Tetrachloroethylene-contaminated soils

No information on analysis of tetrachloroethylene in soil or sediment was located. Several procedures for determination of the chemical in plants and food were located. GC/ECD and GC/HSD are most commonly used to analyze solid samples for tetrachloroethylene contamination. Extraction, purge-and-trap, and headspace analysis have all been used to prepare samples. Analysis of headspace gases by GC coupled with ECD, MS, or HSD has proven relatively sensitive (low- to sub-ppb range) and reproducible for a variety of foods (Boekhold et al. 1989 Entz and Hollifield 1982 EPA 1982c Pocklington 1992 ... 

Nonaqueous phase Hquids (NAPLs) present special problems for soil and ground water cleanup. Contaminant transport through ground water depends in part on the water solubiHty of the compound. Because NAPLs cling to subsurface particles and are slow to dissolve in ground water, they hinder cleanups and prolong cleanup times. Dense nonaqueous phase Hquids (DNAPLs) migrate downward in the aquifer and can coUect in pools or pockets of the substmcture. Examples of DNAPLs are the common solvents tetrachloroethylene (PCE) and trichloroethylene (TCE) which were used extensively at many faciHties before the extent of subsurface contamination problems was realized. 

Pennell, K. D. Jin. M. Abriola, L. M. Pope, G.A. "Surfactant Enhanced Remediation of Soil Columns Contaminated by Residual Tetrachloroethylene." J. Contam. Hydrol. 1994 16, 35-53. 

Pennell, K.D., Jin, M., Abriola, L.M., and Pope, G.A. (1994). Surfactant enhanced remediation of soil columns contaminated by residual tetrachloroethylene. J. Contain. Hydrol., 16,35-53. 

Chlorinated organic contaminants are found at various sites of interest to the U.S. Air Force. Among these contaminants are compounds such as tetrachloroethylene, dichloroethane, trichloroethylene, chlorobenzene, benzene, toluene, and components of JP-4 jet fuel. These materials have a boiling range of 80° to 232°C, have substantial vapor-pressure at 100°C, and can be steam distilled if present in excess of their solubility limit. To establish the feasibility of thermal recovery of such chemical contaminants, tetrachloroethylene (120.8°C, nbp) was selected as a representative contaminant. Uncontaminated (clean) sandy soil from the vicinity of a waste site was spiked with tetrachloroethylene and used in recovery experiments. 

Subsurface soil-gas sampling in test wells was made using an IMS encased in a 51-mm diameter stainless steel probe along with supporting electronics. Resolving power was 38 for DtBP and 31 for tetrachloroethylene or perchloroethylene (PCE). This instrument was placed into service at a site contaminated with PCE. The presence of PCE was confirmed by GC-MS analysis of a gas sample at a laboratory certified by the Environmental Protection Agency (ERA). This demonstrated the viability of a down-well IMS-based analyzer. 

Static traps were prepared by coating about 1 cm of the end of 358 C Curie-point pyrolysis wires with finely powdered activated charcoal. After being precleaned by being heated to the Curie point under vacuum, the traps were transported to the field test site in sealed culture tubes. At the field test site (a site known for ground-water contamination by tetrachloroethylene (PCE)), the static traps were placed in 25- to 35-cm-deep holes, covered with inverted aluminum cans, and the soil replaced in the holes. After 3 days the traps were removed for analysis. 

The transformations of the chlorinated hydrocarbons perchloroethylene (PCE), trichloroethylene (TCE), and 1,1,1-trichloroethane are illustrative of these types of reactions. Cis- and tranj -l,2-dichloroethylene (1,2-DCE), 1,1-dichloroethylene (1,1-DCE), and VC are often found in well water which has been contaminated only with tetrachloroethylene and/or TCE [48]. Some of the transformations of PCE and TCE are biologically catalyzed and occur in soil and sediment, while others are believed to occur in groundwater [49, 50]. 1,1,1-Trichloroethane hydrolyzes to 1,1-DCE in groundwater [51]. Figure 8.1 shows the degradation sequence of tetrachloroethylene and TCE. 

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