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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 0.21 0.09 <br />Gob Leachate Dischar a 33.1 0.07 26.8 1.9 <br />Coal Pile Leachate 4.7 0.01 8.6 0.1 <br />Combined Flow 11,258 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. Three additional alluvial wells (AW-15, AW-16 & AW- <br />17) will be used to monitor the probable hydrologic consequences of the gob pile. <br />A full suite analysis of the alluvial wells will be obtained twice per year to determine <br />if the coal or gob pile leachate has an impact on the water quality in the wells. <br />The predicted pH of the gob pile leachate and coal, based on the data presented <br />in 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 34.8 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 <br />or transmissivity of the saturated portions of the coal bearing member of the <br />MesaverdeFormationareavailablewithinthepermitarea, the experiencebyothers <br />(Brooks, 1983) suggeststhe Mesaverde Formation transmits littlewater. Therefore, <br />the 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 />TR-30 2.05 - 751 - 02/04 <br />APP,eov~/, <br />3/Z3~oy <br />