Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).

Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).

Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).

Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).

Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).