The site consists of a saprolite aquifer and a bedrock ridge that separate the two contaminated source areas. Groundwater was encountered at 6 meters below ground surface (bgs). The overall geology of the site can be described by upthrusts of rock, with dramatic changes in the elevation of the bedrock surface over a small area.
Targeted Environmental Media:
 Fractured Bedrock
No information was provided from the source cited.
Major Contaminants and Maximum Concentrations:
- Polychlorinated biphenyls (PCBs) (8,900 µg/L)
- Polychlorinated biphenyls (PCBs) (8,900 µg/L)
- Coring
- Tracer (dye) Test
- Other (Sudan IV dye)
- Other (aerobic bioremediation)
Comments:
During the Phase I operations, a hopper was used to mix Oxygen Release Compound (ORC®) with water to create a 25 percent slurry mix. A gasoline-powered pump was used to inject the slurry into penetrometer rods that had been previously inserted. The slurry was constantly mixed so that the ORC® slurry did not harden. The slurry injection took place at approximately 0.3 meters above the depth of refusal reached when the penetrometer rods were installed. Injection was continuous for the complete depth of the injection point. Injection pressures ranged from 100 pounds per square inch (psi) to 400 psi. Ground water samples were collected from four monitoring wells located within the injection grid, and ground water was monitored using a downhole analyzer (Horiba U-22 or YSI 600DXL) to examine dissolved oxygen (DO), oxygen reduction potential, pH, specific conductance, and temperature. A Grundfos® Rediflo II submersible pump was used to purge the well volumes and both the baseline and post-injection groundwater samples collected using direct-push technology (DPT). Seven wells were installed in May 2002 during the second phase of the operation. ORC® was injected at approximately 232 injection points. The injection points were measured at 20-foot intervals. Injection pressures ranged from 200 to 300 psi.
To achieve the cleanup criterion of 2.9 mg/L for biphenyl ether using ORC® technology.
After the first 6 weeks, there was no significant increase in DO or oxygen reduction potential. However, by week 7, an increase in both pH and DO was observed in monitoring well E-34, and similarly in well E-71 during week 8. Analysis from Phase I showed that concentrations decreased to below detection limits or below regulatory action levels, which were designated at 2.9 mg/L for biphenyl ether. Phase II showed significant reduction in Dowtherm® A. A slight increase in the concentration of 1,1-biphenyl was observed in monitoring well KKK-41.2. The ORC® injection during Phase I was successful in reducing Dowtherm® A to below cleanup goals in all wells.
Performance monitoring will continue for 3 years, as required by the voluntary cleanup contract between the facility and the South Carolina Department of Health and Environmental Control. The success of Phase I and II had shown successful reductions in Dowtherm® A contaminants. No additional applications are anticipated. Enhanced aerobic bioremediation is showing promise of stimulating desorption of Dowtherm® A constituents from soil while reducing concentrations in ground water.
References: Rhine, Elizabeth M. and Kevin M. Howlett. In Situ and On-Site Bioremediation. 2003. Paper E-27. The Seventh International In Situ and On-Site Bioremediation Symposium (Orlando, Florida). June 2003.
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