FLOOD05827

• County: Boulder
• Community: Boulder
• Stream Name: Boulder Creek
• Basin: South Platte
• Title: Boulder Creek Phase B
• Date: 12/1/1979
• Prepared For: Boulder
• Prepared By: UDFCD
• Floodplain - Doc Type: Floodplain Report/Masterplan

A steel cable debris catchment would be provided upstream of the Justice
Center.

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in conjunction with this Phase B Preliminary Design Report, Drs. Daryl

Simons and Ruh-Ming Li of Water and Environment Consultants, Inc., noted

authorities on river mechanics, erosion and sedimentation, and river

systems analysis, prepared two reports entitled "Erosion, Sedimentation

and Debris Analysis of Proposed Boulder Creek Floodway" and "Erosion,

Sedimentation and Debris Analysis of Do Nothing Condition, Boulder
Creek" in 1979. These reports document the analysis of the impact of
sediment and debris on existing conditions and on the proposed floodway

using state-of-the-art technology and procedures; coupled with Drs.

Simonis and Li's extensive experience.

construction to prevent scour. A hiker-biker path wouid be provided for

general recreational use. All pedestrian bridges are to be designed to

swing away from the main flow area and yet be securely anchored to

prevent being swept away to compound potential debris problems. A low

flow channel designed to convey 300 cubic feet per second (c.f.s.) is to
be provided.

PLAN I I EXCAVATED FLOOOWAY APPROACH BETWEEN CANYON MOUTH AND l7TH

STREET ALL REACHES

The design criteria for the reach between the Canyon Mouth and l7th

Street is to provide an excavated floodway capable of conveying the

estimated 100-year discharge of 12,000 c.f.s. at an average velocity of

less than 12 feet per second.

CANYON MOUTH TO 6TH STREET
The area upstream of Eben Fine Park would not be modified. A debris
catchment basin would be provided in Eben Fine Park by an arrangement of
securely anchored steel cables designed to direct debris towards the
overbanks. The proposed debris catchment would consist of two steel

cables anchored to a common point near the main channel that would

extend downstream to the north and south overbanks at Boulder Creek. In

plan view, the cables would form a vee point upstream.

The following is a summary of the proposed master plan developed under

this agreement and described in detail in this report:

The apartment house at 299 Arapahoe Road would be removed to eliminate

an existing flood hazard and provide an improved flow transition.

All impacted areas would be restored and landscaped to create a parklike

natural setting. Mounds would be provided to retain and protect exist-

ing vegetation wherever possible. Special attention would be directed

towards assuring that the main channel is adequately armored after

In the reach between the apartment house at 299 Arapahoe Road and 6th

Street the north overbank would be excavated to provide increased flood
conveyance.

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