SURFACTANT-INDUCED REDUCTIONS IN SOIL HYDRAULIC CONDUCTIVITY

Surfactant solutions are being proposed for in situ flushing of organi c contaminants from soils and aquifers. The feasibility of surfactant additives in remediation may depend in large part on how these chemica ls affect the hydraulic conductivity of the porous media. While there is evidence in the literature of conductivity loss during surfactant f lushing (Miller et al. 1975; Nash et al. 1987), there has been little research on quantifying the process for unconsolidated sediments. Surf actant-affected hydraulic conductivity reductions were measured in two soils (Teller loam and Daugherty sand). Testing was done with eight s urfactants at a variety of concentrations (10(-5) to 10(-1) mole/kg), surfactant mixtures, and added solution electrolytes. The Teller was a lso tested with its organic matter removed. Maximum hydraulic conducti vity decreases were 47 percent for the sand and more than two orders o f magnitude for the loam. Surfactant concentrations, surfactant mixtur es, soil organic content, and added solution electrolytes all affected the degree of conductivity reduction. Results indicate that surfactan t-affected hydraulic conductivity losses should be considered prior to in situ remediation and may preclude surfactant use in some fine grai n soils.