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Mr Kenneth Earnest . May 5, 1992 Page 2 f Ground water samples collected from monitoring wells MW-1, MW-16, MW-18, MW-20, MW-21, MW-22, MW-23, MW-24, MW-25, MW-27, and RW-1, were submitted to a California-certified laboratory for analysis of benzene, toluene, ethylbenzene, and xylenes (BTEX) and total petroleum hydrocarbons (TPH) as gasoline Monitoring well MW-8 was not sampled due to the presence of free product and monitoring well MW-17 could not be sampled because the well casing is bent A summary of ground water sample analytical results since June 1991 is presented in Table 2 Enclosure C contains a table of ground water analytical results for ground water samples collected at the site since April 1985. A dissolved benzene xsoconcentration map based on the March 1992 ground water sample analytical results is illustrated in Figure 4 Copies of the field sampling information sheets are presented in Enclosure D. Copies of the March 1992 ground water sample laboratory reports are presented in Enclosure E Ground water analytical results indicate the concentration of benzene in the sample collected from monitoring well MW-27 decreased since the previous monitoring event in December 1991 from 210 parts per billion (ppb) to 16 ppb in March 1992 Petroleum hydrocarbon concentrations have remained below detection limits in ground water samples collected from monitoring wells MW-18, MW-21, MW-24, MW-27, and RW-1 The increase in ground water levels at the site allowed samples to be collected from some wells which had been dry for as long as 9 months to 2 years (MW-1, MW-16, MW-20, MW-22, MW-23, and MW-25) The concentration of petroleum hydrocarbons in ground water samples collected from each of these wells, except monitoring well MW-1, decreased since previous sampling