Disinfection treatment, flood protection required at Davenport/Bettendorf sewage treatment plant under amended consent order with Iowa DNR

Sewage from Bettendorf and Davenport will undergo enhanced treatment beginning early next year under revised terms of a consent order signed in February with the Iowa Department of Natural Resources (IDNR).

The revised agreement establishes Feb. 28, 2022 as the deadline for adding disinfection treatment, using ultraviolet light, at the Davenport Wastewater Treatment Plant, which handles sewage from Davenport, Bettendorf, Riverdale and Panorama Park.

The consent order between the cities and the IDNR dates back to 2014, and initially had required construction of a large retention basin to contain high flows to the plant that occur after heavy rains or flooding. Early estimates pegged the cost of that basin at more than $20 million.

City officials pushed back on the retention basin requirement, arguing work to eliminate leaks in the communities' sewage collection systems would significantly reduce flows to the facility even after heavy rains or flooding along the riverfront.

To make sure the cities follow through on work to reduce infiltration of stormwater into sewer lines, the agreement requires the communities to spend $3 million a year from 2020 to 2026 on "infiltration and inflow (I&I)" projects.

The cities also are on the clock to complete flood protection for the plant along Concord Street in west Davenport. That work, estimated at $17 million, is to be completed by November 2026. During recent floods on the Mississippi River, the plant has come close to shutting down the facility because of the high water.

The cities now have until 2030 to submit a report "detailing the feasibility and reasonableness of treatment of wet weather flows" to the plant.

It has been those "wet weather" flows that have exceeded the plant's capacity to fully treat sewage before it is pumped into the Mississippi River. Those partially treated "wet weather" flows – from the plant's outfall 801 – are required to undergo disinfection (by ultraviolet light) by July 1, 2034.

Work already is under way in Davenport to remove bottlenecks in the large interceptor line along the riverfront. That work has tied up traffic along Davenport's River Drive last year and again this construction season.

CLICK HERE to download the amendment to the consent order between the IDNR and the cities of Davenport, Bettendorf, Riverdale and Panorama Park (joint owners of the Davenport Wastewater Treatment Plant).

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