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FILE COPY , <br /> TAL 1!EALTH DEPARTMENT <br /> ENVIRONMENTAL � <br /> �AuilvSAN JOAQUIN COUNTY <br /> Unit Supervisors <br /> Donna K.Heran,R.E.H.S. <br /> Carl Borgman,R.E.H.S. <br /> 304 East Weber Avenue, Third Floor <br /> rq y Direclor Mike Huggins,R.E.H.S..R.D.], <br /> Al Olsen,R.E.H.S. Stockton, California 95202-270$ Douglas W.Wilson,R.E.H.S. <br /> c9�rxoaa�P Program Manager Telephoner(209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> Laurie A.Cotulla,R.E.H.S. Fax: (2 9) 464-0138 Robert McClellon,R.E.H.S. <br /> Program Manager MAR R 1r11SZOfts,R.E.H.S. <br /> PAUL SUPPLE KITTY WALKER <br /> ATLANTIC RICHFIELD COMPANY COS REDEVELOPMENT AGENCY <br /> PO BOX 6549 305 N EL DORADO STREET <br /> MORAGA CA 94570 STOCKTON CA 95202 <br /> 1 <br /> RE: ARCO Station #4493 <br /> 205 N. Center Street <br /> Stockton CA 95202 <br /> San Joaquin County Environmental Health Department(:SJCIEHD) has received the"Monitoring Well <br /> Installation Report"dated February 4, 2003 and the"Quarterly Groundwater Monitoring Report'(QMR) <br /> dated February 5, 2003 that were submitted on your behalf by URS Group, Inc. (URS) and has the <br /> following comments. <br /> A work plan prepared by URS to install two dual-completion, down-gradient groundwater monitoring <br /> wells at this site was conditionally approved by SJC/EHIJ in correspondence dated October 23, 2002. <br /> The installation of two wells had been agreed upon at a site meeting in June 2002. During fieldwork to <br /> install these wells in November 2002, extensive underground utilities at one selected location <br /> prevented the installation of one of the wells at that time] However, it was always the understanding of <br /> SJCIEHD that an alternative location would be selected and the well would be installed at a later date. <br /> The Monitoring Well Installation Report documents the installation of one dual-completed groundwater i <br /> monitoring well (MW-1I-MID) located to investigate the lateral and vertical extent of the plume in the <br /> down gradient direction. As the gradient at this site has historically shifted east to northeast, two dual- ti <br /> completed wells were to have been installed to cover this area. The report states that MW-11-M/D <br /> was sampled on December 5, 2002, However, Table 2-Fuel Oxygenates Analytical Data MW-11-MID s <br /> reports two sample dates and analytical results for this well. One of these sample dates is listed at <br /> September 16, 2002, which is before the wells were installed. Please have URS explain this s <br /> discrepancy and/or correct the data table in this and all future reports. <br /> SJCIEHD will evaluate URS's conclusion that the vertical extent of impacted groundwater has been <br /> delineated in the area of MWA 1-MID after additional monitoring events. However, both the lateral <br /> extent of impacted groundwater and the vertical extent in the areas of MW-8-M/D and MW-9-M/D still l <br /> need to be delineated. Please submit a work plan to continue the investigation at this site and to <br /> install the additional dual-completed well. The work plan is due May 16, 2003. <br /> Donna Heran, REHS, Director <br /> Environmental Health Department <br /> Lori Duncan, Senior REHS Nuel C. Henderson, Jr., RG <br /> LOP/Site Mitigation Unit IV LOP/Site Mitigation Unit IV <br /> cc: James L.L. Barton, CVRWQCB <br /> Bill Brown, Daley& Heft <br /> Vernon Elarth, URS <br />