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The Paducah Gaseous Diffusion Plant contains five landfills: the C-404, U, K, S, and T. The total land area of the five landfills is approximately 80 acres.
The only hazardous waste facility at the Paducah Site that requires groundwater monitoring is the C-404 Landfill. The C-404 Low-Level Radioactive Waste Burial Ground was used for the disposal of uranium-contaminated solid wastes until 1986 when it was determined that, of the wastes disposed there, gold dissolver precipitate was considered a hazardous waste under RCRA. The landfill was covered with a RCRA-compliant cap and was certified “closed” as a hazardous waste landfill in 1987.
The C-746-K Landfill (SWMU 8) is located to the southwest of the industrialized portion of PGDP and covers about 6.8 acres. This unit was used as a sanitary landfill from the early 1950s through the early 1980s. The landfill is known to contain sanitary trash (burned and unburned) and fly ash from coal burning operations. Before 1967, trenches were cut in the ash to form burn pits. After 1967, the trash was buried in the ash without burning. Sludge from the C-615 Sewage Treatment Plant was reported to have been used as fill material. C-746-K possibly contains some slightly radionuclide-contaminated trash.
DOE closed the landfill in 1982 by covering the landfill with a 6-inch clay cap and an 18-inch vegetative cover. Seepage points were identified in a ditch adjacent to the unit in January of 1992. This landfill subsequently underwent an RI. A ROD was signed for this landfill (DOE 1998b). Corrective actions taken (1992) include installation of riprap along creek bank to prevent direct contact with the seeps, re-contouring of the landfill cap to promote rainfall runoff, implementation of institutional controls, and long-term monitoring. The DOE placed deed restrictions on the landfill in 1997. Possible contaminants associated with the landfill are solvents and metals.
The C-746-S Residential Landfill (SWMU 9) is located to the north of the industrialized portion of PGDP. This unit covers about 5.0 acres and was the PGDP sanitary landfill from 1981 to 1995. Before the construction and permitting of the C-746-S Landfill, the area was used for the disposal of scrap and waste. C-746-S consists of 6 cells, each of which was lined with 12 inches of clay. The landfill permit allowed the disposal of industrial operations refuse, debris, and combustible and noncombustible garbage. Trash was compacted daily and covered with 6 inches of soil.
The Kentucky Division of Waste Management (KDWM) issued a permit for the construction of the C-746-S Residential Landfill in April of 1981. DOE complied with required modifications to landfill operations in July 1993, designed to promote groundwater and surface water protection, and completed a 4-31 certified closure of the last landfill cell in June of 1995. A continuing groundwater and surface water monitoring program is in place to trigger corrective action requirements, should actions be needed. An RI for the C-746-S Landfill has not been completed. The landfill is a potential source of solvents, metals, and radionuclides. An SI to determine if the landfill is a source of solvent contamination was completed in February 2006. Further investigation of the area was performed. Results from this RI are expected in early 2008.
The C-746-T Inert Landfill (SWMU 10) is located adjacent to the C-746-S Landfill (SWMU 9). It covers about 8.4 acres and was used for the disposal of industrial trash from 1985 through 1992. Common buried debris includes concrete, wood, and rock, with steam plant fly ash used as filler material. The C-746-T operating permit required that the waste be covered with clay and a vegetative cover for closure. The KDWM issued a permit for the construction of the C-746-T Inert Landfill in February of 1985.
DOE completed a certified closure of the landfill in November of 1992. A continuing groundwater and surface water monitoring program is in place to trigger corrective action requirements, should actions be needed. An RI for the C-746-T Landfill has not been completed. The landfill is a potential source of solvents, metals, radionuclides, and asbestos. An SI to determine if the landfill is a source of solvent contamination was completed in February 2006. Further investigation of the area was performed as part of the BGOU RI. Results from this RI are expected in early 2008.
The C-746-U Landfill (SWMU 208) is an operating RCRA Subtitle D solid waste landfill located directly north of the C-746-S&T Landfills. It covers 59.7 acres and includes a liner and leachate collection system. This landfill started receiving waste in 1997. Waste accepted includes construction debris, industrial waste, asbestos material, incinerator ash, tires, paper, cardboard, and plastics. Leachate from the C-746-U Landfill is treated at PGDP before being released to KPDES permitted outfalls. No releases to groundwater from this landfill are known to have occurred.
In August 2006, KDWM issued a letter to DOE that placed the C-746-U Landfill into groundwater contamination assessment. The letter stated that contaminants had exceeded either MCLs or statistical limits calculated relative to concentrations found in upgradient wells. A groundwater assessment plan has been developed to identify the actions that DOE will take to determine if the contamination is coming from the C-746-U Landfill or from another source. Once the source is identified, appropriate cleanup actions will occur.
Update to the End State Vision for the Paducah Gaseous Diffusion Plant Paducah, Kentucky DOE/LX/07-0013&D1
Paducah Site Annual Environmental Report for the Calendar Year 2008, PRS-ENM-0045, July 2010