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Home My WebLink About38 SE48_3115 NCC Comments to G Berman Report 03_06_19 TO: Nantucket Conservation Committee FROM: Maureen Phillips for the Nantucket Coastal Conservancy Team RE: The 2018 Independent Expert Review, Greg Berman, February 1, 2019 DATE: March 6, 2019 We read this latest report from Mr. Berman with great interest, as it is the first report since any major storms have impacted the area of the SBPF project. We believe this review, as well as the 2016 and 2017 reviews, confirm our continued position, and the Commission’s earlier findings, that the project will have harmful impacts on the resources protected by the law and, therefore, that reasonable alternatives are the best — and only — solution to the concerns about environmental harm (both to the immediate and downdrift areas), public safety, public access to a public beach, and more. Because Mr. Berman was requested to limit this review “on the observed and potential impacts to coastal processes of the existing and proposed geotube array,” our comments will also generally be so limited. Our previous position regarding the necessity of considering reasonable alternatives stands. We believe the following to be a fair distillation of Mr. Berman’s summary of particular threshold issues: ¥ The SBPF projects will never be in stasis; the environment is too dynamic. ¥ Extension of the returns will be required repeatedly in a losing battle to prevent end scour. ¥ Therefore, the adjacent beaches are suffering and will continue to suffer. ¥ It is not feasible to artificially provide the amount of beach nourishment that will be necessary to prevent the need for such extensions. ¥ Extending the project fourfold would accelerate the destruction of the returns and the scouring process because of the greater reduction of natural sand replenishment caused by the longer project. We have highlighted sections of Mr. Berman’s Report, dated February 1, 2019, below that deserve special attention: all emphases [bold] are ours, and NCC comments are so labeled. Berman Report, February 1, 2019, page 2: During lower wave energy the geotubes stay covered with sand and have minimal negative interaction with coastal processes. During even minor storm events portions of the geotubes Maureen Phillips/NCC Comment to ConCom 2 are exposed, and are likely reflecting wave energy in a similar way to a Coastal Engineering Structure (CES) during this period. Due to the scale of this project (947’ length) there is a high potential for currents to set up parallel to the smooth exposed geotube during storm conditions, which can rapidly scour the end of the array. Erosion doesn't stop in areas adjacent to a shoreline stabilization project and “holding the line” can become more and more difficult over time. An analysis on the useable lifespan of the upland properties and eventual retreat (or abandonment) of the array might be helpful. NCC Comment: The Town should be thinking about retreat and abandonment, not long-‐term maintenance. The adverse impacts of this project would increase substantially if the project were extended to almost 4,000 feet. Berman Report, February 1, 2019, page 3: While the erosion rates along this shoreline can be highly variable, it is highly likely that much of the beach sediment at the site has come from updrift areas, as opposed to the site. There is a very large natural volume of sand moving along this stretch of shoreline which helps preserve the width of downdrift beaches and dunes. However, even with this natural volume and the artificially placed sediment nourishment, sand cover on all portions of the geotube array appears to have been difficult to maintain. [See also, page 5 infra.] NCC Comment: Uncovered geotubes act as a coastal engineering structure (CES). (Photo below taken by Susan Landmann in March 2018.) Maureen Phillips/NCC Comment to ConCom 3 (Berman Report, February 2019, page 3 continued.) Most important would be finding the “right” compensatory nourishment volume and requiring that volume be put down every year as a minimum. Then more sand may be needed if filling the sand template requires more than that minimum volume. Ex. 8.8cy/lf/yr as a minimum to be placed each year and 22 cy/lf/yr as a minimum template volume to maintain. Whatever volumes are decided, they may need to be adjusted based on how often the geotubes get exposed. NCC: How much sand is the Town willing to have delivered over existing streets? How often does this beach become a construction site? Berman Report, February 1, 2019, page 4: (N)ow data is available with the geotube array experiencing several larger storms [that occurred in winter and spring of 2018]. While the array has not experienced a tropical storm (i.e. hurricane) of significance, some recent winter events would qualify as “testing” the array. The initial geotube array was installed 12/2013-‐1/2014. Since that time 5 of the top 10 water levels have been observed at the Nantucket Tide Gauge, since measurements began in 1965. NCC comments: Sea level rise predictions argue this trend will continue.1 Berman Report, February 1, 2019, page 7: While maintaining a beach in front of a Coastal Engineering Structure is theoretically possible, at some time in the future (likely tens of years, not hundreds) it will not be feasible. As was previously mentioned, the proposed project would be about 7% of the mostly unarmored eastern shoreline of Nantucket and much of the beach sediment in this area has likely come from updrift areas, as opposed to being placed at the site. If a geotube expansion is approved erosion will continue in adjacent areas, as is occurring now with the current extent of the geotube array. NCC Comment: Erosion is happening now on the adjacent beaches and will continue. According to testimony submitted by the Nantucket Land Council consultants, Applied Coastal, November 30, 2018: “Erosion rates across the entire proposed project reach have increased since the geotextile revetment was constructed. The increase in erosion rates associated with the current project and the proposed project will further jeopardize SBPF’s neighbors to the north and 1 “Sea Level Rise -‐ Climate Science Special Report,” https://science2017.globalchange.gov/chapter/12/ Maureen Phillips/NCC Comment to ConCom 4 south. A properly designed shoreline stabilization project using best-‐available measures should not transfer the burden of losing a home or property from project location to the neighboring properties”. [Page 2.] Berman Report, February 1, 2019, Page 7. With erosion continuing to occur (or made worse) at the end of the structure, properties adjacent to the structure will often request an extension of the CES to cover their property (aka “chasing erosion”). The geotube array has been designed with returns so that it is not compromised by scour. One of the dangers of “holding the line” with a CES is that the array will artificially protrude further seaward than the rest of the shoreline. Flanking may occur if adjacent properties continue to erode naturally, while the project site maintains a shoreline position further seaward to protect the homes. NCC Comment: The SBPF project was designed with returns (extensions on each end) which were to protect the adjoining properties from being scoured (damaged by excessive wave energy caused by the geotubes). Unfortunately, this technique has not succeeded with this project, and repairs to the extensions for the original project were needed after the FIRST season of significant storms.2 In this extremely dynamic local environment, combined with ever-‐worsening storm, tide and sea-‐level rise conditions due to global warming, scouring/flanking appears to be inevitable. Extending the project would extend the damage, as there does not appear to be any chance that the local environment will “calm down,” nor that the multiple destructive impacts of global warming will disappear. The above image an example from Hardings Beach, in Chatham, of an armored property (CES) that was allowed to exist further seaward than the rest of the shoreline properties. This configuration has major implications for wave energy and sediment transport, as well as a lack of “walkable beach” at high tides. Wave reflection can exacerbate erosion on the 2 In September 2018, SBPF applied for an Amended Order of Conditions to address end-‐scour issues. The request stated that 50-‐foot extensions were required at either end of the geotube revetment “to preserve the integrity of the geotube system and to avoid continued erosion at the ends.” [Emphasis added.] See page 2, https://nantucket-‐ma.gov/DocumentCenter/View/23137/Amended-‐Order-‐of-‐Conditions-‐Request-‐SBPF-‐-‐87_105-‐ Baxter-‐Road-‐48_Various-‐SE48_2824?bidId= Maureen Phillips/NCC Comment to ConCom 5 adjacent beach and the property may affect sediment transport parallel to shore (similar to a groin). While this type of setting is different from Baxter Road, it is provided to illustrate the potential ramifications of “holding the line” for too long. NCC FINAL COMMENTS Many times over the years, we have provided data and comments about various aspects of the Baxter Road project. It is unfortunate that SBPF appears to dismiss these comments cavalierly without providing any factual or scientific basis for dismissing them. Mr. Berman’s independent report supports the views we have expressed in the past, as demonstrated in the analysis provided in this memorandum. The applicant (SBPF) has the burden of proving that it satisfies regulatory standards, and challenges to the accuracy or scientific basis of its assertions by others should not be waved aside without exploration. Of course, the issues are often highly complex, requiring scientific knowledge to evaluate. Mr. Berman’s has such knowledge, and his independent report supports our comments in this letter. We have always believed that the threshold issues are: 1. whether this project is/will be destructive of the environment in a way that violates legal protections, and, for the second 2. whether feasible alternatives exist. The answer to these questions in both cases is “Yes.” We find Mr. Berman’s report unequivocal about the first issue, and, for the second, we have provided extensive materials regarding development of alternatives in the past. For ease of review, we will provide a summary in a separate document. We are also deeply concerned about the changing representations made by the SBPF on numerous crucial issues. We believe that the Conservation Commission needs to be especially vigilant in its review of pertinent evidence to be sure that it considers the actual, primary evidence provided by scientific experts, particularly those, such as Mr. Berman, who offer candid peer-‐review assessments. The Conservation Commission needs to be particularly careful in assessing this primary evidence, rather than relying on SBPF’s re-‐characterization of the evidence supplied by others. The purpose of neutral peer-‐review analysis is to provide the Conservation Commission with reliable evidence that is not slanted to serve proponents’ views. The Conservation Commission should also look closely to determine whether the proponents of the project have taken inconsistent positions on crucial matters, since inconsistencies expose areas where assertions may be questionable and should not be taken at face value. Maureen Phillips/NCC Comment to ConCom 6 Again, we ask that you deny the application for the extended project. Maureen Phillips for NCC Coordinating Team Elin Anderwald, Rick Atherton, Burton Balkind, Joyce Berruet, Peter Brace, Barbara Bund, Sunny Daily, Susan Landmann, Susan McFarland, Catherine Nickerson, Maureen Phillips, Linda Spery, Liz Trillos, Mary Wawro, Karen Werner, and D. Anne Atherton