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Groundwater samples were collected after physical parameters (pH, temperature, and conductivity) were monitored and had stabilized. Dedicated disposable bailers with bottom- emptying devices were used to collect samples from the wells. All field activities were performed in accordance with the Field Methods included in Attachment 1. Field purge logs are presented in Attachment 2. LABORATORY ANALYSES Collected groundwater samples were analyzed for benzene, toluene, ethylbenzene, xylenes (BTEX) and total petroleum hydrocarbons as diesel (TPHd) by Sequoia Analytical, a State- certified laboratory, utilizing EPA methods 8020 and modified 8015, respectively. Analytical results are summarized in Table 3. Laboratory data sheets and chain-of-custody documentation are included in Attachment 3. Laboratory results indicate that BTEX was not present above method detection limits in collected groundwater samples. Total petroleum hydrocarbons as diesel (TPHd) were present in samples collected from each well at concentrations ranging from 58 parts per billion (ppb) in MW5 to 210 ppb in well MW3. This is the first monitoring event that TPHd was detected in groundwater samples collected from wells MWl and MWS. WORK IN PROGRESS = � The next groundwater monitoring episode is scheduled to be performed in late May 1995 and will include sample collection from wells MW3, MWb, and MW4 (if free of petroleum product sheen). Please contact John Lane in our Escalon office if you have any questions or comments. Respectfully Submitted, CanonielSmith Environmental Technologies Corporation hn tPLane Project Geologist 's a� r 4'yiGrV�.. 11 Jeanne Homsey, P.E. . / �r'A' f �� flay ll. CA Registered Civil Engineer No. 47410 may, �r E L s'a °i •: - PC: Mr. Jim Escobar, City of Stockton Ms. Elizabeth Thayer, RWQCB 1501151QRTERLY11 QMR 1995.doc