BOARD01263

• Board Meeting Date: 7/18/2005
• Description: Flood Section - Floodplain Designations
• Board Meetings - Doc Type: Memo

CONSENT AGENDA ITEM 2.b
Floodplain resolution number: FPR 05-586
Affected communities: Arapahoe County and City of Greenwood Village
Name of study to be formally acted on: Flood Hazard Area Delineation, Upper Goldsmith Gulch (Arapahoe
County and City of Greenwood Village, Colorado) dated April 2005.
Studied streams: Goldsmith Gulch
Technical Issues: The purpose and scope of the study is to provide local jurisdictions with a basis for management
of Upper Goldsmith Gulch floodplain and floodway through Arapahoe County and Greenwood Village to help
minimize threats from flooding to the public. Information was gathered and assembled for the existing drainage
systems including hydraulic structures, channels, and topography. Water surface profiles were defined for the 10-,
50-, 100, and SOD-year flood events along with 0.5 foot and 1.0 foot floodway determinations. Plan and profile
drawings for Goldsmith Gulch and one of its tributaries were completed for select recurrence intervals. A final report
was published to fully document the study results.
Community response: The Urban Drainage and Flood Control District (District) transmitted a letter to the CWCB
dated April 25, 2005 requesting designation and approval of the subject 100-year floodplain information. The
District Board of Directors also passed a resolution at their April 2005 meeting adopting the subject study.
Staff findings: CWCB staff has determined that the subject 100-year detailed floodplain information for Goldsmith
Gulch is in conformance with the CWCB' s rules and regulations for floodplain designation and approval. The
CWCB staff has relied on the Urban Drainage and Flood Control District and its consulting engineer to complete the
study and provide the necessary technical analyses and reviews. The CWCB therefore endorses this study as
containing the most current floodplain mapping available and urges the affected communities to utilize said study for
land use decision-making purposes.
Staff recommendation: Staff recommends that the Board: 1) designate and approve the detailed 1 DO-year floodplain
information contained in said report for Goldsmith Gulch, and 2) authorize staff to prepare a floodplain resolution to
be signed by the Director and transmitted to the Urban Drainage & Flood Control District, the City of Greenwood
Village, and Arapahoe County. This action is recommended in order to meet statutory requirements.

STAFF RECOMMENDATION SUMMARY
Resolution Number 05-585.-
Staff recommends that the Board: 1) designate and approve the 100-year detailed floodplain information contained in
said report for the South Platte River, and 2) authorize staff to prepare a floodplain resolution to be signed by the
Director and transmitted to the Urban Drainage & Flood Control District, Adams County, the City of Brighton, the
City of Thornton, and Commerce City. This action is recommended in order to meet statutory requirements.

Resolution Number 05-586.-
Staff recommends that the Board: 1) designate and approve the detailed 1 DO-year floodplain information contained in
said report for Goldsmith Gulch, and 2) authorize staff to prepare a floodplain resolution to be signed by the Director
and transmitted to the Urban Drainage & Flood Control District, the City of Greenwood Village, and Arapahoe
County. This action is recommended in order to meet statutory requirements.

Flood Protection. Water Project Planning and Financing. Stream and Lake Protection
Water Supply Protection. Conservation Planning

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