WATER RESOURCES RESEARCH, cilt.30, sa.12, ss.3301-3311, 1994 (SCI-Expanded)
Petroleum products, such as gasoline, leaked from an underground storage tank can be recovered successfully by two-pump operations. The success of the recovery effort depends on the accurate placement of the recovery well at the spill site. An effective recovery operation can minimize the remaining contamination mass in the subsurface. Therefore, a careful evaluation and determination has to be made as to where to locate the recovery well. The location of the well can be decided based on an estimation of the extent and thickness of free product on the water table. Such an estimation should be based on analysis of governing mechanisms. In this study we present analytical solutions to estimate the recovery of oil from an established oil lens. These solutions are obtained by applying the Laplace transformation to averaged linear partial differential equations governing the phenomenon. The governing equation for the free product thickness is derived by averaging the oil phase mass balance equation along the free product thickness and substituting the boundary conditions at the oil/water interface and oil surface. The analytical solutions estimate the temporal and spatial distribution of free product thickness on the water table for a number of recovery scenarios. Results are presented for the temporal and spatial variation of the free product thickness, temporal variation of the free product Volume recovered, and recovery efficiency based on the readings at the monitoring wells. Since they can be utilized without a great deal of data, analytical solutions are quite attractive as screening tools in two-pump free product recovery operations.