2008-05-08_PERMIT FILE - C1981018A ‎(3)‎

• Permit No: C1981018A
• IBM Index Class Name: Permit File
• Doc Date: 5/8/2008
• Section_Exhibit Name: Section V. Mine Surface Facilities Reclamation Plan
• Media Type: D
• Archive: Yes

• The reclaimed D Portal Area will be approximately 44 acres and the total area in Scullion Gulch
which drains into the White River will be 7560 acres. Thus, the reclaimed D Portal Area will be only
0.6% of the total area draining into the White River. Since the reclaimed area will be very small in
comparison to the total drainage area, the overall quality of the water reaching the White River from
Scullion Gulch during a runoff event will not be significantly affected.
An alternative to the use of contour furrowing, mulching, jute netting, and loose rock check dams
would be the construction of a large sediment pond across Scullion Gulch downstream from the D-
Portal Area. To control runoff from the reclaimed area, the pond would necessarily also control
runoff from the Scullion Gulch watershed above the reclaimed area (unless an elaborate diversion
system was constructed to bypass Scullion Gulch runoff). With a drainage area of approximately
5270 acres, the 10-year, 24-hour storm (1.6 inches) would yield about 152 acre-feet (assuming a
runoff curve number of 77). Thus, a sediment pond with a volume in excess of 160 acre-feet would
be required, resulting in a large amount of disturbance. This alternative is, therefore, not
considered feasible or desirable.
Disturbed area runoff will be controlled at the slot storage areas during final reclamation by the use
of surface roughening on contour. Mulching and loose rock check dams may also be used as
necessary to control sediment and enhance reclamation.
• V.C Diversions
A channel diversion of Scullion Gulch was required at the "D" Portal Area to provide adequate area
for parking, mine entry, and surface facilities. This diversion consists of a large diameter
corrugated-metal pipe to bypass the main Scullion Gulch flow with smaller diameter lateral
corrugated-metal pipes to bypass tributary inflows in the portal area. Pipe dimensions and design
details are shown on Maps 29, 30, 31 and 32. Details of the pre-existing channel are shown on
Maps 36, 37, 38 and 39.
Burying the Scullion Gulch drainage through the plant area has the added advantage of decreasing
the possibility of airborne coal dust or spills entering the drainage. In addition, this layout has
significantly reduced the number and size of required sedimentation ponds.
The Scullion Gulch bypass system has been designed to safely pass the peak flows resulting from
the 100-year, 24-hour rainfall event. Peak flows were determined using NRCS methods as
described in TP-149 (for watersheds with drainage areas of 2,000 acres or less) and Section 4 of
the National Engineering Handbook (for larger watersheds). Map 21 shows the drainage basins of
concern. Runoff calculations are included in Illustration 9.
The bypass system was sized using the conservation of energy principle (Bernoulli's equation) to
construct backwater curves along the culvert. Peak flows in the main and tributary channels were
assumed to reach the culvert simultaneously. Results of the backwater analysis are also included
• in Illustration 9.
Mid-Term Review 2002 (8/2002) V-15