Pump and Treat, In Situ Chemical Oxidation, and Soil Vapor Extraction at the Union Chemical Company Superfund Site, South Hope, ME

Site Name:

Union Chemical Company Superfund Site


South Hope, Maine

Period of

January 1996 - Ongoing (data available through October 2000)


Full scale

Pump and Treat of Groundwater:
- The groundwater extraction system consists of 28 wells, all screened in the shallow aquifer.
- The above-ground treatment system consists of: metals removal using precipitation; organics removal using air stripping, UV/oxidation, and granular activated carbon; and discharge of treated water to a nearby stream.
- Vapors from the water treatment units and the soil vapor extraction (SVE) unit treated with thermal oxidation prior to discharge to the atmosphere
- The groundwater monitoring network includes 109 wells. For each monitoring event, only approximately 20 wells were sampled and analyzed. From January 1996 through April 1998, the groundwater was monitored quarterly. After April 1998, groundwater monitoring was performed semi-annually.

Soil Vapor Extraction
- 91 hot air injection wells heat soils and increase volatilization
- 33 vapor extraction wells
- pump-and treat system and clay cap enhanced SVE by dewatering soils and minimizing discharge of surface water into the subsurface
- thermal oxidation of vapors from the water treatment units and the soil vapor extraction (SVE) unit prior to discharge to the atmosphere

In Situ Chemical Oxidation
- Injection of potassium permanganate in a two percent solution and sodium permanganate in a 20 to 40% solution using existing groundwater extraction and monitoring wells

Cleanup Authority:
CERCLA - Remedial Action
- ROD signed 1990; ESD signed 1995

State Contact:
Rebecca Hewett
17 State House Station
Augusta, ME 04333
Phone: (207) 287-2651
E-mail: rebecca.l.hewett@state.me.us

PRP Group:
Randy Smith
Union Chemical Trust
American Environmental Consultants
P.O. Box 310
Mont Vernon, NH 03057
Phone: (603) 673-0004
EPA Contact:
Remedial Project Manager:
Terry Connelly
US EPA Region 1
1 Congress Street, Suite 1100
Boston, MA 02114-2023
Phone: (617) 918-1373
E-mail: connelly.terry@epa.gov

Chlorinated Solvents, VOCs
- Maximum initial concentrations of contaminants in groundwater during RI: TCE (84,000 µg/L), TCA (73,000 µg/L), 1,1-DCE (2,700 µg/L), 1,1-DCA (12,000 ug/L), 1,1,1-TCA (73,000 ug/L)

Waste Source:
Solvent manufacturing and reclamation operations

Type/Quantity of Media Treated:
- 8.4 million gallons of groundwater treated (January 1996 through December 1999)
- Shallow and bedrock aquifer systems
- 48,000 cubic yards of soil treated

Purpose/Significance of Application:
Use of a combination of pump and treat, SVE, and in situ chemical oxidation to treat groundwater and soil contaminated with chlorinated and non-chlorinated VOCs

Regulatory Requirements/Cleanup Goals:
- Groundwater extraction rate of 5.1 gallons per minute
- 1,1-Dichloroethane (DCA) - 5 µg/L (groundwater), 0.5 µg/L (pump-and treat system discharge)
- Trichloroehtene (TCE) - 5 µg/L (groundwater), 0.5 µg/L (pump-and treat system discharge)
- 1,1-Dichloroethene (DCE) - 7 µg/L (groundwater), 0.5 µg/L (pump-and treat system discharge)
- 1,1,1-Trichloroethane (TCA) - 200 µg/L (groundwater), 0.5 µg/L (pump-and treat system discharge)

- From January 1996 through June 1999 about 9,600 pounds of VOCs were removed by the P&T and SVE systems
- In general, contaminant concentrations in the groundwater are decreasing over time
- Contaminant concentrations in the effluent from the pump and treat system were not above discharge criteria
- Contaminant mass reductions from chemical oxidation were estimated at 89% reduction for TCE and 47% reduction for 1,2-DCE, but an increase of 1,1-DCA of 79% was also observed
- Ethane concentrations are decreasing more rapidly than ethene concentrations because the ethenes are responding more rapidly to the permanganate additions

Cost Factors:
- Total capital costs for the remediation in 1995 dollars was $9.5 million.
- Average annual O&M costs for the pump and treat and SVE systems was $0.6 million
- Average annual O&M cost for in situ chemical oxidation was $0.15 million

UCC operated from 1967 to 1986 as a producer and distributor of solvent for the removal of furniture finishes. Operations were expanded in 1969 to include solvent reclamation and recycling services; these services subsequently developed into UCCs primary business. Waste treatment operations were discontinued in 1984, at which time MEDEP and EPA removed from the site 2,000 drums, 30 liquid storage tanks containing 10,000 gallons of liquid waste and sludge, and some contaminated soil.

On-site soil and groundwater and an off-site stream had been contaminated with VOCs. The pump and treat system began operating in January 1996 and continued through December 1999. Pumping was resumed on a limited basis from July to October 2000. SVE was operated at the site since 1996 without any modifications. In October 1997 and June 1998 pilot-scale tests of in situ chemical oxidation using permanganate were performed at the site. Based on the results of those tests, in 1999 and 2000 in situ chemical oxidation was used on a ful-scale basis to treat groundwater at the site.