Clark, Y. Lynn1, Mark Kevin Boyd1, Jennifer A. Rode1
(1) LCA Environmental, Inc, Farmers Branch, TX
ABSTRACT: Successful Degradation of Benzene Groundwater Plume at a Former E&P Location in East Texas After Application of Oxygen Release Compound
An East Texas gas condensate production facility operated from the early 1980s to the
early 1990s and included wellheads, a tank battery, compressor, glycol dehydrator,
separator, and metering equipment. Commencing in 1994, environmental investigations began
to assess possible impacts to soil and shallow groundwater from spills and releases that
might have occurred during production operations. In 1997, a groundwater monitoring well
at the facility contained a benzene concentration of 88,000 ug/l (equivalent to parts per
billion) and 1,200 ug/l of 1,2-dichloroethane.
Natural attenuation seemed to be taking hold adequately from 1997-2000. By mid-2000, LCA Environmental, Inc. (LCA) had noted meaningful change in aquifer geochemistry. Biologically mediated aerobic degradation of benzene had significantly depleted natural stores of dissolved oxygen. Remediation by natural attenuation would take too long. The Texas Railroad Commission agreed with LCA’s plan to inject Oxygen Release Compound (ORC) to accelerate the aerobic degradation of petroleum compounds, particularly benzene, in groundwater.
Limited ORC application began in mid-2001. Results were encouraging and a larger scale injection of 5,100 lbs. was made in September 2002. The contaminant plume geometry has held fairly stable over several years and LCA’s injection pattern capitalized on the stability by injecting greater amounts of ORC into the plume center of mass or “bulls-eye”. Over the next nine months (through summer of 2003), the higher concentrations of the target compound benzene have declined almost two orders of magnitude, from approximately 20,000 ug/l to near 2,000 ug/l.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.