FLOOD09722

• County: Boulder
• Community: Boulder
• Stream Name: Boulder Creek
• Basin: South Platte
• Title: Request for LOMR - City of Boulder
• Date: 1/1/1989
• Prepared For: Boulder County
• Prepared By: Love & Associates, Inc.
• Floodplain - Doc Type: Historic FEMA Regulatory Floodplain Information

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flood velocities across the site varied from one to four feet
per second (fps) and flood depths varied from zero to four
feet, Extensive clean-up would have been required to remove
debris fOllowing a flood,

2.4 Flood Protection Measures

The Drainage, Grading and Wetland Improvements project for
the UCBRP consists of site grading to contain floodwaters to
a limited area adjacent to Boulder Creek, This grading also
has the purpose of providing a wetland habitat for mitigation
purposes, A U.S, Army Corps of Engineers 404 Permit has been
obtained by the University for this project (Ref, 4),

Overlot grades have been raised above existing flood levels
to create safe building pods, and lowered in the vicinity of
the wetlands to allow improved conveyance of the Boulder
Creek flood waters (Fig, 7), The construction of ponds and
related vegetation within the wetlands will help increase
storage of Boulder Creek flood waters, and will increase
flood travel time through the site,

With the construction of the improvements, 100-Year flood
elevations are at or below existing floodplain elevations as
delineated in the 1983 FHAD, The wetlands area of the
UCBRP contains no habitable structures and little property
damage will occur during flooding conditions, The
construction of the wetlands, coupled with the Skunk Creek
Channel Improvements (covered in a separate LOMR) allows for
site development and minimal debris clean-up after flooding,

This study demonstrates the intent to reduce flood hazard to
the UCBRP through site improvement, Detailed construction
plans and as-built mapping of the Drainage, Grading and
Wetland Improvements are included with this submittal
(located at the end of this report package) ,

3.0 ENr.INF.F.RING METHODS

3.1 Hydrolo~ir. Analyses

Hydrologic analyses performed as part of previous studies
were used to augment this study, The hydrology was
originally prepared by the Omaha District, U.5, Army Corps of
Engineers as part of the Floodplain Information Report for
Boulder, dated 1969, This analysis was later revised by the
Corps using the EPA I s 5WMM program, and calibrated using
historical gaging records in conjunction with the UD&FCD for
their Flood Hazard Area Delineation (FHAD) Program, A
complete summary of hydrological analyses is given in that
document (Ref, 1). The results of that study revised the

Love & Associates, Inc.

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