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2.05.6(3) Protection of the Hydrologic Balance <br />• an average conductivity of 4535 uhmos/cm and an average TDS of 3,168 mg/I. In order to <br />account for additional flow from the spring, it will be assumed that the spring flow equals 30 <br />gpm. The maximum measured TDS value for the mine water is 4090 mg/I. The total worst <br />case mine seepage through the coal seam outcrop is calculated above and totals 17.0 gpm. <br />The range in estimated outcrop seepage from the B-Seam and C-Seam is 1.4 to 17 gpm. <br />According to data supplied by the USGS, the annual seven day minimum flow for the North <br />Fork of the Gunnison River is 25 cfs. This low flow value occurred February 17, 1978, is for <br />the period of record from 1934 through 1995 and is measured upstream of the Town of <br />Somerset, CO. <br />The maximum TDS measurement at the upstream North Fork of the Gunnison River <br />monitoring station during 2001 was 140 my/I. The following table presents the estimated <br />affect the slide spring, mine outcrop seepage and alluvial flow will have on the quality of <br />water in the North Fork of the Gunnison River: <br />PHC North Fork of the Gunnsion River <br /> Flow m Flow cfs TDS <br />North Fork 11,220 25.0 140 <br />Slide S rin 30 0.07 3168 <br />Mine Seepage 17 0.04 4090 <br />Combined Flow 11267 25.1 154 <br />Based upon the above calculation, the slide spring, and mine seepage will not have a <br />measurable impact on the quality of water in the North Fork of the Gunnison River. <br />The First North Mains were developed near Lone Pine Gulch and springs G-26A, G-26B & <br />C, and CR-12. Mining ceased in this area at the end of 1994. Spring G-26B and G-26C are <br />south of the proposed mining area and well outside of the potential angle of draw of the <br />mine workings. Springs G-26A and CR-12 and Lone Pine Gulch are relatively close to the <br />mined area. Seven years of monitoring data collected for the annual hydrologic reports has <br />shown the mine has not had a noticeable affect on the above mentioned gulch or springs. <br />(b)(iv) The hydrological monitoring plan is presented in Section 2.04.7(1)(v) and 4.05.13. <br />Monitoring and reporting water data is discussed under Section 4.05.13. Additional infor- <br />mation concerning hydrologic impacts and mitigation measures are set forth in Section <br />2.04.7. <br />n,~ as <br />2.05-55c <br />Rev. 1 /03 <br />y PPRoveD li/14/o3 <br />