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i <br /> Date: January 23,2003 <br /> Quarter: 41h Quarter,2002 <br /> I <br /> ARCO QUARTERLY GROUNDWATER MONITORING REPORT <br /> Facility No.: 5450 <br /> Address: 1617 West Fremont Street, Stockton, CA <br /> ARCO Environmental Engineer: Paul Supple <br /> Consulting Co./Contact Person: URSNernon Elarth <br /> Consultant Project No.: 38465965.00436 <br /> Primary Agency/Regulatory ID No.: San Joaquin County Public Health Services SJCPHS <br /> Assembly Bill 681 Status: Property owned by Atlantic Richfield Company <br /> WORK PERFORMED THIS QUARTER (Fourth 2002): <br /> i <br /> 1. Performed quarterly groundwater monitoring and sampling. <br /> i <br /> 2. Prepared and submitted quarterly groundwater monitoring report. <br /> WORK PROPOSED FOR NEXT QUARTER (First 2003): <br /> I. Perform quarterly groundwater monitoring and sampling. <br /> 2. Prepare and submit quarterly groundwater monitoring report. <br /> QUARTERLY RESULTS SUMMARY (Fourth 2002): <br /> • Current Phase of Project: Monitoring <br /> Frequency of Groundwater Sampling: MW-2 through MW-4 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: 10.9—11.2 feet below ground surface <br /> Groundwater Flow and Gradient: -Southwest @ 0.004 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 /> LCSILCSD results, MS/MSD results, and surrogate recoveries), the data are acceptable as reported by the <br /> laboratory. <br /> i <br /> DISCUSSION: <br /> Total petroleum hydrocarbons as gasoline (TPHg) and benzene, toluene, ethylbenzene, and total xylenes (BTEX), — <br /> were reported as below detection limits in all wells. Methyl tert-butyl ether(MtBE)was detected only in MW-2 at a <br /> concentration of 43 micrograms per liter (pg/L.). No other analytes were detected. Groundwater elevations in site <br /> wells increased relative to the previous quarter. The approximate groundwater flow direction was to the southwest at <br /> an average gradient of 0.004 ft/ft,which is consistent with the previous monitoring event. <br /> I <br /> This report is based on data, site conditions,and other information that are generally applicable as of the date of the <br /> report,and the conclusions and recommendations herein are therefore applicable only to that time frame. <br /> K115 BP ARCOIW45MQu=erlyl4 QTR 0215450 GWMR4Q02.dm Page 1 <br />