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RESNAATERWORK CORPL, INDUSTRIES February 2, 1991 Mr. Steve Schneider San Joaquin County Public Health Services Environmental Health Division P.O. Box 2009 Stockton, CA 95201 Re: First Quarterly Monitoring Report for J.B. Terminal 6700 Grantline Road, Tracy, CA Dear Steve: On January 16, 1991, groundwater monitoring was conducted at the above referenced site on wells Mwl, MW2, and MW3 (Figure 11 . During monitoring, the depths to water were measured, the wells were purged and samples were collected. Depth to water had dropped from 2 to 2.5 feet in all wells since our October 1990 monitoring ( Table 1 ) . The gradient was calculated, using a computer Kriging program, to be in a north- west direction at 0.08 ft/ft, which is consistent with previous gradients (Figure 2) . Samples collected were analyzed for benzene , toluene , ethylberzene and xylenes (BTEX), and total petroleum hydrocarbons as gasoline (TPHG) . BTEX and TPHG were not detected in MW2 and MW3 but were detected in MW1 . Analytical data is presented in Table 2. The laboratory data sheet and chain-of-custody form are attached. Please note that a typographical error was made in summarizing the laboratory results on Table 2 of the Problem Assessment Report ( PAR) . Table 2 of this letter corrects the oversight of the PAR Table 2. Monitoring well MW-1 was also resampled on December 10, 1990. Analysis of that sample showed non-detectable levels of BTEX and TPHG. Results were submitted to you by a letter dated January 3, 1991 . Due to the wide fluctuations 3n analytical results, we propose one additional quarter of groundwater monitoring and sampling to observe seasonal fluctuations in contaminant concentrations and the groundwater table prior to installation of any additional monitoring wells. If lab results of the next quarterly sampling round (April, 1991 ) warrant further 1710 MAIN STREET e ESC ALON CA 95320 . ('209) 838-3307 2350•A NVALSH AVENUE . SANTA CLARA CA 95051 • (408)496-1249