FLOOD01407

• Designation Number: 301
• County: Arapahoe
• Community: Unincorporated Arapahoe County
• Stream Name: Piney Creek Tributaries
• Title: Flood Hazard Area Delineation - Piney Creek Tributaries
• Date: 4/1/1989
• Designation Date: 7/1/1989
• Floodplain - Doc Type: Floodplain Report/Masterplan

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PINEY CREEK TRIBUTARIES FLOOD HAZARD AREA DELINEATTON

Drainagewa,y

AU'l'HORIZATION
This report was authorized and contracted through the Urban
Drainage & Flood Control District in order to address the
objectives of the established work program for 1987 (Resolution
No.69, Series of 1982) which includes master planning and the
delineation of flood hazard areas. The report was prepared by
Greenhorne & O'Mara, Inc. for the District in partial fulfillment
of Agreement No. 87-09.09. Tne study was jointly funded by the
Urban Drainage & Flood Control District and Arapahoe County.

Tenderfoot
Gulch

Sampson
Gulch

Saddle Rock
Ranches
Gulch

South Saddle
Rock Trib.

SCOPE OF WORK
This study consists of !loodplain analyses along five
drairiageways, totalling 12.5 miles, in the Piney Creek basin in
Arapahoe and Douglas CountieS. The scope of work was prepared
under the current format of the District's Flood Hazard Area
Delineation reports and includes the study reaches as described
in Table 1.

Antelope
Creek

Table 1
STUDY REACHES ANALYZED

Reach Descri.ption Length

From Piney Cree~ upstream approximately 1.43 mi.

7,500 feet to a point 3,60 feet north
of the south section line of Sec 17,
T6S, R65W

From Piney Cree~ upstream approximately 3.14 mi.
16,600 feet to ~he east UD&FCD boundary

From Piney Cree~ upstream approximately 3.40 mi.
18,000 feet to a point 1700 feet north
of the south section line of Sec 1, T6S,
R66W

From Saddle Roc~ Ranches Gulch upstream 0.51 mi.
approximately 2/700 feet to a point 2,600
feet north of the south section line of
Sec 1. T6S, R66W

From Piney Cree~ upstream approximately 4.00 mi.
21,000 feet to a point located 500 feet
north of the south section line of Sec 2,
T6S, R66W

Water surface profiles were computed for the 10-, 50- and 100-
year flood events for each of the defined reaches. The flood
profiles and flooded areas presented are based on hydrologic
analyses assuming fully developed basin conditions and the
existing stream channel configurations.

and the corresponding floodplain are often altered by road and
bridge construction, floodplain development, flood control
improvements, or natural processes. Prior to utilization of
this report for planning or design purposes, the user is
advised to contact the Urban Drainage & Flood Control District,
. Arapahoe County, or the City of Aurora to determine if the
information in this report has been amended.

A floodway was also computed ~o designate those areas that must
be kept free of encroachment to convey the 100-year flood event
along each of the drainageways. Floodways are defined as high
hazard floodplain areas that should be kept free from
encroachment to pass large flood events without serious damage.
In this case, encroachment into the floodplain was considered
such that the elevation of the energy grade line increased no

The Flood Hazard Area Maps included in this report provide'
delineations of the 100-year flood boundaries. Water surface
profiles have been plotted for the 10- and 100-year flood
events and are presented along with the corresponding floodplain
maps at the end of the report.

The flood profiles and floodplain delineations are based on
existing floodplain and channel conditions. Flood elevations