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Mr Chuck Carmel Project 0805-11101 <br /> 40September 12, 1994 <br />' Page 2 <br />' State of California Samples were also analyzed for halogenated volatile organic <br /> compounds (HVOCs) using EPA Methods 5030/601, and the samples from wells MW-2 <br /> and MW-6 were analyzed for total oil and grease (TOG) using Standard Methods <br />' (SM) 5520C and 5520F These tramples were analyzed at GTEL Environmental <br /> Laboratories, Inc , in Concord, California The results of analyses are summarized in <br /> 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 <br /> from the seven wells Concentrations of TPHG ranged from 23,000 (well MW-2) parts <br />' per billion (ppb) to 60,000 (well MW-6) ppb, and benzene concentrations ranged from <br /> 850 (well MW-7) ppb to 14,000 (well MW-6) ppb 1,2-dichloroethane was detected in <br /> wells MW-1 through MW-6 at concentrations ranging from less than 1I ppb to 330 ppb, <br />' 1,2-dichloropropane was detected in wells MW-1, MW-2, MW-4, MW-5, and MW-7 at <br /> concentrations ranging from 0 9 ppb to 19 ppb TOG was not detected in wells MW-2 and <br /> MW-6 (see Table 2) Concentrations of TPHG and benzene are shown on Figure 1 <br />' <br /> WORK IN PROGRESS <br /> A problem assessment report (PAR) was submitted to San Joaquin Public Health Services <br /> (SJPHS) and the California Regional Water Quality Control Board (CRWCB) during <br /> second quarter 1994 An addendum to the PAR will be submitted during third quarter <br />' 1994 and will address remedial alternatives ARCO will continue to perform quarterly <br /> groundwater monitoring All wells will be analyzed for TPHG, BTEX, and HVOCs In <br />' addition wells MW-2 and MW-6 will be analyzed for TOG The next sampling event is <br /> scheduled for the month of September 1994 <br />' CONCLUSIONS <br /> The direction of groundwater flow was toward the northeast and consistent with previous <br />' data Dissolved gasoline hydrocarbons were detected in samples from the seven wells <br /> Halogenated volatile organic compounds were detected in samples from wells MW-1 <br /> through MW-6 TOG was not detected in sample collected from wells MW-2 and MW-6 <br /> t The highest dissolved hydrocarbons continue to be detected in the upgradient off-site <br /> monitoring wells Therefore, it is our opinion that the dissolved hydrocarbons detected at <br /> the subject site emanate from an off-site source <br /> ',A0pj(N)8 "X051110 lel-94 pass 4 <br />