HomeMy WebLinkAboutCWMP Needs Areas Matrix and Discussion_201401230916301824NANTUCKET, 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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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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CWMP/DEIR – PHASE II REPORT
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.
xIf 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.
xIf 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-2
CWMP/EIR
TOWN OF NANTUCKET, MASSACHUSETTS
RATING CRITERIA
YES NO 7.333
CRITERIA NAME DESCRIPTION Madaket Warren's Landing Cisco Somerset Miacomet Surfside Tom Nevers Hi-Density
Number Points Number Points Number Points Number Points Number Points Number Points Number Points
CRITERIA POINTS Total Number of Lots 864 99 204 206 127 419 350
Actual Failure 4 Total Number of Developed Lots 435 68 143 161 101 281 255
Imminent Failure 3 Total Number of Unsewered Developed Lots 435 68 143 161 101 281 255
High Likelihood of Imminent Failure 2 Number of Resales since 3/31/95 70 19 27 30 15 44 26
Health / Water Quality Issue 1 Number of Acres per Study Area 394 49 355 151 296 685 129
Number of Net Acres for Developed Lots 232 26 143 103 197 363 63
No. of Acres of Severe Groundwater Limitation 117 10 27 7 8 49 28
Number of Acres of Severe Soil Limitation 86 26 178 96 149 112 61
Actual Failure 3/31/95 to 1999 31 124 4 16 8 32 21 84 8 32 21 84 2 8
1972 to 3/31/95 74 296 2 8 10 40 8 32 6 24 27 108 0
105 420 6 24 18 72 29 116 14 56 48 192 2 8
Adjusted Total based on Developed/Unsewered Developed Ratio 420 24 72 116 56 192 8
Imminent Failure System within Zone I Aquifer Recharge Area 9 27 0 6 18 1 3 0 11 33 0
System within 50 feet of Private Drinking Water Well 0000000
System within 100 feet of Public Drinking Water Supply 0000000
Developed Lots with Less than 10,000 sq. ft. of area per Bedro 260 780 66 198 105 315 152 456 0 0 110 330
269 807 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 #8168 363 20 40 #54 108 #
Systems Built before 1978 (Title 5) 281 562 1 2 43 86 13 26 15 30 72 144 2 4
Lot Size less than or equal to 1/2 acre 246 492 62 124 34 68 100 200 2 4 52 104 97 194
Lots with Severe Soil Limitation 95 190 #36 72 #72 144 #103 206 #51 102 #46 92 #121 242 #
Pumpouts Greater than 2 times per year 0000000
752 1,504 113 226 160 320 224 448 71 142 190 380 274 548
#
Health / Water Quality Issue 2 Density of Systems Greater Than 2 per Acre 435 435 #68 68 #000 161 161 #000 000 255 255 #
1 System within 100 feet of Surface Water Body, Wetlands or Streams 0 0 7 7 8 8 3 3 3 3 0
System located within 100 Year Flood Plain 53 53 0 6 60000
System within Zone II Aquifer Recharge Area 0000028280
System within Harbor Watershed Line or 3,600' of Madaket Ha 435 435 34 34 00000
923 923 102 102 13 13 169 169 3 3 31 31 255 255
Total Criteria Points for Study Area 3,654 550 738 1,192 201 636 1,141
Rating Criteria Points Per Developed Lot 8.40 8.09 5.16 7.40 1.99 2.26 4.47
RECOMMENDED 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/EIR
TOWN OF NANTUCKET, MASSACHUSETTS
RATING CRITERIA
CRITERIA NAME DESCRIPTION om Nevers Lo-Density Siasconset Quidnet Wauwinet Pocomo Polpis Town
Number Points Number Points Number Points Number Points Number Points Number Points Number Points
CRITERIA POINTS Total Number of Lots 195 1,049 77 68 140 100 4,741
Actual Failure 4 Total Number of Developed Lots 122 664 45 50 81 59 3,943
Imminent Failure 3 Total Number of Unsewered Developed Lots 122 127 45 50 81 59 890
High Likelihood of Imminent Failure 2 Number of Resales since 3/31/95 48 27 9 3 11 10 108
Health / Water Quality Issue 1 Number of Acres per Study Area 653 1,012 68 61 457 583 1,922
Number of Net Acres for Developed Lots 374 349 45 51 297 395 1,333
No. of Acres of Severe Groundwater Limitation 31 291 22 29 162 324 419
Number of Acres of Severe Soil Limitation 286 479 19 9 163 371 1,076
Actual Failure 3/31/95 to 1999 13 52 3 12 7 28 3 12 6 24 10 40 43 172
1972 to 3/31/95 15 60 15 60 13 52 11 44 9 36 12 48 99 396
28 112 18 72 20 80 14 56 15 60 22 88 142 568
Adjusted Total based on Developed/Unsewered Developed Ratio 112 376 80 56 60 88 2,516
Imminent Failure System within Zone I Aquifer Recharge Area 0 2 6 0 28 84 0 0 0
System within 50 feet of Private Drinking Water Well 0000000
System within 100 feet of Public Drinking Water Supply 0000000
Developed Lots with Less than 10,000 sq. ft. of area per Bedroom 0 0 21 63 21 63 8 24 6 18 60 180
0 0 2 6 21 63 49 147 8 24 6 18 60 180
High Likelihood of Imminent Failure Lots with Severe Groundwater Limitation 6 12 6 191 382 #15 30 #24 48 #29 58 #33 66 #859 1,718
Systems Built before 1978 (Title 5) 42 84 461 922 30 60 42 84 41 82 40 80 2,439 4,878
Lot Size less than or equal to 1/2 acre 37 74 512 1,024 22 44 8 16 8 16 10 20 3,098 6,196
Lots with Severe Soil Limitation 53 106 #60 120 #12 24 #8168 29 58 #38 76 #498 996
Pumpouts Greater than 2 times per year 0000000
138 276 1,224 2,448 79 158 82 164 107 214 121 242 6,894 13,788
Health / Water Quality Issue 2 Density of Systems Greater Than 2 per Acre 0 0 0 127 127 #000 000 000 000 890 890
System within 100 feet of Surface Water Body, Wetlands or Str 5 5 29 29 28 28 33 33 27 27 60 60 447 447
System located within 100 Year Flood Plain 2 2 1 1 1 1 13 13 8 8 16 16 65 65
System within Zone II Aquifer Recharge Area 0 13 13 0000161161
System within Harbor Watershed Line or 3,600' of Madaket Harbor 0 0 0 50 50 81 81 59 59 1,972 1,972
7 7 170 170 29 29 96 96 116 116 135 135 3,535 3,535
Total Criteria Points for Study Area 395 3,000 330 463 414 483 20,019
Rating Criteria Points Per Developed Lot 3.24 4.52 7.33 9.26 5.11 8.19 5.08
RECOMMENDED 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/EIR
TOWN OF NANTUCKET, MASSACHUSETTS
RATING CRITERIA
CRITERIA NAME DESCRIPTION Town - WPZ Shimmo Monomoy Other
Number Points Number Points Number Points Number Points Number Points Number Points Number Points
CRITERIA POINTS Total Number of Lots 743 284 263 2,539 0 0 0
Actual Failure 4 Total Number of Developed Lots 524 137 184 818 0 0 0
Imminent Failure 3 Total Number of Unsewered Developed Lots 315 137 178 812 0 0 0
High Likelihood of Imminent Failure 2 Number of Resales since 3/31/95 37 21 19 114
Health / Water Quality Issue 1 Number of Acres per Study Area 744 881 276 21,863 0 0 0
Number of Net Acres for Developed Lots 313 380 218 5,422 0 0 0
No. of Acres of Severe Groundwater Limitation 7 171 44 5,263 0 0 0
Number of Acres of Severe Soil Limitation 321 230 150 7,538 0 0 0
Actual Failure 3/31/95 to 1999 23 92 9 36 17 68 60 240 0 0 0
1972 to 3/31/95 24 96 17 68 30 120 110 440 0 0 0
47 188 26 104 47 188 170 680 0 0 0 0 0 0
Adjusted Total based on Developed/Unsewered Developed Ratio 313 104 194 685 0 0 0
Imminent Failure System within Zone I Aquifer Recharge Area 0 0 0 10 30 0 0 0
System within 50 feet of Private Drinking Water Well 0000000
System within 100 feet of Public Drinking Water Supply 0000000
Developed Lots with Less than 10,000 sq. ft. of area per Bedro 137 411 33 99 37 111 0000
137 411 33 99 37 111 10 30 0 0 0 0 0 0
High Likelihood of Imminent Failure Lots with Severe Groundwater Limitation 5 10 5 27 54 #29 58 #197 394 #000 000 00
Systems Built before 1978 (Title 5) 74 148 40 80 108 216 337 674 0 0 0
Lot Size less than or equal to 1/2 acre 229 458 4 8 29 58 73 146 0 0 0
Lots with Severe Soil Limitation 136 272 #36 72 #97 194 #280 560 #000 000 00
Pumpouts Greater than 2 times per year 0000000
444 888 107 214 263 526 887 1,774 0 0 0 0 0 0
Health / Water Quality Issue 2 Density of Systems Greater Than 2 per Acre 315 315 #000 000 000 000 000 00
System within 100 feet of Surface Water Body, Wetlands or Str 9 9 43 43 0 204 204 0 0 0
System located within 100 Year Flood Plain 0 5 5 4 4 72 72 0 0 0
System within Zone II Aquifer Recharge Area 473 473 3 3 116 116 117 117 0 0 0
System within Harbor Watershed Line or 3,600' of Madaket Harbor 0 103 103 184 184 161 161 0 0 0
797 797 154 154 304 304 554 554 0 0 0 0 0 0
Total Criteria Points for Study Area 2,409 571 1,135 3,043 0 0 0
Rating Criteria Points Per Developed Lot 4.60 4.17 6.17 3.72 0.00 0.00 0.00
RECOMMENDED 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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CWMP/DEIR – PHASE II REPORT
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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CWMP/DEIR – PHASE II REPORT
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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