Groundwater Protection and the Development of Risk-Based Contaminated Soil Clean-Up Standards Using Computer Modeling

Abstract

In the early days of remediation of hazardous waste sites in the United States, regulators required the regulated parties to remediate their sites to pristine, or background concentration levels. The superfund experience, under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA), demonstrated that an inordinate amount of money and effort was required to bring a site to clean levels under this definition. A new approach is gaining wide acceptance by regulators and regulated parties where clean-up standards for soil are established on the basis of risk. The risk standards for groundwater are set with the aid of computer models, which are used as tools to predict the contaminant transport and concentrations at potential receptor sites. Regulators in New Hampshire, USA, following the lead of other states, are using a combination of computer models to establish generic clean-up standards for soils across the state. The authors outline the procedure for setting clean-up standards, and detail the benefits of the risk-based approach. The benefits include more realistic clean-up goals, opportunities for responsible parties to more readily achieve final site closure, and a significant cost savings.