Pump and Treat
- Groundwater is extracted using 5 wells, located off site, and 1 trench, located on site, at an average total pumping rate of 23.4 gpm
- Extracted groundwater is treated with coagulation/flocculation and air stripping
- Treated groundwater is discharged to the groundwater through an infiltration trench and spray irrigation system
- ROD Date: 3/21/88
- ESD Date: 6/90
|EPA Point of Contact:|
Darryl Luce, RPM
U.S. EPA Region 1
JFK Federal Building
One Congress Street
Boston, MA 02203
|State Point of Contact:|
6 Hazen Drive
Concord, NH 03301
- Maximum concentrations included PCE (140 µg/L), TCE (210 µg/L), 1,1-DCE (1,200 µg/L)
- Maximum concentrations included benzene (160 µg/L)
Storage of drums and containers, unauthorized dumping, leaking lagoon
Type/Quantity of Media Treated:
- 46 million gallons treated as of May 1997
- Extraction wells are located in 2 aquifers, which are not influenced by a nearby surface water
- Hydraulic conductivity ranges from 0.025 to 42.5 ft/day
Purpose/Significance of Application:
Performed optimization study after two years of operation; relatively low groundwater flow
Regulatory Requirements/Cleanup Goals:
- Cleanup standards were established for the upper overburden and bedrock aquifers on site and the sand and gravel aquifer off site. These standards were required to have been met in all monitoring wells in the respective aquifers for two consecutive sampling rounds.
- Cleanup standards were identified for 1,2-DCA (5 µg/L), 1,2-DCE (7 µg/L), TCE (5 µg/L), PCE (5 µg/L), and benzene (5 µg/L).
- The treatment system was required to meet the cleanup goals for groundwater re-injected into the aquifer.
The extraction system must capture and contain the contaminant plume.
- Average contaminant concentrations at the site have decreased 76% from April 1993 to October 1996. However, individual contaminant concentrations have not been reduced to below the cleanup goals.
- The P&T system has removed approximately 68 pounds of contaminants through February 1997.
- The treatment system has consistently met the performance standards established for this application.
- Plume containment has been achieved.
- Actual cost data for this application show that approximately $2,408,000 ($1,582,539 in capital costs and $826,000 in O&M) were expended through May 1997, which correspond to $52 per 1,000 gallons of groundwater extracted and $35,000 per pound of contaminant removed.
- The mass removed through the treatment system may be significantly lower than the total mass extracted from the groundwater because of volatilization and other loses prior to the treatment plant; therefore, the cost per pound removed may be less than shown above.
Keefe Environmental Services operated from 1978 until 1981 as a spent solvent bulking, recovery, and reclamation facility. The facility consisted of drum storage areas, large bulk storage tanks, equipment shelters, a bulking area, and a 700,000-gallon, synthetically-lined waste lagoon. In 1979, a groundwater monitoring program began, and chlorinated solvents were detected. The site was added to the NPL in 1983 and a ROD was signed in March 1988. An ESD was issued in June 1990.
The current extraction system consists of four wells in the upper overburden aquifer, one well in the bedrock aquifer, and a collection trench. This extraction system was modified in 1995 (two years after startup) to optimize performance. Two wells were added and two others removed; locations for the new wells were selected to increase extraction rates. The treatment system consists of a coagulation/flocculation unit, an air stripping tower, and a vapor-phase carbon adsorption unit; the maximum design flow rate is 60 gpm. After four years of operation, the P&T system has reduced average contaminant concentrations within the plume and contained the plume from further migration. The site has not, however, met cleanup goals.