2023-07-14_PERMIT FILE - C1981010A

• Permit No: C1981010A
• IBM Index Class Name: Permit File
• Doc Date: 7/14/2023
• Doc Name: pgs 3-1 to 3-101
• Section_Exhibit Name: 3.0 Project Plan
• Media Type: D
• Archive: Yes

C Pit will utilize a temporary overburden stockpile, just north of the pit, for the initial boxcut material. The
pit will be divided up into approximately 3 pit sections with the first section starting on the south east side
of the pit. The first boxcut section will move approximately 4,500,000 LCY’s of material to a temporary spoil
pile. Once highwall mining of the bottom seam is complete, the adjacent pit section will be excavated to
backfill the initial boxcut so the L seam may be highwall mined. Highwall mining of the seams in the pit will
be from the bottom up. The initial boxcut dirt that was placed in the temporary overburden stockpile will be
utilized to backfill the final open pit.

In the case of Nighthawk Pit, the backfill is an integral part of the pit operation, where the pit is backfilled
from seam to seam from the bottom to the top as the coal seams in the north and south highwalls, and
potentially endwalls, are mined utilizing Highwall Mining techniques. This pit is developed in sections from
the west to the east and is backfilled as the pit progresses to the east so as to minimize out of pit spoil
placement.

Spoil is placed in a temporary spoil pile adjacent to the west of the pit and is then backfilled from the pile
for reclamation at the end of the life of the pit. The pile is designed for 7.6M LCY, although only a little over
5M BCY are expected to be placed there. Spoil swell is presented on page 3-49 of the Trapper Permit.
Swell on the re-disturbed spoils from A pit will be approximately 10%. AAI has completed a geotechnical
study to assess the global stability of the proposed spoil pile west of the pit and came to the conclusion that
overall, a combined review of the numerical modeling results indicate that the proposed spoil pile is likely
to be stable over its projected life of 4 – 6 years.

The backfilled pit is graded to approximate the pre-mined contour and blended in with the surrounding
topography. Final grading is performed along the contour except where the safety of men and equipment
may be compromised.

The area is then prepared for topsoil replacement. A dozer pulling a drag, or similarly effective equipment,
may be used for areas being reclaimed to cropland. The drag levels ridges made during recontouring to
allow a more uniform depth of topsoil to be laid down.

The topsoil is placed on the graded spoil to a predetermined depth as uniformly as is practicable.
Fertilization (croplands only) and seedbed preparations follow. The areas are then seeded. (Sections 3.5
and 3.6 discuss these reclamation operations in more detail.)

3-15d