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�D ST,TF <br /> S <br /> UNITED STATES ENVIRONMENTAL PROTECTION AGEN <br /> F ,r, <br /> REGION IX <br /> 75 Hawthorne Street ;3 IJrI ?la P I G, 18 <br /> San Francisco, Ca. 94105-3901 <br /> June IS, 1993 <br /> Marshall Cloud <br /> Env. Protection Office, DDRW Tracy <br /> P.O. Box 960001 <br /> Stockton, CA 952960250 1993 <br /> RE: Final Well Monitoring Program Quarterly Monitoring Report (January <br /> Monitoring Round) <br /> Dear Marshall, inal Wl Monitoring program Quarterly <br /> Attached are EPA's comments on1nheRound, for DDRW-Tracy. <br /> Monitoring Report, January 1993 Sampling <br /> for an apparent draw-down effect on upper <br /> EPA's major concern is the evidence <br /> The report made no attempt to explain this apparent draw <br /> property (Figure 3-1)• down of <br /> groundwater elevations in the area at the east-northeastern corner of the DDRW racy <br /> upper horizon. <br /> the water table in the <br /> Trichloroethene (TCE), tetrachloroethane (PCE) and arsenic, chromium and <br /> manganese have historiackground levels <br /> cally been detected rounds. Theattached hisons above torical data summaries <br /> during the quarterly monitoring sampling <br /> Table 2 showing historical <br /> are Table 1 showing historical TCF and PCE concentrations, <br /> chromium and manganese (both dissolved and total) <br /> dissolved metals concentrations, and Table 3 showing total meta Tounds.nOnly ns Table <br /> shows all concentrations of arsenic, <br /> MW s groundwater sampling <br /> ells arc <br /> detected above background during or manganese above the <br /> listed as having concentrations of either arsenic,determined wells LMl 1 and LM12. <br /> background concentrations, as potentially <br /> Should you have any questions, please contact me at (415) 744-2392. <br /> Sincerely, <br /> LA& - auj..&k W <br /> Michael Work H-9-1) <br /> Federal Enforcement Section I <br /> Office of Superfund <br /> Attachments <br /> cc: (See Distribution List) <br /> Pn'nted on Recycled Paper <br />