PERMFILE135522

• Permit No: C1981019A
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 7 Archived Section 2 Part 2
• Media Type: D
• Archive: Yes

Mr. Richard Atkinson
• May 14, 1981
Page Four
Using the disturbed area percentages as listed in the preceding tabulation
weighted CS values were computed with the results being;
Streeter Gulch, CS = 0.092 x 8.6% + 0.013 x 91.4% = 0.020
Gulch A, CS = 0.092 x 15.4% + 0.013 x84.6% = 0.025
The Adequacy Review also questioned the CR factor asking how many diversions
were used in its computation. In our calculations we had used a P factor, the
equivalent of thy: CR factor, of 1.0. This is the maximum value to kle used for this
factor and corre:;ponds to no diversions in the formula CR = 1 /(n+1)2.
Using the revised sediment delivery ratios and the weighted CS factor the 3-year
sediment yields have been recomputed with the results as follows:
Sedimentation Ponds
Taylor Gulch Streeter
Tributary Gulch
Sediment yield - 3 y~~rs
• previously competed (acre-feet) 0.92
Sediment yield - 3 years
as revised (acre-•feet) 1.38
Provided sediment
volume (acre-feet) 1.78(1)
1.07
1.66
Gulch Work Loadout
A Area Area
0.58 0.52 0.32
1.17 0.62 0.74
1.85 1.26(2)12.73 1.04
(1) With principal spillway elevation revised from 6938.0 to
6939.0. No other changes needed.
(2) With principol sf~illway elevation revised from 6614.0 to
6615.0. No other changes needed.
4. Sediment Clean-out; The Adequacy Report requires that ponds have a sediment
marmar er~ins~d at the 60'/o sediment storage volume (60% of the 3 year sediment
yield) elevation. We concur with this requirement and the 60'/o elevations are
as follows:
Elevations
SedimeniationPond Invert 60% Vo 100% Vo .
Taylor Gulc~ Tributary 6935.0 6937.3 6938.4
Streeter Gulch 6581.7 6583.2 6583.8
Gulch A bbl l .0 6613.8 6614.8
• Work Area 7149.5 7149.7 7149.8
Loadout Area 6381.0 6383.9 6384.7