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1 <br />does not drain to the center drain. The perimeter solution <br />ditch invert is set at a minimum of three-ft below the crest <br />t of the berm. The pad area and the perimeter ditches and berm <br />will be double lined with a 12-inch thick lower liner of <br />amended and compacted native fine-grained soils as described <br />in Section D.7.2, and an upper liner of 60-mil HOPE. The lower <br />' liner will be placed on the compacted native <oil prepared <br />foundation. A one-ft thick layer of native sand and gravel <br />soils will be placed between the liners to act a:; a secondary <br />' recovery system. <br />' The pad area is generally sloped to drain the leach <br />solutions from the heap to the solution ponds along the central <br />' axis of the pad. Three 12-inch diameter ADS pipes will be <br />placed in a sand filled drain berm within the heap along the <br />' pad axis to route the leach solutions to the downgradient edge <br />of the pad. The perimeter ditches will be sloped l.o convey any <br />solutions which may drain to the outside of thE~ pad to the <br />' downgradient edge of the pad. A double-lined open channel is <br />provided to carry the solutions from the pad in~o the pond. <br />A two-ft thick layer of clean crushed ore will be placed <br />directly over the liner to enhance the drainage of solution <br />' from the base of the heap and to protect the liner after <br />installation during subsequent ore placement. <br />f D.7.4.2 Process Solution Ponds <br />' The leach pad and pond system has been designed as a <br />closed system which will not discharge in the evens. of a design <br />' storm and total heap draindown. <br />' The solution ponds have been sized to =ontain the <br />following volumes while maintaining a minimum of two ft of dry <br />freeboard: <br />1 <br />' D-49 <br />