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Colowyo Coal Company L.P. Neilson Pit 6.3.3.4 Topsoil and Overburden Topsoil was not stripped prior to the initiation of mining since mining took place directly into the outcrop of the mineral. Additionally, overburden was not removed prior to mining in the Neilson Pit. The entire outcrop is mined and will be reclaimed according to Exhibit D — Reclamation Plan. The pit does not produce any waste rock and all aggregate mined is used by Colowyo. 6.3.3. S Hydrology Geology /Topography The Neilson Pit is located in the Williams Fork Formation of the Cretaceous Mesaverde Group. The Williams Fork Formation is comprised of discordant beds /units of sandstone, siltstone and mudstone and coal seams, with an approximate thickness of 1,200 to 1,300 feet in the mine area. Deposited in a deltaic environment, the beds vary in thickness and lateral extent throughout the Neilson Pit. The sandstones tend to be very fine grained to fine grained and poorly sorted, with various amounts of silt and clay. For the siltstones and mudstones, theses units contain various amounts of finer and coarser materials. The total thickness of the deposit mined is 200 feet thick. The Williams Fork Formation conformably overlies the Iles Formation. At the top of the Iles Formation is the Trout Creek Sandstone (TCSS). The TCSS is a massive, white to light gray, very fine to fine grained, moderately well sorted sandstone with a thickness of between 50 and 70 feet. This is the only mapped continuous unit in the area of the Neilson Pit. Beneath the TCSS, the Iles Formation is comprised of sandstones, siltstones and marine shales. Two major features, the Collom Syncline and the Danforth Hills Anticline/Wilson Dome, control the geologic structure in the area of Neilson Pit. The axis of the Collom Syncline, located approximately 0.5 miles north of the north edge of the reclaimed East Pit for the Colowyo Coal Mine, trends west - northwest (approximately N60 °W) with a slight dip in the axis to the west - northwest. The Collom Syncline is sub - parallel to the Axial Anticline on the north and the Danforth Hills Anticline on the south. The Collom Syncline is asymmetrical, with the north flank of the syncline steeply dipping (20 ° -40 °) to the south - southwest. The south flank dips to the north- northeast at around 10 ° ±5 °. The Neilson Pit is located on the south flank of the Collom Syncline. Topographically, the mine is located on a topographic high, bordered on the east and west by deeply incised valleys. These valleys are Good Spring Creek and Wilson Creek, on the east and west respectively. The valleys slope from south to north, similar to the topographic slope at the Neilson Pit. Hydrology The Neilson Pit is located on both a topographic and structural high. Thus, these highs cause the mined unit of the Neilson Pit to be above any significant recharge source, e.g., surface water. This is because the bottom of the pit is at an elevation higher than the 4