Monitoring of Beachsaver Reef with Filter Blanket and Double-T Sill at Cape May Point, New Jersey, Section 227 Demonstration Site; First Year Monitoring - 2002-2003.

摘要

The first National Shoreline Erosion Control Development and Demonstration project is located at Cape May Point, NJ, the southernmost beach along the New Jersey coast. This site was selected to evaluate the functional, structural, and economic performance of the patented Beachsaver Reef prefabricated concrete submerged breakwater and the less expensive prefabricated concrete structure called a Double-T sill. This demonstration project was developed through a cooperative effort of the U. S. Army Corps of Engineers Headquarters, Coastal Engineering Research Board, Coastal and Hydraulics Laboratory, Philadelphia District, the state of New Jersey and Cape May Point. Cape May Point has a history of beach erosion due to the combined influence of waves and tidal currents due to its location at the north side of the entrance to Delaware Bay. The Beachsaver Reef was installed between August and September 2002 at the seaward end of groin cell 5. The Double-T sill was installed in September 2002 at the seaward end of groin cell 6. Groin cell 4 acted as a control cell without any structures, but a small beach fill was placed twice during the monitoring period. Monitoring includes dune, beach and nearshore beach profile surveys, structure surveys to measure settlement and scour, waves and current measurements, sediment sampling and aerial photography analysis of shoreline change. After one year, evaluation of profiles and shoreline change indicates the functional performance of the Beachsaver Reef has stabilized the shoreline and retained sand within the cell, while the Double-T sill has not. The structural performance indicates that the Beachsaver Reef has experienced settling in the western part of the cell while the Double- T has settled below the surface within the first 6 months. The economic analysis will be evaluated after the third year of monitoring.