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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 <br />have been identified in the vicinity of the New Horizon 1 and New Horizon 2 mining areas. All <br />monitoring wells installed by the permittee and domestic wells within the surrounding area are <br />shown on Map 2.04.7-1-A. Two wells are within the mine area will be affected, the Garvey well <br />(Water Right #42) and the Ernest well (Water Right #1). These wells, as well as the land in which <br />they are located, have been bought by the permittee. <br />Of the 29 water rights within the surrounding area, 27 wells have intakes too deep to be affected <br />by the pit pumping induced drawdowns in the overburden aquifer. These wells are installed in the <br />Burro Canyon Formation, which is below the Dakota coals to be mined. Significant shales separate <br />the coals from the strata of the wells. Two righted wells W-009 and W041 have intakes close to <br />the elevation of the bottom of the mine pit. The wells are located approximately 2,300 feet east of <br />New Horizon 2. At the eastern boundary of New Horizon 2, mining will only extend 10 feet <br />below the water table. Therefore, drawdown impacts to these wells are expected to be small. The <br />wells are righted for irrigation water use. This area has been mined and reclaimed over 6 years ago <br />and there has not been any problem identified with these wells. Although some data on these <br />wells is available in Attachment 1 of this section, WFC will attempt to gather some additional <br />information from a few of the nearby 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 <br />only until the coal has been removed. Following the short-term water level decline on the <br />groundwater system as a result of pumpage of groundwater inflow to the pit, a potential long-term <br />impact to the local groundwater flow is the period of time necessary for resaturation of the spoil <br />material and reestablishment of a flow gradient. Another potential impact is increased recharge <br />into the spoil from 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. Spoil material at the New Horizon 2 mine will be replaced into the mine pit areas <br />using 3 techniques: 1) cast blasting, end dumping of trucks from the spoil bench and dozing. <br />These techniques will increase permeabilities of the material in comparison to the original <br />overburden. Due to truck dumping from the spoil bench, large rock will settle near the bottom <br />of the pit and provide a permeable channel for groundwater flow. The hydraulic conductivity (K) <br />of the spoil, as measured in well GW -N27, is 40 ft/day, which is far greater than any <br />measurement made in the overburden. K values in the overburden generally range from 3.0 to 5.5 <br />ft/day. The New Horizon #1 site has had continued seasonal irrigation from the North Lateral and <br />its secondary ditch which flows immediately north of the New Horizon #1 reclaimed areas. <br />Water from this irrigation and some added precipitation have moved through the spoil and <br />saturated it until it discharges at the low point of the base of the coal which is at the Spoil Spring <br />and the Pond 001 discharge. Flow from this point fluctuates in response to the use of irrigation. It <br />July 2016 (TR -74) 2.05.6(3)-15 <br />