FLOOD04661

• County: Boulder
• Community: Boulder
• Stream Name: South Boulder Creek
• Basin: South Platte
• Title: Floodplain Analyses of South Boulder Creek at Flatiron Property
• Date: 8/12/1996
• Prepared For: University of Colorado at Boulder
• Prepared By: Love & Associates, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Project Sponsors being the UD&FCD, Boulder County and the City of Boulder. The
product of the Beck study was the publication of a document entitled Maior Drainageway
Planning - South Boulder Creek. The R.W, Beck study detennined the loo-year flood
discharge for South Boulder Creek to be approximately 5,600 cfs. The floodplain
hydraulics analyzed in this document utilized the U.S. Bureau of Reclamation (USBR)
backwater analysis model. The R.W. Beck study was one of the earliest studies
undertaken by the UD&FCD following the District's formation in 1969, At the time this
study was undertaken, the exact extent of the 100 and 5oo-year flood boundaries were
not known and only estimated in order to detennine the boundaries of the mapping
required to complete the study, At the conclusion of the work effort, the Beck study
reported that sufficient mapping to cover the resultant floodplain area was not available
and a complete delineation could not be reported accurately in the study. It is interesting
to note that the full extent of the floodplain was not shown on the mapping, yet the
narrative portion of the Beck study reported that floodwaters escape to the north and west
of the Deepe Property and flow in a north/west direction toward the Keewayden
Meadows subdivision, The volume of water escaping to the north and the exact flow
path was not clearly defined due to their lack of mapping, It should also be noted that
the Beck study was undertaken prior to the Flatiron mining operations being commenced.
Following is a quote from the Beck Study:

The area along the north and south side of the Denver-Boulder Turnpike would

have widespread shallow flooding in the event of major flows in the creek. The

possible flooding would be due in part by the construction of the turnpike. Flood

waters could spread northwest around the South Boulder Road interchange, over

the turnpike and into parts of the Keewayden Meadows area. At this point, the

flows would be west of 47th Street (sic now Foothills Parkway) bypass which

could present possible additional drainage problems.

See Figure 2 for the Beck study's 100-year floodplain delineation,

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