2010-05-07_PERMIT FILE - C2009087A ‎(28)‎

• Permit No: C2009087A
• IBM Index Class Name: Permit File
• Doc Date: 5/7/2010
• 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
2.2 Sedimentation Calculations
The SEDCAD4 model calculates storm event sediment yield using the Revised Universal Soil Loss
Equation (RUSLE). Input parameters used in the sedimentation analysis are described in the
following sections.
2.2.1 Rainfall Factor
The Rainfall Factor, or Rainfall Erosivity Index, (R) is a measurement of the amount of erosion
caused by the rainfall event. It is directly proportional to the total storm energy times the maximum
30- minute intensity. Historically, Seneca Coal Company (SCC) used an R- factor of 30 for
sedimentology evaluations at its Seneca II, Yoast and II-W operations — this value is suitable for
bare or disturbed lands that are easily eroded. Consequently, the design evaluations for Pond 002,
as well as, the South Surface Facilities and Portal Area sumps used an R- factor value of 30.
A postmine landscape held, or approved, for bond release is characterized as being well- vegetated
and generates significantly less erosion than disturbed lands. Consequently, the postmine
demonstrations utilized an R- factor of 10, which is representative of conditions in northwest
Colorado (Renard, et al, 1997).
2.2.2 Soil Erodibility Factor
The soil erodibility factors (K) are based on historic soil survey information taken from Tab 9, Soil
• Baseline Study, of the Seneca II Mine permit (Nyenhuis, 1994). The undisturbed lands modeled in
the Pond 002 demonstration utilized an area- weighted value. Consequently, the K values for the
undisturbed area are an average representative of numerous soil series characteristics. The
following table presents the K factor values used for the sedimentology demonstrations.
TABLE 2.05.3 -E2 -2
Soil Erodibility Factor Values
Soil Characteristic
Hydrologic Soil Group
Soil Erodibility Factor
k
Undisturbed
B
0.19
Topsoil Stripped
C
0.29
Parkin Lot/Facilities Area
D
0.36
Reclaimed
B
0.24
2.2.3 Length -Slope Factor
Input parameters to determine the length -slope (LS) factor were measured from the drainage and
sediment control plan maps. The measurements are included in the SEDCAD4 design
demonstrations.
2.2.4 Control Factor
The control factor (C) is used to account for vegetative or mulch cover. The values utilized are
• shown on Table 2.05.3 -E2 -3. They were adapted from Renard et al (1997), as present in Warner et
2.05.3 -E2.8