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fip r <br /> Mr Kyle Christie Project 0805-146 01 <br /> February 13, 1995 <br /> Page 3 <br /> organic compounds (HVOCs) using EPA Methods 50301601, and the samples from wells MW-2 and <br /> MW-6 were analyzed for TOG using Standard Methods (SM) 5520C and 5520F These samples were <br /> analyzed at National Environmental Testing, Inc , in Concord, California The results of analyses are <br /> summarized in Tables 1 and 2 Copies of the laboratory analysis reports are presented in Attachment A <br /> Results of analyses indicated dissolved gasoline hydrocarbons were detected in samples from the four <br /> wells Concentrations of TPHG ranged from 24,000 parts per billion ([ppb] well MW-7) to <br /> 110,000 ppb (well MW-5), and benzene concentrations ranged from 800 ppb (well MW-7) to 8,700 <br /> ppb (well MW-5) 1,2-dichloroethane was detected in wells MW-1, MW-2, MW-5 and MW-7 at <br /> concentrations ranging from 1 1 ppb to 140 ppb, 1,2-dichloropropane was detected in wells MW-2, <br /> MW-5 and MW-7 at concentrations ranging from 16 ppb to 19 ppb TOG was detected in well MW-2 <br /> at a concentration of 12,000 (see Table 2) Concentrations of TPHG and benzene are shown on <br /> Figure 2 <br /> ACTIVITIES PERFORMED DURING THE FOURTH QUARTER <br /> • Performed quarterly groundwater sampling <br /> o Conducted a file search at San Joaquin County Public Health Services (SJCPHS) and City of <br /> Stockton Fire Prevention Bureau, and performed an aerial photograph study of the area to obtain <br /> background information on potential offsite sources <br /> ANTICIPATED WORK <br /> • Prepare and submit a workplan to drill additional soil bornngs to assess hydrocarbons beneath the <br /> underground storage tanks (USTs) <br /> • ARCO will continue to perform quarterly groundwater monitoring The next sampling event is <br /> tentatively scheduled for March 1995 <br /> • Assemble the results of the file search and aerial photograph study in a report and submit to <br /> SJCPHS <br /> CONCLUSIONS <br /> The direction of groundwater flow was toward the northeast which is consistent with previous data- <br /> Dissolved gasoline hydrocarbons were detected in samples from wells MW-1, MW-2, MW-5 and <br /> MW- 7 Sheen was observed in well MW-3, MW-4 and MW-6 HVOCs were detected m samples <br /> from wells sampled TOG was detected In the sample collected from well MW-2 The highest <br /> concentration of dissolved hydrocarbons and HVOCs continue to be present in the upgradient <br /> morutoring wells <br /> SAC/N,\pj0\0805\08051460 1cm-95Imam 5 <br />