2023-12-26_GENERAL DOCUMENTS - C1981044

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Page 8 of 27 Geologic Setting The Williams Fork Mines are situated on the northeast flank of the northwest plunging Moffat Anticline. The Moffat Anticline is part of the larger-scale Axial uplift that extends northwestward across northwest Colorado to the Uinta Mountains in northeast Utah. The northeast limb of the Moffat Anticline dips northward into the Big Bottom syncline. Small-displacement gravity faults have been found in the permit area. The Williams Fork River crosses through the mine permit area and flows into the Yampa River in the northwest corner of the permit area. The Yampa River is one of the largest tributaries of the upper Colorado River system. Bedrock at the ground surface in the Williams Fork Mines permit area is a sequence of sandstones, siltstones, shales, and coals that are part of the Cretaceous-age Williams Fork Formation. The Williams Fork Formation is part of the regionally extensive Mesa Verde Group. The Williams Fork Formation is subdivided into the following three units (in ascending stratigraphic order): the lower Williams Fork,the Twentymile sandstone, and the upper Williams Fork. Approximate thicknesses are: lower Williams Fork, 840 ft.; Twentymile sandstone, 120 ft.; and upper Williams Fork, 850 ft. Unconsolidated alluvial deposits of Quaternary age fill stream drainages in the permit area and surrounding areas. The alluvium is thickest in the Yampa and Williams Fork River valleys. The coal seams formally mined at the Williams Fork Mines comprise the lower and upper units of the Williams Fork Formation exhibiting a thickness of less than 10 feet. The seams mined consisted of the P, F and E seams. Local Coal Mining History. The Williams Fork Mines were formerly operated by Empire Energy Corporation, Cyprus Empire Corporation, RAG Empire Corporation, BTU Empire Corporation, LLC. The mines were formerly known as the Eagle No. 5 and No. 9 Mines, as well as the Eagle Mine Complex. The mine site entered temporary cessation status initially when mining ceased in 1995. The mine was subsequently returned to active status as a result of limited reclamation activities occurring at the site during the period of 2008 to 2010. On June 26, 2013,MCM submitted a request to the Division to return to temporary cessation status. The Division in July 2013 approved a request for the operations return to temporary cessation status. At this time, MCM is completing reclamation of the site and therefore is currently in active status,as of a letter from Peabody Inc, dated 9 November 2016. Previous mining within the Williams Fork Mines permit area took place from the 1930's through the 1970's mining the E, C and the Hart seams. Surface Water Drainages within and adjacent to the permit area are ephemeral and generally extend south to north down the slope in a dendritic pattern. These drainages flow primarily in response to snowmelt or heavy rains eventually entering the Williams Fork River and then to its confluence with the Yampa River. Williams Fork Mines Prepared by: R ReiRey M.S. GISP C1981044 December 2023