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2.05.6 <br />If continuous mine discharge occurs from either the B-Seam or D-Seam, the <br />operator will construct a pipeline from the mine portals to convey mine water <br />to D Gulch, ouffall 006. The mine water will be treated in underground <br />sumps so no outside settling ponds will be required. D Gulch is a well <br />defined ephemeral channel. D Gulch is intercepted by ditch D-H1 south of <br />SH 1336 as shown on Map 21-3. Flow from Ditch D-H1 runs under the <br />railroad tracks in culvert C-H1. Flow from Culvert C-H1 travels along a <br />highway borrow ditch north of SH-133, through a highway culvert and into the <br />North Fork of the Gunnison River. The Deer Tail Ditch is piped under D- <br />Gulch and there is an undershot in D Gulch for the Fire Mountain Canal. <br />Therefore, no structures are required to keep mine water out on the irrigation <br />structures. Furthermore, D Gulch's well defined ephemeral channel, and the <br />design ditches and culverts will assure the mine water has no impact on <br />water users or the alluvial valley floor after if leaves the mine property but <br />before it enters the North Fork of the Gunnison River. The mine waterwill be <br />contained in the D Gulch channel and design ditches and culverts so it will <br />not effect or come in contact with irrigation water for adjacent lands. <br />Leachate from the refuse piles and coal stockpile could also degrade the <br />water quality of the river. The existing refuse piles, proposed refuse pile and <br />• the coal pile will encompass 2.7, 30.6, 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 <br />would be 51.6 gallons per minute. In its Cumulative Hydrologic Impact Study <br />for the North Fork of the Gunnison dated September 25, 1992, the DMG <br />assumed infiltration through a refuse pilers the result of snowmelt and it was <br />estimated 2.8 inches per year would infiltrate during a 60 day period. The <br />equivalent flow for this assumption over the 54.0 acre piles is 50.5 gallons <br />per minute over the 60 day period. The two different leachate production <br />estimates 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 />TR-45 <br />2.05 - 74 oaio7 <br />A PPRou~ <br />~l~~a~ <br />