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CALIFORNIA GEOPHYSICAL GROUP, INC, <br /> 6111VO�. Box ,578341. Modesto, CA 95357 Tel (209) 527-1247 <br /> May 18, 2004 Fax (209) 527-4810 <br /> l� <br /> I� Public Health Services <br /> �� <br /> San Joaquin County <br /> 304 East Weber Ave 3rd Floor `= <br /> Stockton, CA 95202 ,i c, <br /> RE Quarterly Report April 2004 <br /> Darpetro, Inc USA Service Station <br /> 749 E Charter Way -• <br /> w <br />' Stockton, CA Ell <br /> -� <br /> Site No 1060 <br />' This site was sampled on April 14, 2004 Sherwood Labs of Hilmar, California analyzed <br /> the samples, their reports are attached <br /> Table 1 lists the history of the water table depths and elevations at this site since January <br /> 26, 1990 Table 2 lists the hydraulic gradients and bearings and Tables 3 and 3B lists the <br /> analyses of the groundwater <br /> FINDINGS <br /> The groundwater gradient bearing is N 65 E and the gradient is 0 0037 Ft/ft See Table 1 <br />' and Figure 1 <br /> Each well was measured for depth of water prior to any wells being purged The depth to <br /> water in the first measurement is written and noted in the sample sheets <br /> tIn the EHD, San Joaquin County letter dated April 16, 2004 our attention to the process of <br /> this quarter sampling of this site was noted that our sampling protocols were not being <br /> followed properly In the letter it mentioned that the PVC sampling bailer was not <br /> decontaminated Also, that the pump and the hose interior had minimal decontamination, <br /> while the pump and hose exterior was not decontaminated properly After the first <br /> notification our technician was again instructed to follow the Sampling Protocols and <br /> apparently he did not follow through with our instructions We were on site periodically and <br /> did not find the same problems as the EHD regulator experienced We have always <br /> instructed our technicians to take the depth to water measurement from the highest point <br /> of the casing The licensed surveyor, also takes the elevation from the top of the casing <br /> at the highest point of the casing <br /> To prevent this problem from occurring again, we have dismissed the technician and <br /> California Geophysical Group has contracted with Del-Tech Geotechnical Support <br /> Services to perform future quarterly monitoring events As policy of CGG we will be on <br /> site periodically checking that Del-Tech is following our Protocols for quarterly sampling <br /> 1 <br />