Remediation Status: In active remediation

Why the technology was selected:
Bioremediation was chosen beacause reductive dechlorination is an acitve process at the site. PCE daughter products are present in groundwater. Conditions in groundwater are anaerobic (dissolved oxygen ranges from 0.2 - 0.3 mg/L, ORP generally ranged from -80 to -240 millivolts.) Bioaugmentation was chosen because vinyl chloride concentrations were relatively low and no ethene or ethane was detected in groundwater.

Date implemented:
Bioremediation Pilot Study: 12/16/04 - 1/12/05 Bioaugmentation: 4/12/05 & 5/6/05 Full-scale bioremediation: May 4-5, 2006

Final remediation design:
Bioremediation Pilot Test: Utilized 3 MPE wells installed under front of building as injection wells and one MPE well as recovery well to introduce an artificial hydraulic gradient to distribute the amendment. The injection consisted of 15 gal. of 60% potassium lactate solution, 333 grams reagent-grade dibasic ammonium phosphate, 500 grams of yeast extract powder, a rhodamine dye tracer, a 4-ounce sodium thiosulfate/gallon of water solution at 1 milliliter/gal. and approximately 235 gallons of treated groundwater. This injeciton solution had a 16,000 mg carbon/liter (potassium lactate) concentration, an ammonia (as nitrogen) concentration of 74 mgl, and a phosphorus concentration of 82 mg/l. The injection rate was approximatley 1 gpm. The extraction rate was approximatley 1.3 gpm. Bioaugmentation using Dehalococcoides ethenogenes (BCI) was initiated on April 14, 2005 when 20 liters of DHE bacteria (1x10 to the 10th cells per liter) was introduced into the aquifer using a compressed nitrogen source. The recovery system was operated until January 12, 2005 and recovered an estimated 24,000 gallons of groundwater. Full-scale bioremediation was inititiated on May 4, 2006. Four injection wells (former MPE wells installed under the building floor slab) were utilized. One differnce bewteen the full scale injections and the pilot study is the use of a buffereing agent (ammonium bicarbonate) in the full scale injections. the pH of the groundwater is generally below 6 standard units and sampling after the pilot project showed that it had been lowered. The total injection volume for each event injection event was 55 gallons. This consisted of 17.5 galllons of 60% potassium lactate solution, 2,492 grams of reagent grade ammonium bicaronate, 220 grams of reagent grade dibasic potassium phosphate and 500 grams of yeast extract powder. Four ounces of sodium thiosulfate per one gallon of water was added pergallong of water.

Other technologies used:
Bioaugmentation

Results to date:
There were a total of six (6) biormediation injection events conducted at the site: May 4, 2006, June 1, 2006, November 12, 2007, December 17, 2007, January 30, 2008 and Febraury 15, 2008. Based on sampling of MW003, the surficial aquifer monitor well located immediately down gradient of the facility, PCE concentrations in groundwater dropped from a high of 33,700 ug/l to 2.7 ug/l prior to the inititiation of bioremediation. PCE concentrations in groundwater samples collected from one of the MPE wells installed beneath the facility floor slab were as high as 738 ug/l prior to the bioremediation pilot injection and PCE concentrations increased to 3,390 ug/l after the pilot injection event. Post injection sampling saw increases in the duaghter products cis 1,2-DCE (to 2,700 ug/l) and vinyl chloride (to 158 ug/l). No PCE or TCE was detected in groundwater samples collected during a monitoring event conducted in April 2008. Two monitor wells produced groundwater samples with Cis 1,2-DCE concentrations exceeding the MCL: 75.9 and 97.4 ug/l. Bio-fouling has occurred in the injection zone around the MPE wells.

Next Steps:
One more injection event is planned. A long-lasting carbon substrate will be utilized.

Cost to Design and Implement:
$255,100 for all technologies

Why the technology was selected:
Multi-phase extraction was selected in order to depress the shallow water table in the silty sand surficial aquifer and recovery vapor-phase contaminant mass.

Date implemented:
Multi-phase Extraction: 6/18/01

Final remediation design:
Multi-phase extraction: Four (4)recovery wells (screened 2-18 ft BLS) installed beneath the floor slab of the building that formerly housed the drycleaning facility. Vacuum (max.): 24 inches mercury Design radius of influence: 30 ft Design vacuum: 10 inches high Design airflow rate: 70 cfm System is powered by a pre-vac 20 HP liquid ring pump. Recovered groundwater is treated using a 3-tray low profile air stripper with a 3-HP blower. It is then treated by two liquid G.A.C. units and discharged to the POTW. Off gas is treated by two G.A.C. units.

Results to date:
Multi-phase extraction system was shut down on January 12, 2005. the system recovered an estimated 260 pounds of VOCs. PCE concentrations in the source area were reduced one order of magnitude by the MPE system.

Cost to Design and Implement:
$255,100 for all technologies

Date implemented:
Multi-phase Extraction: 6/18/01

Final remediation design:
Multi-phase extraction: Four (4)recovery wells (screened 2-18 ft BLS) installed beneath the floor slab of the building that formerly housed the drycleaning facility. Vacuum (max.): 24 inches mercury Design radius of influence: 30 ft Design vacuum: 10 inches high Design airflow rate: 70 cfm System is powered by a pre-vac 20 HP liquid ring pump. Recovered groundwater is treated using a 3-tray low profile air stripper with a 3-HP blower. It is then treated by two liquid G.A.C. units and discharged to the POTW. Off gas is treated by two G.A.C. units.

Results to date:
Multi-phase extraction system was shut down on January 12, 2005. the system recovered an estimated 260 pounds of VOCs. PCE concentrations in the source area were reduced one order of magnitude by the MPE system.

Cost to Design and Implement:
$255,100 for all technologies

Date implemented:
Multi-phase Extraction: 6/18/01

Final remediation design:
Multi-phase extraction: Four (4)recovery wells (screened 2-18 ft BLS) installed beneath the floor slab of the building that formerly housed the drycleaning facility. Vacuum (max.): 24 inches mercury Design radius of influence: 30 ft Design vacuum: 10 inches high Design airflow rate: 70 cfm System is powered by a pre-vac 20 HP liquid ring pump. Recovered groundwater is treated using a 3-tray low profile air stripper with a 3-HP blower. It is then treated by two liquid G.A.C. units and discharged to the POTW. Off gas is treated by two G.A.C. units.

Results to date:
Multi-phase extraction system was shut down on January 12, 2005. the system recovered an estimated 260 pounds of VOCs. PCE concentrations in the source area were reduced one order of magnitude by the MPE system.

Cost to Design and Implement:
$255,100 for all technologies