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L4 <br /> iEW3miLL•MERKENWa*T. INC. <br /> SITE INVESTIGATION: SOIL <br /> 3. 1 SOIL SAMPLING <br /> Based on previous studies and mapping of the soil gas survey, eight soil borings <br /> were installed and soil samples taken on September 5 and 6, 1990, by LH for <br /> laboratory analysis within and adjacent to the former UST excavation and adjacent <br /> to the existing waste oil UST. Locations of these boreholes are shown on Figure <br /> 3. <br /> Three of the eight soil borings SB2, SB3, and S84 were drilled within the asphalt <br /> patch outline of the former UST excavation. These borings were drilled to total <br /> depths of 20, 35, and 37.5 feet, respectively, with discrete soil samples taken <br /> at 5 foot intervals. <br /> Soil borings S81, SB5, and SB8 were drilled to total depths of 37.5, 20, and 30 <br /> feet, respectively, around the perimeter of the former excavation. Discrete soil <br /> samples were collected at 5 foot intervals from borings SB5 and S68. Boring SBI <br /> was drilled as a continuous core. The core samples were laid out in sequential <br /> order, described and discrete grab samples taken for laboratory analysis and USCS <br /> classification by sieve analysis. Soil boring SB7 was drilled to a total depth <br /> of 15 feet near the pipeline trench where the soil gas survey indicated possible <br /> petroleum hydrocarbon contamination. Discrete samples were collected for <br /> laboratory analysis in boring S67 at 5 foot intervals. Soil boring SB6 was <br /> drilled at the northwest end of the waste oil tank. This boring was drilled to <br /> a total depth of 35 feet with soil samples taken at 5 foot intervals. <br /> Groundwater was encountered in soil borings SBI, SB4, and SB6 at a depth of <br /> approximately 35.5 feet. Soil samples collected at shallower depths were found <br /> to be dry, to slightly moist. After reaching the total depth of these borings, <br /> water quickly rose to a depth of 32 to 33 feet below the ground surface. Grab <br /> water samples were collected from these boreholes with either a bailer or a <br /> "hydropunch", (see Section 4, Site Investigation: Groundwater) . Groundwater was <br /> not encountered in any of the other five soil borings. <br /> Based on the Phase IA soil sampling results collected on September 5 and 6, 1990, <br /> three additional soil borings (MW1 , MW2, and MW3) were drilled on September 20 <br /> and 21, 1990 to further define the soil contamination and for subsequent <br /> conversion to groundwater monitoring wells. As shown on Figure 3, these borings <br /> were drilled in a triangular pattern, centered around the east end of the <br /> excavation. The monitoring well borings MW1, MW2, and MW3 were drilled to total <br /> depths of 44, 43, and 44 feet, respectively, with discrete soil samples taken at <br /> 5 foot intervals. Groundwater was first encountered in the soil borings for MW1, <br /> MW2, and MW3 at a depth of 37 feet and water quickly rose to a depth of 31 to 34 <br /> feet below the ground surface. (See Section 4, Site Investigation: Groundwater, <br /> for further discussion on these monitoring wells. ) <br /> All drilling was conducted dry with no fluids added to the borehole or <br />�. lubrication to the drilling equipment. A sampler attached to the drilling rods <br /> J 7 <br /> J <br />