2013-02-15_REVISION - C1981020 (2)

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Prior to submittal of the central facilities area permit revision request in 1985, the planned surface disturbance related to the mine consisted of the Munger Canyon Mine haul road encompassing a 35 -acre area extending from the mouth of Munger Canyon up to the portal bench. Construction of the central facilities area, coal processing waste disposal area and interconnecting haul road and conveyor system will increase the disturbed area by 87 acres. The central facilities area will consist of a coal stockpile area, wash plant and product piles, office, shop and warehouse, storage yard, parking lot, slurry ponds, fresh water ponds, topsoil stockpile sediment pond and access road. All of these facilities will be constructed on the alluvium of East Salt Creek at the confluence of Munger Canyon. These facilities are shown on Figure 2.2 -2S of Volume VII of the application. Unconsolidated alluvial deposits were mapped by the applicant in the lower reaches of Munger Canyon. The proposed underground development waste pile and associated features are located at the edge of these deposits. Exploratory drilling in the Munger Canyon alluvium by the applicant indicates that ground water is greater than 40 feet below the surface of the valley floor. Also, the absence of mottling in test pits PT -1, TP -2, and TP -3 indicate the lack of natural subirrigation in the Munger Creek alluvium. Mean annual discharges in Munger Canyon were estimated by the applicant to range from 0.02 cfs to 0.48 cfs, with an average of 0.17 cfs. Mean monthly flows were estimated at 0 during winter months and 1 cfs maximum in May. Flow in Munger Creek occurs mainly in response to snowmelt and storm events. The Division has determined that Munger Canyon does not contain an alluvial valley floor. The depth to ground water precludes subirrigation and surface water flows are prohibitively low for use in successful irrigated agriculture without a means of retaining the flows. Grand Valley Coal Company has not supplied information with respect to the presence of an alluvial valley floor in the Big Salt Wash. Therefore, for the purpose of this findings document, the Division will assume that there is a potential alluvial valley floor in the Big Salt Wash. The following analysis will consider potential effects of the operation under this assumption: The only direct effects to the Colorado River could be from the Loma loadout which occupies a rail siding along the D &RGW Railroad right -of -way near the town of Loma, Colorado. This rail siding existed prior to the loadout, and was historically used as a loading site for sugar beets. The total disturbed area at the loadout is 2.9 acres. The loadout is roughly two miles from the Colorado River. All runoff, which only results from direct precipitation over the 2.9 acre disturbance, will be contained at the site, and no runoff will be discharged from the site. Due to the limited surface disturbance, the potential impact of the loadout on the Colorado River alluvial valley floor is insignificant. 35