PERMFILE113133

• Permit No: C1981014
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 19 APPENDIX C SMALL AREA EXEMPTION HYDROLOGIC DOCUMENTATION
• Media Type: D
• Archive: No

•
HYDROLOGIC DOCUMENTATION
SMALL AREA EXEMPTION
SUB-STATION N0.2
The following calculations demonstrate the amount of sediment fence surface area required to
adequately handle the runoff from the sub-station no.2 area.
Runoff volume and peak discharge calculations were performed utilizing the SEDCAD+ Computer
Model consistent with the methodology previously discussed in this exhibit. The sediment fence was
designed to handle the peak discharge from a 10-year, 24-hour storm event.
1.0 Sediment Fence Desien
1.1 Hydrology InRuts
The CN numbers used
Colorado and Technical
numbers were determined
Disturbed
Soil Type:
Ground Cover:
Cover type:
CN:
Gravel
None
85
for Determining Peak Flows in
type and vegetation cover, curve
All other hydrology inputs are shown on the attached SEDCAD+ computer printouts.
l.2 Hydrology Results
Peak Discharge: 0.02 cfs
1.3 Sediment Fence Requirements
Sediment Fence Permissivity: 15 gaVmin/fts or 0.033 cfs/ft'
Required Surface Area: 0.02 cfs/0.033 cfs/ft' = 0.6 ftt
C
were obtained from Procedures
Release No.55. Based on soil
for the following condition.