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recharge and runoff periods occur during the snowfall and subsequent thawing times of the <br />winter and spring. Climatologic records indicate increased precipitation during the summer <br />months; however, due to increased evapotranspiration effects during this warmer period, there is <br />less impact to soil moisture levels. <br />The mine plan area is drained by ephemeral and intermittent stream systems, including (from the <br />north end of the permit area and proceeding southward) Sudduth, Williams, Bush and Bolton <br />Draws. The streams roughly parallel each other and flow to the northeast where they join with <br />the Canadian River, approximately one mile east of the permit area. <br />Near the loadout, the Illinois River has a base flow of approximately six cubic feet per second <br />(cfs) and a recorded 100-year flood discharge of 2,970 cfs. The Illinois River has its source in <br />the Never Summer Range to the southeast. The Illinois River flows in a northwest direction and <br />bypasses the loadout and the town of Walden on the southwest. Approximately one mile <br />northwest of Walden, the Michigan River merges with the Illinois River. From this confluence, <br />the Illinois River flows north to merge with the North Platte River. <br />Soils <br />Soils of the Marr Mine areas are predominantly sandy clay loam and clay textures (Table 42a in <br />the permit application package). The 720 Pit soils consist of mainly Coalmont clay, Aaberg- <br />Barishment complex clays, and areas of very minor Fluetsch sandy clay loams. The Coalmont <br />soils are classified as fine, montmorillonitic Borollic Camborthids and fine, montmorillonitic <br />orollic Paleargids, respectively. Fluetsch soils are classified as fine-loamy, mixed Borollic <br />Haplargids. All of these soils have high clay contents. The Pit 1 soils consist of Coalmont clays <br />and Cryorthents (clayey in this case), with all soils having clay percentages of 50 or more. Pit 2 <br />soils consist of Coalmont sandy clay loams and Cryorthents with surface clay overlain on sandy <br />clay subsoil. Pit 3 soils are mainly Gelkie sandy clay loams (fine-loamy, mixed Argic <br />Cryoborolls). Some minor amounts of Coalmont sandy clay loams also occur in the Pit 3 area. <br />Topsoil suitability ratings are listed in Table 43a of the permit application package. In general, <br />all soils in the Pit 1 area are rated as poor as topsoil sources because of high clay content. Pit 2 <br />soils are rated good except for Cryorthents, which are rated as poor because of the high clay <br />content (surface soil) or high SAR (subsoil). Pit 3 soils are generally rated as good topsoil <br />sources. The 720 Pit area was stripped of topsoil between 1974 and the March 20, 1981 permit <br />issuance, therefore a six-inch layer of topsoil was saved and stockpiled regardless of the <br />suitability rating. <br />Soils in the area of the loadout were not removed prior to construction, since the loadout was <br />built prior to the existence of topsoil salvaging requirements (page 780-64). Additionally, fill <br />material of a sandy loam to loamy sand texture was brought in to improve foundation material, <br />drainage and elevation, due to the proximity of the water table to the surface. Therefore, soil at <br />the site was either buried or used to construct the berm that surrounds the site to the south and <br />east. <br />10