Groundwater fate and transport models can provide an indication of the potential impacts of arsenic from the infiltration of leachate from unlined C&D debris landfills containing CCA-treated wood. A solute transport model, Migration of Organic/Inorganic Chemicals (MYGRT), was chosen to predict groundwater contaminant concentrations at specified locations from a hypothetical source (C&D landfill) that contains CCA-treated wood. MYGRT simulates a single contaminant, generated from a surface source, migrating downward through the unsaturated soil layer, mixing with the underlying groundwater, and then migrating horizontally downgradient through the aquifer. The software incorporates the processes of advection, dispersion and retardation. Because of the slow and complex transport mechanisms involved, groundwater impacts may not be observed for many years. A small fraction of the arsenic from the CCA-treated wood disposed in C&D debris landfills was simulated as leached (17.1%). Although hundreds of years later, exceedances of current and potential groundwater cleanup target levels were predicted.

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