Restoration of an Urban Beach Using a Mixed Sediment Nourishment Material

To address the issues of shore protection and "sediment starvation" along the Winthrop Beach shoreline, a beach nourishment project has been designed to return the shoreline to historic conditions. Unlike most beach nourishment projects in the United States, the beach compatible material needed for restoration of Winthrop Beach consists of mixed gravel and sand sediments. Based upon observations from similar regional beach systems, it is anticipated that the coarse fraction of the nourishment material will be naturally sorted by wave action and form a gravel berm along the upper portion of the beach. Formation of these gravel berms during the winter months will significantly enhance the design life of the project by increasing wave energy dissipation due to the high porosity of the berm and reduce storm-induced erosion of the finer-grained material underlying the gravel. Due to the unique conditions of Winthrop Beach, an offshore borrow site was determined to be the most cost-effective and the only feasible method for providing nourishment material to the beach.