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4 � Brown and Caldwell <br /> G� Consultants <br /> 723 S Street <br /> Sacramento <br /> Calrfomia 95814 7p92V 016)444 <br /> SAX(916)p444 8437F4 r § <br /> August 11, 1992 AUG 17 1992 <br /> N lh)Nh11 N TAI <br /> — HF/\"f H <br /> Mr Chuck Cannel <br /> ARCO Products Company <br /> Post Office Box 5811 <br /> San Mateo, California 94402 017-6732-04/1 <br /> Subject Second Quarter 1992 Report for ARCO Station 2093, 3425 Tracy <br /> Boulevard, Tracy, California: Pilot Program Site 1416 <br /> Dear Mr Carmel <br /> This report presents quarterly water levels and analytical results of groundwater sampling <br /> performed on April 20 and 21, 1992, at ARCO Products Company (ARCO) Station 2093, <br /> located at 3425 Tracy Boulevard in Tracy, California A site location map is shown on <br /> Figure 1 There are seven on-site wells (ATR-1 through ATR-7) and five off-site wells <br /> (ATR-8 through ATR-12), as shown on Figure 2 Five of the on-site wells and all of the off- <br /> site wells were sampled Two on-site wells were not sampled because one contained floating <br /> product (ATR-3) and another was not accessible (ATR-7) <br /> Field and Analytical Methods <br /> Emcon Associates personnel measured depth-to-water levels, purged each well, and collected <br /> groundwater samples at the site Static water levels were measured prior to commencing <br /> purging, and a check for floating product was also made at this time A summary of the <br /> groundwater measurements is presented in Table 1 <br /> Prior to sampling, the wells were purged of a minimum of three well volumes or until <br /> evacuated using a centrifugal pump After purging, each well was sampled using a Teflon <br /> bailer All groundwater samples were analyzed for total petroleum hydrocarbons as gasoline <br /> (TPH-G), and for benzene, ethylbenzene, toluene, and xylenes (B=)by U S Environmental <br /> Protection Agency (EPA) Method 5030/8020/DHS LUFI' <br /> Results <br /> The general groundwater flow beneath the site on April 20, 1992, was to the northeast under <br /> an average hydraulic gradient of 0 003 (Figure 3) Table 2 shows past and present <br /> groundwater flow directions and hydraulic gradients for this site <br /> Analytical results of groundwater samples are summarized in Table 3, along with previous <br /> results The complete laboratory report for the sampling event is presented in Exhibit A <br /> 6732\RF.PORTSIAPR92QTRXP'r <br />