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C. Well Details <br /> Dimensions for wells are based on the design refuse elevation of 180 ft msl. Actual <br /> bottom of wells reached 160 ft msl, 20 feet below the design refuse elevation. <br /> 1) Shallow Probes <br /> Shallow probes of proposed new wells allow sampling from five to ten feet <br /> from the surface (Table 1). Shallow probe of existing well SG-12 allows <br /> sampling to the depth of fifteen feet. <br /> 2) Intermediate Probes <br /> Intermediate probes allow sampling at or near half depth of refuse in most <br /> wells (Table 1). <br /> 3) Deep Probes <br /> Deep probes allow sampling at or near the designed refuse elevation, and <br /> 20 feet below that elevation (Table 1). <br /> Existing monitoring well SG-12 was installed in accordance with the <br /> -� - regulations in force at the time of installation (June 2004), which required a <br /> drill depth to the refuse within 1,000 feet of the well. The design refuse t <br /> depth elevation within 1000 feet of this well is 222 ft. MSL and the well was <br /> drilled to an elevation of 220 ft. MSL. Therefore, the County asks that this <br /> well be accepted in the future, as it was accepted for perimeter monitoring <br /> by the California Integrated Waste Management Board in 2004. <br /> D. Well Construction <br /> The soil gas wells will be drilled by a licensed drilling contractor. Wells were <br /> logged during drilling by a geologist or geotechnical engineer. The geotechnical <br /> engineer characterized soil cuttings using ASTM D2488-84 method for visual <br /> classification. Placement of the bentonite seals between monitoring sections were <br /> adjusted as needed to avoid obstruction of any permeable soil lens layers are <br /> discovered during drilling. <br /> II. DESIGN CONSIDERATIONS <br /> A. General <br /> The monitoring perimeter soil gas wells are designed to account for following site <br /> factors as specified in Title 27, section 20923. Best management practices identified <br /> by California Integrated Waste Management Board (now the California Department of <br /> Resources, Recycling and Recovery— CDRRR) were followed. <br /> Foothill Sanitary Landfill 3 County of San Joaquin <br /> Landfill Gas Monitoring Plan Department of Public Works <br /> June 25,2010 Solid Waste Division <br />