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


Multi-Component Waste

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Case Studies: Coal Tar | Case Studies: Creosote

Case Studies: Coal Tar

Adobe PDF LogoBarrier Wall Installation Within the Vermilion River
D.A. Edwards.
2001 International Containment and Remediation Technology Conference and Exhibition, 3 pp, 2001

A barrier wall and a trench were constructed to control and capture tar seeping into a river from a manufactured gas plant site.

Adobe PDF LogoCarving Sand: Precision Dredging to Make a Mold for a Low-Permeability Cap
E. McLinn, J. Rice, H. Hinke, and J. Macri.
Proceedings of the 41st Texas A&M Dredging Seminar, 7-9 June 2010. Center for Dredging Studies, Texas A&M University , 379-385(2010)

Precision dredging techniques were used to shape the surface of a tar deposit to provide a base grade for the construction of low-permeability cap. After dredging, the fill material had to be placed at highly controlled slopes and thicknesses. The focused dredging program and innovative cap design minimized project cost while achieving the remedial objective of permanently stopping tar migration to the river surface.

Adobe PDF LogoCase Study: Sediment Remediation, Bangor Landing, Bangor, Maine
Howatt, K.
Remediation of Contaminated Sediments Workshop, 29-30 April 2010, Westford, MA. Northeast Waste Management Officials' Association. 14 slides, 2010

RMT, Inc., the Bangor project consultant, completed a remediation project in August 2010 to dredge and cap about 1.5 acres of riverbed heavily contaminated with MGP tar. RMT's NAPL Trapping Cap (patent pending) is designed to control tar migration from sediment permanently and predictably by redirecting migrating tar to a controlled accumulation area, where the tar NAPL is trapped and the gas is vented to the atmosphere. The first full-scale application of the NAPL Trapping Cap was installed at the Bangor Landing site. The cap is constructed of a clay layer, a layer that is impermeable to liquids but allows gases through, and a stone layer that resembles the shoreline. U.S. Patent Application 20090110486, dated April 30, 2009, has been filed for the NAPL Trapping Cap. A brief article about this cleanup is available in the April 2010 issue of Civil Engineering. Although MGP tar is a DNAPL, tar globs at this site have been observed to float on the river's surface. The phenomenon is explained in a paper by E.L. McLinn and T.R. Stolzenburg, "Ebullition-Facilitated Transport of Manufactured Gas Plant Tar from Contaminated Sediment," Environmental Toxicology and Chemistry 28(11):2298-2306(2009)

Adobe PDF LogoDeclaration for the Explanation of Significant Differences: Pine Street Canal Superfund Site, Burlington, Vermont
U.S. EPA Region 1, 31 pp, 2009

At this MGP site, EPA completed construction of a cap over the canal's contaminated sediments in 2004, but the 2006 5-year review found that portions of the cap were leaking oil and coal tar. Where contaminant seepage is occurring, this ESD provides that the existing cap will be redesigned and reconfigured to intercept and sequester the NAPL, likely following the "Alternative 2" design in the June 2008 Final NAPL Controls Report. Alternative 2 would modify the existing cap with the addition of two new layers. The first would comprise a high-permeability, lightweight material (e.g., pumice) in which slotted pipes would be laid to facilitate NAPL capture and removal. This layer would be covered with a reactive core mat in which an absorbent material (e.g., organoclay) binds with the contaminant and prevents its release. See Also: Final NAPL Controls Report, Pine Street Canal Superfund Site, Burlington, VermontAdobe PDF Logo

Adobe PDF LogoDemonstration of Groundwater Containment Through the Use of Barrier Wall and Surface Cover Systems, and Natural Attenuation
D.S. Bausmith, M.D. Brourman, M. Ting, and J.S. Zubrow.
2001 International Containment and Remediation Technology Conference and Exhibition, 3 pp, 2001

Two years of groundwater monitoring data demonstrate that groundwater remedial objectives to contain coal tar DNAPL have been accomplished at a former coke and byproducts facility through the integrated use of barrier wall and surface cover systems and natural attenuation. A 4,500 foot long slurry wall bordering a river and encloses the former process areas. The cover comprises processed dredge material (i.e., sediments from the New York/New Jersey area waterways) stabilized with Portland cement. No active groundwater pumping is required to achieve the containment.

Adobe PDF LogoNAPL Containment at the Former Northern Indiana Public Service Company Manufactured Gas Plant in Fort Wayne, Indiana
E.P. Zimmerman, M. Haney, D. Helmers, and S. Wuellner-Rice.
2001 International Containment and Remediation Technology Conference and Exhibition, abstract only, 2001

Site investigations revealed the presence of discrete pockets of coal tar DNAPL and varying concentrations of dissolved-phase contaminants. A slurry wall was selected to physically contain the coal tar product and dissolved-phase contaminants. This abstract describes the designs of the DNAPL containment and recovery systems.

Case Studies: Creosote

Adobe PDF LogoFirst Five-Year Review Report for Hocomonco Pond Superfund Site, Town of Westborough Worcester County, Massachusetts
U.S. EPA Region 1, 93 pp, 2004

Following a determination of technical impracticability (TI) owing to the presence of large amounts of creosote DNAPL in certain areas of the site, the 1999 ESD changed the remedial objective from groundwater restoration to plume containment. EPA and the Massachusetts DEP concluded that this modified remedy was adequately protective of human health and the environment because institutional controls, long-term monitoring, and continuing DNAPL recovery activities were required as part of the TI waiver.

Adobe PDF LogoInnovative Strategies for DNAPL Containment and Degradation, Nashua, New Hampshire
M. Brourman, S. Sumner, M. Leonard, and M. Wheeler, Jr.
2001 International Containment and Remediation Technology Conference and Exhibition, 4 pp, 2001

Containment technologies were implemented to develop a cost-effective remediation system for migration control and degradation of contaminants in groundwater at this former wood treating facility where creosote DNAPL seeped from the riverbank. A system of conventional screened extraction wells had had limited effectiveness and was costly to operate. In 1997, a remediation system was installed consisting of a sheet pile wall 750 ft long with selective DNAPL extraction wells immediately upgradient of the wall. The rate of groundwater seepage is designed to allow groundwater and dissolved contaminant flux beneath the wall at a rate that can be mitigated to an acceptable level through natural attenuation. Monitoring results show the system is functioning, and approval to halt the original P&T system was obtained.

Adobe PDF LogoInterim Measures to Contain Creosote DNAPL at a Wood-Treating Facility in Grenada, Mississippi, USA
P.A. Rich, R.M. Cohen, J. Abrahams, M.W. Bollinger, R.S. Markwell, and M.D. Brourman.
2001 International Containment and Remediation Technology Conference and Exhibition, 3 pp, 2001

Stream sediments along the central ditch, which received discharge from former lagoon areas of this creosote wood treatment facility, were found to be significantly impacted by DNAPL. To mitigate further discharge of DNAPL into the ditch, interim measures were initiated in 1999 by installing a sheet-pile barrier along the north bank of the ditch, an underdrain system to extract DNAPL beneath the relined ditch, and DNAPL recovery wells behind (and upgradient of) the sheet-pile barrier. As of March 2001, nearly 1,900 gallons of DNAPL had been extracted from the ditch underdrain system, but little DNAPL had been recovered from the wells.

McCormick and Baxter Superfund Site, Portland, Oregon (2007)
Oregon Department of Environmental Quality.

Cleanup at McCormick and Baxter emphasizes alternate strategies for groundwater containment and for removing and retarding creosote DNAPL migrating in subsurface "stringers" toward the river and emerging through seeps by means of the following: cutoff trenches, an impermeable cap constructed over a 15-acre area inside a subsurface vertical barrier wall, an earthen soil cap on 19 acres of the site with low levels of contamination outside the barrier wall, and a mostly sand sediment cap covering 22 acres with thickly layered organoclay targeted to NAPL seep areas to prevent breakthrough (by sorption) of NAPL through the cap.

Adobe PDF LogoQuality Control and Performance of a Cutoff Wall for Containment of DNAPL Plume
J.T. McKnight and L.M. Owaidat.
2001 International Containment and Remediation Technology Conference and Exhibition, 5 pp, 2001

Under an EPA emergency and rapid response contract, a soil-bentonite cutoff wall was constructed at the Taylor Lumber Superfund Site in Sheridan, OR, to contain a DNAPL plume that threatened to contaminate the nearby Yahmill River. The cutoff wall—2,030 feet in length and a maximum depth of 26 feet—completely surrounds the active wood treatment facility. A cap consisting of geosynthetic clay liner, geotextile, and an aggregate base was constructed over the cutoff wall. This project represents the first full closure slurry cutoff wall constructed for EPA Region 10.