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Date. May 19,2003 <br /> Quarter I" Quarter,2003 <br /> ARCO QUARTERLY GROUNDWATER MONITORING REPORT <br /> Facility No 2130 <br /> Address 7906 North EI Dorado Street, Stockton, CA <br /> ARCO Environmental Engineer _Paul Supple <br /> Consulting Co/Contact Person URS/Vernon Elarth <br /> Consultant Project No 38466117 00336 <br /> Primary Agency San Joaquin County Environmental Health Division <br /> (SJCEH D) <br /> Assembly Bill 681 Status Property owned by Atlantic Richfield Company - <br /> WORK PERFORMED THIS QUARTER (First 2003): <br /> I Performed quarterly groundwater monitoring and sampling from site wells MW-10 is still paved over <br /> 2 Prepared and submitted quarterly groundwater monitoring report <br /> 3 Continued to infect ambient air at low flow rates <br /> WORK PROPOSED FOR NEXT QUARTER (Second 2003): <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 selected wells <br /> QUARTERLY RESULTS SUMMARY (First 2003) <br /> Current Phase of Project Monitoring/Remediation <br /> Frequency of Groundwater Sampling MW-1 through MW-7, MW-10, and VW-1 through VW-12 <br /> sampled quarterly <br /> Frequency of Groundwater Monitoring Quarterly <br /> Is Free Product (FP) Present onsite No <br /> Current Remediation Techniques Natural attenuation/Air bubbling <br /> Approximate Depth to Groundwater 38 27 to 40 35 feet below ground surface <br /> Groundwater Flow and Gradient Southeast @ 0 002 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 <br /> laboratory <br /> • The reported result for total petroleum hydrocarbons as gasoline (TPHg) in sample VW-12 is due to a <br /> discrete peak in C6-C8 range(methyl tert-butyl ether(MtBE)) <br /> • The reported result for benzene in sample VW-8 should be considered estimateed because the result <br /> was beyond the calibration range of the instrument <br /> • The elevated reporting limits were the result dilutions performed by the laboratory in order to <br /> 46 quantitate target analytes <br /> K%Wpro ss'M BP AFZC0%02130%Qoatteryl1 QTR 03U130GWMR IQO3 doc Page 1 <br />