The inadequacy of commonly used risk assessment guidance for determining whether solvent‐contaminated soils can affect groundwater at arid sites∗

Publication No. 3848, Environmental Sciences Division, ORNL.

Abstract

Commonly used risk assessment guidance is not adequate when applied to solvent‐contaminated soils in arid environments. The equations that are recommended for calculating how such soils will affect ground‐water assume that liquid phase leaching controls contaminant migration. If vapor phase migration is considered at all, diffusion is assumed to be the dominant process. In contrast, a field study performed at an industrial site in Southern California demonstrated that leaching could not account for the transport of contaminants to the water table and the recent technical literature suggests that gravity‐induced vapor migration may be the principal mechanism for vapor phase migration. Thus, regulatory guidance provided by the United States Environmental Protection Agency and the State of California could result in a significant underestimate of the amount of chlorinated solvent that could contaminate the groundwater at arid sites.

Notes

Publication No. 3848, Environmental Sciences Division, ORNL.

Managed by Martin‐Marietta Energy Systems, Inc. for the U.S. Department of Energy under Contract No. DE‐AC05–840R21400.