PERMFILE107682

• Permit No: C1994082A
• IBM Index Class Name: Permit File
• Doc Date: 9/30/2002
• Doc Name: Highwall Mining
• Section_Exhibit Name: Tab 12 Attachment 12-2
• Media Type: D
• Archive: Yes

1.0 GENERAL
• Seneca Coal Company (SCC) has previously auger mined at Seneca II, Yoast, and II-W. Augering
occurred in the mid- to ]ate 1980's at Seneca II and from June 2000 to December 2001 at Yoast and II
-W. Seneca proposes highwall mining at Yoast shown on Exhibit 12-1A, Operations Plan Mining.
Since the final highwall is the economic limit at which the dragline can uncover coal, other coal
extraction methodology has to be utilized.
Potentially recoverable reserves under and beyond the highwall would be lost if alternative recovery
methods are not implemented. SCC has used augenng in the past and experienced an unacceptably
low recovery rate, therefore SCC is proposing to employ a highwall miner in place of the auger. The
highwall miner is expected to have a higher in-place recovery rate and deeper seam penetration than
experienced with the auger. It is proposed to highwall mine both the ~~/adge and Wolf Creek seams.
Per regulation 4.23.2(1) (there are no highwall miner regulations, therefore auger regulations will be
followed) any auger (lghwall miner) mining associated with surface mining activities shall be
conducted to maximize recoverability of the coal reserves remaining after the surface mining activities
are completed. Therefore, highwall mining operations shall leave areas of undisturbed coal to provide
access for removal of those reserves by future underground mining activities. These undisturbed azeas
of coal shall be a minimum of 250 feet wide at any point between each group of highwall miner
openings to the full depth of the highwall miner hole. They also are to be no more than 2,500 feet
apart measured from the center of one section to the center of the next section. As shown on Exhibit
12-1A, Operations Plan Mining, SCC is proposing to highwall mine these four areas, with existing
pillars of unmined coal being left in place between each highwall mined area. SCC and Peabody
Holding Company, Inc. have looked at underground mining at the Yoast Mine and the entire
• surrounding area and have deternvr~ed that these proposed highwall miner areas would not be an ideal
location for a future underground portal. There are other areas that would be better suited for
potential portal locations.
Rule 4.23.2 (2) is being complied with already, since there are no abandoned or active underground
workings within 500 feet of the proposed auger (highwall miner) operations.
In the interest of contemporaneous reclamation for Rule 4.23.2(3), auger (highwall miner) mining will
be initiated and completed as soon as possible after the surface coal has been removed. The highwall
miner operations will be following the dragline stripping operations along the entire length of the Fnal
highwalls as shown on Exhibit 12-1A, Operations Plan Mining.
For Rules 4.23.2(4) and 4.23.2(5), special plugging procedures are not proposed for this set of auger
(highwall miner) holes. The holes will be plugged by backfilling operations as a normal pazt of the
highwall miner and reclamation operations. Drainage from these holes will not be a problem as
discussed in the Hydrology Section.
For Rule 4?3.2(6) (d), subsidence resulting from auger (highwall miner) mining to any powerlines,
buildings, or other surface facilities is not predicted occur based on the engineering design analysis
conducted by SCC. If subsidence does occur there no structures that will be highwall mined
underneath. If cracks do occur on the surface SCC will repair them. As per accordance with the
MSHA ground control plan, SCC will design pillaz strength with a minimum safety factor of 1.5.
Finally, Rule 4.23.2(7), requires that auger (highwall miner) mining shall be conducted in accordance
• with approved backfdling and grading requirements of Rule 4.14.
72-2-1 'IR-21