FLOOD03253

• County: Boulder
• Community: Boulder
• Stream Name: South Boulder Creek
• Basin: South Platte
• Title: South Boulder Creek Draft Hydrology Study Phase III
• Date: 2/10/2000
• Prepared For: UDFCD
• Prepared By: Taggart Engineering Associates, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

.

r."~ TAGGART
~-' ENGINEERING ASSOCIATES, INC,
2480 West 26th Avenue. Suite 340-8 . Denver, Colorado 80211 . (3D3} 455-3600 . FAX [phone]

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February 10, 2000

Mr. Bill DeGroot
Chief, Floodplain Management
Urban Drainage and Flood Control District
2480 West 26th Avenue, Suite 156.B
Denver, CO 80211

RE: SOUTH BOULDER CREEK DRAFT HYDROLOGY STUDY,
PHASE III

Dear Mr. DeGroot:

This Phase III report presents draft hydrology for the entire South Boulder Creek
Watershed, with emphasis on the reach from the foothills above Highway 36 to
the confluence with South Boulder Creek. The intent of this report is to solicit
reviews, corrections, and suggestions by technical experts and the sponsors. At
your direction we will then incorporate agreed upon modifications and issue a
"final" report which will then be a collaborative document as much as possible.
This document was prepared in accordance with appropriate City, County, Urban
Drainage and Flood Control District (UDFCD), Colorado Water Conservation Board
(CWCB), and Federal Emergency Management Agency (FEMA) requirements. We
believe this report and the hydrology model meets all requirements of the contract
and regulatory requirements. It should serve to reasonably portray the hydrology
and flood hazard in the watershed. Certain refinements are probably appropriate,
as discussed herein.

Our Phase I effort completed in 1996, identified that the Flood Hazard Area
Delineation Report (FHAD) underestimated the flow leaving South Boulder Creek
at Highway 36 ~nd did not portray spillage paths to the west sidp. of the valley,
particularly along Foothills Parkway. The Phase II report, submitted in 1997,
provided an initial reconnaissance of the overflow routes and approximate flows
of the West Valley Overflow north of Highway 36 to the area of the Wellman
Ditch.

We obtained and reviewed additional hydrology information by the U.S. Army
Corps of Engineers (Corps). In Phase I we modified the Corps' Storm Water
Management Model (SWMMj model to better reflect the Viele watershed and its
outfall channel to South Boulder Creek. In Phase II we refined the SWMM model
detail downstream of Highway 36 in order to identify significant flow paths and
approximate discharges in that area.

Hydrology. Hydraulics. Sediment Transport .
Civil Engineering for Flood Control. Waterways. Water Supply and Parks.
Environmental Mitigation. ForenSIC Services.