PERMFILE119844

• Permit No: C1992081A
• IBM Index Class Name: Permit File
• Doc Date: 6/19/2006
• Doc Name: Small Area Exemption SEDCAD Information
• Section_Exhibit Name: Tab 12 Appendix 12-2
• Media Type: D
• Archive: Yes

•
HYDROLOGIC DOCUMENTATION
SMALL AREA EXEMPTION
RAILROAD LOOP
The following calculations demonstrate that the railroad loop meets the intention of the CDMG Regulations,
section 4.0.2(3). The analysis was conductcd on the entire 70.8 acre reclaimed site.
Runoff peak discharge and sediment calculations were performed utilizing the SEDCAD+ computer model. The
analysis was conducted using a l0-year, 24-hour storm event.
Hvdroloev Inputs
The curve numbers (CN) used were obtained from Procedures for Determining Peak Flows in Colorado and
Technical Release No. 55. Based on soil type and vegetation cover, curve numbers were determined for the
following condition.
Reclaimed
Soil Type: B (Topsoil)
Ground Cover: Good
Cover Type: Herbaceous
CN: 62
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All other hydrology inputs are shown on the attached SEDCAD+ computer printouts
SedimentoloQy In u~ts
Reclaimed
Soil Tvpe:
K factor
Average Slope
Average Slope Length
C:
P:
CP:
Hydrology Results
Peak Discharge:
Runoff Volume:
Sedimentolow Results
Sediment:
Peak Settleable Conccntra[ion:
(Topsoil)
32
20
40 ft
0.042 (no canopy, 60% ground cover)
0.6~ (moderate roughness)
0.27
0.027 cfs
0?0 ac-ft
0.3 tons
0.42 mUl
l /L -O oZ.
S ~Bn~iT~/9L Dry7E 9/~~/96