Wiedemeier et al., 1996). Rather, this chapter is intended to help standardize the conceptual process for evaluating source remediation, including data gathering and analysis, setting objectives, and selecting remedial actions. The guidance is general, in that all possibilities are examined and no technology or endpoint is advocated over others.
Decision tools and protocols for general site cleanup date back to the early days of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund) and the Resource Conservation and Recovery Act (RCRA). For example, the nine criteria of CERCLA discussed in Chapter 4 are meant to enable the remedial project manager to select among various alternative remedies. Since the early 1980s, many detailed cleanup protocols have been created, most of which focus on specific types of contamination problems (for example, underground storage tanks, fuel hydrocarbon sites, LNAPLs) other than the recalcitrant chlorinated solvent sites that led the Army to request this study. There are also numerous protocols for using individual cleanup technologies, such as pump-and-treat, soil vapor extraction, or monitored natural attenuation, as well as for using engineering controls (such as containment) and institutional controls.
Protocols for remediation of DNAPL sources are still under development and are a focus of a number of ongoing studies. For example, the Texas Risk Reduction Program’s NAPL management decision process, on its eighth draft, will be useful for remedy selection. The U.S. Environmental Protection Agency (EPA) recently sponsored a white paper outlining key issues for DNAPL cleanup, authored by an independent panel of scientists (EPA, 2003). The Air Force Center for Environmental Excellence and the Strategic Environmental Research and Development Program (SERDP) of the Department of Defense (DoD) are both supporting research into decision tools for source remediation, notably the SERDP project on Decision Support Systems to Evaluate the Effectiveness and Cost of Source Zone Treatment (Newell, 2003). A review of these ongoing efforts reveals that flexibility to incorporate the diverse conditions that exist at individual sites (natural and anthropogenic) is a common theme in many of the protocols. Furthermore, rigorous predictions of the performance of source remediation technologies are not available, such that the predictive tools under development provide only a general sense of how things work and an ability to make relative comparisons between options (e.g., the LNAPL Dissolution and Transport Screening Tool—Huntley and Beckett, 2002). Finally, none of the current protocols under development outline what to expect in a given setting, from a given technology, and with a specific contaminant. These limitations, as well as the lengthy examination of the necessary elements of a natural attenuation protocol described in NRC (2000), were kept in mind as the committee developed the elements described below.
The decision protocol for source remediation takes the form of a six-step process (Figure 6-1) that includes activities (white boxes), data and information collection (gray boxes), and decision points (gray diamonds). The steps are pre-