REV92302

• Permit No: C1982056
• IBM Index Class Name: Revision
• Doc Date: 5/29/2007
• Doc Name: Supplement Information
• From: Twentymile Coal Company
• To: DRMS
• Type & Sequence: TR60
• Media Type: D
• Archive: No

Paa6ody
Twentymile Coal
29575 Routt County Road 27
Oak Creek, CO 80467
May 24, 2007
Mr. Byron Walker, Environmental Protection Specialist
Division of Reclamation, Mining, and Safety
1313 Sherman Street, Room 215
Denver, Colorado 80203
[phone]
RECEIVED
MAY 2 g 2007
Division of Reclamation,
Mining and Safety
RE: Twentymile Coal Company -Foidel Creek Mine (Permit No. C-82-056), Technical
Revision (TR07-60) for New Thickener Underflow Lines and Associated Ancillary
Facilities -Supplemental Information
Deaz Mr. Walker:
On May 1, 2007, Twentymile Coal Company (TCC) submitted a Technical Revision application
(TR07-60) for installation, operation, and reclamation of a vivo new Thickener Underflow Lines and
associated ancillary facilities. The original TR application contemplated two possible options for
installation of the thickener underflow pipeline under Foidel Creek, subject to site conditions at the
time of installation, construction feasibility, and contractor availability. Further review indicates that
the environmentally preferable alternative of boring or jacking the pipelines under Foidel Creek and
the existing railroad spur is feasible, and will be utilized for pipeline installation at the creek crossing.
In addition, a slight shift in the location of the pipeline crossing allows installation of the pipelines in a
previously disturbed area, beneath the existing Foidel Creek culvert crossing for Mine Haulroad B-2,
essentially eliminating any new disturbance within the Foidel Creek floodplain or buffer zone azeas,
and the associated need for temporary diversion of Foidel Creek flows. The two pits required for
installation of the creek crossing will be excavated within existing disturbance azeas on the edge of
Haulroad B-2 (south end of creek crossing) and within the existing drainage ditch on the north side of
the existing rail-bed (north end of creek crossing).
It is anticipated that pipeline installation will occur during the dry summer period of June through
August, however, during pipeline installation activities, drainage and sediment control for construction
disturbance activities will be provided by installation of staked straw wattles along the downgradient
mazgins of disturbance areas. Pipeline installation activities will include backfilling, grading, and
stabilization of construction disturbance areas including all pits, trenches, and associated work areas.
Excavations will be slightly overfilled to allow for settlement, windrowed soil materials will be
redistributed over disturbed azeas, and these areas will be seeded with TCC's approved quick-growing
temporary stabilization seed mixture. For steep slope areas, staked straw wattles will be placed on
contour to limit overland flow and control sediment. Temporary drainage and sediment control
measures will remain in-place until vegetation is sufficiently well-established to effectively control
runoff, erosion, and sediment loss. Longer-term drainage and sediment control for the minor
associated structures, including the Thickener Borehole and any intermediate manholes, will be
provided by Alternative Sediment Controls (ABC's) including berms, wattles, vegetative filters, or
combinations of these methods.