With computational modeling assistance from IIHR’s Marcela Politano and Troy Lyons, Madison (Wis.) Metropolitan Sewerage District’s new Pumping Station 15 recently earned the first Envision Gold Award for sustainable infrastructure in Wisconsin. The award, presented by the Institute for Sustainable Infrastructure, rates projects based on their environmental, social, and economic impacts.

Baxter & Woodman Consulting Engineers hired IIHR to create a CFD model of the existing pump station, which was being retrofitted and reconfigured to handle larger flows. The station has been set in a local green space, Marshall Park, since 1974.

Politano performed CFD modeling of the pump station’s interior and the complex geometry of the wet well pit and pumps. She was able to identify any potential issues with vortices, recirculation, or anything else unfavorable to the operation of new pumps.

Lyons explains that one of the challenges they faced was that the flow coming in to the station is not constant. “It varies a lot,” he says. “There are a lot of unstable or transient flow conditions in the wet well. The modeling was able to simulate those conditions.”

“We simulated existing conditions based on what we saw when we visited—what we saw, what the flows were, and what the water levels were, so that the CFD model could replicate that,” Politano says. “That was basically a validation. And then we ran the higher flows with the bigger pumps to see if there were any issues.” The simulation showed that with minor changes to the inlet configuration, the pumping station could handle higher flows without expanding the wet well—thus saving a significant amount of money.

The $4.3 million Pumping Station 15 project earned the Envision Gold Award for:

• Efficient use of resources. Reducing energy waste and consumption was a key objective of upgrades to the 1970s-era pumps and mechanical equipment. By installing energy-efficient variable speed pumps and other advanced equipment, Pumping Station 15’s energy consumption has been cut by about 20 percent. In addition, solar panels are now providing close to 10 percent of the station’s power needs.
• Greater resilience. Given the pumping station’s location at the bottom of a hill and close to Lake Mendota, hydrologic modeling was used to mitigate the prospect of more severe and frequent flooding in the years ahead. The pumping station was designed in accordance with greater precipitation in mind and is situated more than two feet above the worst-case future flooding scenario.
• Enhancements to public space. Beyond reducing odors and improving the aesthetics of the site, collaboration between the project team and community resulted in much-needed facilities, including a drinking fountain and restrooms. The upgrades are welcome improvements for those who use the adjoining athletic field, as well as the busy boat ramp. Generous support from local businesses provided for the installation of bike racks, a bike repair stand, and an aquatic invasive species boat wash station.
• Stormwater management. The project site contains two bioretention basins and a bioswale designed to reduce the amount of silt and other pollutants reaching Lake Mendota. The bioretention basins, plus changes to the grading of the site, resulted in a 31 percent improvement in the pumping station site’s water storage capacity.

“The district deserves credit for making the right investments and upgrades, at the right time with the right mix of technical know-how, forward vision and community engagement,” says John Stanton, president and CEO of the Institute for Sustainable Infrastructure. “Pumping Station 15 demonstrates that it’s possible to balance environmental stewardship, financial constraints, and the needs of multiple constituencies.”

With current average daily volume of 1.3 million gallons per day, the station’s increased capacity of 8.8 million gallons per day should provide capacity through 2045. Project partners include Baxter & Woodman Consulting Engineers, engineering; IIHR—Hydroscience & Engineering, computational modeling; Potter Lawson, architectural design; Saiki Design, landscape architecture; Kabbes Engineering, environmental engineering; and Miron Construction, general contractor.

For more on the project, visit the district’s website at www.madsewer.org and search “Pumping Station 15.” For more on Marshall Park and Madison Parks, visit: cityofmadison.com/parks/marshall.