My View
By Richard Green

The following My View is in response to October 3, 2007 Nantucket Independent article "Voices Away from the Bluff" featuring John Seidel.

Many of the statements made by Mr. Seidel included inaccuracies that I would like to address.

1. The terraces are required by local regulations to be temporary and pervious; recent design modifications will retain more material on site during storms.

The coastal bank terraces mentioned by Mr. Seidel are required by local regulations to be temporary and pervious (allowing sand to leak out onto the beach during storms); therefore, they are of necessity designed to only withstand storm waves for a maximum of 2 days. The April 2007 storm Mr. Seidel references lasted 3-4 days, almost twice the terraces' 2- day design life. Consequently, the terraces failed; however, over half of the debris stayed near the terrace locations. Loose wooden boards and stakes numbered in the hundreds not in the thousands as Mr. Seidel suggests. SBPF employees undertook a massive cleanup effort of all wooden debris and biodegradable fabric transported away from the project area, mounting beach patrols and responding to every call reporting debris. Similar cleanup efforts have occurred following every storm that damages the terraces. Although the terraces failed during the April 2007 storm due to their required temporary design, terraced portions of the bank retreated less than nearby unprotected sections of bank. Finally, working with the Conservation Commission, SBPF has modified the design of these protective terraces so as to use substantially fewer wooden posts and to retain the fabric on site after it has yielded its sand in future storms.

2. Models used to evaluate impacts incorporated worst-case scenarios and still yielded minimal or no impacts.

Contrary to the assertion of Mr. Seidel that "All the SBPF has presented …are hypotheses from 'best case scenarios,'" SBPF's coastal engineers have used worst-case, extreme scenarios in their modeling efforts. For example, project engineers assessed potential impacts on wave direction, sediment transport, and currents assuming complete excavation of the borrow site (only about 75 percent will be initially excavated) and using 50-year storm as well as average oceanographic conditions. Even the worst-case scenarios (50- year storm conditions) showed that dredging at the borrow site will not impact the Island's existing wave patterns, sediment transport, or currents. In the assessment of potential turbidity impacts, project coastal engineers modeled results assuming the material has 10 percent silt (the main contributing factor to turbidity), whereas it actually has only 1 percent silt. Even with this overestimation, predicted turbidity values are still within the range of existing values measured during storms and quieter conditions. Finally, the potential burial of nearshore cobble habitat was also modeled using conservative assumptions, yielding an approximate 5 percent loss of the available cobble area. Moreover, that loss will be mitigated by creating a like area of vegetated surface area on the ocean bottom in the general vicinity of the covered cobble.

3. Only 5 percent of cobble habitat will be impacted and this loss will be mitigated.

While Mr. Seidel expressed concern over impacts to the Island's fisheries, the amount of hard bottom cobble habitat impacted equates to no more than 5 percent of the total cobble habitat in the area. Additionally, this will be mitigated to ensure that fish habitat is not degraded. Further, local sportfish sampling combined with summer observations of fishing activities show that most fishing occurred outside the beach and nearshore areas that will be impacted by the project. Proposals to offer the fishing community financial compensation for any demonstrated loss of revenue show the SBPF's confidence that impacts will not occur while providing the fishermen with assurance that their interests will be protected.

4. Concrete has been used successfully for decades to create fish habitat.

SBPF is proposing to use concrete railroad ties (never used, chemically compatible) and rock to replicate hard bottom habitat impacted by beach nourishment. The exact mitigation sites are still being refined with input from regulatory agencies and local fishermen; however, concrete and rock material will be placed in an organized fashion within a designated site. While Mr. Seidel questions the use of concrete, project coastal scientists have determined that the dominant species in the existing cobble habitat (sponges and macroalgae) will also settle on concrete or rock. Further, creation of hard bottom habitat using concrete has been occurring since the 1970's. Monitoring of such sites has consistently demonstrated successful use by marine organisms and fish.

5. Marine organisms at the borrow site are conditioned to rapidly repopulate and can tolerate disturbances.

While Mr. Seidel states that "SBPF [will] destroy our seafloor habitat," organisms at the borrow site are adapted to living in a dynamic environment and are able to withstand extreme changes in wave and tidal forces. Our research indicates that benthic (bottomdwelling) populations at the borrow site will recover in 1-3 years, setting the stage for return of all other animal species currently present at the borrow site. The benthic organisms at and around the borrow site are typically mass-spawners (releasing millions of eggs or larvae at a time) that are capable of dispersing their young over long distances. Additionally, adults will migrate within sediment as a means to avoid disturbance events. As dredging will not change the substrate type, adults and larvae from the surrounding populations will settle at the borrow site relatively rapidly following dredging. The renourishment interval will initially be 5 years; however, this interval will lengthen over time and benthic populations will have adequate time to recover in between nourishment cycles.

6. The nourished beach will provide protection during a major storm.

While Mr. Seidel maintains that nourished beaches "do not last during a significant storm," experience with hundreds of projects credited for reducing storm damage to coastal areas speaks otherwise. The nourished beach at Sconset has been designed to withstand a large (50-year) storm event by competent coastal engineers with over 60 previous successful projects. Nourished beaches have two parts: the "design beach," which is a base volume of sand that provides protection during large storms, and the "advance nourishment," which is sacrificial sand that will erode over time. The "advance nourishment" portion can withstand expected conditions over 5 years (including significant storms); after it erodes, the "design beach" will remain in place and can still withstand a major (50-year) storm. SBPF will renourish once the sacrificial "advance nourishment" portion erodes, thereby always maintaining the major storm protection provided by the "design beach."

7. The nourished beach will look and support life similar to the existing beach.

Mr. Seidel is misinformed in his statement that nourished beaches "do not look, feel, or support life similar to a natural beach." The nourished beach at Sconset will look like the natural beach, as the sediment from the borrow site has comparable mediumto coarse grain size and similar color. Sconset Beach is not like certain South Florida beaches that have a high carbonate component with fine-grain size particles which may initially experience some compaction.

The nourished beach at Sconset will support life similar to the existing beach. Organisms living in the extremely active nearshore zone are conditioned to rapidly repopulate because their natural habitat is highly dynamic. These organisms typically repopulate within a one year period, generally tied to their annual (or even higher-frequency) reproductive cycle. The increased beach width will protect the existing and newly-created dunes, which we will vegetate to allow them to support a variety of plant and animal life. Additionally, shorebirds are known to nest where sandy material is deposited --including areas near Sesachacha Pond where sandy material (with gravel mixed in) has been deposited from pond opening activities - and will benefit from the creation of suitable habitat. Other animal species will similarly use the nourished beach just as they would the existing beach.

8. The nourished beach will benefit protected shorebirds by creating some 50 acres of suitable habitat.

Protected shorebirds (the "threatened" Piping Plover and species of "special concern" Least Tern - none are listed as "endangered" as Mr. Seidel states) typically nest at Sesachacha Pond. SBPF has carefully planned construction and coordinated with the Nantucket Beach Manager, MassAudubon, and state and federal experts on Piping Plovers, Least Terns and other shorebirds. The project will avoid impacting the shorebirds by staying a minimum of 100 yards outside the nesting area during the nesting season and providing monitoring. Protected shorebirds will receive substantial benefit by the addition of some 50 acres of suitable habitat areas, as much of the existing beach (everything between Sesachacha and Low Beach) is too narrow to serve as nesting habitat.

9. Adjacent shorelines may experience modest gains in width and will not be subject to increased erosion or changes in sediment transport, currents, or wave patterns.

While Mr. Seidel expressed concern over the fate of adjacent shorelines, beach nourishment is the state's preferred shoreline protection method (as opposed to seawalls and bulkheads) precisely because it does not alter natural coastal processes nor exacerbate erosion in nearby areas. The project will introduce additional beach-compatible sediment to the nearshore sediment transport system. Sediment will move both north and south of the project area, so adjacent shorelines may expect some modest gain in width. For example, the beach immediately adjacent to the project near Sesachacha Pond may widen by approximately 40-feet over 5 years, while farther from the project area, beach width increase will be smaller and will taper off. There will be no increased erosion or change in nearshore wave, sediment transport, or current patterns resulting from the project (based on state-of-the-art modeling results using 50-year storm conditions). Both experience with numerous beach projects and modeling results indicate there will be positive impacts to adjacent beaches from the project and no negative impacts.

10. Despite recent accretion in limited areas, longstanding erosion is the dominant trend and remains a real threat to Sconset and Codfish Park.

While Mr. Seidel suggests that 'Sconset is not really being threatened," our assessment of risk to Sconset and Codfish Park is based on erosion trends over the past half-century. From 1957 to 2005, Codfish Park eroded 317 feet, an annual average of over 6 feet. From 1990 to 2005, that average increased to just over 11 feet per year, to the point where Codfish Park Road was severely threatened.

While recent shoreline change data for Codfish Park show that accretion (approximately 100-150 feet) occurred between 1999 and 2002, this accretion was coincident with the upgraded beach dewatering system installed by SBPF. The beach had built out so far that the end of the discharge pipe was buried in sand and the system had to be turned off, a victim of its own success. Since it has been off, shoreline retreat has resumed. Despite the accretion from 1999-2002, more recent erosion in Codfish Park and the sustained erosion just north of Codfish Park suggests that the shoreline at Codfish Park will continue to erode over the long term unless beach nourishment is implemented.

11. The Project is in compliance with all environmental laws and regulations.

Mr. Seidel wrongly opines: "We have many ordinances and laws, which I believe the SBPF is in serious jeopardy of violating." There is no factual basis for this statement. For the past 2.5 years, SBPF has been pursuing 14 permits or reviews at the local, state, and federal level. Each extensive review process requires a demonstration of compliance with all applicable laws and ordinances. The state Secretary of Environmental Affairs determined that the project "adequately and properly complies with the Massachusetts Environmental Policy Act," which serves as a gateway for state and local permitting. The Nantucket Board of Selectmen's peer review consultant concluded that "The level of care and due diligence delineated within the FEIR is to accepted standards. The beach and borrow area designs have sufficient technical

basis" (Applied Technology & Management). I