PERMFILE64499

• Permit No: C1982056
• IBM Index Class Name: Permit File
• Doc Date: 10/12/2006
• Section_Exhibit Name: Exhibit 08AA Haulroad A - Drainage Designs
• Media Type: D
• Archive: No

Culvert 1
Design Parameters:
Precipitation:
Use 100-yeaz, 24-hour storm precipitation depth = 2.6 inches
Land Use:
Undisturbed area = 0.62 ac with CN = 63 (Sagebrush -Hyd. Soil Gp. C)
Road surface (gravel) = 0.58 ac with CN = 89
Peak flow = 1.05 cfs
Diameter required = 8-inch CMP minimum, with a minimum of 2 feet compacted
cover, and riprap protection at the inlet and outlet. It is recommended, however, that
culverts with a minimum diameter of the up-gradient County Road 27 culverts (36
inches) be used for the haul road culverts so that new down-gradient culverts do not
backup flow onto the haul road embankments.
Culvert 2
Design Parameters:
Precipitation:
Use 100-year, 24-hour storm precipitation depth = 2.6 inches
Land Use:
Undisturbed area = 58.8 ac with CN = 63 (Sagebrush -Hyd. Soil Gp. C)
Peak flow = 7.22 cfs
• Diameter required = 18-inch CMP minimum, with a minimum of 2 feet compacted
cover, and riprap protection at the inlet and outlet. It is recommended, however, that
culverts with a minimum diameter of the up-gradient County Road 27 culverts (36
inches) be used for the haul road culverts so that new down-gradient culverts do not
backup flow onto the haul road embankments.
Culvert 3
Design Parameters:
Precipitation:
Use 100-year, 24-hour storm precipitation depth = 2.6 inches
Land Use:
Undisturbed area = 60.0 ac with CN = 63 (Sagebrush -Hyd. Soil Gp. C)
Road surface (gravel) = 0.23 ac with CN = 89
Peak flow = 7.37 cfs
Diameter required = 18-inch CMP minimum, with a minimum of 2 feet compacted
cover, and riprap protection at the inlet and outlet. It is recommended, however, that
culverts with a minimum diameter of the up-gradient County Road 27 culverts (36
inches) be used for the haul road culverts so that new down-gradient culverts do not
back up flow onto the haul road embankments.
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