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RgnU,L RELEASE DDJC Tracy Private Wells? Current and Future Exposures DDJC Tracy provides alternative water sources to residents of the two affected wells located north-northeast and downgradient of the site, although the carbon tetrachloride present in one well appears to be unrelated to the site. Subsequently, DDJC Tracy has provided a carbon filtration system for residents of the TCE-affected well. The carbon filtration system has effectively removed VOCs to levels below MCLs (Montgomery Watson, 1996b; DDJC Tracy, 1997b). No new private wells are likely to be installed in the area because state legislation allows regulatory agencies to place restrictions on activities within 2,000 feet of a hazardous waste site boundary. Continued monitoring of private wells in the area has not detected VOCs or other site- related contaminants, including chromium, at levels associated with health hazards. DDJC Tracy constructed a groundwater treatment system to control TCE and PCE (and perhaps other VOCs) from migrating off site and to clean up TCE, PCE, and 1,1-DCE to EPA or CA MCLS. e�c„6„ral Wells• Past Exposures Three former agricultural wells (AGs)--AG-1, AG-2, and AG-3—were situated north and downgradient of the depot on the property currently referred to as the Tracy Annex. In the past, these agricultural wells were extensively used for flood irrigation of commercial (e.g., walnuts, . alfalfa, beans) and homegrown row crops during spring and summer months, but not as a drinking water source (Woodward-Clyde Consultants, 1992a). Because AG-2 and AG-3 were situated within the plume, they may have pumped VOC-contaminated groundwater to these crops. AG-2, which is located slightly to the north of the site, also may have changed the plume migration pattern to a more northerly direction (rather than the northeasterly flow of the regional groundwater). Furthermore, pumping of AG-2 also appears to have contributed significantly to vertical migration of the VOC plume to the Middle and Lower Horizons of the Upper Tulare Aquifer. Agricultural well operations were discontinued in 1993, shortly after DDJC Tracy acquired the Tracy Annex (Montgomery Watson, 1995). DDJC Tracy analyzed water samples collected from the agricultural wells for VOCs, and the results are presented in Table 5. TCE (3.5 to 12 ppb) and PCE (1.3 to 4.3 ppb) were consistently detected at levels above ATSDR's comparison values, although no other chemicals were detected. In the Consumption of Locally Grown Foods section that follows, ATSDR evaluates potential health hazards posed by the use of contaminated agricultural well water as an irrigation source for locally grown foods. 12