A Cost-Benefit Analysis of Alternative Remediation Goals for Hexavalent Chromium Contaminated Sites in New Jersey. P. R. D. Williams and D. Proctor, Exponent
Over 200 sites in New Jersey have soil containing hexavelent chromium due to the former use of chromite ore processing residue (COPR) as a fill material. The New Jersey Department of Environmental Protection (NJDEP) requires varying levels of cleanup at these sites to comply with uniform or site-specific health-based standards. For example, NJDEP relies on a "bright line" approach when evaluating residential dermal exposures (i.e., no single soil sample is allowed to exceed the dermal standard), and an "averaging" approach when evaluating residential inhalation exposures (i.e., the 95th percent upper confidence limit of the mean concentration is not allowed to exceed the inhalation standard). Although inconsistent with USEPA guidelines, NJDEP also uses the former, rather than the latter, approach to evaluate remediation goals for residential ingestion exposures. The purpose of the current cost-benefit analysis is to evaluate whether the extra level of cleanup required under NJDEP’s "bright line" approach for complying with the oral standard is justified based on its costs and benefits. Two COPR sites that have been fully characterized are evaluated. Cost estimates are based on average costs for remediation and the difference in the volume of soil requiring treatment to meet the oral standard as either a "bright line" or an "average." Benefits are estimated as the expected change in lifetime cancer risk associated with NJDEP’s approach, and assumptions about the population affected and value per death adverted. Compared to the "averaging" approach, the "bright line" approach yields an additional cost of about $74,000 (Site 1) and $107,000 (Site 2), with a corresponding benefit of $11 and $26, respectively. Sensitivity analyses also yield negative net benefits, even under a best-case scenario. Our findings suggest that NJDEP’s current approach for establishing remediation goals at COPR sites may not be warranted from a cost-benefit perspective.
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