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t a+( r CALIFORNIA GEOPHYSICAL GROUP, INQJNM1-fIfA L IEA LIf O Box 578341, Modesto, CA 95357 11 ' 1'r V!C - Tel (209) 527-1247 October 25, 2003 04 JUN - I PM 3; 58Fax. (209) 527-4810 Public Health Services ✓QlgelvA--1t 6wr -J' � San Joaquin County d 304 East Weber Ave 3rd Floor Stockton, CA 95202 RE Amended Quarterly Report October 2003 Darpetro, Inc USA Service Station 749 E Charter Way Stockton, CA Site No 1060 This site was sampled on October 8, 2003 Sherwood Labs of Hilmar, California analyzed the samples, their reports are attached Table 1 lists the history of the water table depths and elevations at this site since January 26, 1990 Table 2 lists the hydraulic gradients and bearings and Tables 3 and 3B lists the analyses of the groundwater Table 5 lists the readings at the Vapor Extractor during operation Sampling protocols are included FINDINGS The groundwater fell approximately 1 2 feet since the last quarterly monitoring event The gradient bearing is N 55 E The gradient is 0 0018 Ft/ft See Table 1 and Figure 1 In a letter from the EHD San Joaquin County dated November 3, 2003 advised CGG that several deficiencies in the procedures used for the October 2003 quarterly sampling were not met According to the EHD regulator that was on site for a portion of this sampling event reported that there was not a decontamination station in place and the field equipment was not decontaminated before sampling the wells According to the technician, he could not locate a water source because the station had put a charge meter on the water dispenser from where he usually obtained water for the decon station Instead of notifying us of this problem, he took it upon himself to do the quarterly sampling without properly decontaminating the sampling equipment The wells were purged without a decontaminated pump and hose, also the bailer used in acquiring the samples of water Water samples were placed in appropriate glass containers with Teflon-lined seals CGG discussed this problem withthe technician, again he was reminded that if the Protocols could not be followed, he was not to perform the sampling The groundwater in wells BM-1, BM-5, BM-6, BM-7, BM-9 and BM-11, were above California Drinking Water Standards for benzene Wells BM-9 and BM-7 and possibly • BM-6 is related to the contamination entering from the Stations to the west See Table 3 and Figure 2