In Situ Volume Creep for Environmental Dredging Remedies

摘要

The area requiring remediation and required depth of dredging is the basisof estimating the in situ volume of sediments to be dredged when considering environmentaldredging remedy alternatives. Initial estimates of in situ volume to be dredged areusually made for feasibility evaluation and/or remedial design using simple area-depthgeometries, but these estimates may not be appropriate for use in selecting dredge sizes,treatment and disposal requirements, and other project requirements related to production,because the actual volumes requiring removal will often be greater than the initiallyestimated volume. This phenomenon may be termed "volume creep," and it occurs forpractically all projects. Adjustments to the estimated in situ volume should be made toaccount for operational considerations such as the method of dredge operation, allowabledredging overdepth, box cuts for slopes, and layback slopes for deeper excavations. Thispaper discusses the factors involved in volume creep, presents data on the magnitude ofvolume creep for a number of contaminated sediment sites, and provides recommendationsfor adjusting the estimated in situ volumes for purposes of feasibility evaluationand/or remedial design.