Soil-Gas and Geophysical Techniques for Detection of Subsurface Organic Contamination

摘要

The purpose of this effort was to provide guidance to Air Force Installation Restoration Program managers on the use of geophysical and soil gas reconnaissance techniques for detecting organic contaminants in the subsurface. Electromagnetic induction and direct current resistivity surface geophysical techniques and two soil gas monitoring techniques were tested at four Air Force bases. These techniques provide timely preliminary site information to assist in proper placement of monitoring wells. This will reduce the duration of site investigations and expense due to hit-and-miss placement of monitoring wells. In addition, a panel of expert hydrogeologists, chemists, and geophysicists provided guidance on the use of the these reconnaissance techniques. Active soil gas monitoring, where a gas sample is extracted from the soil for analysis, was the most successful method for detecting volatile organic compounds. Passive soil gas monitoring, where vapors are collected on a sorbent trap, often failed to indicate organics when they were present. More research in this area is required with respect to passive soil gas monitor placement and duration of exposure. Generally, geophysical methods were successful for detecting hydrogeological features, buried metal objects, and conductive plumes, but were unsuccessful for detecting organic contaminants. Keywords: Soil Contamination, Groundwater pollution. (aw)