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

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mapping) and the previous hydraulic analysis of flow splits and floodplains by
TEA and others.

4. Simulating the dual stream character of the floodplain downstream of
Highway 93.

5. Calibrating the model to the 1969 flood or at least comparing for
reasonableness, and spot checking major basin runoff using the UDFCD
Colorado Unit Hydrograph Procedure (CUHP) for reasonableness. Review of
the Eldorado stream gage data is also included, but efforts to review the
Eldorado gage data and calibrate to the 1969 flood are limited.

6. Preparing basin and model maps, and model documentation such as
representative hydrographs and discharge profiles.

7. Agency contact (Corps, USGS, CWCB, Natural Resource Conservation
Service (NRCS), City of Boulder, Boulder County, Denver Water, and U.S.
Forest Service (USFS)).

8. General characterization of flow timing, magnitude, and distribution in the
South Boulder Creek floodplain below Highway 93.

9. Specific review and effort to comply with CWCB and FEMA requirements.

10. Summary report and technical appendices.

What is not required: snowmelt hydrology, infiltration testing, reservoir operations
or storage statistical analysis, long term rainfall runoff modeling or statistical
analysis using NWS or other long term rainfall records, extensive field surveys,
floodplain storage routing, rain gage statistical analysis, hydraulics and split flow
analysis beyond specific limits, floodplain hydraulic modeling or mapping.

MODIFICATION OR DEPARTURES FROM SCOPE

As with any study, the investigation raises facts and issues which inevitably lead to
modification or departure from the scope. Some of these are as follows:

1. Rainfall. Contacts with NOAA were generally helpful. We attempted to get
better guidance on arranging the temporal (time) pattern of the critical
rainfall, however two of the references indicated didn't lead to fruitful
results. UDFCD provided consultation with John Henz, meteorologist, which
provided helpful guidance. We attempted to use a storm pattern he
suggested, but were unable to satisfy NOAA statistics. Henz suggested
providing a custom rainfall analysis of the UDFCD network and providing