Remediation Status: In active remediation

Why the technology was selected:
Biostimulation was chosen because strongly anaerobic conditions exist in groundwater (dissolved oxygen ranging from 0.2 to 0.7 mg/L, and an ORP of from -201 to -101 millivolts). Evidence for reductive dechlorination includes the presence of high concentrations of PCE daughter products, and the presence of ethene, ethane and Dehalococcoides ethanogenes. A recirculation system was chosen to facilitate distribution of carbon amendments in the aquifer.

Date implemented:
Biostimulation (EOS), first injection initiated: July 17, 2009. Second injection event: April 2010; and third injection event: June 2011.

Final remediation design:
The bioremediation injection/extraction system consists of three 5-inch diameter injection wells constructed of Schedule 40 PVC. These wells are installed outside the service door of the facility. Two of the injection wells are screened 10-30 ft BLS (shallow injection zone) and the deep injection well is screened 30-50 ft BLS (deep injection zone). Two extraction wells, one screened 10-30 ft BLS and the other screened 30-50 ft BLS were installed outside the front of the facility. The extraction wells are equipped with 1.5 HP Grunfos submersible pumps. Total design pumping rate is 30 gpm. Extracted groundwater is treated via two (2) 2000-lb. G.A.C. units

Other technologies used:
Biostimulation recirculation system.

Results to date:
Three biostimulation injection events have been conducted to date. The first injection event was initiated on July 17, 2009. A total of 275 gallons of EOS + 24,960 gallons of water (1.09% EOS Solution or 7.903 mg/L carbon) was injected into the upper recirculation zone. A total of 275 gallons of EOS + 36,480 gallons of water (0.75% EOS solution or 5,426 mg/L carbon) was injected into the lower recirculation zone. April 2010(second injection event): 360 gallons of EOS +36,480 gallons of water (1.5% EOS solution or 10,867 mg/L carbon) injected into upper zone and 357.5 gallons of EOS + 61,000 gallons of water (0.58% EOS solution or 4,673 mg/L carbon) injected into the lower zone. June 2011 (third injection event): 357.5 gallons of EOS + 97,900 gallons of water (98,257.5 gallons of 0.36% EOS solution or 2,639 mg/L carbon) injected into the upper zone and 357.5 gallons of EOS + 161,200 gallons of water (161.557.5 gallons of 0.22% EOS solution or 1,605 mg/L carbon) injected into the lower zone. Groundwater monitoring conducted on July 18, 2011 found the PCE concentration in the source area monitor well at 4.9 ug/L (down from a high of 135,000 ug/l). Other contaminant concentrations in this well: 3.7 ug/l TCE, 95 ug/l cis 1,2-DCE and 84 ug/l vinyl chloride. The PCE concentration in the shallow zone monitor well installed beneath the facility floor slab was 3,600 ug/l, down from 95,000 ug/l. That sample also had the following contaminant concentrations: 4,700 ug/l TCE, 4,800 ug/l cis 1,2-DCE and 1,700 ug/l vinyl chloride. Through July 25, 2011, the shallow zone groundwter recovery system had produced 5,333,500 gallons of water and the deep zone recovery well had produced 16,331,600 gallons of water.

Next Steps:
Continue to run the SVE system and montior groundwater to determine the need for addtional injections of carbon amendments.

Cost to Design and Implement:
Excavation: $141,000 Design & Implementation of SVE/Biostimulation: $248,200

Date implemented:
Excavation: August 2005

Final remediation design:
Excavation/Removal: Approximately 121 tons of soil (~80 cubic yards) were excavated behind the the facility in the vicinity of the storm water drain/soakage pit. Dimensions of the excavation were approximatley 18 ft x 56 ft to a depth of 5 feet. The soil around the storm drain was excavated to a depth of 10 feet BLS. Concentrations of PCE as high as 6,000 ug/kg were detected in sediment samples in the storm water catchment basin.

Next Steps:
Continue to run the SVE system and montior groundwater to determine the need for addtional injections of carbon amendments.

Cost to Design and Implement:
Excavation: $141,000 Design & Implementation of SVE/Biostimulation: $248,200

Why the technology was selected:
Soil vapor extraction was utilized to remediate contaminants under the facility floor slab and paved areas at the site because the soils were permeable and were not readily accessible for excavation.

Date implemented:
Soil Vapor Extraction: July 17, 2009

Final remediation design:
The soil vapor extraction system consists of three (3) vertical vapor extraction wells. Two of these wells are installed beneath the facility floor slab and the third well is installed and one is installed in the alley behind the service door of the facility. The system is powered by a 15 HP regenerative Rotron blower. Off gas is treated via a 140 lb. G.A.C. vessel. Design flow rate is 285 scfm. The biormediation injection/extraction system consists of three 5-inch diameter injection wells constructed of Schedule 40 PVC. These wells are installed outside the service door of the facility. Two of the injection wells are screened 10-30 ft BLS (shallow injection zone) and the deep injection well is screened 30-50 ft BLS (deep injection zone). Two extraction wells, one screened 10-30 ft BLS and the other screened 30-50 ft BLS were installed outside the front of the facility. The extraction wells are equipped with 1.5 HP Grunfos submersible pumps. Total design pumping rate is 30 gpm. Extracted groundwater is treated via two (2) 2000-lb. G.A.C. units

Next Steps:
Continue to run the SVE system and montior groundwater to determine the need for addtional injections of carbon amendments.

Cost to Design and Implement:
Excavation: $141,000 Design & Implementation of SVE/Biostimulation: $248,200

Why the technology was selected:
Soil vapor extraction was utilized to remediate contaminants under the facility floor slab and paved areas at the site because the soils were permeable and were not readily accessible for excavation.

Date implemented:
Soil Vapor Extraction: July 17, 2009

Final remediation design:
The soil vapor extraction system consists of three (3) vertical vapor extraction wells. Two of these wells are installed beneath the facility floor slab and the third well is installed and one is installed in the alley behind the service door of the facility. The system is powered by a 15 HP regenerative Rotron blower. Off gas is treated via a 140 lb. G.A.C. vessel. Design flow rate is 285 scfm.

Next Steps:
Continue to run the SVE system and montior groundwater to determine the need for addtional injections of carbon amendments.

Cost to Design and Implement:
Excavation: $141,000 Design & Implementation of SVE/Biostimulation: $248,200