available source remediation technologies will work in the most hydrogeologically complex settings such as karst.

The committee believes that by following the elements of a source remediation protocol illustrated in Figure 6-1, project managers will be able to make critical decisions regarding whether and how to attempt source remediation and thereby accomplish a more beneficial distribution of resources. It is evident from the review of source zone remediation projects at Army facilities and elsewhere that the steps presented in Figure 6-1—determining whether a source exists; developing clear absolute and functional objectives and their metrics; selecting, designing, and implementing a technology; and collecting data to support all these decisions—have seldom been conducted in the manner described in this report. The efforts of potentially responsible parties to date suggest that in some cases, source remediation technologies are being prematurely scaled up at poorly characterized sites, at sites where there is known complex hydrogeology, and at sites where there is no clear reason for proceeding with the project.

Finally, Chapter 5 suggests that several technologies show enough promise, in terms of demonstrated mass removal and concentration reduction in monitoring wells, to warrant further investigation to determine their long-term effects on water quality—especially if objectives other than MCLs, such as mass flux reduction, become more prevalent. For almost all of the technologies discussed, their effectiveness is more uncertain in the more complex hydrogeologic settings. Thus, future work should attempt to determine the full range of conditions under which these technologies can be successfully applied, and to better understand how mass removal via these technologies affects water quality.

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