University of Iowa engineers model Dubuque pumping station to ‘make sure that it’s going to work’

CORALVILLE — With more than half of Dubuque’s population working or living in the Bee Branch Watershed — covering 6.5 miles and encompassing six schools, four parks, and affordable housing — the city’s $28 million Bee Branch Stormwater Pumping Station Project is just as much money saved as it is money spent.

“Imagine a big 500-year flood happens — which we have had many of in the state — and this thing doesn't work,” said Larry Weber, director of the University of Iowa-based IIHR-Hydroscience and Engineering and interim director of the Iowa Flood Center. “Heads are going to roll. People's lives are going to get lost. People's homes will get destroyed.”

Given the stakes, the City of Dubuque months ago began collaborating with the IIHR-Hydroscience and Engineering to create a 1:7.5-scale model of a pump station — aimed at tackling any engineering complications or complexities before construction, not after.

“Because of the size and the risk of that pump station failing during an emergency, they did a hydraulic model of the pump station to make sure that it's going to work as it was designed,” Weber said. “So we made some engineering changes to make sure that it performs well during that flood condition.”

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‘Until you see it’

The pump station is part of Dubuque’s larger multi-phased Bee Branch Watershed Flood Mitigation Project to construct new flood gates, replace two existing flood pumps with four new pumps, update electrical service, and install a backup generator in protection of the zone that has over the years been hard hit by flash flooding during significant rain events.

Between 1999 and 2011, the watershed experienced six presidential disaster declarations related to flooding that affected more than 1,300 homes and businesses. Earlier this summer, flash flooding inundated the area — leaving residents with costly water damage.

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Within that context, UI engineers joined representatives from Dubuque, Cascade Pump, Origin Design, and the U.S. Army Corps of Engineers on Monday in Coralville to demonstrate the model and evaluate its final performance by seeing how it will operate under various flow conditions. The goal is to not only expand the city's pumping capabilities but accommodate increases in the rainfall and runoff intensity projected over the next century, UI officials said.

“There are just some things in engineering design that you simply can't get exactly right until you see it,” Weber said.

Like the small underwater vortexes — similar to little tornadoes — that engineers via the model discovered were forming outside the pump, designed to handle flow rates as high as 360,000 to 400,000 gallons a minute. Vortexes in the actual underwater pump could add air and debris that might clog or otherwise damage the station, according to Marc Ruden, project engineer of record with Origin Design.

“So we put in the corrective measure of these six vertical veins that break up these vortexes and makes it where the pump station is working much better,” Ruden said, noting other corrections give the team confidence to begin what is expected to be a two-year construction effort.

“We're getting the site prepared for the actual building of the pump station itself,” he said. “So the construction of this will probably happen in about a year from now.”

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Funding cuts

Dubuque is far from alone in its flood-mitigation efforts involving pump station improvements and upgrades — with the City of Cedar Rapids earlier this month celebrating the completion of a new stormwater pump station in Czech Village.

“There's all sorts of stormwater work that's going on across the state,” Weber said. “We're working a lot with Spencer right now — they were impacted in ‘24 with a big flood. We've worked with the cities of Des Moines, Cedar Rapids, and Iowa City; smaller towns like Kalona, Rock Valley, Rock Rapids.”

Those projects involve millions of dollars from a variety of sources — some local and some federal, like the $8 million Federal Emergency Management Agency grant Dubuque received last year for its pump station project.

That type of federal support is imperative to IIHR work, according to Weber, who said the UI program receives about $12 million annually from the federal government — benefiting not only Iowa, but communities across the country.

“We've got a project right now where we're designing the stormwater system for New York City — a part of New York City called Newtown Creek,” Weber said. “That type of contract work is helpful to offset the cuts that we've gotten on the federal side.”

And those cuts have been meaningful, he said, amounting to more than $40 million in grants that were awarded and then canceled or not funded.

“We had a $25 million (Regional Conservation Partnership Program grant) … to take row crop production out of flood plains and turn it into conservation land to reduce flooding and improve water quality — that was killed,” he said. “We had an $11.3 million project on carbon sequestration that's not been funded. We had several smaller awards on wind and renewable energy that were canceled.”

The real-world implications of funding this work, or not, plays out in flooding and other weather and water events, according to Weber.

“The IIHR program, we work around the world, across the country, and in the state of Iowa,” he said. “And it's always nice for the university that we're supporting another entity in Iowa. And the City of Dubuque is going to benefit from this work.”

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Vanessa Miller covers higher education for The Gazette.

Comments: (319) 339-3158; vanessa.miller@thegazette.com