Pump and Treat and Vertical Barrier Wall -
- Groundwater is extracted using 12 wells at an average total pumping rate of 20 gpm
- Extracted groundwater is treated with addition of chemical (caustic), clarification, filtration, UV/ oxidation, and activated carbon
- Treated groundwater is discharged to a surface water
- A sheet pile wall, 700 ft long, is located at the downgradient portion of the plume
- Non-Time Critical Removal Action Memorandum: 4/1/93
|EPA Point of Contact:|
Karen Lumino, RPM
U.S. EPA Region 1
JFK Federal Building
One Congress Street
Boston, MA 02203
|State Point of Contact:|
Connecticut Department of Environmental Protection
79 Elm Street
Hartford, CT 06106-5127
Chlorinated solvents; semivolatiles - nonhalogenated; PCBs; and heavy metals
- Maximum concentrations detected in 1991 included TCE (41,000 mcg/L), cis-1,2-DCE (110,000 mcg/L), 1,1,1-TCA (320,000 mcg/L), PCBs (85 mcg/L), barium (3,510 mcg/L), cadmium (76.9 mcg/L), chromium (111 mcg/L), lead (175 mcg/L), and manganese (37,200 mcg/L)
Waste lagoons, open pit incineration, incineration residuals handling, drum storage
Type/Quantity of Media Treated:
- 32.5 million gallons treated as of June 1998
- DNAPL was observed in several monitoring wells on site
- Depth to groundwater was not provided for this site
- Extraction wells are located in 2 aquifers, which are both heterogeneous and anisotropic
- Hydraulic conductivity ranges from 0.023 to 300 ft/day
Purpose/Significance of Application:
UV/oxidation has been effective at treating water contaminated with pure phase contaminants, including a mix of VOCs, PCBs, and metals.
Regulatory Requirements/Cleanup Goals:
- No cleanup goals or standards have been established as of the time of this report. A ROD is expected to be finalized in 1999, at which time cleanup standards will be set. The ROD is expected to incorporate a waiver of groundwater standards within the NAPL zone due to technical impracticability.
- A primary goal of the extraction system is to prevent migration of all contaminated overburden groundwater from the operations area at the site.
- Contaminant levels within the containment wall have not been reduced as DNAPL continues to dissolve into the aqueous phase.
- During the past three years, containment of the plume has been maintained the majority of the time, and wells down-gradient of the plume have not had increased contaminant levels. Containment was lost less than four days over the three years of operation.
- From July 1995 to July 1997, approximately 4,344 pounds of VOCs have been removed from the groundwater.
- Actual costs for pump and treat were $5,556,900 ($4,339,600 in capital and $1,217,300 in O&M), which correspond to $265 per 1,000 gallons of groundwater extracted and $1,280 per pound of contaminant removed.
- Expedited review of design documents helped to minimize costs for this application.
Solvent Recovery Services of New England, Inc. (SRS) reclaimed spent industrial solvents for reuse or blending from 1955 until March 1991. Chemicals from site activities and process sludge were disposed of in two on-site unlined lagoons from 1955 until 1967, when they were closed. For several years thereafter, wastes were burned in an open pit incinerator at the southeastern corner of the operations area, and incinerator ash was used as fill at the facility. Operating practices for handling of spent solvents resulted in spills and leaks to the soils. From 1980 to 1982, EPA conducted numerous investigations of the SRS site. The site was placed on the NPL in September 1983 and a non-time critical removal action memorandum was signed in April 1993.
The groundwater containment system consists of 12 extraction wells and a down-gradient steel sheet pile wall that extends to the bedrock. Eleven wells are located along the interior of the wall, and one well is located in the center of the containment area. Containment of the plume has been maintained 98% of the time over a three year period. UV/oxidation has been effective at treating water contaminated with pure phase contaminants, including a mix of VOCs, PCBs, and metals, to levels that meet state discharge standards.