U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Dense Nonaqueous Phase Liquids (DNAPLs)

Treatment Technologies


Halogenated Alkenes

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Case Studies: Chlorinated Solvents | Case Studies: PCE

Case Studies: Chlorinated Solvents

Adobe PDF LogoEPA Superfund Record of Decision: Pease Air Force Base, OU 04 Portsmouth/Newington, NH
U.S. EPA Region 1, EPA ROD-R01-95-109, 201 pp, 1996

The OU-04 ROD defines the Site 32 source area as the region where DNAPL and residual DNAPL are present, including areas of inferred DNAPL as suggested by the presence of substantially elevated levels of TCE in soil and groundwater. The provisions of the selected remedy (resulting from a Technical Impracticability waiver) include installation of a vertical barrier to facilitate containment of the Site 32 source area, extraction and treatment of groundwater from within and below the vertical barrier to prevent migration of contaminants in the source area overburden, and excavation and off-site disposal of Site 36 metals- and VOC-contaminated soil. Extracted groundwater is treated in the modified Site 32/36 treatment plant for discharge via off-site (on-base) subsurface recharge trenches or surface application.

Adobe PDF LogoEvaluation of Recharge Trench System, North Boundary Containment Treatment System, Rocky Mountain Arsenal, Commerce City, Colorado
M.K. Corcoran, D.M. Patrick, N.G. Gaggiani, and J.H. May.
ERDC/GSL TR-05-5, 51 pp, 2005

Testing was conducted and documented to verify the performance of a 6,740-ft-long multicomponent system, the North Boundary Containment Treatment System, which consists of a slurry wall, dewatering wells, treatment plant, and recharge trenches. Arsenal groundwater contaminants include organochlorine pesticides, inorganics, organosulfur compounds, and volatile organohalogens (i.e., chlorobenzene, chloroform, carbon tetrachloride, TCE, PCE, various isomers of DCE, and methylene chloride).

Adobe PDF LogoPilot Project to Optimize Ground Water Remediation Systems at RCRA Corrective Action Facilities: Summary Report and Lessons Learned [2004]
U.S. EPA, Office of Solid Waste and Office of Superfund Remediation and Technology Innovation.
EPA 542-R-04-018, 26 pp, 2004

This report summarizes information derived from remediation system evaluations performed during 2003 and 2004 at 5 RCRA sites with chlorinated solvent contamination (one with contamination present in fractured rock) to optimize the performance of P&T systems.

Adobe PDF LogoPilot Project to Optimize Ground Water Remediation Systems at RCRA Corrective Action Facilities: Summary Report and Lessons Learned [2005]
U.S. EPA, Office of Solid Waste and Office of Superfund Remediation and Technology Innovation.
EPA 542-R-06-001, 26 pp, 2006

This report describes the results of streamlined remediation system evaluations (RSEs) or "RSE-lites" for operating P&T systems at 4 facilities regulated under the RCRA Corrective Action Program, 3 of which have plumes of chlorinated solvents (PCE, PCE/TCA, and TCE, respectively).

Pump and Treat of Contaminated Groundwater with Containment Wall at the Solvent Recovery Services of New England, Inc. Superfund Site, Southington, Connecticut
Federal Remediation Technologies Roundtable Cost and Performance Database, 1998

The groundwater containment system consists of 12 extraction wells and a downgradient steel sheet pile wall that extends to the bedrock—11 wells along the interior of the wall, and one well in the center of the containment area—at a site with DNAPL located in the overburden and bedrock aquifers. Plume containment was maintained 98% of the time over a 3-year period. Maximum organics concentrations in groundwater in 1991: TCE (41,000 µg/L), cis-1,2-DCE (110,000 µg/L), 1,1,1-TCA (320,000 µg/L), and PCBs (85 µg/L). Additional information. The 2005 ROD specifies both treatment and containment components: (1) in situ thermal treatment of the overburden aquifer, (2) excavate, consolidate, and cover contaminated soils and wetland soils on site, and (3) pump, treat, monitor, and restrict use of contaminated groundwater followed by MNA.

Remediation System Evaluation (RSE) Process: Applications
U.S. EPA, Technology Innovation Program.

Individual reports for evaluations conducted at Superfund-financed and RCRA sites (many affected by chlorinated solvents) are posted on this page. Each report contains recommendations, including estimated costs and/or savings associated with those recommendations, for cutting expenses, improving P&T system operation, and clarifying the exit strategy. These recommendations have the obvious benefit of being formulated based upon operational data unavailable to the original designers. The following RSEs for RCRA sites are examples of the many reports available.

  • Adobe PDF LogoDelphi Corporation, Vandalia, Ohio (2003)
    Corrective action interim measures at two neighboring plants—the Delphi Energy and Chassis Systems Plant and Delphi Safety and Interior Systems Plant—involve the operation of a P&T system to contain a plume comprising 64% TCE and 22% TCA, plus carbon tetrachloride, methylene chloride, acetone, PCA, and xylenes. The P&T system uses air stripping. A mobile extraction and separation system operates seasonally from April to October to recover free-product DNAPL from the subsurface.
  • Adobe PDF LogoFormer Honeywell Facility, Fort Washington, Pennsylvania (2003)
    Site investigations revealed groundwater concentrations of TCE exceeding 10,000 µg/L. A P&T system operates at the facility as a final remedy, extracting groundwater from two recovery wells, treating the extracted water with UV/oxidation and polishing with GAC, and then discharging treated water to the POTW.
  • Adobe PDF LogoFormer Occidental Facility, Tacoma, Washington (2004)
    A 25-well P&T system has operated at the site since 1996, extracting groundwater affected by elevated pH, PCE, TCE,cis-1,2-DCE, and VC; treating it with air stripping; reinjecting a portion of the treated water to the subsurface; and discharging the remaining treated water to a waterway. In addition to discharging to surface water above regulatory limits, the elevated pH limits the effectiveness of injection and extraction systems due to fouling.
  • Adobe PDF LogoChemko Technical Services, Inc. Facility Mims, Florida (2005)
    A plume of PCE and its breakdown products has migrated beyond the property boundary of this RCRA corrective action site. An interim measure P&T system was installed for source control in 2004. Six recovery wells send groundwater to a low-profile air stripper for VOC removal, and an infiltration gallery receives the treated groundwater. Monitored natural attenuation has been selected as the interim remedy for the downgradient plume.
  • Adobe PDF LogoEaton Corporation Facility Kearney, Nebraska (2005)
    The current approach to remediation at this RCRA corrective action site includes an on-site P&T system (2 air strippers operating in series) to contain the on-site TCE contamination and an off-site P&T system to intercept the downgradient plume. Because permanent monitoring wells cannot be installed downgradient of the plume due to access constraints, the evaluation team suggests the use of direct-push technology to gather samples in specific locations.
  • Adobe PDF LogoEngelhard Corporation Facility Plainville, Massachusetts (2005)
    Six VOCs—PCE, TCE, 1,1-DCE, 1,2-DCE, 1,1,1,-TCA, and 1,1,-DCA—are consistently detected in the groundwater at this RCRA corrective action site, and a plume (PCE and 1,1,1-TCA) has migrated beyond the property boundary. A groundwater stabilization measure P&T system consisting of six deep bedrock extraction wells and a vertical high-density polyethylene barrier membrane was installed and began operating in 1998. The extracted groundwater is subjected to metal removal (via pH adjustment, coagulation, and precipitation), air stripping, filtration, and carbon adsorption, and then discharged to surface water.

Case Studies: PCE

Effects of a Remedial System and its Operation on Volatile Organic Compound-Contaminated Ground Water, Operable Unit 1, Savage Municipal Well Superfund Site, Milford, New Hampshire, 1998-2004
P.T. Harte.
U.S. Geological Survey Scientific Investigations Report 2006-5083, 87 pp, 2006

Details the successful performance of a low-permeability barrier wall installed to encircle the highest detected concentrations of PCE and the results from a series of injection and extraction wells installed to contain and remove dissolved-phase contaminants.