Terminal Groin and Beach Restoration at Folly Beach County Park, South Carolina

Folly Beach County Park (FBCP) is situated along ~1,000 meters (m) or ~3,300 feet (ft) of shoreline at the southwestern end of Folly Beach near Charleston, South Carolina, U.S.A. Net sand transport is east to west with the adjacent inlet tending to draw sand from the oceanfront. Nourishment in the form of navigation channel disposal and a 50-year federal shore protection project helped maintain the unstabilized spit at FBCP for many years. However, lack of beach fills after 2005 resulted in dune line recession of over 36 m (~120 ft) in five years, loss of parking facilities, and exposure of underlying marsh sediments along the oceanfront. The authors were retained by the Charleston County Park and Recreation Commission (CCPRC) to evaluate the erosion and outline alternatives for restoration. A total of 317,300 m³ (415,000 cubic yards) nourishment and a 225-m (745-ft) steel sheet pile groin with a concrete cap and armor stone toe protection were determined as the optimal means of restoring and maintaining a recreational beach and protecting park infrastructure. The groin at FBCP was designed to follow the local beach profile to the extent practicable in order to reduce the exposure of the structure. It was composed of three sections: berm, beach face, and low-tide terrace. The berm section served to hold the major dry-beach fillet on the updrift side and a minor fillet on the downdrift side, and the beach-face section followed the average slope of the beach across the intertidal wave swash zone. The low-tide terrace section stabilized the profile above the low watermark, and a scour apron of quarry stone was designed at the seaward end of this section for toe protection. Beach nourishment started on 5 May 2013 and finished in 20 days on 24 May. The groin construction was completed over 35 days between 15 May and 19 June 2013. The project was completed on time and without any environmental incident. FBCP re-opened on 3 July 2013 and remains a premier recreational destination in the Charleston area. The American Shore and Beach Preservation Association (ASBPA) announced in May 2015 that the FBCP project is a winner of its 2015 Best Restored Beach award for its successful enhancement of storm protection, habitat restoration, and recreation restoration.