2007-12-17_GENERAL DOCUMENTS - C1981020

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the following determinations have been made by the Division: AVF Determination The proposed permit area for the Munger Canyon Mine occupies parts of four drainage basins distinguishable on a topographic map. These basins include Munger Canyon, Stove Canyon, Buniger Canyon and an unnamed tributary to East Salt Creek. East Salt Creek has been determined to be an alluvial valley floor. The irrigated agriculture which exists in the East Salt Creek Valley is evidence of this conclusion. Irrigated cropland as well as areas used for grazing are shown on Figure 4.1-2 of the permit application. Just south of Munger Canyon, Stove Canyon and Buniger Canyon are sub-basins within the Big Salt Wash drainage system. Munger Canyon and the unnamed tributary are both sub-basins of the East Salt Creek drainage. Development of mine workings during the initial permit term will extend under portions of all of the above-mentioned drainage basins. The central facilities area permit revision increased the permitted area by 273.3 acres. This area will be located along East Salt Creek beginning at the mouth of Munger Canyon and extending southward approximately 1.5 miles to the proposed coal processing waste disposal area. 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 I cfs maximum in May. Flow in Munger Creek occurs mainly in response to snowmelt and storm events. 39