Methods used to estimate mobile LNAPL thickness in theformation have included studies referred to as bail-down,recovery, or recharge tests (e.g., Hughes et al., 1988;Gruszczenski, 1987). These tests involve monitoring LNAPLrecharge to a well following its removal by pumping or bailing.The mobile LNAPL thickness in the formation at each well isthen estimated by various interpretations of depth-to-product,depth-to-water, and product thickness as a function of time.Several potential sources for error exist in the performanceand interpretation of these tests. In general, theseprocedures have not been adequately proven in a variety offield situations (Testa and Paczkowski, 1989) and do notprovide information concerning LNAPL trapped by capillaryforces (Durnford et al., 1991). However, the performance ofsuch tests may provide qualitative information concerning thepotential for LNAPL recovery using conventional pumpingtechnology (API, 1989).