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1 <br /> In 1993, two hand auger borings were drilled at an angle beneath the UST. One sample <br /> from each boring was analyzed by a state-certified laboratory for total petroleum <br /> hydrocarbons (TPH as gasoline) and volatile aromatics (BTE&X). Petroleum hydrocarbons <br /> were detected in one of the analyzed samples. However, the drilling was performed without <br /> a permit and without PHS/EHD oversight; samples were not collected by qualified <br /> personnel. Therefore, the results are questionable and are not acceptable for UST closure <br /> consideration to the PHS/EHD. <br /> 3.0 GROUNDWATER DEPTH AND GRADIENT <br /> According to the San Joaquin County Flood Control District map, the depth to water in the <br /> fall of 1993 was between 65 and 70 feet with a regional southwest gradient. However, <br /> locally, the gradient may vary widely. <br /> 4.0 PROPOSED ASSESSMENT AND UST CLOSURE <br /> PHS/EHD guidelines state that a minimum of "two soil borings and four soil samples per <br /> tank" is required for UST closure in place. Soil samples will also be collected from beneath <br /> the piping. <br /> A total of four soil borings are proposed for the site. Two of the soil borings will be drilled <br /> at an angle of appro�dmately 30° from vertical (Figure 3). These borings will be drilled to <br /> a vertical depth of 15 feet beneath the tank. Samples will be collected at five-foot intervals <br /> and a minimum of two samples from each boring (vertical depths of 10 and 15 feet) will be <br /> analyzed by a state-certified laboratory. <br /> The third soil boring will be placed northeast of the UST and will be drilled to a maximum <br /> depth of 30 feet. Samples will be collected at five-foot intervals. <br /> The fourth boring will be hand-augured to a depth of 3 feet bsg near the piping that <br /> connects the UST with the dispenser (see Figure 2). One sample will be collected from this <br /> boring. The locations of all the borings are illustrated on Figure 2. <br /> 5.0 PROCEDURES <br /> 5.1 Soil Boring Drilling and Sampling <br /> To meet the project objectives, the following procedures will be performed: <br /> 1) Prepare a Site Health and Safety Plan in accordance with the Occupational Safety <br /> and Health Guidance Manual for Hazardous Waste Site Activities - Prepared by <br /> Cmbpnl Mdkrviae,Iec. 2 <br /> Pmd.Wem WPK9chCP445M903 <br />