Chlorinated solvents are one of the most frequently encountered contaminants in environmental investigations (Siegrist, 1993). Trichloroethylene (TCE) and tetra-

chloroethyl~ne (PCB), for example, were detected in 945 groundwater-supplied drinking systems in an Environmental Protection Agency survey of drinking wells in the United States. In September 1997, TCE and PCB were detected at 852 and 771, respectively, of the 1420 National Priority List (NPL) or Superfund sites in the United States (Butler and. Hayes, 1999). As a result of the frequency of detection and toxicity of chlorinated solvents, millions and often billions of dollars are alleged in litigation associated with their investigation and remediation.