2012-06-08_PERMIT FILE - C2009087A ‎(12)‎

• Permit No: C2009087A
• IBM Index Class Name: Permit File
• Doc Date: 6/8/2012
• Doc Name: DRAINAGE AND SEDIMENT CONTROL PLAN
• Section_Exhibit Name: Exhibit 2.05.3-E2 Drainage and Sediment Control Plan
• Media Type: D
• Archive: Yes

Peabody Sage Creek Mine — Drainage and Sediment Control Plan
The SEDCAD4 analysis or the channel utility sub - routine contained within SEDCAD4 was
used to design the runoff ditches and postmine channels. The design methodology used in
the channel sub - routine utility is based on the limiting permissible velocity method. If the
actual design velocity is less than the permissible velocity, the channel is stable.
Four types of design are used for runoff ditches and postmine channels at the Peabody Sage
Creek Mine:
• Earthen channels
• Vegetated channels
• Riprap channels
• Vegetated charmels with a turf reinforcement mat
Channel sections with shallow slopes or low flows are typically earthen or vegetated.
Channels with steeper slopes or higher peak flows have traditionally been stabilized with
rock riprap.
However, PSCM may construct vegetated channels with turf reinforcement matting (TRM)
material in place of rock riprap for channels that require some type of lining material. In
accordance with Rule 4.05.3, PSCM designed all operational runoff ditches and postmine
channels with a minimum freeboard of 0.3 feet.
Operational runoff ditch designs are summarized in Table 2.05.3 -E2 -5, Operational Ditch
Design Schedule; postmine channel designs are summarized in Table 2.05.3 -E2 -7,
Postmine Channel Design Schedule. The design demonstrations for the operational runoff
ditches are presented Appendix 2.05.3- E2.G -2, South Facilities Area Operational Ditch
and Culvert Designs; postmine channel design demonstrations are presented in Appendix
2.05.3 -E2.H, Postmine Channel and Culvert Designs.
4.2.1 Earthen Channel Design
The design methodology used in SEDCAD4 for earthen channels is the limiting permissible
velocity method. Permissible velocity is a function of the type of soil characteristics. If the
actual design velocity is less than the permissible velocity, the channel is stable. PSCM
assumed sediment laden water was used in the operations runoff ditch designs. Channel soil
type and channel slope are the most sensitive parameters.
4.2.2 Vegetated Channel Design
Vegetated channels tend to become unstable when flow velocities exceed five (5) feet per
second (fps). Inputs to the channel utility sub- routine for vegetated channels include the
following:
Peak Flow: the 10 -year, 24 -hour peak flow value is calculated with the hydrology
component of the SEDCAD model.
TR -O/ 2.05.3 -E2.15 Revised 04/12