FLOOD02134

• County: Statewide
• Community: All
• Stream Name: All
• Basin: South Platte
• Title: ASFPM: Managing for Sustainable Watersheds
• Date: 9/30/1998
• Prepared For: ASFPM
• Prepared By: ASFPM
• Floodplain - Doc Type: Educational/Technical/Reference Information

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REHABILITATING A STORMWATER SYSTEM IN A PARTIALLY DEVELOPED WATERSHED
Craig C. Houdeshell, P.E., GEl Consultants, Inc., and Bruce Perryman, P.E., AVI, pc
1998 CASFM Conference, September 30 - October 2, 1998

ABSTRACT

The City of Cheyenne, Wyoming, is experiencing growth along its northern perimeter. As this
development continues, the existing stormwater system in the area of the Dry Creek drainage basin has
become inadequate. Some of the homes in these neighborhoods have a history of flooding during the
past 25 years. In the intervening years since the development began, the strategies involving the
relationship of the watershed, the environment, human use, and the approach to stormwater
management have changed. The city's master plan, written in 1988, called for carrying the water through
the system and away from the area as quickly as possible. The suggested design for accomplishing this
was to build a large-diameter concrete pipe or concrete-lined channel without use of detention facilities.

GEl Consultants, Inc., reviewed the city's stormwater design criteria, written in 1985, 3 years prior to
completion of the master plan. The criteria call for the use of detention ponds. Thus, the plan to build a
concrete pipeline or other conveyance was not in compliance with the city's criteria. The original design
was revisited and numerous alternatives were studied, and community input was solicited. The design
team recommended a change to the original project scope, which included detention and a relatively
smaller diameter pipeline. Storing the water in a detention pond will provide a significant savings over the
cost of a large-diameter concrete pipe and tunnel, as originally planned. This change will also provide the
added feature of community open space and a new park, not considered in the original design.

Silmificant Proiect Features:

1. Provides the city with a multi-function project.
2. Tunneling investigation.
3. 4,500 feet of large-diameter storm drain.
4. Feasibility investigations of 11 alternatives.
5. Jurisdictional wetlands.
6. Proactive approach to community involvement.
7. Communication tools used during construction to inform citizens of project progress.
8. Proactive approach to public/private partnership.

Craig C. Houdeshell, P.E.
GEl Consultants, Inc.
Senior Water Resources Engineer
6950 S. Potomac Street, Suite 200
Englewood, CO 80112
[phone] FAX [phone]
[e-mail]

Bruce Perryman, P.E.
AV!, pc
2035 Westland Road
Cheyenne,VVY 82001