidewater Depth each (ft.) 7
Overflow Rate at Design Flow (gpd/ft2) 795
Overflow Rate at Maximum Day Flow (gpd/ft2) 1193
Overflow Rate at Instantaneous Peak Flow (gpd/ft2) 1750
Detention Time at Design Flow (hrs.) 1.6
C. SBR System
Length, feet 87
Width, feet 87
Maximum Depth, feet 16
Volume (MG) 0.906
Total No. of Units (each) 3
No. of Cycles (per day/basin) 5
Cycle Duration (hours/cycle) 4.8
Hydraulic Retention Time (Day) at design flow 0.776
D. Post Equalization
No. of Units 1
Maximum Sidewater Depth, ft Varies
Volume, MG (Each) 1.8120
Detention Time at Average Flow (hrs.) 12.4
Detention Time at Instantaneous Maximum Flow (hrs.) 8.3
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TABLE 5-3 (cont)
TOWN OF NANTUCKET
CWMP/DEIR
SURFSIDE WWTF DESIGN CRITERIA
Description
Future Design
Summer 2025
E. Ultra - Violet Disinfection
Type of Unit Medium Pressure
Type of Structure Open Channel
Number of Units (each) 2
Number of Modules Per Unit (each) 4
Number of Lamps per Module (each) 24
Total Number of Lamps Per Unit 96
U.V. Dosage, each unit (Microwatts-sec/cm^2) 51,640
U.V. Transmission (percent) 65
Channel Water Depth (inches) 42
F. Sludge Holding
No. of Raw Sludge Tanks 2
Storage Volume (gal), each 130,000
Estimated Daily Sludge Quantity (lbs/day) 10,073
G. Odor Control System
Type of System Single-Stage
Method of Treatment Packed Tower
Inlet H2S, ppm 20
Estimated Air Flow - Grit Chambers (cfm) 300
Estimated Air Flow - Headworks Building 3,600
Estimated Air Flow - Primary Clarifiers 2,700
Estimated Air Flow - SBRs (cfm) 20,500
Estimated Air Flow - Post Equalization Tanks (cfm) 5,300
Estimated Air Flow - Sludge Management Building (cfm) 1,200
Estimated Air Flow-Sludge Holding Tanks (cfm) 1,400
Estimated Total Air Flow - (cfm) 35,000
Equivalent H2S Concentration (ppm) 20
H. Sludge Dewatering
Type of System Centrifuges
Number of Units 2
Throughput (gpm each) 110
Run Time (hours per week) 37
Dry Solids (lbs/day) 10,700
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Siasconset WWTF
Since the abandonment of the Siasconset WWTF project in 1990, the existing effluent
beds have been improved, however untreated wastewater is still being discharged to the
ground through rapid infiltration basins in violation of the Town's Administrative Order,
Docket No. 782 dated June 6, 1989 from Massachusetts DEP. The Order required
completion of construction and commencement of operation of the Siasconset treatment
facility by June 1, 1991. The Town does have a Class 3 Discharge License (# 0-201) for
this site. Due to the abandonment of the proposed site for the treatment facility, the
Town proceeded with a Facilities Plan in July 1994 to find a solution to its wastewater
problems in the Siasconset area. The Town and DEP negotiated Administrative Consent
Order No. SE-97-1006 signed November 1997, with a revised schedule for this project
that provides for completion of an approved treatment facility and the cessation of the
discharge of untreated sewage by May 2002. A copy of this Administrative Consent
Order is in Appendix J.
The Department of Environmental Protection requested that the Town of Nantucket file
an Environmental Notification Form (ENF) under the Massachusetts Environmental
Policy Act (MEPA) to ensure a thorough and coordinated review of the project by all
permitting authorities. An ENF for the proposed project (EOEA No. 11460) was
submitted to the MEPA Unit of the Massachusetts Executive Office of Environmental
Affairs for the January 15, 1998, filing date. Following publication in the Environmental
Monitor, staff of the MEPA Unit conducted a public consultation session on February 13,
1998. The Secretary of Environmental Affairs issued a Certificate on the ENF on
February 24, 1998, requiring the preparation of an EIR and establishing a Special
Procedure under Section 11.12 of the MEPA Regulations. This Special Procedure
requires the submittal of a Phase I Screening Report to screen the set of alternatives to a
reasonable number of alternatives for detailed review. The subsequent filing of a Draft
Environmental Impact Report/Facilities Plan (EIR/FP) and a Final EIR/FP was also
required.
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In accordance with the Secretary’s decision on the ENF, a Phase 1 Environmental Report
– Screening of Alternative Sites - was submitted to the MEPA unit on July 15, 1998. The
Secretary of Environmental Affairs issued a Certificate on the Special Procedure: Phase
I Report, Screening Alternatives on August 28, 1998. The Secretary determined that the
Phase I report fulfilled the requirements set forth in the Phase I report scope outlined in
the ENF Certificate.
The Draft Environmental Impact Report/Facilities Plan was submitted to the MEPA unit
on December 23, 1998. A 30-day public comment period was initiated by a notice of the
Draft EIR/FP’s availability for review in the Environmental Monitor that was published
on January 10, 1999. On February 16, 1999, the Secretary of Environmental Affairs
issued a Certificate on the Special Procedure: Phase II Report, Draft Environmental
Impact Report/Facilities Plan stating that the DEIR/FP adequately and properly complies
with MEPA and with its implementing regulations. The Administrative Consent Order
stated that a FEIR/FP was to be filed within 120 days of the approval of the DEIR/FP.
The initial FEIR/FP was filed with MEPA on June 16, 1999. On July 30, 1999, the
Secretary of Environmental Affairs issued a Certificate on the Special Procedure: Phase
III Report, Final Environmental Impact Report/Facilities Plan stating that the FEIR/FP
adequately and properly complies with MEPA and with its implementing regulations.
Modifications were made to the Special Procedure, which allowed for the submission of
a Supplemental FEIR/FP covering the effluent disposal portion of this Project. The PDR
is based on the initial Facilities Plan, ENF, DEIR/FP, and FEIR/FP which were all
submitted to and approved by MEPA through the Special Procedure under Section 11.12
of the MEPA Regulations.
The Siasconset Wastewater Treatment Facility Project consists of a new WWTF, Influent
Pumping Station and modifications to the existing rapid infiltration basins. The new
Influent Pumping Station will be remote from the WWTF and located off the basin gravel
access road just South of Low Beach Road. The new facilities will be designed to treat a
future summer average daily flow of 0.22 mgd and an instantaneous maximum flow of
1.039 mgd. Refer to Figure 5-9 for the Siasconset WWTF location and Figure 5-10 for
the Process Layout.
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Refer to Table 5-4 for the Siasconset WWTF Design Criteria. The WWTF will be
designed to remove conventional pollutants (BOD and TSS) and to significantly reduce
the amount of total nitrogen in the WWTF effluent to the basins. The following is a
summary of the major treatment components of the new Siasconset WWTF:
• Wastewater Treatment Facility Control and Process Building;
• One influent pumping station;
• One influent flow metering structure;
• Two primary clarifiers with scum collection;
• Five sequencing batch reactor secondary treatment process systems;
• One sodium bicarbonate (NaHCO3) chemical feed system to provide
supplemental alkalinity to the SBR system if needed;
• One post-equalization tank with coarse bubble aeration and effluent
pumping;
• Two sludge-holding tanks with mechanical mixing and decant
equipment;
• Two cloth disk type effluent filters to provide tertiary treatment of the
SBR Effluent;
• Two ultraviolet disinfection units providing final treatment prior to
disposal via the rapid infiltration basins;
• One effluent sump for effluent reuse via plant water and effluent filter
high pressure wash systems;
• One plant water system;
• One effluent flow metering structure;
• Six rapid infiltration basins for final WWTF effluent disposal. The six
basins will consist of modifications to the four existing Town rapid
infiltration basins and modifications to the two existing Coast Guard
basins;
• WWTF effluent piping to the rapid infiltration basins; and
• Two bio-filter type odor control system cells and exhaust fan to treat
odorous air exhausted from the primary clarifiers, sequencing batch
reactors, sludge holding tanks, post-equalization tank and the sludge
pumping truck.
The proposed site for the Siasconset WWTF will be approximately five acres, located on
two parcels of land owned by the United States Coast Guard.
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TABLE 5-4
TOWN OF NANTUCKET
CWMP/EIR
SIASCONSET WWTF DESIGN CRITERIA
Description
Future Design
Summer 2022
A. Flows and Loadings
Residential/Commercial Flow (gpd) 208,500
Infiltration/Inflow (gpd) 11,500
BOD5 Concentration (mg/L) 376
TSS Concentration (mg/L) 345
TKN Concentration (mg/L) 40
Ammonia-Nitrogen Concentration (mg/L) 25
WWTF Design Flow Average Day, Peak Month (mgd) 0.220
Design Flow Peaking Factor 4.93
WWTF Design Instantaneous Maximum Flow (mgd) 1.039
Design BOD5 Load Average Day, Peak Month (lbs./day) 691
Design TSS Load Average Day, Peak Month (lbs./day) 634
Design TKN Load Average Day, Peak Month (lbs./day) 73
Design Ammonia-Nitrogen Load, Average Day, Peak Month
(lbs./day)
46
B. Primary Treatment
No. of Units 2
Type Circular
Diameter (each, feet) 20
Sidewater Depth each, (feet) 12
BOD5 Removal 30%
TSS Removal 60%
Overflow Rate at Monthly Average Flow (gpd/ft2) 384
Overflow Rate at Instantaneous Maximum Flow (gpd/ft2) 1,655
Weir Loading at Monthly Average Flow (gpd/ft) 1,920
Weir Loading at Instantaneous Maximum Flow (gpd/ft) 8,271
C. SBR System
Number of Reactor Basins – Large Units 3
Length of Reactor Basins (feet) 29
Width of Reactor Basins (feet) 29
Depth of Reactor Basins (feet) 20
Maximum Volume (each, Mgal) 0.126
Total No. of Decanters 3
Maximum Decant Rate (each, gpm) 969
Number of Reactor Basins – Small Units 2
Length of Reactor Basins (feet) 29
Width of Reactor Basins (feet) 14.5
Depth of Reactor Basins (feet) 20
Maximum Volume (each, Mgal) 0.063
Total No. of Decanters 2
Maximum Decant Rate (each, gpm) 475
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TABLE 5-4 (cont)
TOWN OF NANTUCKET
CWMP/DEIR
SIASCONSET WWTF DESIGN CRITERIA
Description
Future Design
Summer 2022
D. Post Equalization
No. of Tanks 1
Tank Width (feet) 29
Tank Length (feet) 65
Tank Sidewater Depth (feet) 8
Effective Tank Volume (gals) 112,800
E. Filtration
Type of Treatment Cloth Media Filter
Number of Filter Units (each) 2
Number of Filter Disks per Unit (each) 6
Average Flow to Filters (gpm) 164
Maximum Flow to Filters (gpm) 300
F. Ultra-Violet Disinfection
Type of Disinfection Ultraviolet
Type of Structure S.S. Channel
Number of Units 2
Capacity per Unit (gpd) 500,000
Channel Length, each, including transition boxes (feet) 13.6
Channel Width (feet) 1.25
Channel Depth (inches) 23
Channel Water Depth (inches) 11.5-12.5
U.V. Transmission (percent) 65
G. Sludge Holding
No. of Tanks 2
Tank Length (feet) 14
Tank Width (feet) 12
Sidewater Depth (feet) 10
Total Storage Volume (gal.) 25,130
Estimated Sludge Quantity including decant (lbs./day) 662
Estimated Sludge Volume including decant (gpd) 1,600
Design Storage Time (days) 15.7
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TABLE 5-4 (cont)
TOWN OF NANTUCKET
CWMP/DEIR
SIASCONSET WWTF DESIGN CRITERIA
Description
Future Design
Summer 2022
H. Odor Control System
Type BioFilter
Arrangement Air Upflow
Media Type Organic Mixture
Media Support Type 1- 1/2" Gravel
Estimated Air Flow (cfm) 4,500
Retention Time (sec) 72
Media Depth (feet) 3
I. Effluent Discharge Beds
Total Number of Beds 4
Beds in Use 4
Length of Bed, each (feet) 100
Width of Bed, each (feet) 100
Design Loading Rate (gpd/ft2) 4
Effective Loading Rate 3.7
Madaket WWTF
The proposed Madaket Wastewater Treatment Facility (WWTF) will be located on a
parcel currently owned by the Federal Aviation Administration, located near the Madaket
Study Area. Wastewater treatment, consisting of tanks, equipment and an access road
will encompass approximately four acres of land. The groundwater discharge site will
encompass approximately six and a half acres. The Madaket Wastewater Treatment
Facility will consist of an Influent Pumping Station, which will receive wastewater flow
from the Madaket and Warren’s Landing Study Areas, treatment equipment including
sequencing batch reactors (SBRs), and Infiltrators for groundwater discharge. The new
facilities will be designed to treat a future summer average daily flow of 0.35 MGD. The
WWTF will be designed to remove conventional pollutants such as BOD, TSS and Total
Nitrogen. Refer to Figure 5-11 for the Madaket WWTF location and Figure 5-12 for the
Process Layout.
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Refer to Table 5-5 for the Madaket WWTF Design Criteria. The WWTF will be
designed to remove conventional pollutants (BOD and TSS) and to significantly reduce
the amount of total nitrogen in the WWTF effluent to the groundwater site. The
following is a summary of the major components of the Madaket WWTF:
• Wastewater Treatment Facility Control and Process Building;
• WWTF Influent Pumping Station;
• One influent flow metering structure;
• Two primary clarifiers with scum collection;
• Two sequencing batch reactor (SBR) secondary treatment process systems;
• Two post-equalization tanks with coarse bubble aeration and effluent
pumping;
• Two sludge-holding tanks with mechanical mixing and decant equipment;
• Two cloth disk type effluent filters to provide tertiary treatment of the SBR
Effluent;
• Two ultraviolet disinfection units providing final treatment prior to disposal;
• One effluent sump for effluent reuse via plant water and effluent filter high
pressure wash systems;
• One plant water system;
• One effluent flow metering structure;
• 260 Infiltrators for final WWTF effluent disposal;
• One centrifuge for dewatering of sludge produced during treatment; and
• Two bio-filter odor control system cells and an exhaust fan to treat odorous
air exhausted from the primary clarifiers, sequencing batch reactors, sludge
holding tanks, post-equalization tank, sludge pumping truck, and the
centrifuge area.
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TABLE 5-5
TOWN OF NANTUCKET
CWMP/DEIR
MADAKET WWTF DESIGN CRITERIA
Description
Future Design
Summer 2025
A. Flows and Loadings
Residential Flow (mgd) 0.35
BOD5 Concentration (mg/l) 300
TSS Concentration (mg/l) 200
TKN Concentration (mg/l) 40
NH4-N Concentration (mg/l) 25
Total P Concentration (mg/l) 10
WWTF Design Flow Average Day, Peak Month (mgd) 0.350
WWTF Max. Day, Peak Month (mgd) 0.875
Design Flow Peaking Factor 4.20
WWTF Design Instantaneous Maximum Flow (mgd) 1.470
B. Primary Treatment
No. of Units 2
Type Circular
Diameter (ft.) 18
Sidewater Depth each (ft.) 10
Overflow Rate at Design Flow (gpd/ft2) 688
Overflow Rate at Maximum Day Flow (gpd/ft2) 1,719
Overflow Rate at Instantaneous Peak Flow (gpd/ft2) 2,888
Detention Time at Design Flow (hrs.) 2.6
C. SBR System
Length, feet 36
Width, feet 36
Maximum Depth, feet 18
Volume (MG) 0.174
Total No. of Units (each) 2
No. of Cycles (per day/basin) 5
Cycle Duration (hours/cycle) 4.8
Hydraulic Retention Time (Day) at design flow 0.797
D. Post Equalization
No. of Units 2
Maximum Sidewater Depth, ft 10
Volume, MG (Each) 0.046
Detention Time at Average Flow (hrs.) 6.3
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TABLE 5-5 (cont)
TOWN OF NANTUCKET
CWMP/DEIR
MADAKET WWTF DESIGN CRITERIA
Description
Future Design
Summer 2025
E. Filtration
Type of Unit Cloth Media Filter
Design Flow, mgd 0.700
Number of Units 2
Hydraulic Loading Rate, gpm per ft2 3.25
Filter Area, ft2 107.6
F. Ultra-Violet Disinfection
Type of Unit Medium Pressure
Type of Structure Open Channel
Design Flow (mgd) 0.350
Design Maximum Day Flow (mgd) 0.875
Number of Units (each) 1.0000
Number of Modules Per Unit (each) 7
Number of Lamps per Module (each) 4
Total Number of Lamps Per Unit 28
U.V. Transmission (percent) 65
Channel Water Depth (inches) 21
G. Sludge Holding
No. of Raw Sludge Tanks 2
Storage Volume (gal), each 210,000
Estimated Daily Sludge Quantity (lbs/day) 16,025
H. Odor Control System
Type of System Biofilter
Inlet H2S, ppm 20
Estimated Air Flow, cfm 8,000
Number of Cells 2
Ave. Loading Rate, cfm/ft2 2.50
Area per Cell, ft2 1,600
I. Sludge Dewatering
Type of System Centrifuge
Number of Units 1
Throughput (gpm each) 50
Run Time (hours per week) 16
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4. Existing Pump Stations
The Town of Nantucket currently operates and maintains six wastewater pumping
stations. All six pump stations convey flow to the existing Surfside Wastewater
Treatment Facility. The recommended plan includes installing no new pump stations and
rehabilitating the six current ones. The following are the recommended upgrades:
Airport Pump Station – (a) Replace the station’s badly corroded control panels with a
housing that is epoxy-coated corrosion-resistant; and (b) Install flow-measuring
instrument.
Cato Lane Pump Station – (a) Due to the poor condition of the entire station, demolish
and install a submersible pump station in its place. The replacement of the Cato Lane
Pump Station has been incorporated into the Siasconset Wastewater Treatment Facility
Project. As of the submission of this report, the Cato Lane Pump Station has been totally
replace and put into operation.
Old South Road Station – (a) Perform a detailed hydraulic analysis of the station to
determine the efficiency of the existing pumps. Current and future wastewater flows
should be taken into consideration; (b) Replace the control panel due to inaccessible
replacement parts; and (c) Install an alarm system.
Pine Valley Pump Station – (a) Install flow measuring equipment.
Sea Street Pump Station – (a) Install an alarm system; and (2) Update the VFD’s.
Minimization of the grease entering the station would reduce operation and maintenance
costs. Therefore, investigation of the cause of the consistent grease problems in the area
should be undertaken and addressed.
Surfside Pump Station – (a) Install an alarm system; (b) Replace the control panel due
to inaccessibility to obtain replacement parts; and (c) Replace the generator with a
generator that is capable of handling both pumps.
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Portable Generator - (a) Sandblast housing of the generator to remove rust and apply a
protected epoxy-based corrosion-resistant coating system.
B. INSTITUTIONAL IMPACTS
The recommended wastewater collection, transmission and treatment facilities are currently being
planned, designed and constructed under the guidance and direction of the Nantucket Department
of Public Works and Board of Selectmen. In order to manage and operate the recommended
wastewater collection, transmission and treatment facilities, the Town will need to implement
several institutional and system management procedures. The first being the designation and
delineation of sewer and septic overlay districts on Island. The recommended institutional
arrangements recommended for implementation are as follows and were previously detailed in
Section 4.0 of this report:
• Establishment of Sewer and Septic Overlay Districts;
• Review of the Current Sewer Use Rules and Regulations;
• Cost Recovery Plan;
• Review of Current Sewer User Charge System;
• Sewer System Expansion Control Policy;
• Review of Sewerage System Staffing and Operations Plan;
• Review of Current System Construction Standards;
• Septage Management Plan; and
• Water Conservation Program.
C. ENVIRONMENTAL IMPACTS
1. General
When determining the recommended plan for each Study Area, it is important to take into
consideration and identify and mitigate any environmental impacts. The following
environmental impacts were noted:
2. Historical, Archaeological, Cultural, Conservation and Recreation
There are no known impacts to historical, archeological, cultural, conservation or
recreational resources for any of the study areas. A Step I Historical and Archeological
Survey was conducted for the FAA site and the proposed expansion area of the Surfside
Wastewater Treatment Facility. The survey showed that there would be no impacts on
those sites. A Project Notification Form (PNF) has been filed with the Massachusetts
Historical Commission for these two areas. Refer to Appendix H for a copy.
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3. Wetlands, Flood Plains, and Agricultural Lands
All Study Areas will temporarily impact wetlands. Construction of all collection systems
will potentially impact the 100-foot wetland buffer zone. The impacts would be
temporary and associated with the construction of sewer infrastructure. Any impacts
would be mitigated by erosion control during construction. The Conservation
Commission and the DEP will review all erosion control measures during the Notice of
Intent process.
4. Zones of Contribution of Existing and Proposed Water Supply Sources
None of the recommended plans will impact the Zones of Contribution.
5. Surface and Groundwater Resources Including Nantucket and Madaket Harbor
Watersheds
None of the recommended plans will negatively impact surface and groundwater
resources.
6. Displacements of Households, Businesses and Services
None of the recommended plans will cause displacement of households or businesses.
7. Noise Pollution, Air Pollution, Odor and Public Health Issues Associated with
Construction and Operation
There will be some temporary construction noise associated with any construction
involved with the recommended plan. Limiting the hours and the days of construction
will mitigate the construction noise impacts. Any impacts associated with these
alternatives will be mitigated in the final design.
8. Violation of Federal, State or Local Environmental and Land Use Statutes or
Regulations and Plans Imposed by Such Statutes and Regulations
None of the recommended plans will violate any of the Federal, State or Local
Environment and/or Land Use Statutes or Regulations and plans imposed by any of the
statutes and regulations.
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9. Changes in Development and Land Use Patterns
Building a communal system on the FAA site would have positive impact to the Madaket
and Warren’s Landing area. The parcel has the potential for high density development
with the current zoning and land use patterns in place. This kind of development would
cause a long-term negative change in development and land use patterns.
10. Pollution Stemming from Changes in Land Use
There will be no pollution stemming from changes in land use.
11. Damage to Sensitive Ecosystems
There will be no damage to sensitive ecosystems as part of the recommended plans for
any of the Study Areas.
12. Socioeconomic Pressures for Expansion
Socioeconomics would not be affected by the recommended plan.
D. CAPITAL, OPERATION AND MAINTENANCE COSTS
1. Capital Costs
The estimated Capital Cost for the recommended plan is $92.1 million (Present Day
Cost). As detailed, this capital cost includes furnishing and installing gravity sewer
pipes, low pressure sewer pipes, excavation and backfill, ledge removal, paving;
dewatering, loam and seeding, pumping stations, upgrade to the Surfside WWTF,
Madaket WWTF, engineering (design and construction), legal, fiscal, administrative, and
contingency costs. Refer to Table 5-6 for estimated Capital Costs for the Recommended
Plan.
An analysis was performed on the recommend plan to determine the annual cost to the
Town and the homeowner for both capital cost and debt service. The most user-friendly
funding option for this project is public financing through the State Revolving Fund
(SRF) Loan program which would finance the eligible capital cost. The SRF Loan
Program is a modified continuation of prior Massachusetts Department of Environmental
Protection (DEP) financial assistance programs (grants) and allows communities to
receive low interest loans with a payback period of up to 20 years.
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TABLE 5-6
TOWN OF NANTUCKET
CWMP/DEIR
SUMMARY OF ESTIMATED PROJECT COSTS
Project Description
Estimated
Project Cost
Study Area
Madaket $11,150,000
Warren’s Landing $1,830,000
Somerset $7,620,000
Shimmo $7,340,000
Monomoy $6,130,000
Wastewater Treatment Facilities
Surfside WWTF $32,630,000
Siasconset WWTF Currently Funded
Madaket WWTF $25,380,000
Total $92,080,000
This Program is financed through the Massachusetts Water Pollution Abatement Trust
(Trust), which was established by Chapter 275 of the Acts of 1989 (The Hayes Act), as
amended (Chapter 29C). Under Chapter 29C financial assistance is offered to public
entities for eligible projects at one-half market rate. Currently, the General Court has
authorized additional funding (contract assistance) to be paid to the Trust to buy down
the interest to 2 percent. The analysis in this report assumes a present market rate for AA
municipal bonds of approximately 5.5 percent. For wastewater treatment and collection
projects, the actual planning and design engineering costs are not eligible for the SRF
loan. Each year the DEP’s Division of Municipal Services canvasses all of the state’s,
cities, towns, and districts for projects with a potential to receive financial assistance.
The Town of Nantucket must address the equitable apportionment of the capital costs
amongst the either the general pollution, the system users and/or a combination of the
two. Typically, there are limited financial resources available to enable a community to
undertake such projects. The following sources are frequently used in combination to
arrive at a financing solution:
• Federal and/or state funding through grants and/or loans;
• Betterment assessments based on the fixed uniform rate (linear foot
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frontage and/or property area) or the uniform unit method (number of
existing/potential sewer units). Currently the Town of Nantucket bylaw
develops betterments based on either total square footage of the lot or
linear foot frontage;
• Special assessments (i.e., connection charges, interest, fines);
• User charges; and
• Property taxes.
Betterment Assessment
A betterment is a tax or charge that is permitted where properties within a limited area
receive a special benefit or advantage, other than the general advantage to the community,
from the construction of a public improvement which results in an enhancement of the
value or use of those properties.
Bonding Scenarios
Based on implementation of the recommended plan over 20-year period results in an
annual cost of approximately $ TBD. An analysis was performed to determine the annual
cost to the Town under two funding possibilities: (1) funding through SRF program; and
(2) funding through market rates.
• Bond Scenario One -- SRF Loan at 2 percent, 20-Year Bond.
The construction costs and Town costs (construction engineering, legal,
fiscal, administrative, and contingency) would be eligible for the 2
percent SRF loan while the design engineering would be borrowed at 5.5
percent loan.
• Bond Scenario Two – Market Rate Loan, 20-Year Bond.
The construction costs and Town costs (design and construction
engineering, legal, fiscal, administrative, and contingency) would be
borrowed at the current market rate. This bond scenario assumes a
market rate were 5.5 percent.
These bond scenarios yield an annual debt service cost, which consists of the annual
equalized payments and is presented in Table 5-7.
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TABLE 5-7
TOWN OF NANTUCKET
CWMP/DEIR
BONDING SCENARIOS
Bond Scenario
Immediate
Cost per Unit
Annual Equalized
Payment for Eligible
Items per Unit
Annual Equalized
Payment for Ineligible
Items per Unit
Total Yearly
Cost per Unit
SRF Loan
at 2 percent
(20 Year Bond)
TBD TBD TBD TBD
Market Rate Loan
at 5.5 percent
(20 Year Bond)
TBD TBD TBD TBD
2. Operation and Maintenance Costs
In addition to the capital cost for designing and constructing the recommend plans, there
will also be an annual cost for the Town to both operate and maintain the system. The
estimated Operation and Maintenance Cost for the recommended plan is $2.73 million
(Present Day Cost). The operation and maintenance cost associated with the system
primarily consists of costs to operate and maintain the wastewater collection system,
pumping stations, force mains, maintenance on the mechanical pumping equipment, annual
replacement costs, power costs, and WWTFs.
In areas where low pressure sewers are part of the recommend plan, the Town has elected
to have the individual homeowners operate and maintain the individual grinder pump units.
Therefore, the homeowners will be required to handle all future service issues and
associated costs.
Refer to Table 5-7 for estimated Operation and Maintenance Cost for the Recommended
Plan.
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TABLE 5-7
TOWN OF NANTUCKET
CWMP/DEIR
ESTIMATED OPERATION AND MAINTENANCE COSTS
Description
Estimated
Operation and
Maintenance Cost
Wastewater Treatment Facilities
Surfside $1,290,000
Siasconset $270,000
Madaket $400,000
Infrastructure $520,000
Septage Management Plan $250,000
Total $2,730,000
E. IMPLEMENTATION PLAN
The recommended plan is estimated to be designed and constructed over a twelve-year period.
The recommended plan has been divided into seven construction phases. The construction phases
were developed based on: (1) the need of an area to be serviced as identified in the CWMP/EIR
Phase I Document; (2) funding constraints; (3) recommended on-site solutions; (4) recommended
off-site solutions; and (5) minimizing construction related disruptions to the Town. Table 5-8
summarizes the recommended on-site solutions, recommended off-site solutions, length of time,
estimated costs under each recommended solution and area of construction phase as well as
funding mechanisms required under the Capital Improvement Program FY 2004-2014 for
Wastewater and Stormwater Infrastructure presented to the Town. Once the Town, regulatory
and non-regulatory agencies and the public approve the recommended plan, the seven
construction phases can by further broken down into construction contracts.
This type of program needs to be completed over many years. Based on the scope of work and
the financial commitment required for this recommended plan and other Town projects, it is
recommended that be completed over a 10 to 20-year period. The following is a list of specific
tasks for implementation for each year of the recommended plan in chronological order:
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• Appropriate project funds at the Annual April Town meeting for the Design
Phase;
• Execute a design phase engineering contract and proceed with the engineering
design in mid-July;
• Prepare and submit a Project Evaluation Form (PEF) to the DEP. Currently,
PEF’s are due to the DEP by August 15 of each year. The PEF should include
documentation that the Town has appropriated funds for the design and
construction. The submittal of the PEF will allow the DEP to review and assign
priority points to get the project on the calendar year “Priority List” for funding
on January 1. Submittal of this CWMP to the DEP for approval will result in a
higher rating for each project;
• Appropriate project funds at the Annual April Town meeting for the Construction
Phase;
• Execute a construction phase engineering contract and proceed with the SRF
Loan funding application in July;
• Prepare and submit SRF Loan funding application and contract documents (plans
and specifications) for construction of the project. Currently, loan applications
and contract documents are due to the DEP by October 15;
• Submit required Permit Applications by October 15. Permits and environmental
determinations should be in hand within 2 to 3 months from the date of submittal,
depending on the review and approval by regulatory agencies. It is anticipated
that a Conservation Commission Notice of Intent will be required for each
project. In addition, it should be noted that completed contract documents are
required for most permit applications;
• DEP approves the SRF application for funding and contract documents by
December 31;
• Receive approval from DEP to advertise and publicly bid the project by February
1;
• Advertise and publicly bid the project (typically six to ten weeks depending upon
on the size and type of project);
• Receive bids and prepare a SRF Part B for the project (typically two to four
weeks to prepare Part B depending upon the size of project and completeness of
the contractor information);
• Submit Part B to DEP for review and approval. Receive approval from DEP to
award the project (typically up to six to eight weeks for DEP review and
approval);
• Award to contractor (typically up to two months after bid opening dependent on
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DEP review and approval);
• Construction of project and SRF monthly draw-downs; and
• Complete record plans and do DEP SRF Closeout; (typically up to two months
depending upon size of the project).
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6.0 DRAFT ENVIRONMENTAL IMPACT REPORT
A. PROJECT DESCRIPTION
1. General
This Draft Environmental Impact Report (DEIR) presents an analysis of the impacts
associated with the construction of the recommend wastewater treatment plan for the
Town of Nantucket. This DEIR has been prepared in order to satisfy the procedural
requirements of the Massachusetts Environmental Policy Act (MEPA). The file number
issued for the Project by the Executive Office of Environmental Affairs (EOEA) is
EOEA No. 12617. The Secretary’s Certificate on the ENF and Phase I Report was issued
on October 10, 2001 by the Secretary of Environmental Affairs (Secretary). The
complete MEPA Certificate and the responses to the comment letters are included in
Appendix A. Section 1.0 is devoted in its entirety to addressing the comments received
from the Secretary in the MEPA Certificate and in a letter dated May 17, 2002, which is
also included in Appendix A.
2. Summary
The recommended plan for the Town of Nantucket is detailed in Section 5.0 of this
report. The plan includes the upgrade and expansion of the existing Surfside Wastewater
Treatment Facility, and the design and construction of a new wastewater treatment
facility in Madaket. The new facility in Madaket will be located on the FAA site. The
new facility will include the treatment and disposal of wastewater for the Madaket and
the Warren’s Landing needs areas. The recommended plan also includes the treatment of
the wastewater for the Needs Areas of Shimmo, Somerset, and Monomoy to be treated
within the existing roadways.
3. Needs Areas
The Needs Areas are detailed in Sections 1.0 and 5.0 of this Report and include the
following Study Areas:
Madaket Shimmo
Monomoy Somerset
Pocomo Town WPZ
Polpis Warren’s Landing
Quidnet Wauwinet
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4. Disposal Site Alternatives
The entire Phase II Document details the disposal site alternatives.
5. Threshold Exceedances
The proposed project required the DEIR due to exceedance of the MEPA regulation
Section 11.03 (5) a3 dealing with the construction of more than 10 miles of new sewer.
The proposed project includes approximately 22 miles of sewer main in the areas of
Madaket, Warren’s Landing, Shimmo, Somerset, and Monomoy.
B. WATER SUPPLY
1. General
The Secretary’s Certificate requests more information concerning the water supply to the
Town and how the existing and projected water use fits with the Water Management Act
(WMA)approval for the Town. This is detailed in the water Balance completed for the
Island, which is included in Section 2.0 of this Report. This review shows the effects of
the selected alternative on the Water Management Act.
2. Existing Conditions
The water supply on the Island is from groundwater sources withdrawn for the sole
source aquifer. The water is withdrawn through seven wells on the Island and is
distributed by two municipal water companies. The existing water use is detailed in the
Water Balance contained in Section 2 of this Report.
3. Proposed Water Use
The proposed water use is calculated to show only the effects of the build out of the
Needs Areas that are proposed to be sewered. The build out is based on current buildable
lots as defined by current zoning and state land use codes from the town assessor
database. The proposed water use for the Needs Areas is assumed to be a worst-case
scenario with the build out of the area.
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Madaket and Warren’s Landing
In Madaket and Warren’s Landing Study Areas the current water supply comes from
individual private water wells. The future potential water use is assumed to come from
private water supplies and will not impact the Water Management Act. If municipal
water use is extended to these areas at some point in the future, the DEP and other state
agencies would review the expansion in accordance the Water Management Act.
Somerset
Table 6-1 shows the current water supply for Somerset Study Area as the initial yearly
average flow. The initial yearly average flow for the Somerset Study Area is 30,325 gpd.
The design yearly average flow was calculated based on the build out of current buildable
lots and was calculated to be 88,740 gpd. The water demand in Somerset Study Area
may increase by up to a yearly average 58,415 gpd.
TABLE 6-1
TOWN OF NANTUCKET
CWMP/DEIR
SOMERSET STUDY AREA
WATER USE DESIGN CONDITIONS
Unit Total Flow (gallons)
Design
Condition
Type
Number
Flow
(gpd)
Off
Season
Peak
Season
Year
Average
(gpd)
Initial Residential 157 185 8,858,725 1,742,700 10,601,425 29,045
Commercial 4 320 390,400 76,800 467,200 1,280
30,325
Design Residential 336 260 26,644,800 5,241,600 31,886,400 87,360
Commercial 4 345 420,900 82,800 503,700 1,380
88,740
Difference 58,415
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Shimmo
Table 6-2 shows the current water supply for the Shimmo Study Area as the initial yearly
average flow. The initial yearly average flow for the Shimmo Study Area is 25,295 gpd.
The design yearly average flow was calculated based on the build out of current buildable
lots and was calculated to be 80,165 gpd. The water demand in Shimmo Study Area may
increase by up to yearly average 54,870 gpd.
TABLE 6-2
TOWN OF NANTUCKET
CWMP/DEIR
SHIMMO STUDY AREA
WATER USE DESIGN CONDITIONS
Unit Total Flow (gallons)
Design
Condition
Type
Number
Flow
(gpd)
Off
Season
Peak
Season
Year
Average
(gpd)
Initial Residential 135 185 7,617,375 1,498,500 9,115,875 24,975
Commercial 1 320 97,600 19,200 116,800 320
25,295
Design Residential 307 260 24,345,100 4,789,200 29,134,300 79,820
Commercial 1 345 105,225 20,700 125,925 345
80,165
Difference 54,870
Monomoy
Table 6-3 shows the current water supply for the Monomoy Study Area as the initial
yearly average flow. The initial yearly average flow for the Monomoy Study Area is
34,580 gpd. The design yearly average flow was calculated based on the build out of
current buildable lots and was calculated to be 98,100 gpd. The water demand in
Monomoy Study Area may increase by up to yearly average 63,520 gpd.
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TABLE 6-3
TOWN OF NANTUCKET
CWMP/DEIR
MONOMOY STUDY AREA
WATER USE DESIGN CONDITIONS
Unit Total Flow (gallons)
Design
Condition
Type
Number
Flow
(gpd)
Off
Season
Peak
Season
Year
Average
(gpd)
Initial Residential 180 185
10,156,50
0
1,998,000 12,154,500 33,300
Commercial 4 320 390,400 76,800 467,200 1,280
34,580
Design Residential 372 260 29,499,600 5,803,200 35,302,800 96,720
Commercial 4 345 420,900 82,800 503,700 1,380
98,100
Difference 63,520
Impacts to the Water Management Act
If the Needs Areas are built out according to current zoning and land uses, then the water
demand from these areas may increase by up to a total of 176,805 gpd. The total amount
of water that the Island is allowed to withdraw according to the Water Management Act
is 1.54 million gallons per day (mgd). In the year 2001, the Town withdrew an average
of 1.317 mgd. The potential increase based on the design flow selected alternative would
only increase the withdrawal rate by up to 1.49 mgd. This increase would not exceed the
current Water Management Act approval.
C. MITIGATION MEASURES
The Town is proactive concerning any potentially negative impacts from the selected alternatives
for this project. The majority of temporary negative impacts will come from construction work.
Any temporary construction impacts will be required to be mitigated in the construction contract.
The contract will include mitigation measures that would not allow any construction in roadways
during the summer months, holidays. Construction would not be allowed during key Town
events, such as the Christmas Stroll and Daffodil Weekend.
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D. EXECUTIVE ORDER 385/PLANNING FOR GROWTH
The Town of Nantucket has a Planning and Economic Development Commission (NPEDC). The
NPEDC has created a planning document titled, “Charting the Future: The Nantucket
Comprehensive Community Plan.” The Town agencies have worked together to find a
recommended solution for the future planning and growth in Nantucket. The recommended
solution takes into account the “Charting the Future: The Nantucket Comprehensive Community
Plan” and Executive Order 385. The Community Plan’s goal is not to end growth, nor accelerate
it but rather to develop alternatives in order to manage it, and to keep it at a pace and level where
the Island is still able to:
• Protect the working community of Nantucket and provide for the housing needs
of those whose choose to live on the Island;
• Protect the open spaces and natural resources;
• Enhance the ability of Nantucketers to live and work on the Island;
• Protect the historical integrity of the land and buildings;
• Maintain the strong tourism-based economy;
• Maintain access to the beaches; and
• Provide a healthy environment for the residents.
The Phase II document has taken into consideration Executive Order 385 in its recommended
wastewater collection, treatment and disposal plans for the Island. For example, the
recommended solution for the Madaket and Warren’s Landing Study Areas incorporates low-
pressure sewers instead of gravity sewers. This system is designed as a calculated flow base
system for existing developed lots and those designated as buildable in the future according to the
current state land use codes and local zoning. This will require local approval, special legislation
and the development of new zoning overlays delineating sewer and septic districts. While the
introduction of sewer infrastructure in itself does not serve to promote or deny growth, the local
zoning and by-laws will. The intent of this CWMP/EIR is to solve the problems of the existing
development while at the same time not serving to promote sprawl or unchecked development in
more rural, less dense areas on Island. Section 4.0 details the recommended measures to be taken
by the Town in order to conform to not only Executive Order 385 but its own Community Plan
goals as well.
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As an additional proactive approach to keep unwarranted growth in check, the Town has begun
the process of developing a Septage Management Plan (SMP) for those areas on Island currently
recommended for long-term sustainability with their current on-site wastewater disposal systems.
This SMP will serve prevent the Town of Nantucket from having to finance the high cost of
extending municipal sewers into additional areas in the future. A well managed SMP has the
potential to provide the means with which to prevent areas on Island from over development due
to the construction of infrastructure and utilities in areas previously not serviced by such as well
as preserving the community structure that originally attractive residents to the Island.
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7.0 REVIEW OF PUBLIC PARTICIPATION PROGRAM
A. GENERAL
As part of the scope of this Comprehensive Wastewater Management Plan/Environmental Impact
Report (CWRMP/EIR), the Town of Nantucket will conduct an extensive public education
program. The purpose of this public education/participation program will be to inform the public
of the scope and progress of the planning study, to describe the results of the wastewater needs
analysis and siting alternatives selection process, and to encourage public input throughout the
entire planning process.
Earth Tech, along with the Town of Nantucket Department of Public Works and Nantucket
Planning and Economic Development Commission, undertook a comprehensive public
participation campaign in order to educate and inform all interested parties on the Island of all the
on-going CWMP/EIR work. A presentation of the CWMP/EIR was made to the annual meeting
of the Nantucket Civic League on June 2, 2003. This organization represents members of each
Island village/community. Through this initial meeting with the Nantucket Civic League, a
number of additional, individual community meetings were recommended and arranged. A
CWMP/EIR presentation was made at the annual meeting of the Tristam’s Long Pond
Association in Madaket on August 9, 2003. The CWMP/EIR was also on the annual meeting
agenda at the Quidnet-Squam Association on August 11, 2003. Through continued
communication with these member groups, this effort will continue. Refer to Appendix K for
copies of these presentations.
Additional meetings and presentations have been held with Island groups including the Nantucket
Land Council on August 8, 2003. As a result of this meeting, an additional Depository has been
established at the Land Council’s Ash Lane office.
A meeting with the Nantucket Conservation Foundation resulted in the cooperative efforts of soil
and groundwater testing in the Madaket area.
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Earth Tech, in conjunction with the Department of Public Works, has also initiated a poster
campaign to educate both citizens and visitors to the Island about the Comprehensive Wastewater
Management Plan. Posters have been distributed to the Planning and Economic Development
Department, Town Hall, the Office of Marine Fisheries, the Department of Public Works, and the
Library and have been posted in the Steamship Authority and the Airport. Tri-fold brochures
have also been distributed through the Department of Public Works. A copy of the poster and tri-
fold brochure can be found in Appendix L.
B. PUBLIC MEETING
The Town of Nantucket held a Public Informational Meeting on the results of the CWMP/EIR
Phase I Document on July 29, 1999 and a public meeting with the Nantucket Planning and
Economic Development Commission on September 4, 2001. A copy of the September 4, 2001
presentation can be found in Appendix M. As each successful phase of this CWMP/EIR is
completed, a public informational meeting will be held. These will be widely publicized and
posted in the Town Hall. At the conclusion of the last and final phase, Phase III, Final
CWMP/EIR, a public hearing will be held.
Regularly scheduled meetings are held with the Nantucket Board of Selectmen and the
Department of Public Works. Earth Tech presented a workshop with the Board of Selectmen and
all Town Department Heads on the progress of the CWMP/EIR on October 7, 2002. There are
also, regularly scheduled meetings with state and federal regulators, including the DEP and
representatives from the EOEA Nantucket Watershed Team and the Massachusetts Estuary
Project. All meetings held with Town Officials are posted as required in Town Hall.
C. RESPONSIVENESS SUMMARIES
Earth Tech will prepare and distribute responsiveness summaries after the public meeting. These
responsiveness summaries will identify the public participation activities and document
significant questions, comments, concerns and suggestions by the public and responses by Town
staff and Earth Tech.
The responsiveness summaries will be distributed to the depositories, active participants and the
mailing list. The responsiveness summaries will be included as an Appendix.
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D. SUMMARY OF PUBLIC COMMENTS RECEIVED DURING THE MEPA PROCESS
The Town of Nantucket submitted an Environmental Notification Form (ENF) to MEPA on
October 1, 2001. The 30-day comment period for the ENF ended on November 1, 2001 and on
November 16, 2001, the Executive Office of Environmental Affairs (EOEA) determined that the
project required an Environmental Impact Report (EIR) and established a special procedure for
review of the required EIR.
The MEPA Certificate (EOEA No. 12617), issued by the Secretary of Environmental Affairs to
the Town of Nantucket, requires the preparation of a Comprehensive Wastewater Management
Plan/Environmental Impact Report (CWMP/EIR) for the Town and establishes a special
procedure for review of this project. The special procedure is a phased review during which the
scope for future phases is based in large part on the results of the preceding phase. A project
description was included in the MEPA certificate. The Phase II scope is the “Alternatives and
Site Identification and Draft Environmental Impact Report (DEIR)” and was finalized upon the
completion of Phase I. The Phase III scope is the “Final CWMP/Environmental Impact Report
(FEIR)” and will be finalized upon the completions of Phase II. Each phase of this project is
distributed for review according to MEPA regulations. The MEPA Regulations allow for a 30
day review and public comment period following the filing of each report. Nhe filing is
advertised in the Environmental Monitor and is also widely publicized through local media.
Therefore, there will be opportunity for the appropriate public comment period for all interested
parties to contribute to the outcome of this project.
A copy of the MEPA Certificate and the response to Phase I comments is attached in Appendix
A.
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E. CIRCULATION LIST
Secretary of Environmental Affairs
Executive Office of Environmental Affairs
Attn: MEPA Office
251 Causeway Street, Suite 900
Boston, MA 02114
(Three Copies)
Department of Environmental Protection
Boston Office
Attn: Ron Lyberger
One Winter Street, 5th Floor
Boston, MA 02108
(Two Copies)
Department of Environmental Protection
South East Regional Office
Attn: Frank Mezzacappa
20 Riverside Drive
Lakeville, MA 02347
(Four Copies)
Nantucket Board of Selectmen
Town Hall
16 Broad Street
Nantucket, MA 02554
Nantucket Department of Public Works
188 Madaket Road
Nantucket, MA 02554
(Two Copies plus Depository)
Nantucket Planning & Economic
Development Commission
Attn: John Pagini
4 North Water Street
Nantucket, MA 02554
(One Copy plus Depository)
Nantucket Conservation Commission
Attn: Michael Glowacki, Chairman
Town Hall Annex
37 Washington Street
Nantucket, MA 02554
Nantucket Land Council, Inc.
Attn: Linda Holland, Executive Director
Six Ash Lane
P.O. Box 502
Nantucket, MA 02554
(One Copy plus Depository)
Massachusetts Historical Commission
Attn: Brona Simon
Massachusetts Archives Building
220 Morrissey Boulevard
Boston, MA 02125
Nantucket Board of Health
Attn: Richard Ray
Town Hall Annex
37 Washington Street
Nantucket, MA 02554
Nantucket Division of Marine Fisheries
Attn: Dave Fronzuto
38 Washington Street
Nantucket, MA 02554
Nantucket Community Association
Attn: Dale Stoodly
917 North Rodney Street
Wilmington, DE 14806
Nantucket Community Association
Attn: William K. Tell, Jr.
660 Steamboat Road
Greenwich, CT 06830
Nantucket Community Association
Attn: Duncan Sutphen
1155 Bowline Drive
Vero Beach, FL 32963
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Massachusetts Estuary Project
c/o SMAST – Center for Marine
Science & Technology
Attn: Dr. Brian Howes
706 South Rodney French Boulevard
New Bedford, MA 02744-1221
Division of Marine Fisheries
Attn: Neil Churchill
50A Portside Drive
Pocassett, MA 02559
Nantucket Civic League
Attn: Dual MacIntyre
2 Green Hollow Road
P.O. Box 2926
Nantucket, MA 02554
Sylvie O’Donnell
259 Madaket Road
Nantucket, MA 02554
Mr. Todd Callahan
Coastal Zone Management, 8th Floor
251 Causeway Street
Boston, MA 02114
Marcia Starkey
Massachusetts Department of Food &
Agriculture
251 Causeway Street, Suite 500
Boston, MA 02114
Mr. Thomas B. Erichsen
Smith’s Point Homeowners
34 Rhode Island Avenue
Nantucket, MA 02554
Massachusetts Estuary Project
c/o SMAST – Center for Marine
Science & Technology
Attn: Roland Samimy
706 South Rodney French Boulevard
New Bedford, MA 02744-1221
Division of Marine Fisheries
Attn: Dr. Jack Schwartz
30 Emerson Avenue
Gloucester, MA 01930
Tristram’s Long Pond Association
Attn: Andrea Murphy
12 Long Pond Drive
Nantucket, MA 02554
Wannacomet Water Company
Attn: Robert Gardner
One Milestone Road
Nantucket, MA 02554
Truman Henson/Stephen McKenna
CZM Cape Cod & Islands Regional
Office
P.O. Box 220
Barnstable, MA 02630-0220
Madaket Conservation Association
Ms. Marjorie Colley
52 Tennessee Avenue
Nantucket, MA 02554
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8.0 SRF GRANT/LOAN ADMINISTRATION
A. GENERAL
As part of the scope of this Town-wide Comprehensive Wastewater Management
Plan/Environmental Impact Report (CWMP/EIR), Earth Tech submitted to the Massachusetts
Department of Environmental Protection (DEP) a Calendar Year (CY) 2000 Project Priority
List/Intended Use Plan (IUP) Project Evaluation Form (PEF) on June 30, 1999.
The “Calendar Year 2000 Intended Use Plan and Project Priority List” was finalized on
November 12, 1999 by the Massachusetts Department of Environmental Protection, and the
Town-wide Comprehensive Wastewater Management Plan Project was identified on the Intended
Use Plan as a project (DEP/BRM Project Number CWSRF 625) eligible for financial assistance
from the State Revolving Fund effective January 1, 2000.
On October 13, 2000 Earth Tech prepared and submitted 2 copies of the Town’s SRF Application
for the Comprehensive Wastewater Management Plan/Environmental Impact Report for DEP
Division of Municipal Services and Water Pollution Abatement Trust review and approval.
A Restricted Project Approval Certificate (PAC) was issued for this project on January 29, 2001.
The PAC was restricted until all of the Special Conditions in Exhibit C were satisfied. On
November 16, 2001 the Department of Environmental Protection approved the revised
Comprehensive Wastewater Management Plan/Environmental Impact Report scope and lifted the
restriction.
Grant/Loan administration services are being provided in accordance with DEP financial
assistance guidelines and procedures. Liaison among the Town, DEP officials and Earth Tech,
and contract administration, are being carried out. Earth Tech is assisting the Town in submitting
(on average) monthly SRF drawdown requests to the DEP for reimbursement for costs incurred to
undertake the study. Upon completion of the project, the Town and Earth Tech will prepare and
submit the required loan closeout documents.
The Town will then be responsible to budget for debt service payments to the Water Pollution
Abatement Trust over the 20-year payoff period for this loan.
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