Remediation Status: In groundwater monitoring

Why the technology was selected:
Biostimulation was chosen because reductive dechlorination was an active process in groundwater at the site (PCE daughter products, including vinyl chloride were present in groundwater).

Date implemented:
Five (biostimulation) k-lactate injection events conducted: September 12-14, 2005, February 23-24, 2006, January 31-February 2, 2008, March 26-28, 2008 and June 18-20, 2008.

Final remediation design:
The first two biostimuation injection events utilized four (4) injection wells, screened 5-17 ft BLS. Each injection event used 55 gallons of 60% potassium lactate solution mixed with 3,300 gallons of water. The third and fourth potassium lactate injection events utilized six (6) injection wells. 110 gallons of 60% potassium lactate solution was mixed with 5,290 gallons of water. The final biostimulation injection event utilized six injection wells. 110 gallons of 60% potassium lactate solution plus 165 gallons of EOS were mixed with 5,125 gallons of water and injected.

Results to date:
A groundwater monitoring event conducted on April 2, 2009 found no detectable PCE or TCE in groundwater. The only contaminant with concentrations exceeding an MCL was vinyl chloride (highest concentration 25 ug/l).

Next Steps:
Annual monitoring

Why the technology was selected:
In-situ chemical oxidation using Fenton's reagent was chosen as the groundwater remedial technology based on the presence of a relatively relatively permeable surficial aquifer, the results of bench scale testing and the benefits of not having to extract, treat and dispose groundwater. Additonally, the target area was accessible for direct injection.

Date implemented:
Bench Test & Treatability Study for Chemical Oxidation-February 2002 First Chemical Oxidation Injection -March 19-22, 2002 Second Chemical Oxidation Injection -April 23-24, 2002

Final remediation design:
Two chemical oxidation injections and a soil excavation and five potassium lactate injection events have been completed at this site. The chemical oxidation injections were implemented using Fenton's reagent. Specifically, each injection was implemented using In-Situ Oxidative Technologies, Inc. The injections were conducted approximately one month apart using the following design: Injection points: 40 total (20 clustered dual-zone). Using direct-push reagents were injected from 3 to 11 ft bgs and 11 to 17 ft bgs. Volume: approximately 240 gallons 12% H2O2 and 120 gallons catalyst per injection point. Area: 1,000 square feet Rate of Injection: 10-11 gpm (catalyst) and 8-10 gpm (oxidizer) Radius of Influence: 10-12 ft

Results to date:
A groundwater monitoring event conducted on April 2, 2009 found no detectable PCE or TCE in groundwater. The only contaminant with concentrations exceeding an MCL was vinyl chloride (highest concentration 25 ug/l).

Next Steps:
Annual monitoring

Cost to Design and Implement:
$9,300 (Remedial Action Plan) $10,000 (bench test & treatability study) $117,000 (2 chemical oxidation injections)

Why the technology was selected:
Excavation was chosen as a remedy after additional soil sampling found contamination near the former location of the building that housed the drycleaning operation. The contaminated soil was accesible (shallow depth to water and located under a parking lot).

Date implemented:
Soil Excavation - June 7-12, 2004

Final remediation design:
In June 2004 - 73.86 tons (approximately 57 cubic yards) of soil was removed. The excavated area was approximately 10 ft x 34 ft x 4.5 ft deep.

Results to date:
A groundwater monitoring event conducted on April 2, 2009 found no detectable PCE or TCE in groundwater. The only contaminant with concentrations exceeding an MCL was vinyl chloride (highest concentration 25 ug/l).

Next Steps:
Annual monitoring

Cost to Design and Implement:
$39,506 (Soil Excavation)