Remediation Status: In groundwater monitoring

Why the technology was selected:
In 2002, no other technology seemed feasible to meet the remediation objective based on soil type (i.e. tight clay) and the degree of contamination within the maximum remedial funds available for this site ($140,000). Also, the technology vendor was confident that the remediation objectives could be reached within 120 days of implementation of the HSVE system. (This was a pilot project for the IL Drycleaner Environmental Response Trust Fund). Subsequent legislation increased the Fund's remedial limit to $300,000, and due to the limited sucess of HSVE, soil excavation was recently determined to be the most feasible and cost-effective remedial option.

Final remediation design:
On November 9, 2006 the IL Environmental Response Trust Fund approved costs for the excavation and disposal of approximately 120 tons of impacted soil. Underpinning of the building foundation will be required prior to the start of soil removal. A caisson drill rig will be used for soil removal from depths of 4' to 26' below grade. The excavation area will be backfilled with lean concrete slurry to a depth of 4' below grade, and with crushed gravel to near the surface.

Next Steps:
The consultant is currently in the planning phase for soil excavation and disposal activities. This phase should be completed by Spring 2007.

Cost to Design and Implement:
$79,000 for proposed soil removal

Why the technology was selected:
In 2002, no other technology seemed feasible to meet the remediation objective based on soil type (i.e. tight clay) and the degree of contamination within the maximum remedial funds available for this site ($140,000). Also, the technology vendor was confident that the remediation objectives could be reached within 120 days of implementation of the HSVE system. (This was a pilot project for the IL Drycleaner Environmental Response Trust Fund). Subsequent legislation increased the Fund's remedial limit to $300,000, and due to the limited sucess of HSVE, soil excavation was recently determined to be the most feasible and cost-effective remedial option.

Date implemented:
8/26/2002

Final remediation design:
The HSVE treatment system used a series of in-ground coils to transfer heat, increase the volatility of the organic contaminants, and facilitate removal of the volatile solvents from the soil using a vapor extraction system. Coiled hot-oil piping was installed in the thermal enhancement wells. Heating was performed by circulating hot in 1-inch ID steel coils within the thermal enhancement wells. A total seven thermal transfer, 6-inch ID carbon steel wells were installed. These wells transferred heat by indirect transfer. In addition, a total of six, 4-inch ID, PVC, SVE wells were installed as part of the pilot study. After operation for 120 days, the system was modified slightly. Although the system was working, it was determined that some system modifications should be made to ensure that the remediation of the remaining chlorinated solvents would be completed in a timely fashion. Modifications included an additional heat point and an additional extraction well in the remaining hot spot. No modifications were made, and additional HSVE was not completed. The power consumption of the HSVE system was approximately $160/month for electricity and approximately $225/month for gas, not including ($2,300) for hook-ups.

Other technologies used:
Heat Soil Vapor Extraction (HSVE)- in situ

Results to date:
It was originally assumed that 120 days would be adequate to clean up the site. After 90 days of operation, the HSVE system resulted in lower PCE concentrations, with reductions from soil concentrations of 4,700 mg/kg to 2,400 mg/kg, and one of the two areas where the remediation system was installed also seemed to be cleaned up. Even so, operation of all the heating coils continued at the entire site to provide further remediation at those areas where the objectives had not yet been met. The treatment at the site was extended until June 30, 2003. In July 2003, the confirmatory site investigation showed that the HSVE system failed to meet the remediation objectives after 330 days of operation. It was originally thought that the remedial objectives could be met within 120 days. The system was shut down and additional site investigation was conducted to further identify the source of contamination near the hot spot area especially for potential groundwater contamination.

Next Steps:
The consultant is currently in the planning phase for soil excavation and disposal activities. This phase should be completed by Spring 2007.

Cost to Design and Implement:
$62,000 for HSVE