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Mr. Harlin Knoll <br /> ,F <br /> June 29, 1999 <br /> Page 2 <br /> results of soil and groundwater samples collected ftom beneath the USTs by Geotechnical Research <br /> and Development (GRD) indicated that elevated levels of petroleum hydrocarbons were present in <br /> the soil and groundwater. Analytical results of soil and groundwater samples collected during the <br /> removal of the USTs are summarized in Table 2. Soi and groundwater sample locations are shot n <br /> on Figure 3. <br /> SCOPE OF WORK <br /> Ground Zero will supervise the drilling and sampling of nine soil borings in the vicinity of the former <br /> USTs. Five borings will be advanced utilizing direct ush technology to investigate the vertical land <br /> lateral extent of soil contamination and to investigate the lateral extent of groundwater <br /> contamination, and up to four borings will be advanced through the use of a hand auger;I to <br /> investigate the lateral extent of shallow soil contamination. Proposed soil boring locations are shown <br /> on Figure 4. <br /> All sampling and drilling equipment will be washed t oroughly with laboratory-grade detergent and <br /> water between uses to minimize the potential for cross contamination. All fieldwork will! be <br /> conducted in accordance with the Site Safety Plan included in Attachment A. <br /> Direct.Push Soil Borings <br /> One direct push boring will be advanced in the nter of the former UST pit to a depth!, of <br /> approximately 25 feet to investigate the vertical extent of soil contamination. Four perimeter borings <br /> will also be advanced using the direct push method: c ne boring each will be advanced approximately <br /> 40 to 50 feet to the north, south, and west from th center of the former UST pit to a depth of <br /> approximately 15 feet bgs to investigate the lateral extent of soil and groundwater contamination, <br /> and one boring will be a "floater", advanced in a location to be determined based on conditiib ns <br /> observed in the field. The proposed boring locations are shown on Figure 4. r, <br /> A drilling company licensed in the State of Californi will advance the direct push borings using a <br /> truck mounted Geoprobe 5400 direct push rig. Soil samples will be collected continuously J�for <br /> logging and identification purposes using a 1-inch diameter core sampler lined with clear acetate <br /> sleeves. The portion of the sample to be analyzed w'.1 be immediately capped and placed in an iced <br /> cooler at a temperature of approximately 4° Centigr de pending transportation to a state certified <br /> analytical laboratory. Borings will be backfilled to the ground surface with neat cement grout. <br /> Groundwater is expected to be encountered at approximately 6-8 feet bgs. One discrete <br /> groundwater sample from each of the direct push borings will be collected for laboratory analysis . <br /> t Samples will be collected by driving a Hydropunch sa pler to the desired depth, exposing the screen <br /> to the formation, and using a length of polytetra oroethylene (PTFE) tubing equipped with a <br /> stainless steel bottom check valve to extract the water from the formation. The groundwater sample <br /> will be brought to the surface b gripping the to of a tubing and rapidly movie the tubing u sand <br /> g Y g PP g P g p Y g 13 P 1M <br /> down creating a positive displacement effect. The sa ples will be collected directly into the sample <br /> containers, then placed in an iced cooler at a tempe ature of approximately 4° Centigrade pending <br /> transportation to a state certified analytical laboratory <br /> data/groundzeJmanser/wpO599.doc <br />