Laserfiche WebLink
CALIFORNIA GEOPHYSICAL GROUP, INC. <br /> P O Box 578341, Modesto, CA 95357 Tel (209) 527-1247 <br /> November 10, 1997 Fax (209) 527-4810 <br /> Public Health Services <br /> San Joaquin County <br /> P.O. Box 388 <br /> Stockton, Ca 95201 <br /> RE: Quarterly Report October, 1997 <br /> Darpetro Service Station <br /> 749 E. Charter Way <br /> Stockton, Ca. <br /> Site # 1060 <br /> I The site was sampled on October 20 , 1997 and the water samples were <br /> analyzed by Sherwood Labs of Hilmar. The water table <br /> measurements, sampling parameters and chain of custodies are <br /> I attached. <br /> I <br /> Table 1 lists the water levels and depths to water, since January <br /> 26 , 1990 . Table 2 lists the hydraulic gradients and bearings and <br /> I Table 3 list the chemical analyses taken each quarter. Also <br /> attached is a plot of the water table contours and dissolved <br /> oxygen concentrations on October 20, 1997. <br /> The water purging was performed with a decontaminated pump and <br /> the measured field parameters stabilized during the purging. <br /> Water samples were taken with a decontaminated bailer. See <br /> protocols, Water samples were placed in appropriate glass <br /> containers with teflon-lined lids . The Laboratory Certificate <br /> indicates a blank was taken and tested. This blank was taken at <br /> the end of the purging and testing, in order to test the <br /> performance of new tubing. The test indicated that the tubing <br /> had not been cleaned completely. <br /> Wells MW-1 , 2 and 3 were not measured or sampled, authorized by <br /> Mr. Steve Sasson, the county regulator. <br />' FINDINGS <br /> The groundwater flow is to the northeast at a gradient of 0. 0007 <br /> Ft/Ft. The groundwater level has fallen about 2 feet, since <br /> the last quarterly reading. Figure 1 and Table 1 show the water <br /> table elevations. <br /> I Benzene contamination is present in all of the wells above the <br /> California Action Levels. Benzene has diminished in some of the <br /> wells probably due to the vapor extraction system. The <br /> extraction system is still removing a considerable amount of <br /> gasoline and we did not expect to see a great reduction of the <br /> benzene this quarter. <br /> Page 1 <br />