PARTITIONING TRACER TEST FOR DETECTION, ESTIMATION, AND REMEDIATION PERFORMANCE ASSESSMENT OF SUBSURFACE NONAQUEOUS PHASE LIQUIDS

In this paper we present a partitioning interwell tracer test (PITT) t echnique for the detection, estimation, and remediation performance as sessment of the subsurface contaminated by nonaqueous phase liquids (N APLs). We demonstrate the effectiveness of this technique by examples of experimental and simulation results. The experimental results are f rom partitioning tracer experiments in columns packed with Ottawa sand . Both the method of moments and inverse modeling techniques for estim ating NAPL saturation in the sand packs are demonstrated. In the simul ation examples we use UTCHEM, a comprehensive three-dimensional, chemi cal flood compositional simulator developed at the University of Texas , to simulate a hypothetical two-dimensional aquifer with properties s imilar to the Borden site contaminated by tetrachloroethylene (PCE), a nd we show how partitioning interwell tracer tests can be used to esti mate the amount of PCE coritaminant before remedial action and as the remediation process proceeds. Tracer tests results from different stag es of remediation are compared to determine the quantity of PCE remove d and the amount remaining. Both the experimental (small-scale) and si mulation (large-scale) results demonstrate that PITT can be used as an innovative and effective technique to detect and estimate the amount of residual NAPL and for remediation performance assessment in subsurf ace formations.