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• foot consumptive use right on the Highline Canal which would be used to mitigate the potential 26 acre <br />foot impact on surface water right users from pit inflow drawdown. <br />3) Impact on groundwater rights. Ground water rights within the immediate region (2 mile radius) <br />around the New Horizon Mine are presented in Appendix 2.04.7-1. In all, 29 ground water rights have <br />been identified in the vicinity of the New Horizon 1 and New Horizon 2 mining areas. All monitoring <br />wells installed by the permittee and domestic wells within the surrounding area are shown on Map <br />2.04.7-1-A. Two wells are within the mine area will be affected, the Garvey well (Water Right #42) and <br />the Ernest well (Water Right #1). These wells, as well as the land in which they are located, have <br />been bought by the permittee. <br />Of the 29 water rights within the surrounding area, 27 wells have intakes too deep to be affected by <br />the pit pumping induced drawdowns in the overburden aquifer. These wells are installed in the Burro <br />Canyon Formation, which is below the Dakota coals to be mined. Significant shales separate the coals <br />from the strata of the wells. Two righted wells W-009 and W041 have intakes close to the elevation <br />of the bottom of the mine pit. The wells are located approximately 2,300 feet east of New Horizon 2. <br />At the eastern boundary of New Horizon 2, mining will only extend 10 feet below the water table. <br />Therefore, drawdown impacts to these wells are expected to be small. The wells are righted for <br />irrigation water use. This area has been mined and reclaimed over 6 years ago and there has not been <br />• any problem identified with these wells. Although some data on these wells is available in Attachment <br />1 of this section, WFC will attempt to gather some additional information from a few of the nearby <br />water supply wells to the New Horizon #2 Mine. <br />4) Impact of spoil material on groundwater flow and recharge. The mine pit will remain open only <br />until the coal has been removed. Following the short-term water level decline on the groundwater <br />system as a result of pumpage of groundwater inflow to the pit, a potential long-term impact to the <br />local groundwater flow is the period of time necessary for resaturation of the spoil material and <br />reestablishment of a flow gradient. Another potential impact is increased recharge into the spoil from <br />precipitation and irrigation, resulting in spoil springs developing downgradient. <br />Figure 2.05.6(3)-1 shows a general cross-section downgradient through the New Horizon #2 mine <br />spoil. <br />Spoil material at the New Horizon 2 mine will be replaced into the mine pit areas using 3 techniques: <br />1) cast blasting, end dumping of trucks from the spoil bench and dozing. These techniques will <br />increase permeabilities of the material in comparison to the original overburden. Due to truck dumping <br />from the spoil bench, large rock will settle near the bottom of the pit and provide a permeable channel <br />for groundwater flow. The hydraulic conductivity (K) of the spoil, as measured in well GW-N27, is 40 <br />• (Revised 6/01) 2.05.6 (3) - 20 <br />