Dense Nonaqueous Phase Liquids (DNAPLs)
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Source Area Excavation
Record of Decision: Former Clifton MGP Site, Operable Unit No. 2, Richmond County, New York
New York State Department of Environmental Conservation (NYSDEC), 42 pp, 2006
NYSDEC has selected a remedial alternative that calls for (1) installation of two vertical barrier cutoff walls to prevent the migration of coal tar NAPL from the site source areas to off-site locations; (2) excavation of source materials to an approximate depth of 10 ft bgs to remove approximately 38,000 cubic yds of contaminated soils; (3) removal of former MGP-related structures including foundations and associated grossly contaminated soils determined to contain coal tar with potential for future mobility to their full depth, to the extent practicable; and (4) installation of NAPL recovery wells. Material to be removed will include soil containing visible coal tar or separate phase materials. Some of the area depicted for removal may not be sufficiently contaminated to warrant removal, and the actual extent of removal in these locations will be based on visual observations as the excavation proceeds, with the concurrence of the NYSDEC on-site representative. Dewatering of the excavation will be required, and any water generated will be pre-treated prior to discharge to a permitted facility, such as a publicly owned treatment works. Odor, noise, and dust control measures will be implemented. A visible demarcation barrier will be installed at the bottom of the excavation to mark the extent of soil removal prior to backfilling the excavation. Excavated areas will be backfilled with clean soil from an off-site location. Visually clean material from onsite building demolition may be used to backfill the lower portion of the excavated areas. The top 2 ft of the entire on-site parcel will be filled with clean top soil.
Second Five-Year Review Report for Fairfield Coal Gasification Plant Site, City of Fairfield, Jefferson County, Iowa
U.S. EPA Region 7, 52 pp, 2002
The major components of the selected remedy for the Fairfield Coal Gasification Plant site were excavation and incineration of source material and contaminated soil, bioremediation pilot study and potential full-scale in situ bioremediation of subsurface contaminated soil and ground water, placement of deed restrictions on site property, and extraction and treatment of contaminated ground water. Remediation of coal tar source material and contaminated soil commenced in June 1993 and was completed in June 1995. About 8,280 tons of contaminated soil and source material determined not to be RCRA hazardous waste were excavated, transported off site, and eventually incinerated in the utility boiler located at the Illinois Power Baldwin Station. About 580 tons of RCRA hazardous source material were excavated and sent to Missouri Fuel Recyclers, Hannibal, MO, for incineration while being used as a fuel supplement for the production of portland cement. The site achieved construction completion with the signing of the Preliminary Close Out Report on August 24, 1995.
AT&SF Albuquerque Superfund Site, Bernalillo County, South Valley Area, New Mexico
U.S. EPA Region 6 Fact Sheet, 4 pp, 2007
The facility operated as a wood pressure treatment plant from 1908 until it closed and was dismantled in 1972, and primarily used creosote and oil mixtures in the manufacture of pressure-treated wood products, including railroad cross ties, bridge timbers, lumber, and fence posts. In1990, ~8,250 tons of creosote-tainted plant demolition wreckage were removed and disposed of. About 45,000 square feet of wastewater reservoir soils were excavated to a depth of 2 to 5 feet. In 1996, tie storage areas with total SVOC concentrations above 41.1 mg/kg were excavated and backfilled with clean soil after confirmation testing was performed to ensure that the contaminated soil had been excavated. In April 1999, sludge and process residue from the wastewater reservoir was excavated. Because of the fluid nature of this material and a lack of a well-defined contact between process residues and soil, up to 2 feet of underlying soil was removed, and at some locations, excavations were as deep as 6 feet. Eighty-three gondola cars were filled with ~6,012 tons and transported off site for disposal, thus removing the most highly contaminated soil and sludge. In 1999, three recovery trenches were installed to collect DNAPL through a gravity feed system. In 2000, 5 recovery pumps were installed to extract DNAPL from the Shallow and Intermediate Aquifers. These pumps continue to extract DNAPL from the aquifer. In situ solidification/stabilization, capping, and runoff/runon management comprise the selected remedy for contaminated soils above the remediation goals that do not contain DNAPL. Off-site incineration is selected for DNAPL-contaminated soil encountered during soil excavation. See also the 2002 ROD.
Engineering Design Report, 333 Elliott Avenue West, Seattle, Washington
Washington Department of Ecology, 23 pp, 2006
The J.M. Coleman Company operated the Coleman Creosoting Works at the site until about 1912, producing and storing creosote. Subsequently, the property was occupied by a supplier of wood and coal, the site and adjacent areas were filled and the shoreline was relocated near to its present location, a furnace oil service company occupied the property, and then a restaurant was constructed on the north end of the property. Between 1941 and 1946, all other buildings that were present on the property were demolished. The property's surface is entirely covered at present by pavement and a building. Groundwater at the site is contaminated with PAHs and naphthalenes. DNAPL is known to be present. The cleanup action plan (CAP) involves excavation of the top 18 ft of soil from the entirety of the site, from lot line to lot line. Additional excavation to a maximum depth of 26 ft bgs, or to the extent practical, will be conducted in areas that exceed the site-specific cleanup levels defined in the CAP, and potentially as deep as 30 ft in the suspected source area. Dewatering fluids generated during the anticipated 6 months that the excavation will be open and require dewatering will be collected and treated prior to discharge to a combined sewer located at the site perimeter and to re-injection wells located at the southwest and northwest corners of the site. Soil found to be uncontaminated can be used as clean fill at the site or disposed of as clean fill off site. Soil containing <1% (10,000 mg/kg) contaminant will be disposed of at a RCRA Subtitle D landfill in the State of Washington. Soil containing >1% but <10% (100,000 mg/kg) contaminant will be disposed of at any RCRA Subtitle D facility outside the state of Washington that is authorized to accept this waste. Soil containing >10% of any contaminant must be disposed of at a RCRA Subtitle C facility outside the state of Washington. This waste must be treated and/or disposed of in an equivalent manner to a waste carrying a RCRA F034 waste code.
EPA Superfund Record of Decision: Federal Creosote, Manville Borough, New Jersey
U.S. EPA Region 2, EPA ROD-R02-99-085, 551 pp, 1999
Buried lagoons and canals comprised source areas of creosote contamination in a residential development. The selected remedy for the site includes permanent relocation of residents from properties within the canal and lagoon source areas and temporary relocation where necessary to implement the remedy; excavation of source material from the canal and lagoon source areas, backfilling with clean fill, and property restoration as necessary; and transportation of the source material for off-site thermal treatment and disposal. Additional remedial actions are planned to address residual soil contamination and contaminated groundwater. See also the 2007 update.
Second Five-Year Review Report for the American Creosote Works Superfund Site, Winnfield, Winn Parish, Louisiana
U.S. EPA Region 4, 222 pp, 2005
Through the remedial action defined by the 1993 ROD, highly contaminated soils and waste material (sludge and tars) in a site area identified as the Tar Mat were excavated and incinerated on site. About 56,500 tons of contaminated materials were treated. The resultant ash was then returned to the excavation and placed under a clay cap 3 ft thick. The incineration portion of the RA was completed in February 1998. About 7,000 cubic yd of soil that contained low levels of PCP and PAHs were excavated and buried in the Waste Cell. A fluids recovery system was constructed to extract contaminated groundwater and NAPL from the site's shallow groundwater. A process liquids treatment system (PLTS) was constructed to treat the extracted ground water and NAPL. Finally, an in situ bioremediation system was constructed to remediate contaminated subsurface soils at the site by amending and injecting a portion of the PLTS effluent back into the groundwater.