FLOOD00281

• County: Larimer
• Community: Greeley
• Title: Design Criteria and Construction Specifications volume 2 of 5 Storm Drainage Criteria
• Date: 10/1/1997
• Prepared For: Greeley
• Prepared By: Department of Public Works
• Floodplain - Doc Type: Educational/Technical/Reference Information

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with top latch, shall be placed at 250-foot intervals and
staggered where fence is required on both sides of the
channel.

b.

Ladder-type steps shall be installed not more than 400
feet apart on alternating sides of the channel. Bottom
rung shall be placed approximately 12 inches vertically
above the channel invert.

.

12. Maintenance Access Road

A maintenance access road shall be provided along the .entire
length of all major drainageways with a minimum passage width
of 12 feet. In some situations the City may require
maintenance access on both sides of the channel. The City
shall require the road to be surfaced with six inches of Class
2 road base or concrete slab.

5.4.4

Riprap Channel Linings (Major Drainaqewayl

The criteria for the design and construction of riprap channel
linings shall be in accordance with the USDCM, Volume 2, "Major
Drainage - Riprap." Riprap lined channels shall be designed for a
turbulence factor (Froude Number) less than 0.8 for the 100-year
flood peaks.

The riprap shall be designed and constructed in accordance with
section 10.2 of these criteria. Freeboard and maintenance access
road requirements shall be in accordance with the standards for
grass lined channels as defined in section 5.4.2 of these Criteria.

5.4.5

other Linina TVDes (Major Drainagewavl

The criteria for the design of major drainageway channels with
linings other than grass, rock, or concrete will be dependent on
the manufacturer's recommendations for the specific product. The
applicant will be required to submit the technical data in support
of the proposed material. Additional information or calculations
may be requested by the City to verify assumptions or design
criteria. The following minimum criteria will also apply.

1. Flow Velocity (Major Drainageway)

The maximum normal depth velocity will be dependent on the
construction material used; however, the Froude Number shall
be less than 0.8.

2. Freeboard (Major Drainageway)

Same as for grass lined channels (see section 5.4.2).

3. Curvature (Major Drainageway)

The center line curvature shall have a m1n1mum radius twice
the top width of the design flow but not less than 100 feet.

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