Remediation Status: In active remediation

Why the technology was selected:
Biostimulation using potassium lactate was selected because of the strong evidence that reductive dechlorination is occurring. Saturated zone conditions are highly anaerobic. Dissolved oxygen concentrations are generally less than 0.3 mg/L and Redox values generally range from -200 to -300 millivolts. High concentrations of daughter products present and the groundwater pH ranged from 6 to 7 standard units.

Date implemented:
First potassium lactate injection event: August 24-September 1 and September 21-24, 2004 (interrupted by Hurricane Frances. Second potassium lactate injection event: September 13-18, 2005. Third potassium lactate injection event: August 27-30, 2007.

Final remediation design:
Injection wells were utilized for the introduction of potassium lactate into the aquifer. Nineteen (19) 2-inch diameter PVC injection wells, screened 8-25 ft or 8-23 ft BLS were installed. Two of these wells were installed beneath the drycleaning facility floor slab. The rest were installed outside the facility (3 upgradient and 14 downgradient of the facility. The first potassium lactate injection event utilzed nineteen (19) 2-inch diameter injection wells, screened 8-25 ft BLS and 8-23 ft BLS. A total of 105,682 gallons of 0.5% potassium lactate solution was injected or approximately 5,564 gallons of solution per well. The injection rate ranged from 2.0 to 7.5 gpm. In the second potassium lactate injection event, nineteen (19) injection wells were utilized. A total of 50,566 gallons of 0.63% potassium lacate solution (by volume) was injected. Flow rates ranged from 6.46 to 15.86 gpm (average 8.47 gpm). Injection pressures ranged from 10.0 to 27.15 psig and averaged 23.10 psig. A total of 3,614 pounds of 60% potassium lactate solution was utilized. The third potassium lactate injection event was conducted from August 27-30, 2007. Six injection wells were utilized. These wells were located near the southeastern corner of the facility. A total of 13,660 gallons of a 1.85% (by volume) potassium lactate solution was injected (409 gallons of 60% potassium lactate + 13,250 gallons of water). Injection rates ranged from 1.23 to 1.75 gpm.

Results to date:
During the most recent groundwater monitoring event, conducted in May 2010, only one well produced groundwater samples with detectable concentrations of PCE (7,100 ug/L). That well is installed beneath the facility floor slab adjacent to the drycleaning machine. That same groundwater sample had the only detectable concentrations of TCE (6,300 ug/L) and the only concentrations of cis 1,2-DCE (3,000 ug/L)that exceed the MCL. The predominant contaminant in the down gradient portion of the plume is vinyl chloride.

Next Steps:
Additional injections of a carbon substrate are planned. The focus of future injections will be beneath the facility floor slab and in the near proximity of the drycleaning facility.

Cost to Design and Implement:
All technologies: Design: $22,900 Implementation: $175,400

Why the technology was selected:
Soil vapor extraction was selected beacuse it is an effective remedial technology for the removal of VOCs from permeable, unsaturated soils. Contaminanted soil is located beneath the facility floor slab.

Date implemented:
Soil vapor extraction startup: October 14, 2004.

Final remediation design:
Soil vapor extraction: System consists of two vertical vapor extraction wells screened 1.6 - 6.5 ft BLS. One well is installed beneath the facility floor slab near the drycleaning machine. The other well is installed outside the service door of the facility. The system is powered by a 3 HP Rotron blower. Off gas is treated via a 200 lb. G.A.C. vessel. Design flow rate is 23 scfm.

Results to date:
During the most recent groundwater monitoring event, conducted in May 2010, only one well produced groundwater samples with detectable concentrations of PCE (7,100 ug/L). That well is installed beneath the facility floor slab adjacent to the drycleaning machine. That same groundwater sample had the only detectable concentrations of TCE (6,300 ug/L) and the only concentrations of cis 1,2-DCE (3,000 ug/L)that exceed the MCL. The predominant contaminant in the down gradient portion of the plume is vinyl chloride.

Next Steps:
Additional injections of a carbon substrate are planned. The focus of future injections will be beneath the facility floor slab and in the near proximity of the drycleaning facility.

Cost to Design and Implement:
All technologies: Design: $22,900 Implementation: $175,400

Why the technology was selected:
Soil vapor extraction was selected beacuse it is an effective remedial technology for the removal of VOCs from permeable, unsaturated soils. Contaminanted soil is located beneath the facility floor slab.

Date implemented:
Soil vapor extraction startup: October 14, 2004.

Final remediation design:
Soil vapor extraction: System consists of two vertical vapor extraction wells screened 1.6 - 6.5 ft BLS. One well is installed beneath the facility floor slab near the drycleaning machine. The other well is installed outside the service door of the facility. The system is powered by a 3 HP Rotron blower. Off gas is treated via a 200 lb. G.A.C. vessel. Design flow rate is 23 scfm.

Results to date:
During the most recent groundwater monitoring event, conducted in May 2010, only one well produced groundwater samples with detectable concentrations of PCE (7,100 ug/L). That well is installed beneath the facility floor slab adjacent to the drycleaning machine. That same groundwater sample had the only detectable concentrations of TCE (6,300 ug/L) and the only concentrations of cis 1,2-DCE (3,000 ug/L)that exceed the MCL. The predominant contaminant in the down gradient portion of the plume is vinyl chloride.

Next Steps:
Additional injections of a carbon substrate are planned. The focus of future injections will be beneath the facility floor slab and in the near proximity of the drycleaning facility.

Cost to Design and Implement:
All technologies: Design: $22,900 Implementation: $175,400