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Map ID MAP FINDINGS Direction Distance EDR ID Number Elevation Site Database(s) EPA ID Number DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN SHARPE SITE (Continued) 1000368504 represents the most recent significant construction activity at Sharpe. For most of its existence, the installation has had both supply and maintenance missions. The supply mission remains active and Includes storage, handling, preservation, packaging, and shipment of general supplies and equipment. The maintenance mission at one time Included the repair and reconditioning of both heavy equipment and aircraft. The heavy equipment mission began In the late 1940s, and the aircraft mission was added in 1957. These missions were discontinued in 1976. The major waste-generating activities from these operations were paint stripping, metal finishing, and painting. Other activities Included engine overhauls, hydraulic and electrical repairs, airframe and body work, and component repair and reconditioning. Since 1976, the maintenance mission has included only maintenance of installation facilities and vehicles used in performing the supply mission. Soil and groundwater contamination were first detected at Sharpe in 1982. In 1982, the U.S. Army Environmental Center [USAEC, formerly the U.S. Army Toxic and Hazardous Materials Agency (USATHAMA)] Initiated a Remedial Investigation (RI). Early RI work Indicated groundwater contamination with offpost migration of VOCs. Base-neutral/acid-extractable (BNA) compounds and nitrates were also investigated during the early phases of the RI and were not found to be chemicals of concern (COCs). Additionally, arsenic, selenium, and bromacil have been detected sporadically in groundwater samples. Available data indicate that the primary source of VOC contamination Is associated with past mission-related activities (e.g., vehicle maintenance) at Sharpe. As a result of early investigations conducted at Sharpe, an interim groundwater extraction and treatment system (referred to as the South Balloon Area Groundwater Treatment System) was put Into operation in March 1987 to control migration of contaminated groundwater in that portion of the site. A separate interim RI and Feasibility Study (FS) was also prepared to identify and evaluate interim remedial action alternatives in the North Balloon Area. As a result of this investigation, a second Interim groundwater pump-and-treat system was constructed in the North Balloon Area. This system began operation in October 1990. The agencies reviewed and informally approved the design and construction of the interim systems. The RI was finalized In June 1991 . Following this, USAEC prepared a Groundwater FS to evaluate alternatives for remediating VOC-contaminated groundwater. This FS was finalized in November 1991 , The Proposed Plan for groundwater was released to the public on Feb. 63 1992, and the Public Meeting was held on Feb. 27, 1992. The January 1993 ROD for groundwater was designated operable unit 1 (OUi ) and addressed VOCs, arsenic, selenium, bromacil, and nitrates in groundwater. Construction of the third and last groundwater treatment plant, located In the Central Area was completed In the South Balloon Area, North Balloon Area, and Central Area Is being conducted in accordance with the January 1993 ROD. Work on the Soils FS, which addressed TCE-contaminated soils, lead- and chromium-contaminated soils, and NFA sites was finalized on December 1994. The Proposed Plan for OU2 was released to the public on February 22, 1995; the Public Meeting was held on March 1 , 1995. Limited soil remediation has been conducted to date. ISV via vacuum extraction is currently being conducted as part of a long-term pilot test in the South Balloon Area and North Balloon Area. Additionally, pesticide-contaminated (DDT and chlordane) soils from the North Balloon Area have been excavated and disposed of in an appropriately-licensed offsite landfill. That action, documented in a Removal Action Memorandum finalized October 1994, was completed in March 1995. In December 1992, approximately 3,000 yd3 of soils contamination with petroleum constituents were excavated from the North Balloon Area and transported to an appropriately-licensed offsite landfill. Other actions have also been completed at Sharpe. A total of 26 non-fuel underground storage tanks were identified during the initial phases of CERCLA work conducted at Sharpe. Sharpe, U.S. Environmental TC4755450.2s Page 19