IMPORTANCE OF HANDLING LOSSES TO BEACH FILL DESIGN

R.D. Hobson, W.R. James

Abstract


Beach nourishment models commonly employed by the U.S. Army Corps of Engineers compare textural properties of native beach and dissimilar borrow sediments to determine overfill and renourishment requirements for beach fill projects. It is assumed for these comparisons that the texture of borrow sediments is unchanged by dredging and handling operations but investigations have shown that significant handling losses do, in fact, occur. This paper presents results from four field studies that document textural changes caused by dredging and sediment handling at Rockaway Beach, NY, and at New River Inlet, NC. Errors associated with calculating volumes of sediment dredged and lost using standard surveying and production methods are discussed and an alternate method is presented as a handling-loss model that compares bottom and dredged sediment texture to determine volumes lost. The results of the studies presented are that handling operations do create significant changes in bottom sediment texture which, in turn, do affect beach fill model calculations by generally improving the predicted performance of these sediments as fill. The proposed handling-loss model predicts volumetric losses that greatly exceed losses generally anticipated during project construction. Discrepancies between loss estimates are discussed in terms of possible inadequacies of the model and of mechanisms that might consistently minimize losses using the standard methods for determining dredged sediment volumes.

Keywords


fill loss; beach fill; beach design

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