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2.05.6 If continuous mine discharge occurs, the operator will construct a pipeline from the mine portal to convey mine water to D Gulch. The mine water will be treated in underground sumps so no outside settling ponds will be required. D Gulch is a well defined ephemeral channel that drains into the North Fork of the Gunnison River. The predominant vegetation in the ephemeral channel is oak brush. The DeerTail Ditch is piped under D-Gulch and there is an undershot in D Gulch for the Fire Mountain Canal. Therefore, no structures are required to keep mine water out on the irrigation structures. Furthermore, D Gulch's well defined ephemeral channel will assure the mine water has no impact on water users, the alluvial valley floor or prime farmland, if any, after if leaves the mine property but before it enters the North Fork of the Gunnison River. The mine water will be contained in the D Gulch channel so it will not effect or come in contact with irrigation water for adjacent lands. Leachate from the proposed refuse and coal stockpile could also degrade the water quality of the river. The proposed refuse and coal pile will encompass 5.5 and 4.9 acres at full capacity respectively. Based on the geochemical analysis presented in Volume III, Exhibit 6, the average conductivity of the roof, interburden and floor samples is 4,263 and coal is 810 umhos/cm. According to Section 2.04.8 the average annual rainfall in the area is 18.5 inches. If all of this rainfall percolated through the piles during the year, the equivalent flow would be 10 gallons per minute. In its Cumulative Hydrologic Impact Study for the North Fork of the Gunnison dated September 25, 1992, the DMG assumed infiltration through a refuse pile is the result of snowmelt and it was estimated 2.8 inches per yearwould infiltrate during a 60 day period. The equivalent flowforthis assumption over the 10.4 acre piles is 9 gallons per minute over the 60 day period. The two different leachate production estimates produce similar equivalent flow values. However, based on the estimated equivalent flow figures, leachate production and associated potential degradation is insignificant compared to the potential degradation from mine water discharge. Alluvial wells AW-1 through AW-6 were installed to monitor groundwater • contamination. AW-1, AW-2 and AW-3 are nearthe coal stockpile and AW- 4, AW-5 and AW-6 are near the gob pile. The water quality in the wells is PR-07 2.05 - 74 - 02103 APIRO~D s/,Z~o~