PERMFILE40093

• Permit No: C1981022A
• IBM Index Class Name: Permit File
• Doc Date: 5/14/2003
• Section_Exhibit Name: 2.05 Minimum Requirements for Operation and Reclamation Plans
• Media Type: D
• Archive: Yes

Sazico: - 2.OS.3
controlling drainage and sediment and the use of disturbed area runoff collection ditches and
sedimentation ponds u required. Six existing sedimentation ponds, described as follows, are used to
control drainage and sediment from larger or older disturbance azeas:
A. Sedimentation Pond Al -The original sedimentation Pond A was a small pond
located near 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 area
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
area and designed a small replacement pond (Sedimentation Pond Al) to control
drainage and sediment contributions from this area.
Pond Al is a completely incised pond with a bottom elevation of 6,038 feet. Pond
interior sideslopes are designed at 2.SIi1V. The principle spillway is a 12-inch
discharge culvert with riser with the lowermost discharge 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 doting the 25-year, 24-
hour or larger storm event. Design information for the Sedimentation Pond Al is
provided in Exhibit 2.05-E3, Drainage and Sediment Control Plan, and the pond
configuration a 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 intenor sideslopes are at 3H:1 V.
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 u
illustrated by the Sedimentation Pond B Map, (Map 2.05-MSB).
G Sedimentation Pond C -Sedimentation Pond C, located at the nwuth of the first
ephemeral drainage west of Elk Creek and adjacent to the Union Pacific railroad
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 3I L1V and the concrete wall
is tied into aloes-permeability compacted soil and clay liner to m~n~m~~a 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-MSC).
D. Sedimentation Pond D -Sedimentation Pond D, located north of the Elk Creek coal
stockpile, provides drainage and sediment control for the Ells Creek Mine surface
facilities area, further up Ells Creek Pond D is a completely incised pond with a
bottom elevation of approximately 6,125 feet. Pond interior sideslopes area 3H:1V.
PR04 2.05-34 Revered August 2000