2011-06-20_PERMIT FILE - C1981041

• Permit No: C1981041
• IBM Index Class Name: Permit File
• Doc Date: 6/20/2011
• Doc Name: Soils Loss Comparison Roadside South Portal and North Decline
• Section_Exhibit Name: Tab 14 Appendix 14-12
• Media Type: D
• Archive: No

SOIL LOSS COMPARISON - NORTH DECLINE
RECLAIMED VERSUS BASELINE (ADJACENT) CONDITIONS
The following calculations are presented to determine if untreated drainage from the reclaimed North
Decline is contributing suspended solids to streamflow or runoff outside the permit area in excess of
premining levels. Ponds 7 and two sumps collect run off from the North Decline.
The baseline data for comparison are considered to be those conditions that exist in the adjacent area. The
adjacent area for vegetative cover comparison is the Greasewood reference area. The vegetation on the
reclaimed and adjacent areas are presented in detail in Cedar Creek Associates 2010 Revegetation
Evaluation and are summarized below.
Greasewood Reference Area
Baseline
Total Perennial Cover +Rock
18.9%
Perennial Cover:
Grasses, etc.
4.85%
Forbs
0.15%
Shrubs
11.25%
Trees
0.00%
Other - Rock
2.60%
Total Perennial Cover +Rock
18.85%
Litter
31.20%
Total Perennial Cover +Rock +Litte
50.1%
,Canopy Trees and Shrubs
11.3%
North Delcine
Reclaimed
Total Perennial Cover +Rock
32.4%
Perennial Cover:
Grasses, etc.
10.0%
Forts
0.0%
Shrubs
16.36/o
Trees
0.0%
Other - Rock
6.1%
Total Perennial Cover +Rock
32.4%
Litter
23.5%
Total Perennial cover+Rock+Liftei
55.9%
Ca no Trees and Shrubs
16.3%
The Universal Soil Loss Equation will be used to calculate the soil loss from the reclaimed area and
the adjacent baseline area to determine if untreated drainage from the reclaimed mine site is contributing
suspended solids in excess of premining levels. The following sediment volume calculation is prepared in
accordance with U. S. Department of Agriculture, Technical Notes, Agronomy Note #50, dated January,
1977. The tables and figures utilized in the LISLE calculations are obtained from the referenced Agronomy
Note #50.
USING THE UNIVERSAL SOIL LOSS EQUATION
R (rainfall) factors are assigned by geographical regions based on weather data furnished by the U.S.
Weather Service. R values are based on rainfall amount, time, and intensity. In the mountains, R values
were computed primarily for valley areas and have been increased to account for run -off from snow melt.
The R factor of 20 used for this calculation is derived from an iso- erodent map, presented in the referenced
Agronomy Note #50, and is the same for both the reclaimed slopes and the adjacent natural slope.
K (soil erodibility) factors are assigned to each soil series and they are used to predict the erodibility of a
soil and its tolerance to erosion in relation to specific kinds of land use and treatment. Soils having the
highest K value are the most erodible. The K value used for this calculation is picked from the U.S.
Department of Agriculture Soil Survey, Douglas Plateau Area, and is based on the soils classification;
Torriorthents. The K factor of 0.37 is the same for the adjacent and reclaimed areas.
TR -61 A14 -12 -5 03111