Contaminant leaching model for dredged material disposal facilities

This paper describes the hydrologic evaluation of leachate production and q uality model, a screening-level tool to simulate contaminant leaching from a confined disposal facility (CDF) for dredged material. The model combines hydraulics, hydrology, and equilibrium partitioning, using site-specific d esign specifications, weather data, and equilibrium partitioning coefficien ts from the literature or from sequential batch or column leach tests of dr edged material. The hydraulics and hydrology are modeled using Version 3 of the hydrologic evaluation of landfill performance model. The equilibrium p artitioning model includes provisions for estuarine sediments that have var iable distribution coefficients resulting from saltwater washout. Model out put includes contaminant concentrations in the CDF profile, contaminant con centration and mass releases through the bottom of the CDF, and contaminant concentrations and masses captured by leachate collection systems. The pur pose of the model is to provide sound information for evaluating the potent ial leachate impacts on ground water at dredged material CDFs and the effec tiveness of leachate control measures.