An overlaid Google Maps image shows the site of a $3.6 million improvement project at the Southwest Wastewater Treatment Plant in Springfield. (Illustration by Springfield City Utilities)

On a typical day, 35 million gallons of sewage flows through the Southwest Wastewater Treatment Plant.

The Springfield City Council will consider a bill for final adoption July 25 that calls for $3.6 million worth of upgrades for equipment that has been described as corroded, outdated and past its useful life. When it comes to treating Springfield’s most foul waste, the people who work at the treatment plant want to make sure they are following state and federal regulations, and taking care of Wilson’s Creek.

The bill contains a $3.6 million contract with Irvinbilt Constructors, Inc. for rehabilitation of part of the plant. An additional pump will increase the plant’s capacity for incoming contaminated water from 75 million gallons per day to 100 million gallons per day.

Fassnight Pool is the Springfield-Greene County Park Board’s largest swimming pool at 660,000 gallons. On a typical day, the Southwest Wastewater Treatment Plant sees the sewage equivalent of 53 Fassnight Pools.

The Southwest Wastewater Treatment Plant sits on Farm Road 166 just off Highway 60 in southwestern Springfield. It is placed where South Creek and Wilson’s Creek meet, so that effluent — the water product that remains after sewage has been treated — can be discharged into Wilson’s Creek and eventually end up in the James River and in Table Rock Lake.

Springfield Superintendent of Treatment Plants Brian Wirth said the added capacity will reduce the risk of the Springfield plant falling subject to state or federal regulations during heavy rain events, when stormwater flows are at peak levels. Wirth said the contractors will replace large metal gates used to control sewage as it moves through the treatment plant.

“Those are the big gates that we can open and close to direct flow, send it to different basins — and there’s a lot of them,” Wirth said.

There are more than 30 gates.

“The gates that are being replaced are beyond their functional life,” Wirth said. “They range from 20 to 30 years old — they’re made of aluminum, they’ve corroded and we’ve had some fail. There are a lot of them that are about to fail or are nonfunctional, so they’re literally falling apart in some cases.”

The new gates will be made of stainless steel and will have automatic actuators that allow the gates to be controlled remotely from a control room.

Additional work involves replacing conduit, wiring, weirs and mixers in sewage basins. The contractor will also add oxygen sensors that detect how much oxygen is present in the sewage. Sometimes, sewer plant operators have to add oxygen to effluent before it can be released into a stream.

“That will be used to automate and control the aeration,” Wirth said. “Currently, that’s manually controlled, so this will automate it based on the amount of oxygen in the water. This will provide more consistent treatment and reduce the energy costs for aeration.”

The project has been in the works for five years.

In addition to sewage, the Southwest Wastewater Treatment Plant treats industrial waste, oil and grease removed from restaurants and hauled waste from septic systems in areas without sewer service. The plant was built in 1959.

Rance Burger

Rance Burger covers local government for the Daily Citizen. His goal is to help people know more about what projects their government is involved in, and how their tax dollars are being spent. He is a graduate of the University of Missouri-Columbia with 15 years experience in journalism. Reach him at rburger@sgfcitizen.org or by calling 417-837-3669. Twitter: @RanceBurger More by Rance Burger