PERMFILE138571

• Permit No: C1980006
• IBM Index Class Name: Permit File
• Doc Date: 5/17/2004
• Doc Name: Postmining Drainage Permanent Impoundment Documentation
• Section_Exhibit Name: Exhibit 42B
• Media Type: D
• Archive: No

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• K = 0.28 (dav loam)
2.3 LENGTH SLOPE FACTOR ILS)
The LS factor accounts for the effects of hillslope length (L) ahd hillslope gradient (S) on erosive and
transport forces. The follo~~dng equation was used to detemvne the LS factor:
For slopes < 9%
is = (L/72.6)"' x po.ax s1n(s)+0.03)
For slopes > 9%
LS = (L 172.6)" x (16.8 x sin(s) + 0.5)
\X/here:.L =Slope length
S =Slope angle
m = 0.3 for slopes < 3%
0.4 for slopes = 4%
0.5 for slopes > >% and < 7 0%
0.6 for slopes > 7 0%
Average slope lengths and angles for the current reclaimed conditions for all three major mine
disturbance areas were determined from recent aerial topograph}• maps. Slope lengths and angles for
the premising conditions were determined from the Pre-1\7ine Topography Map (h4ap 35a) in the
Kerr Mining and Reclamation Plan document. LS factors for each sub-drainage within the three
major mine disturbance areas were determined and then averaged for each area. The closed contour
• furrows constructed during reclamation on the steeper slopes in the 720 Pit and Pit 7 areas were taken
mto account when determining representative slope lengths. LS calculations are summarized in
Attachment ], Calculation Spreadsheets.
2.4 COVER MANAGEMENT FACTOR IC)
The cover management (actor represents the effects of vegetation, management. and erosion-conuol
practices on erosion and soil loss. C factors detemvnations for the premising and reclaimed
conditions for the three major mine disturbance areas were based on cover data from the Report of
Findings- Reclamation Monitoring (ESCO Associates, ]999). C factors for various vegetation n•pes
and cover percentages a-ere determined from Table S.A.3 in Applied Ilvdrolog~~ and Sedimemologc
for Disturbed Areas. Barfield. \\" arner, and Haan. The selected C factors and their basis are
summarized be Table 7,

TABLE 9
C Factors
Area % Canopy Type % Ground C
and Hei ht Cover Factor
Mart Pit Reclaimed (Pre 1986 Reclamation) 0% G 57% 0.05
Mart Pit Premising (Alkali Sagebrush and Sagebrush- 25%/0.5m G 44 %/56 0.075
Grass) °h
720 Pit Reclaimed 11995 Reclamation) 0% W 64% .07
720 Pii Premising (Alkali Sagebrush and Sagebrush- 2596/0.5m G 44%/56 .074
Grass) %
Pit 1 Reclaimed 11996 Reclamation) 0°h W 67% .07
Pit 1 Premising (Alkali Sagebrush and Sagebrush-Grass) 25%/0.5m G 44°k/56 .079
o~
Notes: % Ground Cover includes litter and standing dead.
G -Majority of ground cover is grass
W - Ma~orit o7 round cover is broadlea7

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