Laserfiche WebLink
<br />EXHIBIT SSA <br />STREAM CHANNEL PARAMETERS AND CHANGES <br />DUE TO MININGINDUCED SUBSIDENCE <br />INTRODUCTION TO STUDY <br />Wright Water Engineers, Inc. (WWE) and Emest Pemberton, P.E.t, have determined the extent <br />to which projected subsidence will impact stream channel stability and sediment transport at <br />Mountain Coal Company's (MCC) West Elk Mine. The following text summarizes WWE's <br />approach and findings. This discussion applies to the South of Divide (SOD) permit revision <br />area, herein referred to as the study area. <br />Figure 1 shows the drainage basins of 14 streams in the vicinity of the mining areas. Each basin <br />has an identification number that will be used throughout this discussion of stream channel <br />• parameters and subsequent changes. As shown in Figure 1, Basins 4 through 6 and 26 through <br />35 are located in the Dry Fork of Minnesota Creek (Dry Fork) drainage; Basin 36, Lick Creek, is <br />a direct tributary to Minnesota Creek. Minnesota Creek is a tributary to the North Fork of the <br />Gunnison River (North Fork). Table 1 identifies which streams may be impacted by the <br />proposed mining. Due to the fact that impacts to tributaries would be maximized in the lower <br />segments of the streams, this study focuses on the lower reaches of the tributary watersheds. As <br />shown in Table 1, the mine area will underlie portions of 11 separate minor tributaries of the Dry <br />Fork and Lick Creek in the study area. A detailed discussion of the mine plan for these aeeas is <br />given in Exhibit 60B. The remaining 3 basins were determined to be outside the influence of <br />mining activities. <br />The first portion of this hydraulic and hydrologic evaluation establishes pre-mining, or baseline, <br />conditions. The second portion of this evaluation describes the potential and likely impacts of <br />mining operations on the surface drainage system and channel chazacteristics. <br />[Adjunct Scientist with WWE, Former Head of Sedimentation and River Hydraulics Section, Hydrology <br />Department, Chief Engineer and Assistant Commissioner's Office, U.S. Bureau of Reclamation. <br /> <br />