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HomeMy WebLinkAbout2018-10-1ConCom Minutes for October 1 2018 adopted Oct. 17 CONSERVATION COMMISSION PUBLIC MEETING 2 Bathing Beach Road Nantucket, Massachusetts 02554 www.nantucket-ma.gov Monday, October 1, 2018 4 Fairgrounds Road, Community Room — 4:00 p.m. Commissioners: Andrew Bennett(Chair), Ashley Erisman(Vice Chair), Ernie Steinauer, Ben Champoux, Ian Golding, Joe Topham David LaFleur, Called to order at 4:04 p.m. Beach Preservation Fund — 59-119 Baxter Road (49&48 -various) Area SE48-3115 Staff in attendance: Jeff Carlson, Natural Resources Coordinator; Joanne Dodd, Natural Resources Office Administrator, Terry Norton, Town Minutes Taker ,.a _-i Z Attending Members: Bennett, Erisman, Steinauer, Champoux, Golding, Topham m C Absent Members: LaFleur Stephen Cohen, Cohen & Cohen LP Late Arrivals: None Dwight Dunk, Epsilon Associates Inc. Earlier Departure: None C Town Counsel: George Pucci, K&P Law, PC 0:' Agenda adopted by unanimous consent r. *Matter has not been heard CO I. PUBLIC MEETING Arthur D. Gasbarro, Nantucket Engineering & Survey A. Announcements G B. Public Comment — None Hugh Ruthven, III, Applied Coastal Research and Engineering, for Nantucket Coastal Conservancy II. PUBLIC HEARING A. Notice of Intent 1. *Sconset Beach Preservation Fund — 59-119 Baxter Road (49&48 -various) Area SE48-3115 Sitting Bennett, Erisman, Steinauer, Champoux, Golding, Topham Recused None Documentation Supporting documents and plans; PowerPoint® presentation. Applicant Stephen Cohen, Cohen & Cohen LP Representatives Dwight Dunk, Epsilon Associates Inc. Gordon Thomson, Baird Associates Les Smith, Coastal Geologist Epsilon Associates Inc Jamie Feeley, Construction Manager Cottage and Castle Inc Josh Posner, 77 Baxter Road, Chairman'Sconset Beach Preservation Fund Arthur D. Gasbarro, Nantucket Engineering & Survey Public Emily Molden, Nantucket Land Council (NCL) Hugh Ruthven, III, Applied Coastal Research and Engineering, for Nantucket Coastal Conservancy Beau Overlook, 18 Baxter Road Discussion 1. Review of Current Order of Conditions 2. Review of Coastal Engineering Cohen — The SBPF presentation will cover engineering, sand migration, and overview of this project's compliance with state and local performance standards. Dunk — Reviewed the scope of this project. His topics are to briefly review compliance of the existing project, SE48-2824, with its order of conditions; questions were raised about the design and modeling. Les Smith will discuss compliance of the proposed project. SE48-2824 had three groups of conditions: pre -constriction, which is complete; construction conditions were completed; post -construction conditions have numerous monitoring and reporting conditions. Reviewed the on-going monitoring requirements for SE48-2824; compliance is being tracked and presented to ConCom annually. Four years of data shows the unprotected bluff contributes 5.8 cubic-yards/linear-foot per year (CLY); five years shows the geotube area provides 16.5 CLY. As of May 2018, the geotube contribution was 20.3CLY while the unprotect bluff contributed 17.4. Thompson — Reviewed the existing 4 -tier system, which will be mirrored by the extended structure except that the bottom tube will be set deeper; the additional model is for scour and overtopping using COSMOS and North Atlantic Coast Comprehensive Study (NACCS) data. Summarized the COSMOS wave modeling, which covers: refraction, shoaling, breaking, set down & set up; runup; and grain size. NACCS modeling, developed by the Army Corps of Engineers (ACE), looks at the 100 -year storm event. The survey done over time extends out to Station 684, which was used for the NACCS model; 100 -year storm is a significant event that can impact this area with wave runup from 13.1 feet to 15.4 feet. The 200 -year event model indicates the limit of wave runup to 15.8 feet. Explained the fourth tier is a built-in safety factor to prevent overtopping of the structure during that 100 -year storm event. The tubes will be placed deeper in the extended project because of the potential of scour. Page 1 of 4 ConCom Minutes for October 1 2018 adopted Oct 17 Smith — He will focus on the resource areas, which include coastal bank, coastal beach, and land subject to coastal storm flowage. Reviewed the proposed project's compliance with the performance standards of the Massachusetts Coastal Wetland Regulations and Nantucket Wetland Bylaws. The proposed project area has an erosion rate of 2.8 feet per year. The proposed project bank contribution will be 7.7 CLY; annual sand mitigation is proposed to continue at 22CLY, which is 2.9 times the natural bank contribution. Reviewed past erosion control and renourishment projects applied for but denied. Explained the compliance of the proposed project with Nantucket Coastal Bank Performance Standard: Section 2.05 B and Section 2.02 B. Nantucket Coastal Beaches Performance Standard: Section 2.02 B. Nantucket Land Subject to Coastal Storm Flowage Performance Standard Section 2.10. Reviewed waiver requests. Erisman — Regarding the change in sand mitigation to adaption management Mr. Thomson made the statement that they are building the geotubes out in front of the bluff; that is why to her this is contributing more than the surrounding bluff Dunk — There are several factors: there's 1000 feet that stick out from the adjacent bluff and the existing bluff is based upon glacial -compacted sediment that have been there for 1000s of years. The sand tubes are covered with imported sand and is compacted by bulldozers; it doesn't match the sediment structure of the bluff. It is the same grain size. Erisman — That speaks to the difficulty of mimicking the natural system. Thomson — The third and fourth tier aren't allowed to be built into the bluff, if they start carving and refilling the bluff, they over steep it. The lower tubes are below the existing beach profile. Champoux — It isn't wise to compare the sand contribution from adjacent beaches that might not getting full impact of a storm because the project area projects out taking the brunt of the storm. Cohen — The structure isn't being constructed to match the bank; that can't be done. We have a project that mimics the volume of sand that would otherwise be contributed. It is not a legal nor is there an environmental standard requiring us to focus on the moment. We need to focus on whether or not the volume of sand is sufficient and is it being delivered efficiently. Steinauer — We heard testimony about the importance of sand from the bluff and its impact on the environment. He'd like to hear expert testimony explaining that and if that sand is available for down -drift beaches. Carlson — Sediment transport and mitigation volume is scheduled for the third hearing three weeks from now. Golding — Asked the amount of sand is set in front of the geotube. Most of the mitigation this past Spring was on top of the geotubes. Smith — This really is a topic of the next hearing; they'll look at volume to address concerns. This is a highly complex system. Bennett — CZM letter that led to approval of the current structure agreed with the 22 CLY nourishment Cohen — CZM thought caution should be built into the initial project Here we want to propose a project that will make nearly three times the amount of sand available. We've had discussions with Department of Environmental Protection (DEPP and they are comfortable with reducing that Bennett — In designing for the 100 -year storm, you design to protect the bank but not the unprotected bank. Protecting is becoming more important than the effect on the bank in that storm. Curious when the last 100 - year storm occurred. Thomson — In 1991 probably; he'll get that information. A wave event can be area specific. He'd have to go back to the NACCS and see what they used. We are trying to protect the bank; failure at the top can't be built back out. We look at average retreat: the bottom retreats first then the top slumps and fails at a later date. When we look at 2017 versus 2018 data, you can see that in the profile. Smith — It's all about the volume made available. We are providing three times the normal contribution which is going into the system and being deposited down drift. Golding — Asked about the NACCS model used. Thomson — NACCS provided wave data only. The COSMOS model moves the sand around and accounts for waves and gets into the underlying physics of how waves act. Golding — Station 684, it is over 4000 feet from the beach; feels that would have a bearing on the wave height at the point versus on the beach. Thompson — The COSMOS model takes that into account; it covers the area from the station to the shore. Topham — Asked how wave energy changes between 4000 feet out and the beach. Thomson — COSMOS is a cross model that looks at the wave energy dissipation and sediment moving off shore. Explained the returns will be longer and extend more into the bluff. Bennett — In the last big storm, there was heavy erosion to the south to include a property with a coir bag structure that lost a lot of bluff. We want to make sure there are no gaps in nourishment during a major storm event. Given tripling the size of the current structure, thinks the numbers can't be kept the same. The effects will become larger and larger. Thomson — If you aren't providing sufficient sediment, the down -drift beaches will be starved. We are contributing more to the system so areas to the north and south will end up with higher volume. Bennett — Asked why the lowest bag will be four feet lower. Page 2 of 4 ConCom Minutes for October 1 2018 adopted Oct. 17 Thomson — He recommended it; when he looked at this, there had been a change in the FEMA storm surge elevation; there is the potential for scour to be deeper. Erisman — When the model was run, it assumed there was cover on the template; asked if the model shows what happens when the front template runs out of cover. The template was uncovered between March 4 and March 24, 2018. Thomson — In the model profile, there is no loss or gain of sand from the template; it shows the sediment being moved off shore. It removes sand from the front until the close near -shore component is no longer talking scour. He'd have to look at exactly where the model toed in, probably several hundred feet out. It removes sand until the amount of energy hitting the structure meets the energy of waves hitting; it moves the wave energy out. Feeley — Reviewed the sand delivery reports from during the March storms when the tubes ended up uncovered and when the sand template was rebuilt. Bennett — We're relying on data where birds are nesting presently. Argued that building up the bank prevents the birds from nesting in that area. Dunk — Bob Kennedy looked at the nesting patterns. From his study, it was decided not to bring sand up to the level where Bank Swallows would nest. Part of his study was to see what areas they are using and adapting the design to preserve those habitats. Erisman — Would like to know the impact of actual construction on nesting birds when equipment is on the bluff above their nesting areas. Found data from Cornell about the causes for the decline in Bank Swallows. Dunk — Bob Kennedy identified Nantucket's Bank Swallow population as being fairly stable. Steinauer — He suspects that as the bank erodes, the swallows move their nesting area. SBPF is deciding what area won't be available to them. Other birds use that bank: Peregrine falcons, petrels, merlins. Dunk —They will look at additional native plant species that can be put on the bluff to both stabilize the bank and provide habitat. Molden — Referred to a letter she submitted outlining issues NLC has in regards to maritime habitat. Mr. Ruthven's letter did not make it in before the deadline so wasn't posted until earlier this afternoon. Ruthven — The current structure has been in place five years providing plenty of time to see how it works. It is not giving off sand during a storm; yes, we can't duplicate the bluff exactly, but the template should be giving off sand. He hopes the mitigation system will be designed to provide sediment during storms when ies needed. That section of bluff should be giving off more sand; adaption management will compromise the system. We need to design mitigation that mimics the bluff as close as possible. During a storm, when the bank is giving off sand, it is breaking up wave energy; this structure isn't doing that. Overlock — There was talk about the geotubes starting further from the bluff; the notion of a starting point from the bluff is a moving target due to erosion and attrition. If we're following the sand, why don't we have 20% of the sand colored so it can be tracked. Bennett — That was tried in the past, but the system is too complex. Erisman — It was stated some of the models factor in sea level rise. Asked how much sea level rise is being modeled. One meter of sea level rise is a low -ball shot for the end of the century. Thomson — Sea level rise is not being factored into the model; he didn't say that it is. FEMA lowered the water level of the 100 -year storm; that was incorporated into the model. Dunk — Ms Hartnett and he identified 1 -foot of sea level rise, which would overtop the fourth roll. We did not use a specific sea level rise number because there is such a variation in range among models. Golding — There is a reference in October's Scientific American on coastal erosion to another statistic the acceleration of coastal erosion from 2050 to 2100 could be as high as 12 feet in the Northeast. Dunk — DEP models don't go as high as the Scientific American article referenced. We were trying to show that even the lowest level supports the need for a fourth tier. Cohen — Requested a continuance to October 22. Next hearing Carlson — Future hearings: October 22 and November 5; October 22 will focus on sediment transport and mitigation volume. The November 5the meeting might focus on wildlife habitat and waiver requests. He'll hold a slot open for any topic to come back for further review. Asked that any information or written comments submitted for the October 22 meeting be in by Friday October 19; of it is in by noon, he will post it for all to review. Motion Public Hearing Continued to October 22 at 4:00 p.m., 4 Fairground Road Community Room by unanimous consent Vote N/A Page 3 of 4 ConCom Minutes for October 1, 2018, adopted Oct. 17 III. PUBLIC MEETING A. Oth r Business 1. Enforcement Actions a. 36 Liberty Street Sitting Bennett, Erisman, Steinauer, LaFleur, Champoux, Golding, Topham Staff Ms Fader will be at the Wednesday meeting to talk about this. Part of the resolution is to put together an appropriate management plan; pumping into adjacent wetlands is not appropriate. Discussion (:07) None 2. Repc rts: a. C C, Golding: Have 15 2019 requests 3. Commissioners Comment a. Golding — Asked Town Counsel for his input on the SBPF waiver requests. 4. A strator/Staff Reports a. None Adjourned at 6:11 p.m. by unanimous consent. Submittedy: Terry L. N rton Page 4 of 4