Applied Coastal provided the engineering design and permitting services to Barnstable Clean Water Coalition for the back-passing of dredged material from the western end of Sampson’s Island to the eastern end of Dead Neck for the purposes of constructing a beach and dune nourishments. DNSI provides protection of wildlife habitat and nesting habitat for coastal waterbirds of high conservation Priority. In addition, DNSI provides flood control and storm damage protection for the bays and estuaries to the north. The fact that DNSI shoulders the entrance channels to West Bay, Cotuit Bay has helped create a relatively shallow coastal estuary creating a variety of habitats and resource areas.
The eastern end of Dead Neck experiences excessive erosion, which reduces the ability of that portion of DNSI to maintain habitat for bird nesting and foraging and to provide storm damage prevention for inland areas. At the western end of Sampson’s Island, an 800-foot sand spit has accreted that is currently blocking a substantial portion of the historical navigation channel at the entrance of Cotuit Bay. The reduced channel width has increased current speed and directed flow towards Cotuit, causing erosion along portions of that shorefront and negatively impacted navigation into and out of the harbor. The DNSI Restoration and Management Project involves maintenance dredging of the Cotuit Entrance navigation channel at the western end of Sampson’s Island, and utilization of that material for beach and dune nourishment at the eastern end of the system. By “back-passing” the sand in this manner, the project will close the loop of the system and provide a source of sand to stabilize the island that continues to be starved at the eastern end. Which restores and stabilizes the beach and dune at the east end of the Dead Neck with sand nourishment, in order to restore habitat for endangered shorebirds and stabilize barrier beach functions, and restores the historic navigation channel at the entrance to Cotuit Bay by maintenance dredging of the area where a spit accreted at the west end of Sampson’s Island.
Applied Coastal provided quantitative assessment of the potential impacts associated with proposed dredging activities in the Cotuit entrance channel, the following analyses were performed: a) An historical analysis of shoreline; b) a numerical modeling assessment of the alterations to tidal hydrodynamics as well as the influence coastal erosion potential; c) the influence of the existing barrier beach spit on preventing flood protection and/or storm damage prevention for properties landward of the barrier beach system; and d) permitting and engineering support through the MEPA and subsequent Local, State, and Federal permitting process.