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parking lot. The other two borings will be drilled with a hollow-stem auger rig. Both of these borings, and at least one of the Geoprobe borings,will be drilled to groundwater and a water sample will be collected. One of the auger borings will be completed as a groundwater monitoring well so that groundwater quality beneath the UST cavity can be monitored. The well design is illustrated in Figure 3. Two additional borings will be drilled and completed as monitoring wells so that the groundwater gradient can be determined. These will be located near the northeast and southwest comers of the parking lot (Figure 2), and should be well beyond the extent of soil contaminated by the UST. However, if we encounter contaminated soil, perhaps even from another source, further drilling may be necessary. Soil samples will be collected at 5-foot intervals in each boring, and groundwater samples will be collected from the boring(s) that are not completed as wells. Soil cuttings will be added to the existing stockpile, which is covered by plastic sheeting. The borings will be backfilled with cement grout. No sooner than 48 hours after the wells have been drilled, Upgradient will survey the elevation of the well casings and collect water samples. All soil and water samples will be shipped to McCampbell Analytical Laboratories and analyzed for Total Petroleum Hydrocarbons a gasoline, BTEX, and MTBE using EPA methods 8015m and 8020. Any sample in which MTBE is detected will then be reanalyzed using EPA method 8260 for confirmation. After the laboratory results have been received, Upgradient will prepare a Preliminary In-,estigation and Evaluation Report, summarizing and interpreting the results of the investigation. The field and laboratory procedures are summarized below. 4.OPROCEDURES 1)Notify San Joaquin County EHD at least 48 hours prior to field work. 2) Drill seven borings to a depth of at least 10 feet below the apparent base of the contami fated zone. 3)Collect soil samples at 5-foot intervals in each boring and groundwater samples in three of the borings. 4)Record the sample descriptions on the boring log in accordance with the Unified Soil Classification System. 5)Preserve the sleeve by covering the ends with plastic caps. 6) Place auger returns on plastic sheeting.