Published: 1997
Total Pages: 69
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The Cooperative Research and Development Agreement (CRDA) document was signed to undertake development of a portable innovative contaminated sediment dredge. Three major problems are associated with dredging of contaminated sediments: (1) The contaminated sediment are mostly fine and highly compacted, and specialized devices are needed for cutting and loosening them before transporting, (2) the dredged fine sediments are vertically resuspended and dispersed easily within the entire water column and adversely affect the aquatic plants and water quality, and (3) the sediments have a very low rate of deposition, and they may be transported over great distances from the point of origin even under a very weak current. Laboratory tests were conducted at WES in which different mixtures of clays, sand and water were pumped through a pipe, and pressure in the pipe was measured. The effectiveness of a positive displacement pump for pumping sediments with a very low water content was established, and the extent of the addition of clays and water for improving the relative ease of pumping was determined. The dredge was then used in a field trial for removing bottom sediments from a lake at WES. The new dredge removes sediments at near in situ water content with the use of a clamshell bucket. The sediments are placed in a hopper and are pumped by a positive displacement pump to the required disposal site.