2007-06-29_PERMIT FILE - C1981022A ‎(2)‎

• Permit No: C1981022A
• IBM Index Class Name: Permit File
• Doc Date: 6/29/2007
• Section_Exhibit Name: 2.05 Operation and Reclamation Plans
• Media Type: D
• Archive: Yes

Section - 2.03.5
controlling drainage and sediment and the use of disturbed area mnoff collection ditches and
• sedimentation ponds is required. Eight existing sedimentation ponds, described as follows, are used
to control drainage and sediment from larger or older disturbance areas:
A. Sedimentation Pond A] -The original sedimentation Pond A was a small pond
located neaz the coal storage silo. When the silo was replaced by the new batch
weigh loadout in conjunction with the mine facility expansion, modifications to the
existing railroad siding and trackage eliminated Pond A. Because it is a small azea
with limited drainage, the area was designated and approved as a Small Area
Exemption. As a result of drainage from water used to flush the silo after burning
coal was discovered and in order to continue to provide effective drainage and
sediment control for this area OMI reviewed the drainage considerations for this azea
and designed a small replacement pond (Sedimentation Pond A]) to control drainage
and sediment contributions from this azea.
Pond Al is a completely incised pond with a bottom elevation of 6,038 feet. Pond
interior sideslopes aze designed at 2.SH:1V. The principle spillway is a 12-inch
discharge culvert with riser with the lowermost dischazge orifice set at an elevation of
6,039 feet. The adjacent paved mine access road (elevation 6,046 feet) will serve as
an emergency spillway for any overflow from the pond during the 25-yeaz, 24hour
or larger storm event. Design information for the Sedimentation Pond AI is
provided in Exhibit 2.05-E3, Drainage and Sediment Control Plan, and the pond
configuration is illustrated by the Sedimentation Pond Al Map, (Map 2.05-MSA)
B. Sedimentation Pond B -Sedimentation Pond B, located adjacent to the main
entrance haul road, provides drainage and sediment control for the Elk Creek coal
• handling, support, and ancillary facilities area. Pond B is an incised pond in natural
ground with a bottom elevation of 6,062 feet. Pond interior sideslopes are at 3H:IV.
The pond can be dewatered either through a 4-inch gated trickle tube at elevation
6,063 feet or through an open slot emergency spillway at elevation 6,068 feet. The
designs for Pond B were reviewed in conjunction with the 1997-1998 mine
expansion and modified, as appropriate, to reflect changes in drainage areas and
conditions. Pond B was subsequently modified and expanded to provide required
additional capacity. Design information for the Sedimentation Pond B is provided in
Exhibit 2.05-E3, Drainage and Sediment Control Plan, and the pond configuration is
illustrated by the Sedimentation Pond B Map, (Map 2.05-MSB).
C. Sedimentation Pond C -Sedimentation Pond C, located at the mouth of the first
ephemeral drainage west of Elk Creek and adjacent to the Union Pacific raikoad
right-of--way, provides drainage and sediment control for the West Valley Fill coal
refuse and development waste disposal area. It is also designed to contain any
drainage from the West Valley Fill underdrain system. Pond C is an incised pond
with a bottom elevation of 6,035 feet and a 10-foot reinforced concrete wall on the
outlet side of the pond. Pond interior sideslopes are at 3H:7 V and the concrete wall
is tied into aloes-permeability compacted soil and clay liner to minimize the potential
for undercutting. The pond can be dewatered either through an 8-inch gated outlet
pipe at elevation 6,037.5 feet or through an open slot emergency spillway at elevation
6,043.5 feet. Design information for the Sedimentation Pond C is provided in
Exhibit 2.05-E3, Drainage and Sediment Control Plan, and the pond configuration is
illustrated by the Sedimentation Pond C Map, (Map 2.05-M5C).
• D. Sedimentation Pond D -Sedimentation Pond D, located north of the Elk Creek coal
stockpile, provides drainage and sediment control for the Elk Creek Mine surface
facilities area, further up Elk Creek. Pond D is a completely incised pond with a
bottom elevation of approximately 6,]25 Feet. Pond interior sideslopes area 3H:1V.
TR-43 2.05-34 Revised August 2003