2016-10-20_REVISION - C1981018 ‎(4)‎

• Permit No: C1981018
• IBM Index Class Name: Revision
• Doc Date: 10/20/2016
• Doc Name: Adequacy Review - Preliminary
• From: Blue Mountain Energy
• To: DRMS
• Type & Sequence: TR70
• Email Name: CCW
• Email Name: JRS
• Media Type: D
• Archive: No

DESERADO MINE
BLUE MOUNTAIN ENERGY
3607 County Rd. 65
Rangely, CO 81648
[phone]
fax [phone]
October 20, 2016
Mr. Clayton Wein
Division of Reclamation, Mining and Safety
1313 Sherman Street, Room 215
Denver, CO 80203
RE: Technical Revision #70 — B -Seam Dewatering System #2
Response to Preliminary Adequacy Review
Deserado Mine — Permit No. C-1981-018
Dear Clayton:
The following is our response to the Adequacy Review questions received today for
Technical Revision (TR -70) addressing the addition of a second system to dewater the 13 -
seam:
1.) The dewatering system will most likely be subsided. However, the cover in this
area is over 1300 feet thick without massive sandstone horizons near the surface. This will
help minimize any impact from the subsidence in this area. We will be closely monitoring
the effects of subsidence as we mine under the ponds as well as when we pass under any
other part of our facilities.
2.) The riprap thickness design is consistent with the "Design of Roadside Channels
with Flexible Lining, HEC 15, September 2005" from the U.S. Department of
Transportation. This assumes that the thickness of the riprap lining is equal the diameter
of the largest rock size in the gradations. Since these channels are hand placed, any
oversized rock can be positioned or removed to satisfy this requirement within the
specified 1.5 times the thickness of the D50.
3.) We understand this can get somewhat confusing. First, the new dewatering system
(ponds, ditches, etc.) covers an estimated 10.85 acres. 1.0 acre was previously approved
for disturbance under MR169 for a net increase of 9.85 acres to `B -Seam Dewatering
Systems' and TOTAL. We also moved acres disturbed for SH -4 (MR164 and MR167)
into the category `B -Seam Dewatering Systems' for an additional increase of 0.85 acres for
a total increase to this category of 10.70 acres. The category of `Degas, development
drilling, etc.' was decreased by 0.85 acres for the removal of SH -4. The TOTAL was
increased by the net increase in disturbance of 9.85 acres.