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identified in the vicinity of the New Horizon 1 and New Horizon 2 mining <br />areas. All monitoring wells installed by the permittee and domestic wells <br />within the surrounding area are shown on Map 2.04.7-1-A. Two wells within <br />the mine area will be affected, the Garvey well (Water Right #42) and the <br />Ernest well (Water Right #1). These wells, and the land in which they are <br />located, have been purchased by the permittee. <br />Of the 29 water rights within the surrounding area, 27 wells have intakes too <br />deep to be affected by the pit pumping induced drawdown in the overburden <br />aquifer. These wells are installed in the Burro Canyon Formation, which is <br />below the Dakota coals that were mined. Significant shales separate the coals <br />from the strata of the wells. Two righted wells, W-009 and W04, have intakes <br />close to the elevation of the bottom of the mine pit. The wells are located <br />t e) 11 n 1,. + . C Rr u and "' L Fl a L <br />ayproxiiTia?eI 2-YU Lee" cas of ivew HoiiZoii 4 ariu will not uc aiicC?c vy <br />the New Horizon #1 Mine Area. At the eastern boundary of New Horizon 2, <br />mining will only extend 10 feet below the water table. Therefore, drawdown <br />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 for over 6 years <br />ago and there has not been any problem identified with these wells. <br />2. Impact of spoil material on groundwater flow and recharge. The mine pit has <br />been fully reclaimed for many years in the New Horizon 1 area. A potential <br />long-term impact to the local groundwater flow is the length of time necessary <br />for resaturation of the spoil material and reestablishment of a flow gradient. <br />Another potential impact is an increased recharge into the spoil from <br />precipitation and irrigation, resulting in spoil springs developing <br />downgradient. These springs may have acid conditions and high dissolved <br />solids. <br />Spoil material at the New Horizon 1 mine has increased permeability in <br />comparison to the original overburden. The hydraulic conductivity (K) of the <br />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 <br />range from 3.0 to 5.5 ft/day. The New Horizon #1 site has had continued <br />seasonal irrigation from the North Lateral ditch and a secondary ditch that <br />flows immediately north of the New Horizon #1 reclaimed areas. Water from <br />irrigation and some added precipitation has moved through the spoil and <br />saturated it until it discharges at the low point of the base of the coal at the <br />Spoil Spring and the Pond 001 discharge. Flow from this point fluctuates in <br />response to the use of irrigation. <br />Utilizing several resources, the following recharge data has been calculated: <br />2" from rain and snowmelt, 13" from irrigation and 1" from underburden and <br />overburden recharge at the uphill spoil/overburden contact. Total long-term <br />recharge is therefore 16" per year. These predictions are approximate but <br />suffice in predicting the behavior of the groundwater in the spoil. <br />28