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Date: April 28,2005 <br /> Quarter: ?Quarter,2005 <br /> ARCO QUARTERLY GROUNDWATER MONITORING REPORT <br /> Facility No: 2130 <br /> Address: 7906 North El Dorado Street, Stockton, CA <br /> ARCO Environmental Engineer: Paul Supple <br /> Consulting Co./Contact Person: URS/Vernon Elarth <br /> Consultant Project No: 38466468.0A143 <br /> Primary Agency: San Joaquin County Environmental Health Division <br /> (SJCEHD) <br /> Assembly Bill 681 Status: Property owned by Atlantic Richfield Company <br /> WORK PERFORMED THIS QUARTER (First 2005): <br /> 1. Performed quarterly groundwater monitoring and sampling from site wells. VW-6 and VW-9 were not sampled <br /> due to insufficient groundwater. <br /> 2. Prepared and submitted quarterly groundwater monitoring report. <br /> 3. Continued to inject ambient air at low flow rates into well VW-10. <br /> WORK PROPOSED FOR NEXT QUARTER (Second 2005): <br /> 1. Perform quarterly groundwater monitoring and sampling. <br /> 2. Prepare and submit quarterly groundwater monitoring report. <br /> 3. Continue bubbling of ambient air at low flow rates into well VW-10. <br /> QUARTERLY RESULTS SUMMARY (First 2005): <br /> Current Phase of Project: Monitoring/Remediation <br /> Frequency of Groundwater Sampling: MW-1 through MW-7, and VW-1 through VW-12, MS-1A, <br /> MS-1 B, MS-2A, MS-213, MS-3A, and MS-313 sampled <br /> quarterly <br /> Frequency of Groundwater Monitoring: Quarter) <br /> Is Free Product (FP) Present onsite: No <br /> Current Remediation Techniques: Natural attenuation/Air bubbling <br /> Approximate Depth to Groundwater: 40.65 to 42.82 feet below ground surface <br /> ce (bgs) <br /> Groundwater Flow and Gradient: Northwest to Southeast @ 0.003 feet/foot (ft./ft.) <br /> ANALYTICAL DATA REVIEW: <br /> Based on the review of the analytical and hardcopy data (chain-of-custody records, blanks, dilutions,holding times, <br /> LCS/LCSD results,MS/MSD results,and surrogate recoveries),the data are acceptable as reported by the laboratory <br /> with the following limitations: <br /> The reported results for gasoline range organics (GRO) in samples MW-2 and MW-6 are due to <br /> chromatographic peaks present in the gasoline quantitation range, however, the peaks present do not <br /> resemble the pattern for gasoline. <br /> • The sample MS-3B was analyzed twice for ethanol because the initial result exceeded the calibration <br /> range of the instrument.The data from the reanalysis is summarized in this report_ <br /> KAWpr cmV5 BP ARCCW21301QuanerW00511 QTR 05 2130 GWMR 1QOSAd Page 1 <br />