INTRINSIC BIOREMEDIATION OF FUEL CONTAMINATION IN-GROUND WATER AT A FIELD SITE

A spill of gasoline occurred at an automobile service station in 1986. Oily phase residue in the subsurface has continued for the past 8 yr to release water soluble fuel hydrocarbons into the aquifer. The site was characterized for implementation of intrinsic remediation. The sub surface was a beach sand with sea shell fragments, The water table was near 1.3 m below ground surface. Surface dimensions over the plume we re about 200 m downgradient and 60 m in width. Three points to coincid e with direction of ground-water flow were selected in the plume for w ater quality assessments. Both methane and trimethylbenzene were used as surrogate tracers to normalize loss of contaminants, Aerobic respir ation and methanogenesis accounted for most biodegradation obtained, A ssimilation capacities of dissolved oxygen, ferrous iron, and methane distributions when compared to BTEX concentrations showed that the gro und water has sufficient capacity to degrade all dissolved BTEX before the plume moves beyond 250 m downgradient. Evidence obtained from los s of contaminants, geochemistry, and microbial breakdown chemicals sho wed that intrinsic bioremediation technology would be a viable option to restore the site.