2012-07-20_REVISION - M2004009 (9)

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Cell 3 6.4.4 Exhibit D — Mining Plan Mining has been completed in the western half of Cell 3. Overburden will be striped from the eastern half of Cell 3 and placed in the western half of Cell 3. Mining will proceed from west to east. Cell 4 Prior to mining west of Boulder Creek, a low water crossing will be constructed to allow haul trucks to access Cells 4, 5 and 6. The design for the low -water crossing, utilizing large culverts, was approved by both the USACOE and the CDRMS in 2004 as part of the original approval for this permit. A report titled, "Turnpike Mining Resource Low Water Crossing Design Report" should be contained in the file for this permit. Prior to any mining activity below the water table west of the creek, a hydraulic barrier trench will be constructed as shown on Exhibit C -2 Mine Plan Map, Sheet 1 for the purpose of hydraulically isolating the Plumb & Dailey Ditch from dewatering operations. Hydraulic Barrier Trench Construction The hydraulic barrier trench is to be constructed during the non - irrigation season when the ditch does not typically run (November- March). The plan and detail for the trench are shown on Exhibit C -2 Mine Plan Map, Sheet 1. Construction of the hydraulic barrier trench is to be completed as follows: 1) Begin excavation of a trench approximately 4 ft wide on the northeast portion of the ditch (lowest point) as shown on Exhibit C -2 Mine Plan Map, Sheet 1 and work to the south. 2) During excavation of the trench, begin dewatering as soon as water is intercepted. Excavate a low point for water to drain and keep the excavation drained. 3) Excavate all sand and gravel into haul trucks and haul to processing. This will insure backfill does not get mixed with coarse gravel. 4) Place 40 mil PVC plastic liner into the bottom of trench as shown in the hydraulic barrier detail to create an anchor by wrapping around the ditch side of the keyway approximately 2 ft X 2ft X 2ft. Backfill keyway on both sides of the anchor with native overburden (ML -CL). Do not backfill with coarse materials. 5) Backfill both sides of the PVC liner equally as backfilling proceeds upward. Following construction of the hydraulic barrier trench, overburden will be stripped from Cell 4 and stockpiled in Cell 4 as shown in Exhibit C -2 Mine Plan Map, Sheet 1. As gravel extraction progresses in Cell 4, concurrent backfilling adjacent to oil and gas structures will occur no later than two weeks following excavation, as indicated on Exhibit C -2 Mine Plan Map, Sheet 1. Turnpike Mining Resource M- 2004 - 009 -AM -2 Regular 112 Amendment