Streamlining The Risk Assessment Process: Integration of Generic Criteria and Site-Specific Risk Assessment

Abstract

The Canadian government applies a tiered approach to assessing and remediating the risk at contaminated sites. This merges the strengths of national guidelines, site-specific objectives, and site-specific risk assessment in a tiered framework intended to achieve both economically and environmentally feasible decisions. The tiers of this framework include Canadian Soil Quality Guidelines that are developed for four categories of land use based on defined exposure scenarios that are protective of both human health and the environment. Where these exposure scenarios are not feasible for a site, guidance is provided on setting site-specific objectives that takes into account variations in receptors and exposure through the modification of the soil quality guideline. Where such objectives are not appropriate due to several triggering factors, including uncertainty, a full site-specific risk assessment is conducted to set remediation goals. This risk assessment is itself tiered, and driven largely by uncertainty in the estimate of risk. In this paper we present the generic framework plus recent work on applying this tiered framework to the remediation of petroleum contaminated sites.