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WASTE DISCHARGE REQUIREMENTS - 2 - <br /> DEFENSE <br /> 2 -DEFENSE DISTRIBUTION REGION WEST TRACY <br /> SAN JOAQUIN COUNTY <br /> Planning of this phase of expansion to complete the full scale ground water treatment <br /> system began in mid 1995. The full scale system is known as the Operable Unit 1 system <br /> (OU#1). <br /> 6. Order No. 90-275 is not adequate for the complete expansion of the treatment and disposal <br /> system. <br /> 7. Ground water recharge was determined to be the most desirable disposal alternative since it <br /> would minimize ground water depletion. <br /> 8. The Defense Logistic Agency is conducting Remedial Investigation/Feasibility Study <br /> (RI/FS) activities at DDRW Tracy in accordance with Comprehensive Environmental <br /> Response Compensation and Liability Act(CERCLA) as part of the Department of Defense <br /> (DOD) Installation/Restoration Program. Ground water pollution by chlorinated solvents, <br /> predominantly trichloroethene (TCE) and tetrachloroethene (PCE)up to 560 ppb and 340 <br /> ppb, respectively, has been detected. Other pollutants have been detected, though <br /> infrequently and/or at levels substantially below drinking water standards. These include <br /> 1,1-dichloroethane, 1,2-dichloroethane, 1,1-dichloroethene, 1,2-dichloroethene, <br /> tetrachloroethane, carbon tetrachloride, chloroform, acetone, chromium, selenium, toluene, <br /> benzene, ethylbenzene, xylene, total petroleum hydrocarbons, and dieldrin. <br /> 9. The U.S. EPA and the California Department of Toxic Substances Control (Department) <br /> provide regulatory oversight of DOD Installation/Restoration Program activities conducted <br /> by DLA and DDRW Tracy pursuant to CERCLA. <br /> 10. Approximately 150 monitor wells have been installed. Six contaminant source areas have <br /> been identified. These source areas are associated witb past solvent storage, handling, and <br /> use practices, rather than ongoing sources (i.e., underground tanks and leaking pipelines). <br /> Ground water pollution is predominantly within the upper 100 feet, although there are <br /> indications that TCE and PCE are moving vertically downward as the plume migrates to the <br /> north, off the DDRW Tracy main facility. <br /> 11. The sampling and analysis of RI/FS monitoring wells has been done quarterly for several <br /> years. The lateral and vertical extent of several plumes have been determined. The <br /> remedial phase of this project has proven effective and will now be expanded to cleanup all <br /> VOC plumes. <br /> 12. The objective of the full scale ground water cleanup system is to clean up all of the VOC <br /> plumes at DDRW. Operation of the system will also provide hydrologic and water quality <br />