2025-10-31_PERMIT FILE - C1981019 ‎(5)‎

• Permit No: C1981019
• IBM Index Class Name: Permit File
• Doc Date: 10/31/2025
• Section_Exhibit Name: 2.05 Operations and Reclamation Plans
• Media Type: D
• Archive: No

RULE 2 PERMITS

Rule 2 Permits 2.05-15 Revision Date: 8/6/25
Revision No.: PR-05
Colowyo will use the explosive equation of 4.08.4 (10)(c)(i) to limit the pounds of explosive per
8ms period, similar to that shown on the Blasting Analysis Map (Map 26A). Some previous
seismographic measurements were made during blasting operations at Colowyo; the results are set
forth in Exhibit 14 - Seismographic Measurements. Although seismographic measurements have
been made in the past seismographic records will not be used to demonstrate compliance with
maximum peak particle velocities. Colowyo has chosen to continue the use of the -scaled-distance
formula in Rule 4.08.4(10) (c) (i) to demonstrate compliance with ground vibration requirements.

Colowyo will conduct airblast monitoring to ensure compliance with airblast standards. All blast
events will be monitored for airblast. On these reports Colowyo will record the name of the
company doing the monitoring, the person taking the periodic airblast reading, the name of the
person analyzing periodic airblast records, and the distance of the instrument from the blast.
Airblast monitoring will be taken from the closest dwelling to the blast area. An Instantel Inc.
MiniMate Series III , model DS-477 are maintained at the Durham Ranch and Wilson Creek
resident area. Details regarding the monitor specifications are included in Exhibit 14.

Airblast monitoring will be recorded on a seismograph report (See Figure 2.05-4) for review by
in-house personnel, agency representatives, and requesting publics. The airblast data is recorded
under the “PSPL” (Peak Sound Pressure Levels) in decibels (dB).

Additional information concerning the use of explosives is found in Section 4.08.

Disposal of Excess Spoil

Two additional pits have be developed within the permit boundary at Colowyo. One of the pits
was developed in Sections 15 and 16, south of the existing operation and the other pit, defined as
the West Pit, was developed in Section 4.

The pit in Sections 15 and 16 (Section 16 Pit) was a single seam dragline operation. To develop
the dragline operation, an initial cut must be opened near outcrop. A permanent excess spoil fill
of approximately 2 million yd3 of excess spoil was constructed to accommodate the initial cuts.
Please see Map 23 for historical mining areas of the Section 16 Pit.

The West Pit was a multiple seam operation utilizing truck/shovel and dragline methods, similar
to the East Pit operation. Approximately 45 million yd3 of box cut material was placed in an
external fill (approximately 22 million yd3) north of the box cut excavation or as backfill
(approximately 23 million yd3) in the initial pit area. Over 3 million yd3 was moved from the
external fill and backfilled within the pit limits of the East and West Pits. Approximately 19 million
yd3 of excess spoil will remain in place as a permanent excess spoil fill, consistent with applicable
provisions of Rule 4.09(3).

The West Pit Fill and Section 16 Fill are considered complete and have been mostly if not all Phase
III released. No additional excess spoil exists for the West or Section 16 Pits.
Detailed geotechnical investigations were completed for both the West Pit Fill and the Section 16
Fill by CTL/Thompson, Inc. Reports of the investigations are found in Exhibit 19. Construction