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GeosyntecO <br /> consultants <br /> (locations BI through B4). The rationale for each of the proposed well locations are <br /> discussed in Section 3.2. The installation of these wells will result in four(4) additional <br /> well pairs for the site for further evaluation of vertical gradients between the A- and <br /> B-Zone aquifers. <br /> 4.2.2.1 Well Construction <br /> The monitoring wells will be installed and constructed in accordance with SJEHD <br /> requirements, the SAP (Appendix A), and SOP 3.0 (Appendix B). In general, each of <br /> the groundwater wells will be constructed using schedule 80, 2-inch diameter polyvinyl <br /> chloride (PVC) casing with a flush mount surface completion. A-zone wells shall be <br /> installed to a total depth between 75 and 77 feet bgs with a screen interval of 55 to <br /> 75 feet bgs. B-zone wells shall be installed to a total depth of 130 to 132 feet bgs with a <br /> screen interval of 110 to 130 feet bgs. Screens shall be constructed with schedule 80, <br /> 2-inch diameter PVC with 0.01-inch slots. A silt trap constructed of up to 2 feet of <br /> blank casing and a bottom cap will be installed at the bottom of each well. Centralizers <br /> shall be installed approximately every 50 feet within the well. <br /> A filter pack consisting of#2/12 (or equivalent) sand shall be installed 6 inches below <br /> the bottom of the well casing and continue to a depth two feet above the top of the <br /> screen. When the filter pack is installed to the desired depth, the screened interval shall <br /> be surged to settle the filter pack around the well screen (preliminary development). <br /> During surging, the well casing shall be secured at the surface to prevent settling of the <br /> casing. Surging shall continue until the filter pack stops settling. Upon completion, <br /> sand shall be added to bring the filter pack up to the desired depth. At least two feet of <br /> bentonite will be installed above the filter pack to create a seal. The remainder of the <br /> boring outside the well casing shall be backfilled with cement bentonite grout. <br /> 4.2.2.2 Well Development <br /> Monitoring well development shall be performed, as soon as practical, after well <br /> installation, but not sooner than 24 hours following placement of the grout seal in <br /> accordance with SOP 4.0 (Appendix B). Weather conditions may increase grout set time <br /> and, consequently, further delay development. <br /> Development of wells shall be accomplished with a submersible pump, peristaltic pump, <br /> and/or bailer that shall preferably remain solely dedicated to that well. Bailers shall be <br /> used to develop wells only where the volume of water is so small that other development <br /> methods are clearly inappropriate. Pumps used for well development shall be periodically <br /> Pre-Design Investigation Work Plan 19 18.05.12 <br />