Remediation Status: In groundwater monitoring

Why the technology was selected:
Biostimulation was chosen to polish low contaminant concentrations (primarily vinyl chloride) in groundwater. The aquifer is strongly anaerobic and reductive dechlorination is an active process in groundwater at the site.

Date implemented:
Bioremediation pilot test: July 14-15, 2004. Seven ethyl lactate injection events: February 2006 - October 2007.

Final remediation design:
Eight biostimulation injection events were conducted between July 2004 and October 2007. A total of 330 gallons of ethyl lactate was injected into 8 injection wells screened 6-30 and 6-40 ft BLS. The ethyl lactate was mixed with water to create a solution that was approximately 4% ethyl lactate by volume.

Other technologies used:
Biostimulation

Results to date:
In the latest groundwater monitoring event, conducted in January 2010, vinyl chloride was the only contaminant detected in groundwater in concentrations exceeding an MCL. Four monitor wells produced groundwater samples with detectable concentrations of vinyl chloride. Two of these wells had concentrations of 100 and 300 ug/l, compared to non-detect for the previous sampling event.

Next Steps:
Groundwater monitoring.

Cost to Design and Implement:
(for all technologies:) Design: $112,000 Implementation: $1,251,000

Why the technology was selected:
Chemical oxidation was chosen because contaminant concentrations indicated DNAPL was present in groundwater. In-situ remediation was determined more cost effective than removing, treating and re-injecting treated groundwater. Addtionally, matrix oxidant demand was low.

Date implemented:
First Excavation: May 10, 2000. A total of 166.7 cubic yards of soil was removed from Stoddard UST/distillation unit area. Chemical Oxidation Pilot Test: June 19-26, 2000. 2nd Chemical Oxidation Pilot Test: August 7 - 14, 2000. 1st full scale chemical

Final remediation design:
The chemical oxidation (Fenton's Reagent) pilot test consisted of two injection events. In the first injection event, a total of 2,600 gallons of catalyst and 5,200 gallons of 12% hydrogen peroxide solution was injected in to six four-inch diameter Schedule 40 PVC injection wells were installed. These wells screened 6-30 ft BLS with 0.20-inch slot screen. Bentonite seals were installed in the annulus at depths of 12-14, and 20-22 ft BLS. Injection was through a one and one-quarter inch diameter PVC pipe with K-packers straddling a screen interval in piping. The injection piping was lowered to the bottom screened interval and the K-packers bracketed the first inejction inteval 22-30 ft BLS. The K-packers and bentonite seals limited vertical migration of the injectant. The injection piping was then raised and injection occurred in the 14-20 ft interval and finally the 6-12 ft interval. The second injection of the pilot study occurred from August 7-14, 2000 and utilized the same injeciton wells and injection method. A total of 3,000 gallons of catalyst and 7,700 gallons of 12% hydrogen peroxide solution was injected. There were 3 full-scale chemical oxidation events. All utilized Fenton's reagent. The first one used 41,580 gallons of reagnet (incuded 12% hydrogen peroxide, injected into 31 injeciton wells (screened 6-30 ft BLS, 18-20 ft BLS, & 30-40 ft BLS. and 30 direct push borings, spaced 15 feet on denter, injection interval 12-18 feet. The second injection event also utilized 31 injeciton wells and 30 dierect push borings, with similar injeciton intervals and 45,870 gallons of reagent (including 12% hydrogen peroxide). The third full scale chemical oxidation event used 25,080 gallons of reagent (12% hydrogen peroxide). Injection was into 12 injection wells and 70 direct push borings.

Results to date:
In the latest groundwater monitoring event, conducted in January 2010, vinyl chloride was the only contaminant detected in groundwater in concentrations exceeding an MCL. Four monitor wells produced groundwater samples with detectable concentrations of vinyl chloride. Two of these wells had concentrations of 100 and 300 ug/l, compared to non-detect for the previous sampling event.

Next Steps:
Groundwater monitoring.

Cost to Design and Implement:
(for all technologies:) Design: $112,000 Implementation: $1,251,000

Why the technology was selected:
Soil vapor extraction was chosen because it is an effective technology for removing VOCs from permeable, unsaturated sediments.

Date implemented:
Soil vapor extraction system startup: April 17, 2001.

Final remediation design:
The soil vapor extraction system consisted of two horizontal extraction wells with screen lengths of 30 and 10 feet. Each lateral was installed at a depth of approximately 2 feet six inches below grade. One well was installed due east of the facility in the vicinity of the former location of the distillation unit and the Stoddard solvent UST. The other lateral was installed north of the facility near the former location of the fuel oil USTs. The SVE system is powered by a 20 HP Rotron blower. Off gas is treated via four (4) 140-lb. G.A.C. vessels. Design flowrate is 635 scfm @ 40 inches of w.c.

Results to date:
The SVE sytem was shut down on May 3, 2002. In the latest groundwater monitoring event, conducted in January 2010, vinyl chloride was the only contaminant detected in groundwater in concentrations exceeding an MCL. Four monitor wells produced groundwater samples with detectable concentrations of vinyl chloride. Two of these wells had concentrations of 100 and 300 ug/l, compared to non-detect for the previous sampling event.

Next Steps:
Groundwater monitoring.

Cost to Design and Implement:
(for all technologies:) Design: $112,000 Implementation: $1,251,000

Date implemented:
Soil vapor extraction system startup: April 17, 2001.

Final remediation design:
The soil vapor extraction system consisted of two horizontal extraction wells with screen lengths of 30 and 10 feet. Each lateral was installed at a depth of approximately 2 feet six inches below grade. One well was installed due east of the facility in the vicinity of the former location of the distillation unit and the Stoddard solvent UST. The other lateral was installed north of the facility near the former location of the fuel oil USTs. The SVE system is powered by a 20 HP Rotron blower. Off gas is treated via four (4) 140-lb. G.A.C. vessels. Design flowrate is 635 scfm @ 40 inches of w.c.

Results to date:
The SVE sytem was shut down on May 3, 2002. In the latest groundwater monitoring event, conducted in January 2010, vinyl chloride was the only contaminant detected in groundwater in concentrations exceeding an MCL. Four monitor wells produced groundwater samples with detectable concentrations of vinyl chloride. Two of these wells had concentrations of 100 and 300 ug/l, compared to non-detect for the previous sampling event.

Next Steps:
Groundwater monitoring.

Cost to Design and Implement:
(for all technologies:) Design: $112,000 Implementation: $1,251,000

Why the technology was selected:
Excavation/removal was selected because contaminated soil was accessible (building that formerly housed the drycleaning operation was razed).

Date implemented:
First Excavation: May 10, 2000. A total of 166.7 cubic yards of soil was removed from Stoddard UST/distillation unit area. Second excavation: June 2-7, 2004. Approximately 127.8 tons of contaminated soil excavated from former Stoddard Solvent UST/disti

Results to date:
In the latest groundwater monitoring event, conducted in January 2010, vinyl chloride was the only contaminant detected in groundwater in concentrations exceeding an MCL. Four monitor wells produced groundwater samples with detectable concentrations of vinyl chloride. Two of these wells had concentrations of 100 and 300 ug/l, compared to non-detect for the previous sampling event.

Next Steps:
Groundwater monitoring.

Cost to Design and Implement:
(for all technologies:) Design: $112,000 Implementation: $1,251,000