1.1 This provisional guide covers risk-based corrective action (RBCA), that is a consistent decision-making process forthe assessment and response to chemical releases, based on the protection of human health and the environment. Chemical release sites vary greatly in terms of complexity, physical and chemical characteristics, and in the risk that they may pose to human health and the environment. The RBCA process recognizes this diversity by using a tiered approach that integrates size assessment and response actions with human health and ecological risk assessment to determine the need for remedial action and to tailor corrective action activities to site-specific conditons and risks. The evaluations and methods used begin with sample analyses in Tier 1 and move to more complex evaluations in Tier 2 and Tier 3. The process of gathering and evaluating data is conducted in a scaled fashion. Consequently, only that data that are necessary for that tier's decision-making are collected at each tier.

1.2 This provisional guide describes an approach for risk-based corrective action. It is intended to help direct and streamline the corrective action process and to complement but not to supersede federal, state, and local regulations. It can be used where there may not be a regulatory framework for corrective action where the user wishes to conduct corrective action such as sites in voluntary cleanup programs or under Brownfields initiatives. In addition, it can also be used as an over-arching framework when several different agency programs affect the site. Furthermore, the user should be aware of the federal, state, and local corrective action programs that are applicable for this site, and regardless of the program, federal, state, and local agency approvals may be required to implement the processes outlined in this provisional guide. Finally, regardless of whether a corrective action is specifically governed by a regulatory program, the user should consult with the regulatory agency to identify the appropriate technical policy decisions prior to implementing the RBCA process.

1.3 There are numerous technical policy decisions that must be made to implement the RBCA process, including defining data quality objectives, determining target risk levels, and addressing resource protection. It is not the intent of this provisional guide to define appropriate technical policy decisions. The user must identify the appropriate technical policy decisions.