Client: City of Waukesha

Location: Waukesha, Wisconsin

Donohue completed an XP-SWMM 2D model for the City of Waukesha as part of a Stormwater Management Plan. Prior to this project, large storms caused unacceptable levels of stormwater flooding in the City. To determine “unacceptable stormwater ponding,” the project team evaluated two rainfall events. Protection requirements to be met during the 24-hour, 6-inch rainfall or the 3.8-inch rainfall events are:

• No basement or first floor storm water flooding from either ponded water or wave action, defined as a water level on the street that is one foot lower than the lowest potential water entry point in a building
•  No unacceptable overland flooding on private property from stormwater overflowing from city streets.

Donohue developed and evaluated alternatives to mitigate flooding in 10 identified flood-prone areas with areas of concern using a 2-D application of XP SWMM. Donohue also performed a capacity evaluation of the remainder of the system to identify additional potential flood-prone areas.

The end result is a comprehensive plan that, when implemented, will deliver an acceptable level of service and protection from flooding for the entire community.