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Date February 5, 2003 <br /> Quarter 4`h Quarter,2002 <br /> ARCO QUARTERLY GROUNDWATER MONITORING REPORT <br /> Facility No 4493 <br /> Address 205 N Center St ,Stockton,CA <br /> Environmental Engineer Paul Su Ie <br /> Consulting Co/Contact Person URS/Vernon Elarth <br /> Consultant Project No 38465950 00436 <br /> Primary Agency/Regulatory ID No _San Joaquin County Environmental Health Department(SJCEHD) <br /> Assembly Bill 68I Status Property owned by City of Stockton <br /> WORK PERFORMED THIS QUARTER (Fourth 2002): <br /> 1 Performed quarterly groundwater monitoring and sampling <br /> 2 Prepared and submitted quarterly groundwater monitoring report <br /> 3 Installed down-gradient monitoring wells MW-11M/D and replaced damaged sidewalk sections <br /> WORK PROPOSED FOR NEXT QUARTER (First 2003): <br /> 1 Conduct quarterly groundwater monitoring and sampling <br /> 2 Prepare and submit quarterly groundwater monitoring report <br /> 3 Prepare and submit monitoring well installation report <br /> • QUARTERLY RESULTS SUMMARY (Fourth 2002): <br /> Current Phase of Project Monitoring/Assessment <br /> Frequency of Groundwater Sampling MW-1 through MW-LID sampled quarterly <br /> Frequency of Groundwater Monitoring Quarterly <br /> Is Free Product(FP)Present Onsite No <br /> Current Remediation Techniques Natural attenuation <br /> Approximate Depth to Groundwater 14 02 to 20 64 ft <br /> Groundwater Flow and Gradient Northeast @ 0 011 ft/ft <br /> ANALYTICAL DATA REVIEW' <br /> Based on the review of the electronic 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 /> • Total petroleum hydrocarbons as gasoline(TPHg)results for sample MW-5 are confirmed as gasoline <br /> • TPHg results for samples MW-8D and MW-9D are due to a discrete peak at C6-C7 (probably MtBE) <br /> • Due to the associated continuing calibration verification (CCV) falling outside acceptance criteria, <br /> results for ethanol and tert-butyl alcohol for samples MW-8 and MW-9 may be biased low <br /> • Due to associated CCV falling outside acceptance criteria, the results for tert-butyl alcohol (TBA) in <br /> samples MW9D,MW-1,MW-10D,MW-11M and MW-11D should be considered estimated <br /> K V5 BP ARC00"931Qua"eriyl4_QTR 0214493 GWMR4Q02 doc Page 1 <br />