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Title: Problems with the use of near-surface soil gas results for source identification

Conference · · Journal of Environmental Health; (United States)
OSTI ID:6066245
 [1]
  1. Radian Corp., Sacramento, CA (United States)

This study was conducted to determine if near-surface [3 to 6 feet below ground surface (BGS)] soil gas results accurately determine source areas and indicate soil gas concentrations at greater depth. A statistical analysis of more that 200 near-surface and associated downhole soil gas results for trichloroethene (TCE), tetrachloroethene (PCE), and total halogenated volatile organic compounds (HVOCs) from a Superfund site in Sacramento, California was performed. The analysis showed a poor correlation between near-surface and downhole concentrations. In addition, the analysis indicated that the use of near-surface soil gas concentrations could result in a high probability of NOT locating contaminated soil gas (false negatives) or placing needless borings thereby incurring useless drilling and analytical costs (false positives). For this site, impermeable layers between 3 and 8 feet BGS impeded the vertical migration of soil gas, resulting in the low correlation between near-surface and deeper soil gas concentrations. For sites with similar geologic characteristics, soil gas samples should be collected from below the impermeable layers. Near-surface soil gas investigations may not be applicable to identification of deeper soil gas contamination at some sites, where impermeable lithologic layers impede the vertical migration of soil gas.

OSTI ID:
6066245
Report Number(s):
CONF-9310166-; CODEN: JEVHAH
Journal Information:
Journal of Environmental Health; (United States), Vol. 56:3; Conference: Association of Ground Water Scientists and Engineers (AGWSE) educational seminar on chlorinated volatile organic compounds in ground water, Kansas City, MO (United States), 17-20 Oct 1993; ISSN 0022-0892
Country of Publication:
United States
Language:
English