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I .. I I I I I I I .. I I I I I I I. I I D. Site Contamination and Remediation TCAAP is owned by the federal government and is listed on the National Priority List of the EPA with a score of 59. Until recently, Federal Cartridge Company (formerly Federal Cartridge Corporation) was the primary operating contractor, except for a period (1946-1950) when the plant was operated by the federal government directly. Currently most of TCAAP is in standby status. Alliant Techsystems, Inc., operates on the site. This section of the report reviews the contamination issues on the site and how they may impact planning for the future use of the site. 1. Background TCAAP was used primarily for the production of small-caliber anununition and explosives between 1942 and 1976. On-site manufacturing used solvents in the production of metal shells and anununition. In 1978, environmental studies were begrm to determine if there were a significant potential hazard for migration of contantination from the site. In 1981, groundwater contamination was discovered in the municipal water supply of the City of New Brighton. Since then, the sources and extent of groundwater contamination have been better dermed through numerous investigations. Fourteen contamination disposal sites have been identified, with the main contantinants being solvents and metals. A nwnber of interim remedial actions have been taken remove contamination. These actions have included source removal, groundwater treatment, temporary clay capping, soil vapor extraction, soil incineration and soil washing. In 1991, the U. S. Army Corps of Engineers developed a list ofl82 studies and reports available forreference in the Environmental Library at TCAAP. These documents cover many issues, including water quality, groundwater, water systems, reactive wastes, solid waste, PCBs, sewer systems, general studies, remedial investigations, and other miscellaneous topics. Additional reports and studies have been conducted since 1991. It is not within the scope of this report to review or swnmarize all the data gathered to date at TCAAP, but merely to identifY how contamination may affect future use of the site. 2. Existing Conditions Many investigations have been conducted at TeAAP. As a result of these investigations, fourteen source areas or disposal sites have been identified (Figure 11). Existing conditions in each of these fourteen areas are discussed below. Site A is located on the north-central edge of TCAAP. Sewage sludge, off-specification shells and bullets, spent solvents and mercury-contaminated crack cases were buried here. The site was also probably used for open burning. Contaminants of concern are VOCs, benzene, toluene, xylenes, explosives, pesticides, dioxins, PCBs and metals. Soit and groundwater contamination are present. Interim Remediation: To remove and treat contaminated groundwater, a recovery well was installed in June 1988 to remove the groundwater and treat it with a granular activated carbon system. Since that time, this system has been shut down and a more extensive recovery system installed. Eight recovery wells have been installed to prevent off-site migration. This system purnps rougWy 60 gallons per minute into the Shoreview sanitary sewer system. Camiros, Ltd./SEH. Inc./LHDL. Ltd, TeMP Framework Plan Page 23 Chapter II