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gifJkE' [' IT,sI «t <br />' CALIFORNIA GEOPHYSICAL4 �- �' <br /> O Box 578341, Modesto, CA 95357 "; ;;r,j Tel (209) 527-1247 <br /> [ October 27 , 1995 <br /> v � `` PH ; f?0 Fax (209) 527-4810 <br />' Public Health Services <br />' San Joaquin County <br /> P.O. Box 2009 <br /> Stockton, Ca 95307 <br />' RE: Quarterly Report October, 1995 <br /> Darpetro Service Station <br /> 749 E. Charter Way <br /> Stockton, Ca. <br /> Site # 1060 <br /> The site was sampled on October 11, 1995 and the laboratory <br /> analyses of the water samples were done by Sherwood Labs of <br />' Hilmar, California. The water table measurements, sampling <br /> parameters and chain of custody are attached. <br />' Table I lists the history of the water analyses taken at the site <br /> since Jan. 26, 1990 . Table II is the history of the water table <br /> measurements, and Table III list the history of hydraulic <br /> gradients. Attached is one water table elevation plot showing <br /> the approximate groundwater gradient. <br /> The water samples were obtained by using a pre-cleaned bailer. <br /> This was performed after the measured field parameters had <br /> stabilized during the purging with a pump. See protocols. Water <br /> samples were placed in appropriate glass containers with teflon- <br /> lined lids. <br /> Wells MW-1 , 2 and 3 were measured for depth of water only. Mr. <br /> Steve Sasson, the county regulator, authorized us to not sample <br /> these wells, since they are located near other wells and no <br /> additional informations would be obtained. <br />' FINDINGS <br /> The groundwater flow is to the Northeast at a gradient of 0. 0023 <br /> Ft/Ft. The groundwater level has fallen about 1 . 26 feet, since <br /> the last quarterly reading. Figure 1 shows the water table <br /> elevations. <br /> I Gasoline contamination is present in all of the wells above the <br /> California Action Levels. Well BM-9 had TPH contamination of <br /> 27100 ug/kg, which is more than twice the amount of contamination <br /> found in well BM-7. Well BM-7 is located closer and up gradient <br /> to the contamination source on this site, therefore, the <br /> contamination found in BM-9 is suspected to have originated from <br /> another source. <br /> Page 1 <br />