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• 2.05.6 <br />PHC North Fork of the Gunnsion River <br /> Flow m Flow cfs Iron m Mn m <br />North Fork 11,220 25 0.37 0.016 <br />Gob Leachate Dischar a 5.3 0.01 332 7.5 <br />Coal Pile Leachate 4.7 0.01 9 1 <br />Combined Flow 11 230 25.02 0.53 0.020 <br />Based upon the above calculation, if leachate from the gob and coal piles <br />reached the North Fork of the Gunnison River, it will not have a significant <br />impact on the quality of water in the river. A full suite analysis of the alluvial <br />wells will be obtained twice per year to determine 'rf the coal or gob pile <br />leachate has an impact on the water quality in the wells. <br />The predicted pH of the gob pile leachate ranges from 8.0 to 8.7 which <br />should not have an adverse effect on the North Fork of the Gunnison River <br />which has pH values in the 8.5 range. The one sample available to predict <br />• the pH of the coal leachate is 9.1 which is a little high. However, based on <br />the predicted low flow of coal pile leachate (4.7 gpm) the high pH value <br />should not adversely impact the river. <br />Flooded mine workings could also impact the water quality in the area. <br />When the mine is sealed it will slowly fill with water. Although no data for <br />permeability or transmissivity of the saturated portions of the coal bearing <br />member of the Mesaverde Formation are available within the permit area, <br />the experience by others (Brooks, 1983) suggests the Mesaverde Formation <br />transmits little water. Therefore, the abandoned mine workings would not be <br />expected to transmit water to the surrounding strata. The quality of the water <br />in the flooded mine workings could be similar to the water in old Oliver Mine <br />No. 1 located east of Somerset, CO which mined in the D-Seam in the <br />1940's and 1950's. This mine is discharging water that is monitored by <br />Oxbow Carbon & Minerals as spring 8. This "spring" water has a <br />conductivity in the range of 3,000 to 4,000 umhos/cm (ref. OCM 1994 <br />Annual Hydrologic Report). The salinity characteristics of the Oliver No. 1 <br />Mine discharge are similar to the assumed quality of the mine water <br />• discharge presented above. Based on the above discussion, if the mine <br />workings fill with water and discharge through the portals, the impact on the <br />FR-o3 2.05 - 75i - iorss <br />