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%1 Wright Environmental Services, Inc. i ' Construction # Engineering # Remediation 11 tiECEVED September 4,2002 Project No 4090-P OCT Q 2002 Ms Janice Brown ENVIRONMENT HEALTH c/o Cox&.Cox PERMIT/SERVICES 1593 Arrowhead Drive St Helena,California 94574 Re: Cox&Cox,Quarterly Monitoring Well Sampling Report Site at 595 East 11th Street,Tracy,CA Dear Ms Brown, Wright Environmental Services, Inc (Wright) has prepared this quarterly report for the above referenced site As you know, several phases of work have been performed at this site This quarterly groundwater monitoring work is in response to a request from the San Joaquin County Public Health Services(PHS EHD)for site monitoring Monitoring Well Sampling Methods The site was sampled on August 2, 2002 The attached table lists the wells historic and current groundwater level data (see Table 1) The contract sampler proceeded to purge well volumes of groundwater using a submersible electric purging pump (a volume calculation was done for each well following sounding measurements) Conductivity, pH, and water temperature readings were obtained between each well volume purge, and these were noted on the attached groundwater sampling information sheets Once these readings stabilized after two consecutive purge volumes, aquifer water is assumed to be entering the well When the well recovered to about 80% of the initial water level, the sample was collected Purge water was stored on-site in drums The well sampling information sheets are attached The groundwater sample was collected with a new disposable bailer The groundwater sample was then poured with minimum cavitation into the appropriate laboratory prepared sample containers leaving no headspace The sample container was then immediately capped, labeled under chain-of-custody documentation and placed in a chilled ice chest for shipment to Chromalab, Inc in Pleasanton, California(a State Certified Testing Lab) Groundwater Contour Map and Flow Gradient A groundwater contour map to a known datum was prepared for the data listed in Table I (see Figure 1) The groundwater flow direction was northerly under a calculated gradient of 0 005, which is consistent with historic observed trends Overall groundwater levels appear to have risen slightly from the previous quarter near the canal and are interpreted to be caused by canal seepage creating a small groundwater mound near MW-7 a • 67 E i 0th Street . Tracy, CA 95376 209 833 0758 # Fax 209 832 5152 wright@inreach com Lic #651501 A-B HazMat Page I i4M. websit http//home inreach comhvright