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rt <br /> F 3 ,SOIL BORINGS <br /> } <br /> Six exploratory soil borings were drilled at the site on May 29 and 30, 1990. Three of the <br /> borings were drilled to a 'ie- h of 25 feet and were later converted to groundwater <br /> monitoring wells. A fourth boring was drilled down to a depth of approximately 11 feet just <br /> above the water table. The remaining Lwo borings were drilled at a 60' angle under an <br /> abandoned 500 gallon underground leaded gasoline tank. The location of the six borings is <br /> shown in Figure 3. <br /> • Borehole drilling and sampling operations was,accomplished using a truck mounted hollow <br /> stem auger drill rig. The three borings which were converted to monitoring wells were <br /> drilled to approximately 10 feet below the water table to accommodate a 15-font well screen. ' <br /> The entire length of the borehole was continuously Iogged for the purpose of describing the <br /> vertical variations in the soil profile encountered. Soil samples for laboratory analysis were <br /> ., collected at five (5) foot intervals. All samples collected were submitted for chemical <br /> analysis. In accordance with general Regional Water Quality Control Board (RWQCB) <br /> requirements, one sample front each borehole was collected from directly above the <br /> R... groundwater interface. <br /> In accordance with San Joaquin County Department of Health and RWQCB practices, all <br /> soil cuttings generated by the borehole drilling and sampling operations were contained and <br /> stored on-site. However,since subsequent analysis has shown that this material contains no <br /> detectable levels of petroleum hydrocarbon or purgeable halocarbon compounds, these <br /> - cuttings will be used to back fill the proposed re-excavation. The two angle borings were <br /> drilled at an angle of 60° from the horizontal. Soil samples were collected at 7 and 12 foot <br /> _ . intervals in AB-1, and 9 and 13 foot intervals in AB-2 corresponding to vertical depths of <br /> 6 and 10 feet respectively in each boring. These borehole configurations enabled soil <br /> T samples to be collected at the base of the tank and at a depth of approximately 4 feet, <br /> immediately beneath the tank in each boring. <br /> a <br /> 6 <br />