NAPL and Contaminant Transport in the Soil Matrix

by Yoram Cohen, Univ of California, United States,
Patrick A. Ryan, Univ of California, United States,

Document Type: Proceeding Paper

Part of: Environmental Engineering


A one-dimensional multiphase mass transport model for the migration of a Non-Aqueous Phase Liquid (NAPL) containing sparingly water soluble organics in the unsaturated soil zone is described. The model consists of a two phase immiscible flow model linked to a four phase chemical transport model. The immiscible flow model incorporates a front tracking algorithm to determine the front of the invading NAPL as a function of penetration time. The NAPL penetration toward groundwater is shown to be a function of 4 dimensionless groups - NAPL Capillary number, the ratio of the NAPL Reynolds number to the NAPL Froude number, and the ratio of the defending phase to NAPL phase densities and viscosities. Simulations for the migration of organic chemicals revealed that contaminant concentrations in the air and aqueous phases past the front can be significant. Finally, mass transfer limitations for interfacial transport between the NAPL and the water phases and between the water and solid phases were shown to be important in describing chemical migration associated with a NAPL leak.

Subject Headings: Nonaqueous phase liquids | Soil pollution | Matrix (mathematics) | Water supply systems | Fluid flow | Hydrologic models | Groundwater pollution | Solubility

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