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OMEN <br /> Sm ON <br /> 11 Em�M S, <br /> J <br /> AuL*ust 27. 1991 <br /> Mr. Chuck Carmel <br /> ARCO Products Company <br /> Post Office Box 5811 <br /> San Mateo.California 94402 017-5690-3811 <br /> Subject-. 1991 Second Quarterly Report for ARCO Station 2133, <br /> 2908 Benjawin Holt Drive,Stockton. California <br /> Dear Mr.Carmel: <br /> This report presents the second quarterly water levels and analytical results of groundwater <br /> sampling performed at ARCO Froducts Company (ARCO) Station 2133, located at 2908 <br /> Benjamin Holt Drive in Stockton,California. The work was performed on April 23,1991 under <br /> Task Order 2133-91-5A. There are fifteen on-site wells: E-2 through E-12 and PR-1, PR 2, <br /> BHD-1, and BHD-2 (Figure 1). Eight wells were sampled during this sampling event. The <br /> sample bottles used during the April 23, 1991, sampling ware not correctly manufactured and <br /> allowed air into the samples. All of the wells were resampled on:day 2, 1991 as a result cf the <br /> faulty bottles. <br /> Field and Analytical Methods <br /> Brown and Caldwell personnel measured depth-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 /> readings is included as Exhibit B. <br /> All groundwater samples were analyzed for total petroleum hyd,-ocarbons (TPH)'and benzene, <br /> ethylbenzene,toluene,and xylenes(BEi'X)by Modified U.S.Environmental Protection Agency <br /> Method 801515030. <br /> Q� Results <br /> The groundwater flow direction is to the north-northeast. The hydraulic gradient is approximately <br /> 0.002. Table i presents the water level data in tabular form. Table 2 presents the flow direction <br /> and gradient for this and post-sampling events. Comparison of the water levels measured on <br /> April 23. 1991, with those measured in February 1991 indicate no significant change in the <br /> general groundwater flow direction or hydraulic gradient. However,the groundwater elevations, <br /> " � as measured on April 23,1991,reflect the intermittent pumping of the extraction well. Figure 1 <br />