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JD -6 Mine Environmental Protection Plan 46 <br />10.1.2 Monitoring Well Design, Installation, Development, and Reporting <br />A professional engineer or geologist will prepare monitoring well specifications and designs. Any new <br />wells will be installed and developed by a licensed water well drilling contractor under the direct <br />supervision of Cotter or their consultants. Final well depths, screened intervals, filter pack, and other <br />relevant well construction features will be determined in the field by the supervising engineer or geologist. <br />Monitoring wells will be drilled using an air rotary rig and environmental grade thread lubricant (pipe <br />dope). Injected water or drilling foam may be used during drilling to suspend and remove cuttings from the <br />boring. The borehole diameter will be a minimum of 6.5 inches and the monitoring wells will be <br />completed using 3 -inch or 4 -inch ID, flush - threaded, stainless steel casing and 0.02 -inch (20 -slot) wire - <br />wound stainless steel screen. A 5 -ft sump (blank casing) will be installed below the screen. <br />The annulus of each shallow well will be filled with 10 -20 Colorado silica sand that is tremied into place to <br />10 ft above the screen, followed by a 10 -ft seal of bentonite chips or coated pellets. The filter pack will be <br />mechanically agitated and settled prior to installing the bentonite pellet plug. A high - solids bentonite grout <br />will be tremied into the annulus from the pellet plug seal to 20 feet below ground surface. The upper 19 ft <br />of annular space will be filled with Portland cement. The surface completion will include a locking steel <br />well cap set in a concrete pad that slopes slightly away from the well. <br />Well drilling and construction must follow standard practices for environmental monitoring wells <br />(including non - metallic environmental pipe dope on drill rods and wearing clean latex or nitrile gloves <br />while handling casing). An example monitoring well completion diagram is provided in Figure 12. <br />4148A.120927 Whetstone Associates • <br />