Plans for New Tunnel to Reduce Sewage Overflow in Rivers

Written by: Rachel Abraham, Kristine Lindal, Ali Rairigh, Emily Yager

Fort Wayne, Ind.—City Utilities will begin construction of the $240 million Three Rivers Protection and Overflow Reduction Tunnel project in 2017, according to Kelly Bajic, city utilities professional engineer, to reduce the amount of sewage discharged into the St. Marys and Maumee Rivers during storms.

According to a city 3RPORT and Tunnel Works release, the project responds to a federal mandate for the city to reduce combined sewer overflow from 100 billion to 100 million gallons by 2025.

Matthew Wirtz, deputy director of engineering for the city, said during heavy storms, the sewage system overflows and raw sewage mixed with rainwater flows into the river.

According to Bajic, the tunnel will have a capacity of 31 million gallons, although it will primarily be used for conveyance and not storage.

Wirtz said once the tunnel is constructed, the majority of the flow currently discharging into the river will drop into the tunnel.

The 5-mile tunnel will begin south of Foster Park and run to the existing sewage treatment plant on the Maumee River. According to Wirtz, they will drill 150 to 250 feet into the bedrock where the tunnel will run underneath downtown and around Foster Park. The tunnel will convey flows to the wet weather ponds located north of the Water Pollution Control Facility, according to Bajic.

Wirtz said the construction will take 4 to 5 years because they will have to bore the hole underground, come to the surface and connect the existing sewers.

According to Bajic, 13 drop shafts will be constructed to convey the flow from the near surface sewers down into the tunnel.

“The tunnel itself will be done in a few years, but then getting all the rest of that stuff done will take a couple more,” Wirtz said.

Robert Gillespie, associate professor of biology at IPFW, said he and a team of students have been helping the city monitor river water quality during intense events. According to Gillespie, there are some great students who are eager to work on the tunnel project, helping the city accomplish what they couldn’t do on their own.

Gillespie said once the tunnel is completed positive impacts on water quality could be seen after only one season.

Wirtz said in addition to improving river water quality, the tunnel will reduce street and basement flooding and help move water from homes to the treatment plant faster.

“We’ll still have problems in really large storms, but the more normal, small storms will provide much better protection,” Wirtz said.

“It’s trying to fix something that’s been a problem not only in our community but in a lot of midwest communities,” Bajic said. “There’s a lot of different communities that have combined sewer systems, so it’s not just Fort Wayne.”

According to Bajic, the project is currently in the design phase and the next step for the project is getting documents ready for the bidding process by the end of Fall 2016.

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