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<br /> <br />Groundwater Impacts <br />The proposed mining and reclamation plan will require wet mining the aquifer on the east side <br />of the S. Platte River (See Exhibit C-2, Mining Plan Map). Approximately 30 acres that is <br />bounded by the S. Platte River on the west and the Fulton Ditch on the east will be mined in <br />an unlined wndition using a draglineJbackhoe. The exposed groundwater lake will exist over <br />the life of the mine. This area will serve as a silt pond for the processing operation as mining <br />progresses to the west side of the river. This silt pond will be gradually filled in by silts and <br />clays washed from the mined material. The only impact that would occur on the east side of <br />the river would be from evaporative losses from the exposed lake surface. Once mining and <br />reclamation is completed, there will be no exposed lakes left. The consumptive water losses <br />incurred during mining would be augmented by the operator in an approved substitute water <br />supply plan. There will be no impacts on the groundwater table on the east side of the river. <br />The operator proposes to install a slurry wall around the perimeter of the property west of <br />the S. Platte River prior to beginning dewatering operations. The slurry wall will prevent <br />any draw down on the groundwater table outside of the property. Quantification of the <br />"laterial and vertical" extent of the mounding or shadow effect will vary depending on <br />time of year, and return flow patterns established in the area. The vertical mounding <br />of groundwater against a slurry wall could range from I to 5 feet. The current depth <br />to groundwater in the proposed mining area ranges from between 5 to 7 feet which <br />indicates a very shallow groundwater table. Proposed monitoring wells will give better <br />field data to determine what impacts will be, but the mounding affect of the slurry wall <br />is not expected to cause any flooding of basements. The "lateral" extent of mounding <br />would be function of seasonal conditions. Generally, return flows, precipitation and <br />recharge from sources such as ditch seepage, tailwater, etc. would be expected to extend <br />between 500 to 1,000 feet beyond the slurry wall. This means that the elevated <br />groundwater levels in the aquifer would be dissipated within this distance. The shadow <br />affects of the slurry wall for this particular location are expected to be minor. The area <br />would be on the north side of the mining area on the west side of the river. Most of the <br />adjacent property downstream of the site is unlined mined gravel pits and would not <br />be adversely impacted. These pits are adjacent to the river, which would supply some <br />recharge to the area. There may be a reduction in the groundwater table of 1 to 3 feet <br />during some times of the year, but this would not be expected to adversely impact any <br />wells in the area. <br />4 <br />