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The pH of the North Fork of the Gunnison River varies from 7.5 to 8.8 <br />according to the 2007 AHR. The average pH of the mine discharge water is <br />8.4. Therefore, the mine discharge water should not adversely affect the pH <br />in the North Fork of the Gunnison River. See the following table for addition <br />PHC analysis. <br />Leachate from the refuse piles and coal stockpile could also degrade the <br />water quality of the river. Refuse Pile #1, refuse piles #2 & 4, refuse pile #3, <br />and the coal pile will encompass 1.1, 36.4, 15.8 and 4.9 acres at full capacity <br />respectively. Based on the Upper B -Seam geochemical analysis presented <br />in Volume III, Exhibit 6, the average conductivity of the roof, interburden and <br />floor samples is 1190 and coal is 505 umhos /cm. According to Section <br />2.04.8 the average annual rainfall in the area is 18.5 inches. If all of this <br />rainfall percolated through the piles during the year, the equivalent flow would <br />be 55.6 gallons per minute. In its Cumulative Hydrologic Impact Study for the <br />North Fork of the Gunnison dated September 25, 1992, the DRMS assumed <br />infiltration through a refuse pile is the result of snowmelt and it was estimated <br />2.8 inches per year would infiltrate during a 60 day period. The equivalent <br />flow for this assumption over the 58.2 acre piles is 51.2 gallons per minute <br />over the 60 day period. The two different leachate production estimates <br />produce similar equivalent flow values. <br />Alluvial wells were installed to monitor groundwater contamination. AW-1, <br />AW -2 and AW -3 are near the coal stockpile. AW -4, AW -5 and AW -6 are <br />near the gob pile No. 1. AW -15, AW -16 and AW -17 are below Gob Pile No. <br />2. The water quality in the wells is poor to good. Following is a summary of <br />baseline conductivity measurements (umhos /cm) for the alluvial wells <br />obtained from the Annual Hydrology Reports. <br />Predicted based on conductivity measurement from an Upper B -Seam coal sample. <br />• PR -12 2.05-111 02/10 <br />�9 PPRovED <br />11�j4/10 <br />AW -1 <br />AW -2 <br />AW -3 <br />Min <br />8900 <br />1075 <br />3600 <br />Max <br />9300 <br />9700 <br />3600 <br />Average <br />9100 <br />5344 <br />3600 <br />Coal Pile Leachatel <br />505 <br />505 <br />505 <br />Predicted based on conductivity measurement from an Upper B -Seam coal sample. <br />• PR -12 2.05-111 02/10 <br />�9 PPRovED <br />11�j4/10 <br />