2025-07-30_PERMIT FILE - C1981019 (7)

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RULE 4 PERFORMANCE STANDARDS South Taylor – Rule 4, Page 7 Revision Date: 7/21/25 Revision No.: MR-267 foundations located along the ridge between Wilson and Taylor Creeks. Copies of the surveys are included in Exhibit 14, Item 4. 4.09 DISPOSAL OF EXCESS SPOIL Spoil removed from the South Taylor pit will be stockpiled as shown on Maps 45 and 20B. Colowyo expects a 20% swell of excavated materials; therefore, part of the material stockpiled in the East and West Taylor Fills will remain at the conclusion of the project as shown on Map 19. Placement will occur as described in previous sections of this volume and in Volume 1. Design of the two (East Taylor and West Taylor) fills associated with the South Taylor Mine plan are provided in Exhibit 21. The East Taylor Fill will contain approximately 26.6 million yards of temporary out- of-pit spoil and approximately 7.5 million yards of permanent out-of-pit spoil. The West Taylor Fill will contain approximately 10.9 million yards of temporary out-of-pit spoil and approximately 22.6 million yards of permanent out-of-pit spoil. Both fills will be regraded in accordance with the approved post mine topography shown on Map 19. The final configuration of the fills is designed to minimize erosion. This takes into account a number of the components of the other fill piles at the mine, which have proven successful. The final outslope will not exceed 3h:1v. Fill Name Temporary Volume Permanent Volume East Taylor Fill 26,663,608 Cubic Yards 7,511,137 Cubic Yards West Taylor Fill 10,993,667 Cubic Yards 22,609,016 Cubic Yards Designed terrace ditches will be constructed at approximately 100 foot vertical increments. Terrace ditches will be backsloped to direct runoff against the face to prevent flows from overflowing the edge of the ditch. These terrace ditches will direct surface runoff perpendicular to the face into a permanent drainage channel designed to pass safely the runoff from a 100 year, 24 hour precipitation event. Terrace ditches are shown on Map 12 and design information is provided in Exhibit 7, Item 20, Parts A and B. Reclamation, specifically topsoil replacement, seeding etc. will be implemented consistent with the Section 2.05 of the permit. CONSTRUCTION PLAN All available topsoil will be removed and either stockpiled for later use or direct haul replaced to a reclaimed area. Due to the fact that the valley fill locations are in close proximity to the initial boxcut area means the entire footprint of these fills must be stripped of topsoil. As described in further detail in this submittal under Section 2.05.3(1); “The entire seam sequence from the top overburden through to the bottom G8 seam, which resides in the area of the initial boxcut, will be placed in the valley fill locations; this will allow Colowyo enough spoil room to reach the desired mining depth.” It is anticipated the valley fill drains and associated lateral drains will be constructed as one project during the first two years of operation in the South Taylor operation for practical purposes and as a necessary step in preparation of the area for full scale mining. Channels constructed along the outside of the valley fills (perimeter relief drains) will be built immediately after the logical completion of each terrace ditch across the faces of the fills, which obviously cannot be