Remediation Status: Site closed

Why the technology was selected:
Original assuptions include: 1. the plume area was less than 200 ft with a vertical extent of about 10 ft. 2. Majority of contamination was trapped in the sandy layer less than 12-15 ft bgs. 3. Approximately 2 percent of foc can be overcome by relatively high concentration of chemical oxidant. 4. NaMnO4 would have strong enough penetrating power even in clay area by setting the injection points close to each other (e.g. about 2-3 ft apart).

Date implemented:
May 2004 - NaMnO4 Injections

Final remediation design:
A 10 percent (by weight) of NaMnO4 solution was injected into the surface of the 200-ft² area on a 24-point grid pattern. 15-19 gallons of the NaMnO4 were injected at each injection point at depths of 2, 4, and 6 feet bgs. At total volume of 420 gallons NaMnO4 was injected. Each of the 24 injection points were installed via direct push technology.

Results to date:
Post injection samplings, including groundwater sampling, were conducted at 30- and 60-day intervals following the completion of the initial injection to measure the effectiveness of chemical oxidation with the NaMnO4. Groundwater: The results of post injection samplings indicate that one of the MWs showed an increase in PCE contamination (from 26 µg/L right before injection to 56 µg/L 30 days after injection, and to 150 µg/L 60 days after injection). The increase of PCE in groundwater after injection was likely caused by a loss of buffering capability in soil because of destruction of natural organic matter by NaMnO4. In other words, NaMnO4, which was supposed to oxidize the PCE contamination in soil, also destroyed the natural organic matter in soil that had been trapping the PCE contamination. Soil: Based on the concentration and volume of NaMnO4 injected and the close proximity of the injection grids, NaMnO4 should have remediated (i.e. oxidized) the PCE contamination in soil. Although the 30-day post-injection sampling showed a reduction of PCE contamination in soil, however, the 60-day post-injection sampling showed much higher PCE concentration (e.g. 2,000 mg/L and 2,800 mg/L) in the vicinity of the original hot-spot area.

Next Steps:
Although the rebound of groundwater contamination can be dealt with by performing additional NaMnO4 injections, the Illinois Fund Administrator and the consultant agreed to abandon the chemical oxidation method with NaMnO4. Based on the post-injection samplings, the recalcitrant nature of PCE contamination in soil is expected to persist for the following reasons: 1. The delivery of chemical oxidant (i.e. NaMnO4) does NOT seem to be efficient in soil. 2. It appears that NaMnO4 is following preferential pathways (sand or minor gravel layers) in the soil, which prevents it from reaching the target area with high PCE contamination. 3. It is possible that more PCE can be released to the groundwater if more of the natural organic matter in soil is destroyed. Therefore, it has been proposed that about 145 tons (e.g. area of 15 ft x 25 ft with 8- 12 ft of depth) of contaminated soil be removed via excavation. SOIL EXCAVATION: Soil removal and disposal activities were performed in the area of the historical dry cleaning, between April 6-8, 2005. The dry cleaning facility was closed during all soil excavation activities. The soil removal activities were conducted with a track-mounted backhoe. The excavated materials were placed into wheel barrels and manually transported to the exterior of the facility, where the soils were loaded into two roll-off-boxes licensed to haul hazardous waste. A total of approximately 30 tons of impacted soil were removed from the subject property for proper off-site treatment. As a note, due to the presence of PCE concentrations exceeding the "land ban" limit (60 kg/kg), the excavated soil was shipped to EQ The Environmental Quality Company Michigan Disposal Waste Treament Plant in Belleville, MI. The excavated area measured approximately 12ft. x 6.5ft. x 6.5ft. Following soil removal, the excavation was backfilled and the concrete was restored. Post excavation soil samples were collected and analyzed. Laboratory analyses indicated that a small volume of soil near the north foundation wall of the building remained impacted with PCE concentrations exceeding the site specific soil saturation limit. These soils were left in place during soil excavation activities due to safety concerns regarding the structural integrity of the building. Pioneer (consultant) performed a Tier 3 evaluation to demonstrate that further remediation was impractical and the the applicable exposure routes could be eliminated. Based on the cumulative analytical data and the results of the Tier 3 endangerment assessment performed in accordance with Part 742 regulations, the consultant was able to demonstrate that the use of institutional controls and an engineered barrier would be sufficient to mitigate the risk associated with the remaining contamination. In the Remedial Action Completion Report, dated July 1, 2005, Pioneer recommended "No Further Remediation" with the following conditions and institutional controls: * Industrial/commercial land use restriction; * Use of local groundwater ordinances prohibiting the use of groundwater for potable purposes; * Engineered barriers, which included the current asphalt pavement and the concrete building floor slab and foundation, must remain intact above the soils contaminated at levels above the ingestion and/or inhalation pathways; and * A Site Safety Plan must be developed to provide safety precautions for construction workers if excavation is to be performed in any areas identified as exceeding construction worker SROs. A "No Further Remediation" letter was issued by the Illinois Environmental Protection Agency on November 23, 2005.

Cost to Design and Implement:
$32, 285.00 (chem-Ox and post injection sampling) $30,000 for soil excavation and closure sampling

Why the technology was selected:
Original assuptions include: 1. the plume area was less than 200 ft with a vertical extent of about 10 ft. 2. Majority of contamination was trapped in the sandy layer less than 12-15 ft bgs. 3. Approximately 2 percent of foc can be overcome by relatively high concentration of chemical oxidant. 4. NaMnO4 would have strong enough penetrating power even in clay area by setting the injection points close to each other (e.g. about 2-3 ft apart).

Date implemented:
April 2005 - Soil Excavation

Next Steps:
Although the rebound of groundwater contamination can be dealt with by performing additional NaMnO4 injections, the Illinois Fund Administrator and the consultant agreed to abandon the chemical oxidation method with NaMnO4. Based on the post-injection samplings, the recalcitrant nature of PCE contamination in soil is expected to persist for the following reasons: 1. The delivery of chemical oxidant (i.e. NaMnO4) does NOT seem to be efficient in soil. 2. It appears that NaMnO4 is following preferential pathways (sand or minor gravel layers) in the soil, which prevents it from reaching the target area with high PCE contamination. 3. It is possible that more PCE can be released to the groundwater if more of the natural organic matter in soil is destroyed. Therefore, it has been proposed that about 145 tons (e.g. area of 15 ft x 25 ft with 8- 12 ft of depth) of contaminated soil be removed via excavation. SOIL EXCAVATION: Soil removal and disposal activities were performed in the area of the historical dry cleaning, between April 6-8, 2005. The dry cleaning facility was closed during all soil excavation activities. The soil removal activities were conducted with a track-mounted backhoe. The excavated materials were placed into wheel barrels and manually transported to the exterior of the facility, where the soils were loaded into two roll-off-boxes licensed to haul hazardous waste. A total of approximately 30 tons of impacted soil were removed from the subject property for proper off-site treatment. As a note, due to the presence of PCE concentrations exceeding the "land ban" limit (60 kg/kg), the excavated soil was shipped to EQ The Environmental Quality Company Michigan Disposal Waste Treament Plant in Belleville, MI. The excavated area measured approximately 12ft. x 6.5ft. x 6.5ft. Following soil removal, the excavation was backfilled and the concrete was restored. Post excavation soil samples were collected and analyzed. Laboratory analyses indicated that a small volume of soil near the north foundation wall of the building remained impacted with PCE concentrations exceeding the site specific soil saturation limit. These soils were left in place during soil excavation activities due to safety concerns regarding the structural integrity of the building. Pioneer (consultant) performed a Tier 3 evaluation to demonstrate that further remediation was impractical and the the applicable exposure routes could be eliminated. Based on the cumulative analytical data and the results of the Tier 3 endangerment assessment performed in accordance with Part 742 regulations, the consultant was able to demonstrate that the use of institutional controls and an engineered barrier would be sufficient to mitigate the risk associated with the remaining contamination. In the Remedial Action Completion Report, dated July 1, 2005, Pioneer recommended "No Further Remediation" with the following conditions and institutional controls: * Industrial/commercial land use restriction; * Use of local groundwater ordinances prohibiting the use of groundwater for potable purposes; * Engineered barriers, which included the current asphalt pavement and the concrete building floor slab and foundation, must remain intact above the soils contaminated at levels above the ingestion and/or inhalation pathways; and * A Site Safety Plan must be developed to provide safety precautions for construction workers if excavation is to be performed in any areas identified as exceeding construction worker SROs. A "No Further Remediation" letter was issued by the Illinois Environmental Protection Agency on November 23, 2005.

Cost to Design and Implement:
$32, 285.00 (chem-Ox and post injection sampling) $30,000 for soil excavation and closure sampling