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' I <br /> PUBLI& HEALTH SEk* ICES PQ�IM. <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> r <br /> Ernest M. Fujimoto, M.D., M.P.H., Acting Health Officer <br /> 445 N. San Joaquin Street • P. O. Box 388 • Stockton, CA 95201-0388 c���FOR�•P <br /> 209/468-3420 <br /> D <br /> EDWARD RALSTON <br /> UNOCAL CORPORATION <br /> P O BOX 5155 �'-`=t 2 P 1994 <br /> SAN RAMON CA 94583 <br /> RE: UNION OIL SS#6348 <br /> 3788 Tracy Blvd. <br /> Tracy, CA 95376 <br /> The Unocal Corporation and Mittelhauser Corporation met with the San Joaquin County Public Health i <br /> Services/Environmental Health Division (PHS/EHD) Technical Review Committee (TRC) December 14, 1994. <br /> Mittelhauser summarized the site assessment and site remediation activities relating to petroleum hydrocarbon <br /> contamination releases which impacted both soil and groundwater at this site. <br /> The TRC has reviewed the analytical results obtained from soil and groundwater samples and has determined that f <br /> further assessment of areas with documented residual contamination needs to be conducted before this site can be <br /> considered for closure. <br /> Further soil characterization of areas north, east, and south of the former tank field is required. Residual soil <br /> contamination of concern exists in the area of sample PL-7, SW-7, and SW-11. Sample PL-7 contained elevated <br /> gasoline constituents and the current vertical extent must be characterized. Sample SW-7 contained detectable levels <br /> of oil and grease but was not analyzed for chlorinated hydrocarbons which were discovered in soil samples collected <br /> at the time of the waste oil tank removal. Sample SW-1 I indicated the presence of gasoline and further delineation <br /> of residual contamination of the eastern wail of the excavation needs to be addressed. <br /> Groundwater contamination in MW-3 was noted in several samples prior to its destruction during overexcavation. <br /> A petroleum like substance was observed floating on the groundwater in the final excavation and the pit was <br /> dewatered but no sampling of the groundwater occurred after recharge. The current groundwater conditions in the <br /> backfilled area and east of soil sample SW-11 needed to be evaluated. {! <br /> f <br /> If you have any questions or need clarification regarding the TRC's concerns contact Harlin Knoll at(209)468-3442. <br /> Donna Heran, RENS, Director ' <br /> Environmental Health Division <br /> Harlin Knoll, Senior REHS Diane M. inson, ZH7 <br /> Site Mitigation Unit Supervisor <br /> HK:lb } <br /> cc: SWRCB, Lori Casias cc: Mrs. Kathleen Gayner Deutsch <br /> cc: CVRWQCB, Elizabeth Thayer 13655 Dunbar Road <br /> Dundee, MI 48131 <br /> A Division of San Joaquin County Health Care Services <br />