Leachate Testing and Evaluation for Estuarine Sediments. Long-Term Effects of Dredging Operations Program.
1997
Myers, Tommy E. | Brannon, James M. | Tardy, Barbara A. | Townsend, Dan M.
Contaminated dredged material is sometimes placed in confined disposal facilities (CDFs) where the potential for movement of contaminants to groundwater and surrounding surface water by leaching is an important environmental concern. Column leach tests have been developed as laboratory-scale physical models of contaminant leaching in a CDF that include advective-dispersive and other mass transfer effects. Column leach tests are recommended for predicting leachate quality in CDFs containing estuarine dredged material leached by low-ionic strength water. Under the influence of decreasing ionic strength, contaminant release from estuarine dredged material is complicated by destabilization of the sediment colloidal system. These effects are better predicted with the column leach test described in this report than with the sequential batch leach test previously recommended for leach testing of freshwater sediments. This report describes procedures for conducting column leach tests and provides guidance on interpretation of results for estuarine sediments. Mathematical formulation of sorption descriptors that account for salt washout effect is also described.
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