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1 12 APPLICATION PAGE 8 OF 35 <br />• (2) Next, the overburden in the excavation pit area will be removed. The <br />overburden high wall area is anticipated to be approximately 400-If long and <br />12-ft tall. The overburden will typically be hauled and used as backfill material <br />behind the active sand and gravel high wall area. However, until a high wall <br />area is constructed, the overburden material will need to be temporary <br />stockpiled until area has been mined and is ready for backfill. Overburden <br />removal operations will occur slightly ahead of the sand and gravel high wall <br />area to minimize overburden from sloughing off into active sand and gravel <br />high wall area. <br />(3) The sand and gravel materials to be mined are expected to be located at and <br />below the groundwater table elevation. Therefore, in order to mine the sand <br />and gravel and place the backfill material in the previously mined areas, the <br />excavation pit area will need to be dewatered. Portable pumps will be used to <br />dewater this area, and they will be moved as the mining progresses across the <br />permit area. The pumps will discharge the groundwater into a settlement pond <br />that will be located near the southwest corner of each of the respective mining <br />areas. Once the groundwater enters the settlement pond, it will percolate and <br />recharge back into the water table or discharge to the 33 Road Ditch located <br />west of the project site. <br />(4) Mining for sand and gravel will lag slightly behind the overburden high wall. The <br />height of the sand and gravel high wall will be approximately 400-ft long and <br />12-ft tall. As the sand and gravel material is removed, it will be conveyed or <br />trucked out of the pit for further processing. The sand and gravel high wall <br />located within 100-ft of the north, south or west Permit boundary areas, and all <br />mining below the water table shall occur at a 3:1 max slope to minimize the <br />potential of a landslide large enough to damage offsite structures. <br />(5) Once the area has been mined for the sand and gravel, overburden material <br />removed in front of the active sand and gravel high wall area (and imported <br />inert fill material) will be placed. The backfilling operations will lag behind the <br />active sand and gravel high wall area. The backfill will be placed such that <br />adequate compaction of the fill material can take place. The may be <br />accomplished by backfilling the area in lifts, or by placing the fill on a gradual <br />slope such that equipment have safe access to place and compact the fill <br />material. Backfill materials will not be placed underwater. <br />(6) Site reclamation in accordance with the reclamation plan section. <br />(b) Earthmoving <br />Initial earthmoving on the project site will be performed to ensure all drainage will <br />be contained within the project site. Mining excavation will create two ponds. The <br />ponds will be formed upon removal of sand and gravel below the ground water <br />elevation. When ground water is encountered, the water must be pumped so that <br />the sand and gravel material can be removed and the area can be reclaimed. <br />The pumped ground water will be conveyed via surface drainage swales toward <br />. settlement ponds located at the southwest corner of each of the respective mining <br />areas.