PERMFILE51446

• Permit No: C1994082
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: SEDIMENTATION STRUCTURE PON 010
• Section_Exhibit Name: TAB 13 ATTACHMENT 13-3
• Media Type: D
• Archive: No

•
watershed
No.
Flow Path
No. (Continued)
Hor. Di s[.
Ift.)
Vert. Dist.
(ft.)
Land Use
Category
TC
Ihr.)
6 5a 680 35 7 0.041
8 5h 1800 270 3 0.164
8 Sc 1400 299 1 0.333
9 1 1660 150 7 0.092
9 la 560 20 7 0.041
9 lb 320 30 3 0.014
9 lc 4120 647 6 0.193
9 ld 960 53 7 0.056
10 6a 2800 75 7 0.236
10 6b 660 322 1 0.160
10 6c 480 75 7 0.017
11 lla 1320 96 7 0.062
12 lib 1120 40 7 0.082
Sedimentology. The SEDCAD+ computer program was utilized to calculate the sediment
flowing into and through the principal spillway using the DEPOSITS portion of the program.
Sediment flow from the pond was calculated to be within the limits of the NPDES permit.
To determine the sediment loading to the pond, the Average Annual "R" Method was utilized
• to quancify the sediment storage. The amount of sediment storage is determined for a
defined length of time and is based on the design storm R, design storm sediment load,
average Annual R, and the number of years of sediment storage desired. R Ss the rainfall
erosivity factor. The equation utilized for Required Sediment Storage is:
Required Storage = (Annual R) IXYea rs) (Storm Sediment Loadl
Storm R
Annual R and the number of years are input. Storm R and Storm Sediment Load are
calculated for [he design storm by Sedcad+.
A value of 30 for [he average Annual R value and a period of one year was used. Sedcad+
determined [he required Sediment Storage for the one year period to be 2.94 ac-ft. The
amount of available sediment storage 1s 10.31 ac-ft (elevation 6765.10). Therefore, when
60 percent of the sediment storage capacity has been consummed 16.19 ac-ftl, the pond will
be cleaned out.
•
13-3-5 Revised 09/06/95