PERMFILE117568

• Permit No: C1981014
• IBM Index Class Name: Permit File
• Doc Date: 8/19/2002
• Doc Name: pages 197 to 210
• Section_Exhibit Name: Exhibit 19 Small Area Exemptions
• Media Type: D
• Archive: No

same methodology and assumptions discussed in this exhibit. The input
parameters and results are shown on the SEDCAD printouts located in
Attachment 1, Sediment Pond SEDCAD Results, and summarized in Table 1.
The CN numbers used for Ponds 4 and 5 watershed were obtained from
Procedures for Determining Peak Flows in Colorado and technical Release
No. 55 (USDA-SCS, 1980). Based on soil type and vegetation cover, curve
number were determined using Table 2-2a and 2-2 d, USDA-SCS TR55, for the
following conditions:
Undisturbed
Soil Type: s
Ground Cover: <30$, Poor
Cover Type: Pinyon, Juniper
CN: 75
Reclaimed (>2 years)
Soil Type: a
Ground Cover: Fair
Cover Type: Herbaceous
CN: 71
Reclaimed (< 2 years)
Soil Type: B
Ground Cover: <30$, Poor
Cover Type: Herbaceous
CN: 80
Cover Factors (C) were determined using Table S.A.3 found in Applied
Hydrology and Sedimentology for Disturbed Areas.
Reclaimed (>2 years)
Type: No Appreciable Canopy
Ground Cover: 408
C: .10
Reclaimed (< 2 years)
Type: No Appreciable Canopy
Ground Cover: 20$
C: .20
Pond 4 employs a principal spillway that consists of a 30 inch cmp
riser, with a 30 inch cmp outlet culvert. Pond 4 employs two 30 inch
culverts as Emergency Spillways. The outlet structures are designed to
safely pass the peak discharge from the 25-year, 24-hour storm event
while maintaining 1 foot of freeboard.
Pond 5 employs a principal spillway that consists of a 30 inch cmp
riser, with a 24 inch cmp outlet culvert. Pond No. 5 employs a ripraped
trapezoidal channel as an Emergency Spillway. The outlet structure is
designed to safely pass the peak discharge from the 25-year, 24-hour
storm event while maintaining 1 foot of freeboard.
Refer to Table 1, Sedimentation Pond - Design Summary, for design
results.
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