Nearshore placement of dredged material for estuarine shoreline restoration in Berkeley Township, New Jersey

Abstract

Nearshore placement of sediments for beach nourishment has become a standard, cost-effective method for shore protection along ocean-facing shorelines but is not a widely adopted practice within tidal estuaries due to environmental concerns such as turbidity, burial of benthic and shore organisms, and pollution. This paper describes the monitoring and evaluation of nearshore placement of dredged materials at Goodluck Point, Berkeley Township, New Jersey. A total of approximately 4,500 cubic meters of dredged material was placed in the nearshore to create a parallel bar along a 0.5 km stretch of existing beach. The narrow beach is the front edge of a marsh system severely impacted by erosion due to lack of sediment supply compounded with local currents and waves that transport sediment out of the beach system offshore and alongshore. This beach erosion is exacerbated during coastal storms events. The Goodluck Point marsh is part of the Edwin B. Forsythe Wildlife Refuge managed by the U.S. Fish and Wildlife Service. Nearshore placement was determined to be part of an experimental project designed to evaluate methods of restoration for the marsh and reduce future impacts. The design for the nearshore placement called for sand to be placed in a temporary parallel bar just offshore of the existing beach, and over time it would weld to the beach. Analysis of pre- and post-placement surveys indicate that much of the dredged material placed in the project area remained there throughout the 18-month monitoring period. However, a combination of storms during and after placement, as well as ongoing longshore transport processes, resulted in the sand being washed south along the beach and accumulating in just the southern 200 meters of the project area. This paper introduces and suggests that the concept of “process-based design” will maximize resiliency benefits through more extensive pre-placement monitoring and modeling to identify optimal placement strategies. Process-based design is a beneficial use strategy that takes advantage of natural sediment transport processes to enhance or re-create nature-based shore protection features.