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Mr Kenneth Earnest <br /> Ultramar Inc <br /> July 29, 1992 <br /> Page 2 <br /> Sub ective Anal sis <br /> No evidence of petroleum product or sheen was detected in monitoring wells at the site during the <br /> June 1992 site visit <br /> Analytical Results <br /> Ground water samples collected from monitoring wells MW-1, MW-16, MW-18, MW-20, MW-21, <br /> MW-22, MW-24, MW-25, MW-27, and RW-1, were submitted to a California-certified laboratory <br /> for analysts of benzene, toluene, ethylbenzene, and xylenes(BTEX) and total petroleum hydrocarbons <br /> (TPH) as gasoline A summary of ground water sample analytical results since June 1991 is <br /> presented in Table 2 Enclosure C contains a table of ground water analytical results for ground <br /> water samples collected at the site since April 1985 A dissolved benzene iso concentration map based <br /> on the June 1992 ground water sample analytical results is illustrated in Figure 4 Copies of the field <br /> sampling information sheets are presenter) in Enclosure D Copies of the June 1992 ground water <br /> sample laboratory reports are presented in Enclosure E <br /> Ground water analytical results indicate that since the previous sampling event in March 1992, <br /> concentrations of benzene have decreased in samples wliected from monitoring wells MW-1 (260 <br /> parts per billion (ppb) to 240 ppb), MW-16 (1 9 to less than 0 5 ppb), and MW-22 (1 6 to less than <br /> 0 5 ppb) Concentrations of benzene have increased in samples collected from monitoring wells <br /> MW-27 (16 to 20 ppb) and RW-1 (less than 0 5 to 4 3 ppb) Petroleum hydrocarbon concentrations <br /> have remained below the limits of detection in ground water samples collected for monitoring wells <br /> MW-18, MW-20, MW-21, and MW-24 and have decreased to below the limits of detection in the <br /> sample collected from MW-25 <br />