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all <br /> Brown and Caldwell <br /> C� <br /> Consultants <br /> ( 723 S Street <br /> Sacramento <br /> Callorma 95814 7092 <br /> (916)444 0123 <br /> -AX 19161 444 6437 <br /> January 12, 1993 <br /> ,SAN 13 1993 <br /> Mr Chuck Carmel <br /> ARCO Products Company ENVIRONMENTAL HEALTH <br /> Post Office Box 5811 <br /> San Mateo, California 94402 017-6746-04/1 <br /> 7 <br /> Subject Fourth 1992 Quarterly Report for ARCO Station 2133, <br /> 2908 Benjamin Holt Drive, Stockton, California <br /> Dear Mr Carmel. <br /> This report presents water level measurements and results of groundwater sampling performed <br /> during the fourth quarter of 1992 at ARCO Products Company (ARCO) Stauon 2133 located <br /> at 2908 Benjamin Holt Drive to Stockton, California. The sampling was performed on <br /> October 29, 1992, by Emcon andiXspociates (Emcon). This report was prepared under Task <br /> Order 2133-92-5A. There are fifteen)on-site wells: E-2 through,E-12, PR-I, ,PR-2, BHD-1, <br /> and BHD-2 (Figure 1). A total of,11 wells w�re,sampled. Four of the fifteen wells (E-3, E-5, <br /> E-6, and E-7) were dry The most likely cause of these wells gong dry,is the operation of <br /> the groundwater extraction system <br /> Field and Analytical Methods <br /> Emcon personnel measured depth-td-water, supervised purging of each well, and collected <br /> groundwater samples at the site. A copy of Emcon's field notes is included as Ealubit A <br /> The purge water generated during this sampling event was temporarily stored on site in <br /> 55-gallon barrels then transported off site by Balch Petroleum Company <br /> All groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPH-G) <br /> and benzene, ethylbenzene, toluene, and xylenes (BETX) by Modified,U.S. Environmental <br /> Protection Agency Methods 5030/8020/DHS LUFT Method. <br /> Results <br /> Table 1 (Exhibit B) presents the water-level data for this site while Table 2 (Exlubit C) <br /> summarizes historical groundwater flow direction and gradient data for this site Figure 1 <br /> shows the water-level elevations for each well and the contours of equal water-level elevation <br /> for October 29, 1992 <br /> Analytical results are summarized in Table 3 (Exhibit D) The complete laboratory report for <br /> the October 1992 sampling is presented in Exhibit E Figure 2 shows BETX and TPH-G <br /> concentrations for each well sampled In addition. Figure 2 presents an approximation (dashed <br /> line) of the lateral extent of benzene in the groundwater <br /> 6746-RHP0RTS4)Cr92QTR1tPT <br />