Laserfiche WebLink
5 <br /> Date October 26,2005 <br /> Quarter 3`d Quarter 2005 <br /> • ARCO QUARTERLY GROUNDWATER MONITORING REPORT <br /> Facility No 6020 <br /> Address 1711 E Yosemite Ave , Manteca, CA <br /> ARCO Environmental Engineer Paul Supple <br /> Consulting Co/Contact Person URSNernon Elarth <br /> Consultant Project No 38466530 OA143 <br /> Primary Agency/Regulatory ID No _San Joaquin County Environmental Health Department <br /> Assembly Bill 681 Status Property owned by Atlantic Richfield Company <br /> WORK PERFORMED THIS QUARTER (Third 2005): <br /> 1 Performed quarterly groundwater monitoring and sampling <br /> 2 Prepared and submitted quarterly groundwater monitoring report <br /> WORK PROPOSED FOR NEXT QUARTER (Fourth 2005): <br /> 1 Perform quarterly groundwater monitoring and sampling <br /> 2 Prepare and submit quarterly groundwater monitoring report <br /> QUARTERLY RESULTS SUMMARY (Third 2005): <br /> . Current Phase of Project Monitoring <br /> Frequency of Groundwater Sampling MW-5 through MW-12, and MW-13D 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 20 41 to 23 39 feet below ground surface (bgs) <br /> Groundwater Flow and Gradient Northeast to Southeast 0 0 002-0 008/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 <br /> laboratory <br /> DISCUSSION <br /> MtBE was the only analyte detected above laboratory reporting limits in groundwater samples collected from site <br /> monitoring wells MW-6 and MW-13D this quarter Concentrations of MtBE concentrations in MW-6 decreased to <br /> the lowest level reported historically MW-13D was generally consistent with the previous quarter No other analytes <br /> were detected above laboratory reporting limits in groundwater samples collected from site monitoring wells this <br /> quarter <br /> Groundwater elevations decreased relative to the previous quarter The inferred direction of groundwater flow across <br /> the site generally ranged from the northeast to southeast at an average hydraulic gradient that ranged from 0 002 to <br /> 0 008 ft/ft <br /> • <br /> K%WMLeScVS$P ARC01060205Quarte4y\2005\3 QTR 05\5020 CJWMR 3Q05 doe Page 1 <br />