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6.4.4 Exhibit D - Mining Plan <br />"Turnpike Mining Resource Low Water Crossing Design Report" should be <br />contained in the file for this permit. Prior to any mining activity below the water <br />table west of the creek, a hydraulic barrier trench will be constructed as shown <br />on Exhibit C-2 Mine Plan Map, Sheet 1 for the purpose of hydraulically isolating <br />the Plumb & Dailey Ditch from dewatering operations. <br />Hydraulic Barrier Trench Construction <br />The hydraulic barrier trench is to be constructed during the non-irrigation season <br />when the ditch does not typically run (November-March). The plan and detail for <br />the trench are shown on Exhibit C-2 Mine Plan Map, Sheet 1. Construction of <br />the hydraulic barrier trench is to be completed as follows: <br />1) Begin excavation of a trench approximately 4 ft wide on the northeast <br />portion of the ditch (lowest point) as shown on Exhibit C-2 Mine Plan Map, <br />Sheet 1 and work to the south. <br />2) During excavation of the trench, begin dewatering as soon as water is <br />intercepted. Excavate a low point for water to drain and keep the <br />excavation drained. <br />3) Excavate all sand and gravel into haul trucks and haul to processing. This <br />will insure backfill does not get mixed with coarse gravel. <br />4) Place 40 mil PVC plastic liner into the bottom of trench as shown in the <br />hydraulic barrier detail to create an anchor by wrapping around the ditch <br />side of the keyway approximately 2 ft X 2ft X 2ft. Backfill keyway on both <br />sides of the anchor with native overburden (ML-CL). Do not backfill with <br />coarse materials. <br />5) Backfill both sides of the PVC liner equally as backfilling proceeds upward. <br />Following construction of the hydraulic barrier trench, overburden will be stripped <br />from Cell 3 and stockpiled in Cell 3 to the south. As gravel extraction progresses <br />in Cell 3, concurrent backfilling adjacent to oil and gas structures will occur no <br />later than two weeks following excavation, as indicated on Exhibit C-2 Mine Plan <br />Map, Sheet 1. <br />Cell 4 <br />Overburden will be stripped from Cell 4 and backfilled into Cell 3. Enough <br />overburden will be left behind to backfill adjacent to oil and gas structures. As <br />gravel extraction progresses in Cell 4, concurrent backfilling adjacent to oil and <br />gas structures will occur no later that two weeks following excavation, as <br />indicated on Exhibit C-2 Mine Plan Map, Sheet 1. The majority of Cell 4 will be <br />reclaimed as a clay-lined pond. <br />Cell 5 <br />Prior to mining Cells 5 or 6, construction of the hydraulic barrier trench on the <br />west side of the Plumb and Dailey Ditch will be completed as described in <br />Hydraulic Barrier Trench Construction. Following mining of Cell 5, stripping will