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-aww <br /> _ ' <br /> c. <br /> grown aryl calnweli <br /> C_ , �i4ai'rc <br /> ._ramea�n <br /> lama"23: - <br /> November 18, 199E <br /> Mr. Chuck Carmel <br /> ARCO Products Company <br /> Post Office Box 5811 <br /> San Matto, California 94402 017-5690-04/1 <br /> Subject: 1991 Third Quarterly Report for ARCO Station Zla3, <br /> 2908 Benjamin Holt Drive, Stockton, California <br /> Dear Mr. Carmel: <br /> This report presents the third quarterly water levels and analytical results of groundwater <br /> sampling performed at ARCO Products Company (ARCO) Station 2133 located at 2908 <br /> Benjamin Holt Drive in Stockton,California. The work was performed on July 15 and 15,1991 <br /> under Task Order 2133-91-5A. There are fifteen Ora-sire wens: E-2 through E-12,PR-1,PR-2,. <br /> BHD-11,and BHD-2(Figure 1). Although all of the wells were scheduled to be sarnplzd during <br /> this sampling event,"six (E-3, E-4, E-5, E-6. E-7, and E-9)of the fifteen wells were dry or did <br /> not recharge enough for sampling after purging. Therefore, a total of nine wells were sampled. <br /> The most likely cause of some of the wells near the extraction well going dry is the operation <br /> of the groundwater extraction system. <br /> Field and Analytical Methods <br /> Brown and Caldwell personnel measured Jepth-to-water levels,supervised purging of each well, <br /> and collected groundwater samples at the site. Refer to Exhibit A for detailed field methods <br /> description. A copy of the field notes containing the pH,electrical conductivity,and temperature <br /> icadings is included as Exhibit B. <br /> All groundwater samples were analyzed for total pet;oieum hydrocar=bons as gasoline (l'F'H-G) <br /> and benzene, ethylbenzene, toluene, and xylenes (BETX) by Modified il.S. Environmental <br /> Protection Agency Method 8015/5030. !� <br /> Resuats <br /> The groundwater extraction systems at this site has been in operation since June 1991. .Since the <br /> start-up,the system;nas been pumping at a rate of approximately 10.1 gallons per minu'_. (gpm). <br /> The groundwater extraction system has influenced the groundwater now pattern locally,as shown <br /> in Figure 1. Table 1 (Exhibit C) pr.,zents the water-level data for this site in tabular form,and <br /> Table 2 (Exhibit D) presents historical flow direction Wid gradient data for this site. Figure 1 <br /> also shows the water-level elevations for each well and the contours of equal water-level <br /> elevation calculated from the July 15, 1991 data. <br /> s r,�wtr�ttrsv�r.9 i Qmc.iipr <br /> if. <br />