Sewage overflows return as flood water, heavy rains infiltrate lines; exceed treatment plant capacity

Flooding and heavy rains early this month once again forced Bettendorf to pump raw sewage into the Mississippi River.

That's because the Davenport Sewage Treatment Plant wasn't able to handle inflows to the facility and closed gates to the main interceptor along the Mississippi riverfront, requiring Bettendorf to pump sewage from its riverfront lines into storm water pipes that flow into the river.

If the city did not use the pumps, sewage could back up into riverfront businesses and homes.

On October 6, with the Mississippi River three feet over flood stage and after nearly 4 inches of rainfall, the city pumped 24.7 million gallons of untreated sewage into the river.

Similar sewage system overflows occurred June 20 (4.3 million gallons) and September 6 (1.3 million gallons). In the June occurrence, the river was four feet below flood stage and the area had 2.8 inches of rain. In September, the overflow occurred when the river was at its 15-foot flood stage and the city received 3.46 inches of rain.

Sewage overflows in Davenport have fallen from 104 in 2016 to 18 in 2017 thanks to wastewater system improvements in Bettendorf and Davenport mandated under a 2013 consent order with the Iowa Department of Natural Resources (IDNR).

In Bettendorf, only two overflows were reported in 2017.

In addition to sewer line upgrades to reduce infiltration of rainwater, the capacity of the treatment plant along Concord Street in Davenport was increased to 55 million gallons per day with a $7 million "optimization" project. The plant is jointly owned by Davenport, Bettendorf, Riverdale and Panorama Park.

In its annual report to the IDNR, engineering firm Veenstra & Kim stated flows to the wastewater treatment plant after heavy rains now are noticeably lower because of the sewer line upgrades.

CLICK HERE for the Sewage System Overflow (SSO) events in Bettendorf so far in 2018 from the Iowa Department of Natural Resources.

CLICK HERE for additional information on the sewage system overflow issue.

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