Non-Aqueous Phase (NAPL) Mobility Limits in Soil -
API Soil & Groundwater Research Bulletin No. 9  (June 200)

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Conservative screening concentrations for non-aqueous phase liquids (NAPL) that could be considered immobile in unsaturated zone soils are presented.  Total concentrations measured at a crude oil or petroleum product release site (using total petroleum hydrocarbon [TPH] or similar method ) can be compared to the screening concentrations to determine the potential for NAPL to migrate in soil . 

This paper addresses immobile bulk NAPL in soils at concentrations up to the threshold of mobility.   This document does not address the movement and flow of NAPL, the dissolution of NAPL chemical into soil pore water solution, nor NAPL volatilization into soil pore air.

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