Risk variability due to uniform soil remediation goals

If a single contaminant concentration in soil,were to be used as the remediation goal at all potential remediation sites in a region, risk would be expected to vary across sites due to differences in site characteristics that affect transport and fate. A methodology is developed to evaluate such variability. It is applied to Ross County, Ohio, a region for which compiled, detailed hydrogeologic information is available. Four carcinogenic contaminants (benzene, trichloroethylene, chlordane, and benzo[a]pyrene) and exposure scenarios (on-site commercial, on-site recreational, and on-site and off-site residential) are evaluated. Results vary, but in general, indicate that for contaminants that are highly degradable such as benzene or immobile in the subsurface such as benzo[a]pyrene, specifying a uniform soil remediation goal would result in relatively small degree of regional risk variability. However, for highly mobile and persistent contaminants like trichloroethylene, a uniform goal would result in a large degree of regional risk variability. Application of the methodology to a larger, less well-characterized region is analyzed.