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2.05.6 <br />PHC North Fork of the Gunnsion River <br />TR-44 <br />ff PPRo~~ <br />s/~~~o~ <br /> Flow gpm Flow cfs Iron (ppm) Mn (ppm) <br />North Fork 11,220 25 0.21 0.09 <br />Gob Leachate Discharge 34.4 0.08 26.8 1.9 <br />Coal Pile Leachate 4.7 0.01 8.6 0.1 <br />Combined Flow 11,259.1 25.1 0.292 0.095 <br />Based upon the above calculation, if leachate from the gob and coal piles reached <br />the North Fork of the Gunnison River, it will not have a significant impact on the <br />quality of water in the river. <br />The predicted pH of the gob pile leachate and coal, based on the data presented in <br />Volume III, Tab 6, are 9.2 and 9.3 respectively. The North Fork of the Gunnison <br />River has pH values in the 8.3 range. If the entire 39.1 gpm of leachate entered the <br />River, the pH of the River would increase from 8.3 to 8.303 which is insignificant. <br />Flooded mine workings could also impact the water quality in the area. When the <br />mines are sealed they will slowly fill with water. Although no data for permeability or <br />transmissivity of the saturated portions of the coal bearing member of the Mesaverde <br />Formation are available within the permit area, the experience by others (Brooks, <br />1983) suggests the Mesaverde Formation transmits little water. Therefore, the <br />abandoned mine workings would not be expected to transmit water to the <br />surrounding strata. The quality of the water in the flooded mine workings could be <br />similar to the water in old Oliver Mine No. 1 located east of Somerset, CO which <br />mined in the D-Seam in the 1940's and 1950's. This mine is discharging water that <br />is monitored by 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 Annual <br />Hydrologic Report). The salinity characteristics of the Oliver No. 1 Mine discharge <br />are similar to the assumed quality of the mine water discharge presented above. <br />Based on the above discussion, if the mine workings fill with water and discharge <br />through the portals, the impact on the North Fork of the Gunnison River would be <br />less than or equal to the mine water discharge analysis presented above. <br />2.05 - 75i 12!06 <br />