Disguising flood control
This summer, the Flood Control District of Maricopa County, Ariz., completed construction of the first segment of a $67 million, 4.5-mile-long stormwater drainage channel that will travel through parts of Phoenix and Glendale. The Bethany Home/Grand Canal Flood Control Project, which is scheduled for completion in 2009, is designed to direct stormwater to the New River and to serve as a park/trail corridor.
Average annual precipitation in Maricopa County is only 7.7 inches, so residents usually are not troubled by rain. However, when rain arrives, it can come in brief, intense downpours that have been known to dump nearly an inch of rain in five minutes, which can cause flooding.
Along the Grand Canal, which carries irrigation and domestic water for the Salt River Project (SRP), occasional flooding began to cause problems for nearby homes and businesses. To control stormwater from downpours, the county needed to build a substantial — but infrequently used — flood control channel without scarring the landscape with a large trench. “The public doesn’t want to see just a channel carrying water, or a big hole in the ground holding water,” says Hasan Mushtaq, floodplain manager for Phoenix. “They want to see some soccer fields, picnic ramadas, children’s playgrounds and so forth.”
However, as city and county officials prepared to present the idea of a combination park/trail corridor and stormwater facility to residents, they expected residents to have many concerns about the safety of letting their children play in a park that is designed to flood. “We knew, up front, that we’d better get as much public input as possible,” says Scott Vogel, senior project manager for the district.
New York-based DMJM+Harris was hired to design the first two-mile segment of the project and to collect residents’ reactions to it. The district also created a newsletter, a Web site and a telephone hot line to provide residents with project updates. The final design called for a landscaped channel with a trail, lighting, water fountains and benches.
In January 2003, Phoenix-based Pulice Construction began building the channel’s first segment and the park. Most of the channel runs along the uphill side of the Grand Canal, but for one-half mile, it needed to swerve to the downhill side to avoid cutting through a neighborhood. The contractor coordinated with SRP, who diverted two sections of the canal flow until January 2004, to build two culverts to carry the channel under the canal. Once the culverts were constructed, the canal was restored to its original course.
In addition to excavating the channel, the contractor built two bridges to carry it under roads. Turf, landscaping, irrigation, a 10-foot-wide concrete trail, equestrian paths, lighting, drinking fountains and benches also were installed. By June 2004, the segment was completed.
Situated near the site of the Arizona Cardinals football stadium and the Glendale Arena, the first segment of the park already is attracting visitors who use the trail for walking, jogging and other recreation. As of last month, the county had not experienced any major rainstorms that tested the channel.
The first segment cost $9 million and was funded by the district, Glendale and Phoenix. The next segment’s construction, which will extend the channel and park/trail corridor along the canal, will begin next year. Both cities will maintain the parts of the channel and trail corridor that are located in their jurisdictions. Once the channel is completed, the district will build storm drains to carry additional stormwater to the channel.