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Clayton [\S IRO-WE VIA lii\Si ll4♦IS -� 10 -' Clayton Environmental Consultants, Inc was retaint-d by Orchard Supply Hardware (OSH) to install one monitoring well and properly abandon two additional wells at the northeast corner of MacArthur Drive and Grant Line Road in Tracy California �. (Figure 1) Mr. Michael D. La Tourette authorized this project on November 29, 1990, by accepting Clayton s Proposal No 90-B-281 and its accompanying terms and conditions. 20 AME BACKGROM Clayton was contracted by OSH in January 1990 to conduct a Phase I environmental assessment of the subject site. The assessment revealed that a gasoline underground storage tank(UST)was removed in 1986. Kapreal.an Engmeenn& Inc. (KEI) had been retained by the owner, Mr. Jim Joseph, to install a groundwater monitoring well A water sample from the well was analyzed for total petroleum hydrocarbons (TPH) as gasoline and the volatile hydrocarbons, benzene, toluene, ethylbenzene and xylenes (BTEX). All of these constituents were below detectable limits Clayton could not find the well during the assessment. We were later informed that it had been abandoned Clayton was retained by OSH to install three monitoring wells to sample and analyze soil and groundwater at the subject site (Clayton Project No. 28094 00) The three wells were, installed on March 28, 1990 and locations of these wells are provided in Figure 2. The analytical results of soil samples taken from the monitoring wells (MW-1, MW-2 and MW-3) are summarized in Table 1. Analysts of soil samples from boreholes for wells MW-1 and MW-2 did not show detectable levels of gasoline or BTEX, except for a very low concentration of toluene in MW-1 at 5 feet bgs. The source of the toluene is unclear. Toluene was not detected deeper in the boring nor was it detected in the groundwater. Concentrations of gasoline, toluene, ethylbenzene, and xylene in soli samples from the borehole for well MW-3, nerd to the old gasoline tank, exceeded LUFT guidelines. 'fable 2 shows only those compounds detected All other compounds were below detection umits or not analyzed Monitoring wells MW-1 an MW-2 showed no detectable petroleum hydrocarbons. Monitoring well MW-3 showed traces of petroleum hydrocarbons well below -� regulatory guidelines. Based on the analysis of the soil and groundwater samples from the monitoring wells, Clayton recommended excavation and aeration of the gasohne-contaminated soil m the vicinity of the former location of the gasoline tank.