Read more about the work in Clinton, and other water quality successes, in Working For Clean Water, the DNR's annual watershed success story publication.
Move over, gray. Clinton is going green.
The City of Clinton, located along the Mississippi River, has been working over the past decades to separate their combined sewer system, where both the treated wastewater from the sanitary sewer and the untreated stormwater runoff combine. Separating the two will also reduce the amount of untreated water discharging directly to the river. Clinton uses the Clean Water State Revolving Fund (CWSRF) to finance the project, and an additional award helped them take stormwater efforts a notch higher.
“With the help of a CWSRF Water Resource Restoration Sponsored Project, Clinton has used a green stormwater infrastructure approach to address urban stormwater quality and quantity associated with combined sewer overflows,” says Patti Cale-Finnegan, Iowa SRF coordinator with the DNR.
Instead of using traditional “gray” infrastructure, which has a lower initial cost, the city chose to use greener practices in making streetscape improvements to a historic district. With the goal of soaking up more rain and snowmelt into the ground rather than having it run off into the storm sewers, the city installed permeable pavers in parking bays and alley ways – a big improvement for residents over the rough gravel alleys.
A Silva Cell system for tree planters provided not only beautified sidewalks with permeable brick pavers, but the 4-foot chamber below filled with topsoil and sand allows tree roots to stretch out and water to soak in, not run off. A bioretention cell with native prairie plantings adds color and drinks up runoff. A city park lawn had a soil quality restoration to loosen up the soil and allow it to take on more rainwater. The practices also filter out pollutants and avoid overloading the separated sewer system.
Having the funds available from the SRF sponsored project allowed the project to go green, says Jason Craft, Clinton City Engineer. “This allowed us to focus on proactive stormwater management and treatment and filtration, rather than just standard storm sewer installation – gray infrastructure. The money made available by SRF allowed a cleaner and greener project to be constructed.”
Residents took notice and learned about water quality along the way. “The public really enjoys the attractiveness of the permeable pavers, and it is always interesting to them to hear the stormwater quality aspects of the project,” says Craft. “Green infrastructure instead of grey is so much more satisfying to the public. While it may cost a small percentage more, the environmental and aesthetic value of the project is something that cannot be measured.”
In addition, the Iowa League of Cities named Clinton an All-Star Community, and Craft received the 2016 Iowa Stormwater Award for the project. “With Clinton being situated on the banks of the Mississippi, we realize its importance as a natural resource which is vital to our community. We want to do our part to reduce the nutrient pollution from our drainageways,” Craft says. They’re not done yet, either. Another sewer separation project a block north of this project will include about 2 acres of permeable pavers.
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