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1 <br />' Mr Chuck Carmel Project 0805-11101 <br /> September 9, 1994 <br />' Page 2 <br />' Groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHG) <br /> and benzene, toluene, ethylbenzene, and total xylene isomers using Environmental <br /> Protection Agency (EPA) Method 5030/LUFT and EPA Methods 5030/8020 These <br /> samples were analyzed at GTEL Environmental Laboratories, Inc , in Concord, California <br /> 1 The results of analyses are summarized in Table 2 Copies of the laboratory analysis <br /> reports are presented in Attachment A <br />' TPHG and benzene were below laboratory detection limits in the upgradient wells (MW-7 <br /> and MW-8) and downgradient wells (MW-3 and MW-h), benzene was detected in well <br /> MW-6 at a concentration of 0 3 parts per billion (ppb) However, this concentration is <br /> below the maximum contaminant level (MCL) established in Title 22 California Code of <br /> Regulations (CCR) TPHG concentrations from the other wells ranged from 910 ppb <br />' (MW-1) to 1,700 ppb (MW-4), and concentrations of benzene ranged from 5 ppb <br /> (MW-10) to 930 ppb (MW-4) TPHG and benzene concentrations are shown on Figure <br /> 1 <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 (RWQCB) during <br /> t second quarter 1994 An addendum to the PAR outlining additional remedial alternatives <br /> and establishing a "zero" line for both boil and groundwater will be prepared during the <br /> third quarter 1994 Authority to construct the vapor extraction system (VES) was obtained <br />' from the San Joaquin Valley Unified Air Pollution Control District A contractor has been <br /> selected by ARCO to perforin the final installation of the VES, field operations are <br /> tentatively scheduled to begin in third quarter 1994 ARCO will continue to perform <br />' quarterly groundwater monitoring The next sampling event is scheduled for the month <br /> of September 1994 <br />' CONCLUSIONS <br /> Hydrocarbon concentrations continue to fluctuate in groundwater underlying the site The <br />' groundwater flow direction was Mowing towards the east-southeast which is generally <br /> consistent with past data Based on data collected to date, it is our opinion that some data <br /> collected during the first quarter 1994 is anomalous Results of the second quarter <br /> sampling event is consistent with data gathered prior to first quarter 1994 <br /> sAC/p^8051t18051110 la11-94 pas 5 <br /> I <br />