noted that effectiveness data that would be pertinent to these objectives and others discussed in Chapter 4 are infrequently gathered. Most pilot- and field-scale studies of source remediation measure effectiveness in terms of mass removal and occasionally concentration reduction (although these latter data can be very difficult to interpret). Mass flux and source migration measurements have rarely been documented. Indeed, virtually no data exist on the life cycle costs associated with the technologies. Furthermore, most reports of case studies are not published in the peer reviewed literature. These facts should be kept in mind throughout this chapter, especially when interpreting summary tables. The qualitative comparison is conducted for each of the hydrogeologic settings described in Chapter 2. Because these settings are generalizations, whether a certain technology will work for a given site depends on a complex integration of a wide range of site and contaminant properties.

The two contaminant types of concern in this report—dense nonaqueous phase liquids (DNAPLs) and chemical explosives—have varying characteristics and have been handled differently with respect to source remediation. This chapter covers DNAPLs in greater detail than explosives because most of the research to date has focused on DNAPL contamination. However, when a certain technology has been used or is applicable to chemical explosives, it is mentioned. The discussion of DNAPL treatment focuses on contamination of the saturated zone, as this medium presents the greatest difficulties in terms of site cleanup. Thus, technologies that target the unsaturated zone (e.g., soil vacuum extraction, bioventing, biosparging, etc.) are not discussed here.

Table 5-1 provides an overview of the technologies discussed in this chapter. Although excavation, containment, and pump-and-treat are considered conventional approaches for addressing DNAPL contamination, they are discussed here

TABLE 5-1 Source Remediation Technologies in This Chapter

Technology

Approach

Page #

Excavation

Extraction

180

Containment

Isolation

182

Pump-and-Treat

Extraction/Isolation

185

Multiphase

Extraction Extraction

187

Surfactant/Cosolvent

Extraction

194

Chemical Oxidation

Transformation

206

Chemical Reduction

Transformation

218

Steam Flushing

Extraction/Transformation

224

Conductive Heating

Extraction/Transformation

236

Electrical Resistance Heating

Extraction/Transformation

242

Air Sparging

Extraction

250

Enhanced Bioremediation

Transformation

256

Explosives Technologies

Extraction/Transformation

288



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