Print this pageApplication of Environmental Assessment to Remediation of Abandoned Oil Field Sites
DUTTON, ALAN R., JEFFREY G. PAINE, and JOHN J. TINTERA
Hydrogeologic mapping and environmental geophysics can track contamination sources, map subsurface contamination, and obtain data for cleanup of abandoned oil field sites while minimizing the cost and risk involved in more intrusive environmental drilling. For example, investigation into a complaint about a vegetation kill next to an abandoned oil field site in East Texas turned up a subsurface plume of sulfuric acid, leaching from spoil most likely taken from a sour-gas processing plant for driveway material. Plume migration appeared downslope in a seasonally saturated soil zone overlying a regional aquifer system. A ground-conductivity (EM) survey conducted at multiple coil spacings showed a shallow plume of high conductivity extending no farther than the stressed vegetation. Modeling results predicted the depth of the conductive plume and also matched expected subsurface geologic contacts. A minimum of intrusive auger cores sufficed to prove that most of the sulfuric acid was limited to the uppermost 4 ft of ground, with a gradation to background at a depth of 10 ft, with little potential for downward migration. The total mass of acid to be neutralized as part of site remediation was estimated from an integration of EM and laboratory data.