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�I <br /> Date July 29,2003 <br /> Quarter. 2"d 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 /> (SJCEHDL _ <br /> Assembly Bill 681 Status Property owned by Atlantic Richfield Company <br /> WORK PERFORMED THIS QUARTER (Second 2003): <br /> 1 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 (Third 2003). <br /> I 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 /> 4 Continue to work with the City of Stockton to obtain permission to locate and destroy MW-10 <br /> QUARTERLY RESULTS SUMMARY (Second 2003): <br /> Current Phase of Project Mon itorin /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 37 61 to 39 00 feet below ground surface <br /> Groundwater Flow and Gradient Northeast to Southeast @ 0 001 to 0 003 feet/foot 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 reported results for toluene in samples VW-8 and MS-1B and xylenes (total) in sample MS-1B <br /> should be considered estimated since the primary and confirmation results varied by g eater than 40% <br /> relative percent difference <br /> • The elevated reporting limits reported in the Method 8260 analysis of samples VW-8 and VW-10 were <br /> due to the presence of TPHg and BTEX <br /> K 1WPr-ctssV5 BP ARC(W2I301Qua .,1yV QTR 0312130 GWMR 2QO3 do Page 1 <br />