Laserfiche WebLink
Date: September 30,2004 <br /> Quarter 3d Quarter 2004 <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 OL058 <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 2004): <br /> 1 Performed quarterly groundwater monitoring and sampling <br /> 2 Prepared and submitted quarterly groundwater monitoring report <br /> WORK PROPOSED FOR NEXT QUARTER (Fourth 2004): <br /> 1 Perform quarterly groundwater monitoring and sampling <br /> 2 Prepare and submit quarterly groundwater monitoring report <br /> QUARTERLY RESULTS SUMMARY (Third 2004): <br /> • Current Phase of Project Monitoring <br /> Frequency of Groundwater Sampling MW-5 through -12,and MW-13D sampledquarterly <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 23 00 to 25 68 feet below ground surface (bgs) <br /> Groundwater Flow and Gradient North to Northeast @ 0 002 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 ethanol in samples MW-8,MW-9,MWA 1,MW-12,and MW-13D maybe <br /> biased low because the associated continuing calibration standard was outside of acceptance criteria <br /> DISCUSSION <br /> Total xylenes and methyl tert-bury] ether(MtBE) were the only analytes detected above laboratory reporting limits in <br /> groundwater samples collected from site monitoring wells this quarter In MW-6, MtBE concentrations decreased <br /> relative to the previous quarter MtBE concentrations in MW-13D decreased to the lowest concentration reported <br /> since sampling began in July 2003 and total xylenes were not detected above laboratory reporting limits this quarter <br /> Other analyte concentrations were generally consistent with the historic concentrations <br /> K 1WPmn ssV5 BP ARC0\W201Qv-ner1y\2004%3 QTR 041,020 GWMR 3Q04 dm Page 1 <br />