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excavation, and water samples were not collected. The excavated soil was subsequently returned to the excavation and covered with visquine. Additional imported soil was placed on top of the visquine to bring the excavation up to surface grade, and a thin layer of gravel was poured over the surface to match the surrounding area. The samples were analyzed by EPA methods 8015m for Total Petroleum Hydrocarbons as diesel, and 8020 for benzene, toluene, ethylbenzene, and xylene (BTEX). Diesel was reported in all of the samples, ranging from 200 to 4900 mg/kg (parts per million). Benzene was not detected in any of the samples, nor was ethylbenzene. Toluene and xylene were detected at low concentrations, mainly in the stockpile(Table 1). 4.0 WELL SURVEY A survey of the area within 2,000 feet of the site has been conducted to identify private and municipal wells that could act as contaminant receptors if groundwater beneath the site has been impacted. Upgradient personnel visited the State Department of Water Resources in Sacramento to review the DWR well files for information pertaining to nearby wells. The results of this review are shown in Table 2 and the wells are located in Figure 3. In addition, a drive-by inspection of the area was conducted on June 16 to locate the wells reported in the DWR files and find additional wells that were not listed in the DWR files. Five wells within the 2000-foot radius were identified. These wells are also included in Table 1 and shown on Figure 3. 5.0 PROPOSED ASSESSMENT 5.1 Vertical Extent of Contamination The vertical extent of contamination will be delineated by drilling one soil boring near the center of the former tank cavity (Figure 2). The boring will be drilled with a hollow-stem auger drilling rig. Beginning at 20 feet (six feet below the previously collected tank samples), soil samples will be collected at 5-foot intervals and screened for evidence of petroleum with a portable photo-ionization detector or organic vapor meter, and will be preserved for laboratory analysis. The minimum anticipated depth of the boring is 30 feet, but drilling will continue until two consecutive samples exhibit no contamination. The estimated depth to groundwater is 40 feet, and if groundwater is reached before two consecutive uncontaminated soil samples have been collected, a well will be constructed in the boring. The well will use 2-inch-diameter PVC casing, following the design shown in Figure 4. Ager the well has stabilized, it will be purged of at least 5 well volumes of water, and a sample will be collected. Soil and water samples will be analyzed for diesel and BTEX by EPA methods 8015, 602, and 8020.