FLOOD00385

• County: Boulder
• Community: Boulder
• Stream Name: Boulder Creek
• Title: South Boulder Creek Interim Hydrology Study
• Date: 7/1/2000
• Prepared For: Boulder County
• Prepared By: Taggart Engineering Associates, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

......
C"~TAGGART
~, ENGINEERING ASSOCIATES, INC.
2480 West 26th Avenue. Suite 340-8 . Denver, Colorado 80211 . [phone] . FAX [phone]

July 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 INTERIM HYDROLOGY STUDY,
PHASE III

Dear Mr. DeGroot:

This Phase III report presents hydrology for the entire South Boulder Creek
Watershed, with emphasis on the reach from the foothills upstream of
Highway 36 to the confluence with South Boulder Creek. 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 meet all requirements of the contract and
regulatory requirements. It should serve to reasonably portray the flood
hydrology and related general hazard in the watershed.

Our Phase I effort, completed in 1996, identified that the Flood Hazard Area
Delineation Report (FHAD, July 1986) underestimated the flow leaving South
Boulder Creek at Highway 36 and did not portray spillage paths to the west side
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 from the U.S. Army
Corps of Engineers (Corps). In Phase I we modified the Corps' Storm Water
Management Model (SWMM) 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.

After Phase II, the University of Colorado joined the effort as a sponsor. The
sponsors directed both a Hydrology Study (Phase III) and a Master Planning
(Phase IV) effort.

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