Technology selection and cost analysis of risk-basked correction action

The University of Tennessee has been tracking technology selection and remediation costs for Tennessee underground storage tank site cleanup for the past five years, in order to study the cost-effectiveness of cleanup methodologies for different site characteristics. A computer model has been developed from information collected from over 400 sites that evaluates costs of assessment, cleanup and monitoring. One way that Tennessee and other states are attempting to encourage cost-effective cleanups, while also safeguarding human health and the environment, is through the implementation of risk-based corrective action (RBCA) plans. Tennessee requires owners to input geological parameters, exposure pathway parameters and contaminant concentrations into a formula that assigns a numerical score to each site. For sites that score below 500, owners are allowed to bypass cleanup and monitor the plume only (e.g., amenable to natural attenuation). The cost model was used to determine the efficacy of Tennessee's RBCA system in promoting cost-effectiveness in the management of these contaminated sites. Also, the current and potential future impact of RBCA on the composition (e.g., site characteristics, location) of sites undergoing cleanup was examined, as well as the cleanup methods used (technologies were grouped as soil priority, water priority, on-site versus off-site treatment and in-situ versus ex-situ). A statistical model was used to test the validity of the scoring system to capture the risky sites while avoiding false positives and to evaluate the technologies used