2020-03-24_PERMIT FILE - C1981019A ‎(2)‎

• Permit No: C1981019A
• IBM Index Class Name: Permit File
• Doc Date: 3/24/2020
• Type & Sequence: TR135
• Section_Exhibit Name: Rule 2 Permits -ST
• Media Type: D
• Archive: Yes

RULE 2 PERMITS
material that is removed and stockpiled by the Truck/Shovel operation to cap the regraded areas. It was
also noted through review of Exhibit 6, Item 6, that in the region of the initial boxcut area, no unsuitable
material was found in the seam sequence from the F6 coal seam to the G8 coal seam that will be removed
by the Truck/Shovel operation. 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.
In the following analysis, Colowyo has demonstrated that no Truck/Shovel spoil material will exceed the
suitability range for overburden criteria as described in Volume 1, section 2.05. This demonstration will
be completed by showing the total percentage of unsuitable material in comparison to the total amount of
suitable material in the truck/shovel sequence as it relates to the drill hole data shown in Exhibit 6, Item 6.
It was discussed with DRMS, that as long as the total percentage does not exceed 15% of the total truck
shovel sequence for each drill hole, spoil suitability will not be an issue based upon the overburden
seams.
Drill Hole 83-D3-06
Unsuitability range in feet of Truck Shovel Sequence:
SAR > 15 = N/A
Se > 0.3 = 6.7 feet
B>5.0=N/A
Sat <25 or >80 = 28.5 feet
Mo > 1.0 = 7.8 feet
Total Depth from surface to Bottom of Truck Shovel Sequence (F6) = 184.7 feet
Total Percentage of each criteria for Truck Shovel Sequence:
SAR = N/A
Se = 6.7 feet/184.7 feet = 3%
B = N/A
Sat = 28.5 feet/184.7 feet = 15%
Mo = 7.8 feet/184.7 feet = 4%
Suitability analysis for Drill Hole 83-D3-06 shows all criteria within the suitable range.
Drill Hole 83-D3-07
Unsuitability range in feet of Truck Shovel Sequence:
SAR > 15 = 7.6 feet
Se > 0.3 = 5.0 feet
B>5.0=N/A
Sat <25 or >80 = 8.4 feet
Mo > 1.0 = 15.8 feet
Total Depth from surface to Bottom of Truck Shovel Sequence (F6) = 295.1 feet
Total Percentage of each criteria for Truck Shovel Sequence:
SAR = 7.6 feet/295.1 = 3%
Se = 5.0 feet/295.1 feet = 2%
B = N/A
Sat = 8.4 feet/295.1 feet = 3%
Mo = 15.8 feet/295.1 feet = 5%
Suitability analysis for Drill Hole 83-D3-07 shows all criteria within the suitable range.
South Taylor/Lower Wilson — Rule 2, Page 69 Revision Date: 4/7/17
Revision No.: RN -07