ON THE MOVEMENT OF AN LNAPL LENS ON THE WATER-TABLE

The penetration of light nonaqueous phase liquids (LNAPLs) in quantiti es that lead to an accumulation in the form of a lens above the water table is considered. First, the three-phase vertical gravity-capillary equilibrium of water, NAPL, and air above the water table is specifie d. The hypothesis of 'vertical equilibrium phase distribution' is used to derive averaged asymptotic equations describing NAPL flow as a thi n lens floating above the water table. Some problems of unsteady NAPL lens movement and the development of a NAPL mound, spreading along an inclined or horizontal phreatic surface are discussed and the analytic al solutions are obtained.