The ASTM standards provide a logical process for implementing the RBCA approach at petroleum and chemical release sites. Furthermore, the ASTM standards provide appendices that contain equations, sample calculations, and other information useful to remedial project managers when establishing risk-based screening levels and response actions at contaminated sites. A major strength of the RBCA approach is its emphasis on determining the data required for technical decisions rather than on following specific process steps. Successful use of the RBCA process depends upon developing an effective conceptual model of site conditions. The conceptual site model identifies the chemicals of concern, the complete or potential exposure pathways, transport mechanisms, and the likely dispersion of the chemicals of concern.
Remedial decisions using the RBCA process potentially involves a three-tier process.
Project managers make remediation decisions at the tier that provides them with the information necessary to make scientifically sound and defensible remedial decisions within the appropriate regulatory framework. The RBCA also uses classifications of known site conditions to determine if early actions are needed and to help identify interim actions consistent with final remedies. Class 1 sites are those sites that pose an immediate threat. Concentrations of contaminants at the site are then compared to the values in the table to determine the need for and possible extent of remediation. A decision to use these non risk-based criteria should be made in consultation with the appropriate regulators and stakeholders.