Remediation Status: In groundwater monitoring

Why the technology was selected:
Air sparging was selected as the groundwater remedy because

Date implemented:
Air sparge/soil vapor extraction system startup: February 13, 2008. October 3, 2008: Startup of modified AS/SVE system.

Final remediation design:
Air sparge system: Two sets of sparge wells were installed at four locations (8 total sparge wells) outside the east and west walls of hte facility. Sparging is through 3.34 foot screens constructed of porous polyethylene. Sparging is in two zones. The gross interval for the shallow zone is 21-31 ft BLS and the deep zone is from 34-41 ft BLS. The shallow sparge wells are powered by 10-HP rotary van compressor and the deep sparge wells are powered by three rotary scroll compressors. Recovered water is treated via a 220-lb. liquid G.A.C. unit and discharged to an onsite infiltration gallery. The system design flow rate is 60 scfm with 10/scfm/well @ 40 psi wellhead pressure.

Results to date:
In February 2008 the SVE system was shut down and a limited scope remedial action plan was submitted to modifly the AS/SVE system based on results of membrane interface probe logging. In August 2003, three additional deep zone sparge wells were installed at locations outside the west wall, the east wall and the south wall of the facility. In October 2003, an additional lateral vapor extraction well was installed outside the east wall of the building. In July and September 2008, two deep zone sparge wells and two lateral vapor extraction wells were installed near the southwestern corner of the building. The AS/SVE system was re-started on October 3, 2008, focusing on the area around the southwestern corner of the building. In 2005, a water table monitor well in the septic drainfield had a PCE spike. This well had been producing groundwater samples with cis 1,2-DCE and vinyl chloride. A wastewater sample collected from the septic tank had the following contaminant concentrations: 31.2 mg/L PCE, 0.935 mg/L TCE, 4.27 mg/L cis 1,2-DCE and 3.57 mg/L vinyl chloride. A second interim source removal was conducted in June 2007. Approximately 2,030 gallons of wastewater/sludge was pumped out of the septic tank and the septic tank/drainfield was replaced. Approximately 51.2 cubic yards of debris and contaminated soil were removed and shipped offsite. The air sparge/SVE system was shut down on October 26, 2009.

Next Steps:
The site is currently in post-active remedial monitoring. The highest contaminant concentrations detected in a groundwater monitoring event conducted on May 2, 2011 were: 7.87 ug/L PCE, 2.84 ug/L TCE, 0.57 ug/l cis 1,2-DCE and 0.830 ug/L vinyl chloride.

Cost to Design and Implement:
$398,300 (all technologies)

Date implemented:
Air sparge/soil vapor extraction system startup: February 13, 2008. October 3, 2008: Startup of modified AS/SVE system.

Final remediation design:
SVE system: Five 2-inch diameter horizontal vapor extraction wells with 5-foot screens were installed at one foot below grade. Two of these wells were installed outside the east wall, two were installed outside the west all and one was installed outside the south wall of the facility. The system is powered by a 15 HP regenerative blower. Off gas is treated via a 2,000 -lb. G.A.C. vessel. Design flow rate is 425 scfm @ 50 inches w.c. Air sparge system: Two sets of sparge wells were installed at four locations (8 total sparge wells) outside the east and west walls of hte facility. Sparging is through 3.34 foot screens constructed of porous polyethylene. Sparging is in two zones. The gross interval for the shallow zone is 21-31 ft BLS and the deep zone is from 34-41 ft BLS. The shallow sparge wells are powered by 10-HP rotary van compressor and the deep sparge wells are powered by three rotary scroll compressors. Recovered water is treated via a 220-lb. liquid G.A.C. unit and discharged to an onsite infiltration gallery. The system design flow rate is 60 scfm with 10/scfm/well @ 40 psi wellhead pressure.

Results to date:
In February 2008 the SVE system was shut down and a limited scope remedial action plan was submitted to modifly the AS/SVE system based on results of membrane interface probe logging. In August 2003, three additional deep zone sparge wells were installed at locations outside the west wall, the east wall and the south wall of the facility. In October 2003, an additional lateral vapor extraction well was installed outside the east wall of the building. In July and September 2008, two deep zone sparge wells and two lateral vapor extraction wells were installed near the southwestern corner of the building. The AS/SVE system was re-started on October 3, 2008, focusing on the area around the southwestern corner of the building. In 2005, a water table monitor well in the septic drainfield had a PCE spike. This well had been producing groundwater samples with cis 1,2-DCE and vinyl chloride. A wastewater sample collected from the septic tank had the following contaminant concentrations: 31.2 mg/L PCE, 0.935 mg/L TCE, 4.27 mg/L cis 1,2-DCE and 3.57 mg/L vinyl chloride. A second interim source removal was conducted in June 2007. Approximately 2,030 gallons of wastewater/sludge was pumped out of the septic tank and the septic tank/drainfield was replaced. Approximately 51.2 cubic yards of debris and contaminated soil were removed and shipped offsite. The air sparge/SVE system was shut down on October 26, 2009.

Next Steps:
The site is currently in post-active remedial monitoring. The highest contaminant concentrations detected in a groundwater monitoring event conducted on May 2, 2011 were: 7.87 ug/L PCE, 2.84 ug/L TCE, 0.57 ug/l cis 1,2-DCE and 0.830 ug/L vinyl chloride.

Cost to Design and Implement:
$398,300 (all technologies)

Why the technology was selected:
The septic tank was pumped out and pressure washed because a sludge sample collected from the septic tank during the assessment activities found contaminants in the following concentrations: 2,360 mg/kg PCE, 0.472 mg/kg TCE, 0.671 mg/kg cis 1,2-DCE & 0.451 mg/kg vinyl chloride. A wastewater sample collected from the septic tank had a PCE concentration of 18.7 mg/L.

Date implemented:
First Interim Source Removal: Septic tank pump out and drainfield removal replacement: April 12-16, 1999. Second interim source removal (septic tank cleanout and replacement of septic tank/drainfield): June 25-29, 2007.

Final remediation design:
First Interim source removal: Septic tank pumped out and steam cleaned. Drain field piping replaced. Approximately 2,030 gallons of wastewater/sludge and 51.2 cubic yards of contaminated soil/debris removed.

Results to date:
In February 2008 the SVE system was shut down and a limited scope remedial action plan was submitted to modifly the AS/SVE system based on results of membrane interface probe logging. In August 2003, three additional deep zone sparge wells were installed at locations outside the west wall, the east wall and the south wall of the facility. In October 2003, an additional lateral vapor extraction well was installed outside the east wall of the building. In July and September 2008, two deep zone sparge wells and two lateral vapor extraction wells were installed near the southwestern corner of the building. The AS/SVE system was re-started on October 3, 2008, focusing on the area around the southwestern corner of the building. In 2005, a water table monitor well in the septic drainfield had a PCE spike. This well had been producing groundwater samples with cis 1,2-DCE and vinyl chloride. A wastewater sample collected from the septic tank had the following contaminant concentrations: 31.2 mg/L PCE, 0.935 mg/L TCE, 4.27 mg/L cis 1,2-DCE and 3.57 mg/L vinyl chloride. A second interim source removal was conducted in June 2007. Approximately 2,030 gallons of wastewater/sludge was pumped out of the septic tank and the septic tank/drainfield was replaced. Approximately 51.2 cubic yards of debris and contaminated soil were removed and shipped offsite. The air sparge/SVE system was shut down on October 26, 2009.

Next Steps:
The site is currently in post-active remedial monitoring. The highest contaminant concentrations detected in a groundwater monitoring event conducted on May 2, 2011 were: 7.87 ug/L PCE, 2.84 ug/L TCE, 0.57 ug/l cis 1,2-DCE and 0.830 ug/L vinyl chloride.

Cost to Design and Implement:
$398,300 (all technologies)

Why the technology was selected:
Soil vapor extraction was selected as the primary unsaturated remedial action because it is effective in remediating VOCs in permeable unsaturated soils.

Date implemented:
Air sparge/soil vapor extraction system startup: February 13, 2008. October 3, 2008: Startup of modified AS/SVE system.

Final remediation design:
SVE system: Five 2-inch diameter horizontal vapor extraction wells with 5-foot screens were installed at one foot below grade. Two of these wells were installed outside the east wall, two were installed outside the west all and one was installed outside the south wall of the facility. The system is powered by a 15 HP regenerative blower. Off gas is treated via a 2,000 -lb. G.A.C. vessel. Design flow rate is 425 scfm @ 50 inches w.c.

Results to date:
In February 2008 the SVE system was shut down and a limited scope remedial action plan was submitted to modifly the AS/SVE system based on results of membrane interface probe logging. In August 2003, three additional deep zone sparge wells were installed at locations outside the west wall, the east wall and the south wall of the facility. In October 2003, an additional lateral vapor extraction well was installed outside the east wall of the building. In July and September 2008, two deep zone sparge wells and two lateral vapor extraction wells were installed near the southwestern corner of the building. The AS/SVE system was re-started on October 3, 2008, focusing on the area around the southwestern corner of the building. In 2005, a water table monitor well in the septic drainfield had a PCE spike. This well had been producing groundwater samples with cis 1,2-DCE and vinyl chloride. A wastewater sample collected from the septic tank had the following contaminant concentrations: 31.2 mg/L PCE, 0.935 mg/L TCE, 4.27 mg/L cis 1,2-DCE and 3.57 mg/L vinyl chloride. A second interim source removal was conducted in June 2007. Approximately 2,030 gallons of wastewater/sludge was pumped out of the septic tank and the septic tank/drainfield was replaced. Approximately 51.2 cubic yards of debris and contaminated soil were removed and shipped offsite. The air sparge/SVE system was shut down on October 26, 2009.

Next Steps:
The site is currently in post-active remedial monitoring. The highest contaminant concentrations detected in a groundwater monitoring event conducted on May 2, 2011 were: 7.87 ug/L PCE, 2.84 ug/L TCE, 0.57 ug/l cis 1,2-DCE and 0.830 ug/L vinyl chloride.

Cost to Design and Implement:
$398,300 (all technologies)