2023-12-26_GENERAL DOCUMENTS - C1981044

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Page 24 of 27 plan(4.20.1(2) and 4.20.3(1)). 2. The Division has previously found that the permittee' s subsidence monitoring program complies with Rule 2.05.6(6)(c),and is designed to determine the commencement and magnitude of subsidence movements. All facilities, including private homes are identified and facilities undermined or proposed for undermining were flagged. The "E" Seam Longwall Subsidence Monitors map submitted with the semi-annual subsidence report depicts the location of monuments installed and structures monitored within the permit and adjacent area. Anticipated subsidence results are presented on Table 80,and worst case is summarized on Table 79 of the permit document. Active mining ceased in 1995 and no mining has occurred since then. XI. Operations on Alluvial Valley Floors The applicant has determined that alluvial valley floors exist along both the Yampa and the Williams Fork valleys within the permit and adjacent area. This determination is based upon the fact that flood-irrigated agricultural activities are practiced on unconsolidated streamlaid deposits along both rivers. The Division concurs with this determination. The boundary of the alluvial valley floors is shown on Map 25 of the permit application. Three alluvial valley floors have been identified: the Williams Fork alluvial valley floor,the Yampa River/Big Bottom alluvial valley floor, and the Yampa River/Round Bottom alluvial valley floor. Alluvial Valley Floor Exemption Mining operations that, in the year preceding August 3, 1977, 1)produced coal in commercial quantities and were located within or adjacent to alluvial valley floors, or 2) obtained specific permit approval from the State to conduct surface coal mining and reclamation operations within an alluvial valley floor, are exempted under Rule 2.06.8(5)(a) from the alluvial valley floor provisions prohibiting mining in or adjacent to certain alluvial valley floors. On November 12, 1980, Empire Energy Corporation, one of the previous permit holders, submitted a request to exempt their existing and proposed mining operations from these alluvial valley floor provisions. (See Exhibit 4 of the permit application.). DRMS granted the exemption. The geographical extent of the area exempted for the No. 9 Mine was determined from the No. 9 Mine Projection Map dated August 1976 (Exhibit M of the November 1980 Alluvial Valley Floor Exemption request). Surface coal mining operations conducted within the geographic extent of the area eligible for the exemption are not required to comply with the requirements of Rule 2.06.8(5)(a)(1) and(ii). Operations eligible for the exemption,however,are required to restore the essential hydrologic functions of affected alluvial valley floors as a part of the reclamation plan. Williams Fork Alluvial Valley Floor The approximate boundary of the Williams Fork Alluvial Valley Floor is shown on Map 25 of the permit application. Several hay fields exist throughout the site. These hayfields are flood irrigated. The Williams Fork Mines Prepared by: R ReiRey M.S. GISP C1981044 December 2023