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4� <br /> .1 Date. January 29,2004 <br /> Quarter- 4t°Quarter,2003 <br /> ARCO QUARTERLY GROUNDWATER MONITORING REPORT <br /> FacilityNo 1 <br /> 2 30 <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 38466468 OL058 <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 (Fourth 2003): <br /> 1 Performed quarterly groundwater monitoring and sampling from site wells MS-313 was not sampled or <br /> monitored due to insufficient water <br /> 2 Prepared and submitted quarterly groundwater monitoring report <br /> 3 Continued to inject ambient air at low flow rates <br /> WORK PROPOSED FOR NEXT QUARTER (First 2004): <br /> 1 Perform quarterly groundwater monitoring and sampling <br /> • 2 Prepare and subnut quarterly groundwater monitoring report <br /> 3 Continue bubbling of ambient air at low flow rates into selected wells <br /> QUARTERLY RESULTS SUMMARY (Fourth 2003): <br /> Current Phase of Project Morntorm /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 Quarterly <br /> Is Free Product (FP) Present onsite No <br /> Current Remediation Techniques Natural attenuation/Air bubbling _ <br /> Approximate Depth to Groundwater 40 75 to 42 70 feet below ground surface <br /> Groundwater Flow and Gradient South to Southeast @ 0 0006 to 0 0017 feet/foot ft At <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 benzene, ethylbenzene,toluene, and total xylenes in sample VW-10 should be <br /> considered estimated since these results exceeded the instrument calibration range and the sample was <br /> reanalyzed one day outside the U S EPA recommended hold time The data from the reanalysis has <br /> been reported <br /> • <br /> r,%wVmcessUS BP ARC0\0211MQumer1y14 QTR 03\2130 GWMR 4Q03 do Page 1 <br />