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Ns Date: April 29,2003 <br /> Quarter I" Quarter,2003 <br /> • ARCO QUARTERLY GROUNDWATER MONITORING REPORT <br /> Facility No 2186 <br /> Address 3212 North California Street, Stockton, CA <br /> ARCO Environmental Engineer Paul Supple <br /> Consulting Co/Contact Person URSNernon Elarth <br /> Consultant Project No 38466088 00436 <br /> Primary Agency/Regulatory ID No San Joaquin County Environmental Health Services <br /> (SJCEHS) <br /> Assembly Bill 681 Status Property owned by Atlantic Richfield Company <br /> WORK PERFORMED THIS QUARTER (First 2003): <br /> 1 Performed quarterly groundwater monitoring and sampling <br /> 2 Prepared and submitted quarterly groundwater monitoring report <br /> WORK PROPOSED FOR NEXT QUARTER (Second 2003): <br /> i <br /> 1 Perform quarterly groundwater monitoring and sampling <br /> 2 Prepare and submit quarterly groundwater monitoring report <br /> • QUARTERLY RESULTS SUMMARY (First 2003): <br /> Current Phase of Project Monitoring <br /> Frequency of Groundwater Sampling MW-1 through MW-7, and VW-1 A through VW-3B <br /> sampled quarterly <br /> Frequency of Groundwater Monitoring Quarterly <br /> Is Free Product (FP) Present on Site No <br /> FP Recovered this Quarter NA <br /> Cumulative FP Recovered to Date NA <br /> Current Remediation Techniques Natural attenuation <br /> Approximate Depth to Groundwater _ 44 98 to 47 01 feet below ground surface <br /> Groundwater Gradient Northeast @ 0 02 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 matrix effects for methyl tert-butyl ether (MtBE) in sample MW-1 cannot be determined, the native <br /> concentration of MtBE in the sample was greater than 4-times the spike level <br /> • Elevated reporting l nuts were due to dilutions performed by the laboratory in order to quantitate a target <br /> analyte <br /> + The reported results for total petroleum hydrocarbons as gasoline(TPHg) in sample VW-3B may be biased <br /> high as demonstrated by a high surrogate recovery due to matrix interference <br /> K V5 HP ARC01027961Quartu1y%1 QTR 0312186 GWMR IQ03 doe Page 1 <br />