Remediation-Focused Hydrogeological Investigations of Abandoned Oil Field Cleanup Sites

Alan R. Dutton, principal investigator; Robin C. Nava, Jeffrey G. Paine, Rebecca C. Smyth, E. Jeri Sullivan; assisted by Wan-Joo Choi, William H. Doneghy, Jordan W. Forman, Jr., Andy M. Graham, and Susan Palachek

The Railroad Commission of Texas (RRC) oversees the cleanup of abandoned oil field sites throughout Texas to protect public health and safety and the environment. The Bureau's investigations focused on defining the subsurface source and extent of contamination, applying, to the largest extent possible, low-cost, nonintrusive, and state-of-the-art hydrogeological models and investigation techniques. Since 1995, 15 oil field sites have been studied for the RRC. Work during 1999 focused on three sites having saltwater or crude-oil contamination. Research at a saltwater site in an unincorporated area on Houston's northeast side followed a phased approach: tracking saltwater contamination using electromagnetic geophysics; proving up the geophysics results using a truck-mounted hydraulic probe to core, log, and sample the shallow subsurface; and constructing monitoring wells in the inferred saltwater plume. At the other two sites, crude oil has been found seeping out of the banks of two rivers. At one site we cored 12 boreholes and constructed monitoring wells to assist the RRC in identifying which operator might be responsible for the oil seep. At the other we conducted a contaminant-vapor soil-gas survey (using a hydraulic probe to get soil-gas samples for field analysis on a gas chromatograph) and drilled more than seven core holes to identify the position and most likely source of the oil plume.