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�.�� i-ia w FO-M-i�-U-M-4- R 51 -M g -2 OWN., Baa` mss. Mr. Chuck Carmel May 29, 1991 Page 3 Analytical results of groundwater samples and water-level elevation are summudzcd in Table 1, along with previous results. The complete laboratory report for the February 1991 sampling is presented in Exhibit B. Figure 2 shows BETX and TPH concentrations sampled for each well. Discussion The general groundwater flow direction has not changed at this site since the last groundwater monitoring (September 21990). Water-level elevations have increased in 11 of the 15 wells by an average of 0.44 feet. Water-level elevations in monitoring wells E-8, E-9, and E-10 have decreased an average of 0.71 feet. Monitoring wells PR-1,PR-2,and 1314D-2 do not contain detectabJe concentrations of BETX and TPH. Benzene concentrations increased in wells E-4, E-8, E-9, E-10, E-11, and BHD-I and decreased in wells E-5,E-7,and E-12. Ethylbenzene concentrations have increased in wells E-7, E-8, E-9, E-11, E-12, and B HD-I and decreased in wells E-4 and E-5. Toluene concentrations have increased in wells E-7,E-8,E-10,E-11,E-12,and BHD-I and have decreased in wells E-4, E-5 and E-9. Xylenes concentrations have increased in wells E-8 and E-1 I and have decreased in wells E-4,E-5,E-7,E-9,E-10,E-12,and BHD-I. TPH concentrations have increased in wells E-4, E-5, E-7, E-9, E-10,E- 1, E-12 and have decreased to nonde tectable in BHD-2. The current groundwater monitoring plan will continue through 1991. If you have any questions, please contact me at (916) 444-0123. Very truly yours, BROWN AND CALDWELL Steven Misner Project Manager SDM:MTT:mkw Enclosures cc: Mr. Laurie Cotulla, San Joaquin County Health Department Mr. John Randall, Chevron Mr. Chris Winsor, ARCO Products company Brown and Caldwell