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kn KLEINFELDER <br /> 3 FIELD ACTIVITIES <br /> 3.1 HYDROCARBON SURFACE STAIN AREAS <br /> During the initial investigation the highest TPH concentrations were detected at HS-1 <br /> (5,600 mg/kg), HS-4 (1,100 mg/kg), and HS-2 (50 mg/kg). On November 3 through 11, <br /> 1988, additional soil samples were collected; three monitoring wells were installed, and <br /> ground water samples were collected from HS-1, HS-2, and HS-4 (Plate 2, Appendix A). <br /> At each of the three HS areas, a central soil boring was drilled through the area of obvious <br /> surface staining. The central borings MW-1/13-2, MW-2/13-10, and MW-3/13-11 were <br /> advanced in the vicinity of the original HS sample locations of the June, 1988 soil sampling <br /> investigation. Ground water monitoring wells were installed in the central borings to assess <br /> the water beneath the areas of obvious staining. Because the surface samples at HS-1 and <br /> HS-4 had high concentrations based on the June, 1988 soil sampling investigation, <br /> additional radial borings were drilled in these two areas. A single monitoring well was <br /> installed at HS-2 to assess first encountered water and provide a third well for estimation of <br /> the ground water flow direction. <br /> The locations of the HS areas and borings are shown on Plates 2 and 3, Appendix A. HS-4 <br /> is located in the central portion of the Weston Ranch parcels. Five soil borings were <br /> drilled at HS-4; boring B-2/MW-1 was used as the central boring and B-1, B-3, B-4, and B- <br /> 5 were placed at 901 degree increments 15 to 25 feet radially away from B-2/MW-1. HS-1 <br /> is located in the southwest portion of the Weston Ranch parcels. Five soil borings were <br /> drilled at HS-1; boring B-10/MW-2 was used as the central boring and B-6, B-7, B-8, and <br /> B-9 were placed at 901 degree increments approximately 10 feet radially away from B- <br /> 10/MW-2. Boring B-11/MW-3 was drilled at HS-2, which is in the northwest section of the <br /> Weston Ranch parcels. <br /> 3.1.1 DRILLING AND SOIL SAMPLING PROCEDURES <br /> A truck-mounted CME-55 drill rig equipped with 8-inch hollow-stem augers was used to <br /> advance the borings. During the drilling, an experienced environmental geologist classified <br /> the subsurface soil and logged the boreholes. A copy of the Unified Soil Classification <br /> System (used to identify the soil) is included as Plate 7, Appendix A. Descriptions of the <br /> 161-89-107 4 <br />