PERMFILE66875

• Permit No: C1981016
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: Sedimentation Control & Diversion Structure Calculations
• Section_Exhibit Name: APPENDIX XXI to Section XXI.8
• Media Type: D
• Archive: No

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SUBSTATION SEDI~IENTATIOPI POND
•
Flow Design Calculations
1. Determine drainage area (Exhibit _)
1.08 acres 100%
2. Determine weighted curve number 89 for disturbed
(Pp 2-5, SCS)(AF1C I?)(Pp 23, SCS)
3. Determine precipitation.
l0yr - - 24hr (Fig 5-7) = 1.6"
25yr - - 24hr (Fig S-6) = 1.8"
• 4. Determine volume of runoff for CN 89 (Pp 69, SC)
l0yr -- 24hr = 0.71 inches A = 1.08 acres
= 0.77 acre in
= 0.06 acre ft.
25yr -- 24hr = 0.86 inches
5. Determine Peak Discharge of runoff for CN89 (Pp18, SCS, FIG 5-lA)
25yr -- 24hr = 3.05 cfs/inch of runoff (0.86 inches) = 2.62 cfs
Pond Design from Exhibit _
1. Pond volume
• 0.11 acre ft.