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Access Road Runoff <br />Six rip rap lined plunge pools will be constructed on the north side of the access road, one for <br />each culvert outlet. Each plunge pool will consist of a well - graded mixture of rock sizes, with an <br />in place thickness of the rock lining at least two times as thick as the maximum stone diameter. <br />A rock check dam will be placed around each plunge pool, with a series of rock check dams <br />placed down gradient of each of the rip rap lined plunge pools. The dams will be no taller than <br />three feet, have centers that are at least six inches lower than the sides and be spaced so that the <br />base of the upstream dam is at the same elevation as the top of the next downstream dam. <br />Concrete inlet structures will be installed on the south side of the road, discharging captured <br />flows directly into the culverts, which will then flow onto the previously constructed rip rap <br />plunge pools. Straw wattles will be placed on the down gradient side of the road to capture silt <br />and sediment which may wash from the roadway surface. <br />Perimeter Silt Fencing and Earthen Berm <br />An Earthen Berm will be constructed on the east side of the site. Silt fencing will be installed <br />along the perimeter of the site which will act as a sediment barrier to minimize the migration of <br />potential sediment -laden stormwater on and off the site. The silt fencing will begin on the up <br />gradient side of the road, run south and wrap around operations area until it joins with the <br />earthen berm on the east side of the operations area. Perimeter silt fencing will begin again, on <br />the other side of the earthen berm, continue around the perimeter of the operations pad and the <br />north waste rock stockpile and end perpendicular to the road, just before the first plunge pool. <br />The silt fencing will be maintained in place throughout construction activities and will remain <br />until final stabilization has been achieved. <br />Stormwater Detention Ponds <br />Stormwater retention ponds are proposed for the operations area to capture and hold stormwater <br />runoff. All ponds are sized to hold a minimum volume of water resulting from runoff generated <br />from a 100 -year, 24 -hour storm event. A total of four stormwater retention ponds will be <br />constructed. <br />Ponds #1 and # 3 will be located on the north side of the site (see Appendix A: Figure 2). Pond <br />#I will capture potentially sediment laden stormwater runoff from the undisturbed area above the <br />mine and a short section of the upslope road grading activities entering the site. Pond #3 will <br />capture and contain flows from the operations area. Pond # 4 will capture and contain the on -site <br />stormwater runoff resulting from the stockpile development on the south side of the site, south of <br />the mine portal area. <br />Pond # 2, the ore pad pond, will be sized to contain runoff resulting from the 100 -year, 24 -hour <br />storm event. Pond #2 is located adjacent to the ore storage pad and will capture water, primarily <br />from the ore storage stockpile and pad. Pond #2 will be lined with High Density Polyethylene <br />(HDPE) to protect groundwater and retain any radioactive sediments. Collected stormwater from <br />the ore pad will be used to support mining operations and will be pumped into the mine recline. <br />Sediments from the pond will be carefully removed and placed in the ore stockpile for transport <br />5 <br />