FLOOD10337 ‎(2)‎

• County: Arapahoe
• Community: Greenwood Village
• Stream Name: Upper Goldsmith Gulch
• Title: Flood Hazard Area Delineation, Upper Goldsmith Gulch
• Date: 4/1/2005
• Prepared For: Urban Drainage and Flood Control District, Arapahoe County and Greenwood Village
• Prepared By: Moser and Associates
• Floodplain - Doc Type: Floodplain Report/Masterplan

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SECTION 1 STUDY AREA
1.1 AUTHORIZATION AND SCOPE 1.2 SUMMARY OF DATA OBTAINED
On June 14, 2004 the Urban Drainage and Flood Control District (District), in joint sponsorship with Data for the study was obtained from a variety of sources and the data used in the study includes:
Arapahoe County and the City of Greenwood Village, contracted with Moser & Associates Engineering . Mapping (2-foot contours and Triangular Irregular Networks (TIN) model) for the Study Area was
(Moser) for the provision of engineering services for an Outfall Systems Planning (OSP) and Flood Hazard supplied by the District as AutoCAD electronic files. The mapping originated from the City of
Area Delineation (FHAD) Study for the Upper Goldsmith Gulch area. Specific project tasks were Greenwood Village.
performed in accordance with Agreement Number 04-03.09. . Arapahoe County supplied electronic files containing cross-section survey information and aerial
photos for a portion of Goldsmith Gulch.
The scope of this FHAD study is as follows: . The 1989 "Hydrology Study for the Goldsmith Gulch Drainage Basin" written by James c.y. Guo
1. Gather and assemble information on the existing drainage system including hydraulic structures, (1989 study) was furnished by the District along with several electronic modeling files used to
channel characteristics, and topographic information. prepare the 1989 report.
. A copy of the 1976 "Flood Hazard Area Delineation, Goldsmith Gulch and Tributaries" written by
2. Define the water surface profile and flood boundaries for the 10,50, 100, and 500-year flood events Gingery Assoc., Inc. was obtained.
and also for the 0.5 foot and 1.0 foot floodways.
The above information was used to better understand the existing drainage system and to also assist in the
3. Prepare plan and profile drawings of Goldsmith Gulch and the West Tributary showing the limits of defining the floodplain characteristics.
the 100-year floodplain and the 10-year and 100-year flood profile.
1.3 MAPPING
4. Document the study results in the FHAD Report. Mapping (2-foot contours and TIN model) for the Study Area was supplied by the District as AutoCAD
electronic files. The mapping was prepared by IntraSearch and is based on aerial photography dated
The following individuals from Moser & Associates Engineering, Inc. contributed to the determination of April 22, 1998 with revisions from photography taken April 17, 2002. The mapping horizontal datum is
the flood hazard characteristics along Goldsmith Gulch and the West Tributary. State Plane Modified NAD83 and the vertical datum is NA VD88. The aerial photography and mapping
originated from the City of Greenwood Village.
Rick Moser, P.E. Principal Engineer
Rich Ommert, P .E. Project Engineer The TIN model obtained from the District did not accurately portray the invert of the channels because of a
Teresa Patterson, P .E. Engineer lack of points defined along the channel bottom. Moser & Associates added additional vertices to the
John Yager, E.!. Engineer channel invert and then generated a new TIN model that was more representative of the actual low-flow
Rebecca Baker, E.!. Engineer channel. This TIN model was then used to evaluate the existing channel cross-sections.
Jacob Marquez Technician
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