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INFORMATION SHEET <br /> WASTE DISCHARGE REQUIREMENTS ORDER NO. R5-2002-0213 <br /> DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN <br /> SHARPE GROUNDWATER REMEDIATION SYSTEM <br /> SAN JOAQUIN COUNTY <br /> Site Description and Background <br /> Defense Distribution Depot San Joaquin Sharpe Site (DDJC-Sharpe) is an active storage and <br /> distribution facility for various supplies common to U.S. military services in the Western United <br /> States and throughout the Pacific Region. DDJC-Sharpe is located in San Joaquin County <br /> approximately 9 miles south of Stockton, and northeast of Lathrop, California. The installation <br /> forms a rectangle that is approximately 0.5 mile wide (east-west) and 2 miles long (north-south) <br /> covering approximately 720 acres. <br /> The facility was established in 1940, and since that time the facility has received, stored,packaged, <br /> and shipped military supplies. The facility's operations in later years included maintenance of <br /> equipment and aircraft. Environmental investigations in 1979 revealed that on-base activities had <br /> contaminated site soils and groundwater. In 1987 the facility was placed on the U.S. <br /> Environmental Protection Agency's (USEPA's) National Priorities List (NPL) due to groundwater <br /> and on-site soil contamination by cleaning and degreasing solvents (including the volatile organic <br /> compounds (VOC's) trichloroethylene (TCE) and tetrachloroethylene (PCE)) and, to a lesser <br /> extent, by metals, pesticides, and nitrate. <br /> Facility Remediation <br /> Most of the soil cleanup activities have been completed. The Discharger owns and operates a <br /> treatment and disposal system designed to extract and treat groundwater contaminated with <br /> VOC's. Currently, groundwater is extracted from three distinct areas known as the South Balloon, <br /> Central, and North Balloon Areas. Cleanup of the plume is being conducted under the <br /> Comprehensive Environmental Response Compensation and Liability Act (CERCLA). <br /> Groundwater cleanup for the South Balloon began in 1987. Groundwater cleanup in the North <br /> Balloon and Central Area began in 1990 and 1995, respectively. The groundwater remediation <br /> system consists of approximately 40 extraction wells and three separate VOC treatment, air- <br /> stripping Groundwater Treatment Plants (GWTPs). Except for maintenance purposes, these three <br /> GWTPs operate continuously, and can treat and discharge a combined maximum design flow of <br /> 1,300 gallons per minute (1.9 million gallons per day(mgd)) of groundwater. <br /> Although DDJC-Sharpe is currently working to optimize their groundwater remedial system and <br /> reduce the volume of treated groundwater, groundwater extraction and treatment is expected to <br /> continue for another 20 years or more. <br /> The long-term groundwater remedial system may include additional treatment technology, in <br /> addition to the current air-stripping treatment, to meet Best Practicable Treatment or Control," <br /> (BPTC) according to State Water Resources Control Board Resolution 68-16. Evaluation of the <br /> treatment effectiveness of the existing system and an evaluation of additional treatment is provided <br /> in Annual Monitoring Reports to the Regional Board. The air-stripping units effectively remove <br />