APPLICABILITY OF SHARP-INTERFACE MODELS FOR NAPL TRANSPORT .2. SPREADING OF A LNAPL

This paper, the second in a two-part series, examines the applicability of the sharp-interface approach to modeling initial accumulation and spreading of a light nonaqueous phase liquid (LNAPL) in the ground-water aquifer. The sharp-interface approach models NAPL transport by developing a time-distance profile from Darcy's law by assuming a piston or plug flow. The approach is tested here against an immiscible-phase model that includes capillarity effects in the formulation. Although significant assumptions are included in the sharp-interface model, it may be useful for initial screening, in obtaining an order-of-magnitude estimate of travel times, and in describing the approximate extent of the free and dissolved NAPL contamination. In the absence of data for calibration, the paper introduces guidelines for estimating the parameters of the model. By integrating the formulation in Part 1 and this part, a practical approach for analysis of NAPL contamination is defined; the underlying assumptions and simplifications have to be recognized, however.