A FUGACITY-BASED SCREENING MODEL TO ASSESS CONTAMINATION AND REMEDIATION OF THE SUBSURFACE CONTAINING NONAQUEOUS PHASE LIQUIDS

A screening model is developed and illustrated for evaluating the part itioning and fate of components of non-aqueous phase liquids (NAPLs) p resent in the subsurface environment. The model provides estimates of the effectiveness, in terms of recovery time, of a variety of remedial technologies, including water and solvent flushing, air and steam str ipping, and enhanced biodegradation. An illustration is given of an ex isting fractured bedrock site in Smithville, Ontario, which is contami nated with a NAPL containing polychlorinated biphenyls (PCB), trichlor obenzene (TCB), and trichloroethylene (TCE). The model results suggest that concentrations in water in the proximity of the DNAPL originally spilled in 1979 to 1985 were approximately PCB 75 mu g/l; TCB 1070 mu g/l; and TCE 8019 mu g/l, and that the estimated half-lives are 9312, 150, and 4.4 years, respectively, for the present pump and treat oper ation. The model is applied illustratively to assess the feasibility o f a number of remediation strategies. In total, the approach can provi de screening level insights into NAPL behavior and possible remediatio n and can serve as a justification for more detailed modeling.