Application of Health Risk Assessment to Derive Cleanup Levels at a Fuel-Oil Spill Site

Risk-based corrective action (RBCA) has been becoming an accepted approach for the remediation of contaminated sites. This paper described the application of four different risk assessment approaches, including the North Carolina risk analysis framework (Framework), Illinois tiered approach to correction objectives, RBCA tool kit for chemical releases (RBCA tool kit), and exposure and risk assessment decision support system, to conduct a risk evaluation task and demonstrate the application strategy at a fuel-oil spill site. After the risk evaluation processes, the soil and groundwater remediation goals for target compounds (total petroleum hydrocarbon, benzene, toluene, ethylbenzene, and xylenes) were determined. The calculated remediation levels met with the requirements for minimum target risk levels (i.e., cancer risk of $1\times {10}^{-6}$ and hazard quotient of one). After completion of the RBCA process, the remediation time and cost could be minimized in some cases due to the adoption of more achievable and flexible remediation goals. Among these applied risk assessment methods, the RBCA tool kit was an appropriate and feasible tool for the future risk assessment application due to its thorough considerations of the exposure pathway and transport model selection. Results from this study provided a streamlined process and guidelines for future risk assessment work at petroleum–hydrocarbon contaminated sites in Taiwan. Based on the findings from this study, RBCA was believed to be a more sound and defensible basis for site closure.