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The volume of natural fines from Phase 3 to be replaced in the pit is 30% x 438,500 cy = 131,500 <br />cy. It is also estimated that the average silt and overburden in the Phase 3 mining area above the <br />gravel is 2.5 feet thick. Therefore, the volume to be excavated is 60,900 cy. This overburden will be <br />placed in the bottom of the Phase 1 lake as it is stripped. As fines become available from the pro- <br />cessing operation, they will be used to baclil"ill Trench #1. The total volume required to backfill this <br />trench is 23,300 cy, as described earlier. Trench backfilling will be in 12" to 18" lifts compacted to <br />90% of the maximum dry density as tested by a certified laboratory. Trench #2 will remain filled as <br />long as mining continues in Phase 3. Subtracting the 23,300 cy needed to fill Trench #1 from the <br />total fines (131,500 cy) leaves 108,200 cy to backfill the slopes of Phase 3 and fill Trench #2 at the <br />end of the mining. <br />To backfill the perimeter of the excavation (3420 ft) from a 1H:1V slope to a 3H:1V slope requires <br />61,300 cy, therefore, 108,200 - 61,300 = 46,900 cy is left over to fill Trench #2. Since only 13,068 <br />cy is needed to fill Trench #2, approximately 33,832 cy is excess material which will be used to <br />backfill in the pit. The extra fill will be used to create slopes of between 3H:1V and 6H:1V, as. <br />shown in the reclamation plan. The bottom of excavation is expected to be 4438' for a gravel zone <br />of approximately 18-21 feet thickness, the backfilling will raise the average level possibly 1.0 feet <br />to 4439'. Since the ground water level is expected to be 4448-4449', this would leave a lake of ap- <br />proximately 9.0-10.0 feet depth. Once Phase 3 is mined out, the barrier berms between Phases 1 <br />and 2 and Phases 2 and 3 will be dozed on the surface so that the surface of the berm is approxi- <br />mately the same level as the equilibrium ground water, which is 4448-4449'. The berms will also be <br />slightly excavated where they meet [he outside perimeter to a depth of 4446', so that the resulting <br />berm areas will form two wetland islands of approximately 40 feet width. These islands should be <br />excellent for wildlife habitat once the site is reclaimed. <br />Oneration Items <br />The entire reserve consists of 1,226,000 tons of sellable aggregate over an expected mine life of 6.1 <br />years. Most of the washed sand and gravel is planned to be used for asphalt. Asphalt production <br />will normally occur periodically between the months of March and November and all asphalt pro- <br />duction which occurs will be limited to the identified staging area. Maximum production for porta- <br />Gilsoni[e Pit 5/03 13 <br />