The remediation is being conducted within the ground water in a permeable sandstone zone or sand channel. The geology consists of silty clay overburden overlying a sandstone formation composed of fine to medium grained sandstone in the upper portions and very fine-grained sandstone in the deeper portions.
Targeted Environmental Media:
 Dense Non-aqueous Phase Liquids (DNAPLs) - Fractured Bedrock
The plume is approximately 1000 ft. long.
Major Contaminants and Maximum Concentrations:
- Trichloroethene (35,000 µg/L)
No technologies selected.
- Bioremediation (In Situ)
- Reductive Dechlorination (In Situ Bioremediation)
Comments:
In late 2000 approximately 2,0005 gallons (22,500 lbs) of HRC was injected into 52 wells (5" diameter). An additional 330 gallons was injected in June 2001 into 7 wells within the most heavily-impacted portions of the plume. In order to further maintain reductive dechlorination , 2,392 gallons (26,312 lbs) of HRC was injected during August 2002 into 33 existing and 38 new injection wells.
Initial sulfate ground water concentrations in the sandstone ranged from 100 mg/l to 1500 mg/l. Elevated sulfate levels potentially can impede the reductive dechlorination process by consuming the generated hydrogen. Significant reductive dechlorination has occurred despite the presence of ongoing high sulfate concentrations. Although some reduction in sulfate levels have been observed during the remediation, observed sulfate concentrations are generally in the range of 100 mg/l to 500 mg/l, and as high as 1,400 mg/l in the area with the most significant reduction in chlorinated VOC concentrations.
None provided
From an initial concentration of 35,400ug/l, the total chlorinated concentration had decreased to below approximately 9,100 ug/l within one year and by late 2002 was below 1,000 ug/l. The total solvent contamination mass has been reduced by approximately 90% over the last 27 months at a cost of approximately $1.3 million.
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