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Cedar Rapids tests new weapon to battle flash flooding: permeable pavement

Alley near Coe College to be a demonstration site

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CEDAR RAPIDS — An unremarkable alley near Coe College is to serve as a sample battleground for a possible new, albeit more expensive weapon in the fight against flash flooding — permeable pavement.

Stormwater passes through permeable pavement into the ground rather than running off or pooling as with typical concrete or asphalt. In this case, it would divert water that normally drains into Cedar Lake.

“I’ll be very anxious to see the results,” said Cedar Rapids City Council member Scott Overland, noting the project could be a great example of how to retrofit existing, old parking spaces, as well as other parts of the developed city. He also noted the environmental benefits, “especially as it pertains to our increasingly difficult stormwater problem.”

The Cedar Rapids City Council authorized a contract estimated at $99,300 to use permeable pavement to retrofit rundown pavement in the alley between E Avenue NE and D Avenue NE from College Drive to 14th Street NE during a meeting this week. The alley is a demonstration site that could influence the city’s approach to alleys in the future.

This is the latest effort as Cedar Rapids builds its arsenal for flash flooding and water pollution.

Earlier this year the city adopted a new stormwater rate policy with a dual-fold mission: incentivize better stormwater management by large businesses and collect more money from big stormwater system customers to pay down a backlog in maintenance needs. Also, the city is nearing completion of a new topsoil ordinance to require developments are left with more or better conditioned soil to absorb water and filter toxins.

Permeable pavement is not all together new in Cedar Rapids. Parking lots near the downtown library and the new Northwest Recreation Center have it, but it hasn’t been tested on alleys.

“We are choosing to do it in permeable pavement as a pilot project for future similar installations,” said Sandy Pumphrey, a Cedar Rapids flood mitigation engineer.

The project includes monitoring ports to measure water quality overtime, he said. The installation is supposed to begin in November and be complete before spring 2017.

While the method has environmental benefits, it’s also more costly. Typically, concrete costs $7 a square foot, while permeable pavement costs about $13 a square foot, Pumphrey said.

City Council member Scott Olson voiced concern that this is just a demonstration, not a new standard.

“Once we pave one alley, where do we stop?” he said. “I just want to make sure we describe this as a demonstration project for this type of permeable paving versus a process of how we are going to start paving alleys throughout the city.”

An Iowa Department of Agriculture and Land Stewardship grant is supporting about a third of the cost. The grant was awarded for stormwater infiltration practices that provide water quality and quantity benefits, along with educational value.

Cedar Rapids received a $99,237 grant for four best management practice pilot projects — permeable pavement in the alley near the Coe campus and bioswales — landscape elements designed to remove silt and pollution from surface runoff water — near three schools — Bowman Woods Elementary, Kennedy High School and St. Pius Elementary. The four pilots have a total cost of $242,000, and the other three are still being designed. Coe College also received an $80,000 grant for a separate $221,000 project that incorporates permeable pavers as part of campus improvements to reduce runoff, including in a parking lot adjacent to the alley.

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