design team becomes the construction team, and there is a seamless transition from design to construction as each team member understands how each decision is made along the way, Randall explained.
The team engaged in a year-long alternative analysis phase to investigate many potential solutions to reduce costs, improve habitat, and simplify construction. The original master plan design called for building vertical concrete walls on both sides of the ditches and a secondary box culvert along the west side of the ditches for irrigation flows. In contrast, the chosen alternative involved intercepting storm flows before they enter the ditches and conveying them south via a 102-inch storm sewer through a series of five detention / water quality ponds. The design included redirecting the outfall for an existing pond to further reduce storm flows in the adjacent ditches.“ We shaved( stormwater) flow from every place we could,” said Andrea Faucett, Ayres Associates’ project manager.
The design team implemented several innovative technologies to accomplish the goals of the project while maintaining public trust. For example, the team designed a round baffle structure, rather than the traditional rectangularshaped structure, to slow the large volume of water at the final outfall so it would not create a large scour hole in the pond. This round design dramatically changed the look of the structure and made it more aesthetically appealing. It also incorporated a custom hand-carved form liner, which allowed the City to use Art in Public Places funding that had been set aside for stormwater projects.
Additionally, great effort was made during the design to avoid creating traditional“ bathtub” detention ponds. Instead, the team designed multipurpose facilities for not only flood mitigation but also wildlife habitat and public trails.“ The majority of residents who travel through the ponds via the trails do not realize this open space is also providing flood storage,” Randall said.
To convey storm flows to the regional ponds, excavation depths of 30 feet in some
Top: The energy dissipation structure at the outfall into Red Fox Pond. Middle: Detail of the concrete form liner. Bottom: The Red Fox Pond after construction.
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