BY CHUCK VANDENBERG
FORT MADISON – It’s an icky subject, but the money that goes into the city’s handling of a flush can be mindboggling.
The City of Fort Madison is currently overseeing the construction of basically an entire new waste water treatment facility along the river just southwest of Hall Towing. The project is in its 2nd phase at a cost of about $15 million, according to City Public Works Director Larry Driscoll.
Phase 1 was completed in 2016 at a cost of about $1.5 million. That phase resulted in replacing almost every pump and light in the facility. Phase 2 is basically the reconstruction of the facility including bringing a larger generator replacing all the moving parts on any stirring or circulation mechanisms, removing and replacing all outdated parts, and replacing and extending “screw pumps” on the grounds.
The whole process is simply to take the water from the city’s sewers, extract solids, decontaminate the water and get it ready for release into the mighty Mississippi. And you can’t do it with screen. This process utilizes aeration, chemical treatments, multi-stage water flows, huge pumps, a plethora of electrical switches, power generation and even some doodie eatin’ bugs.
But the results are two fold, a fertilized sludge that can be used by local farmers in fields and an environmentally approved end water product that can be released into the natural waterway.
So why now?
“It’s old,” said Jeff Helling, water pollution control superintendent for the city. “We have had some pumps out here that have been running for 49 years.”
Driscoll said in addition to the age of the facility, the city has to keep up with federal guidelines for phosphorous and ammonia.
“This is phase two, phase 1 was replacing mechanical pumps and the 2nd phase is the treatment process,” Driscoll said. “There are new state laws for phosphorus and ammonia and we had to meet the new guidelines.”
He said the current construction is refurbishing control systems and tanks, adding new filters to remove some of the phosphorus and a larger sludge tank to handle the thicker sludge that will come from the facility, as well as allowing the plant to hold more longer. Driscoll said the facility usually thickens the sludge to 3 percent, but will add a thickener to move that percentage to 10% so it doesn’t have to be hauled off as often, which is a savings to the city because the city pays to have the sludge hauled away.
“We’re lucky because we have a lot of sand in this part of the state and we can apply a lot of that sludge to the ground and have it drain away. And we’re an agriculture community so we can help the farmers with this,” Driscoll said. “Up north where there’s a lot of clay they have to dry the sludge. It’s like dirt when it’s done…doesn’t smell like dirt, but it’s a dry product so you can incinerate it or put it on the fields.”
Leander Contracting out of Canton, Ill. is the lead contractor on the project. The city recently took steps to borrow just over $19 million that the state had set aside to do the project. Driscoll said the first phase was completed using sewer revenues, but that money will be replaced with the money now accessible from the state and phase 2 work will be paid for out of the loan notes.
“We’re basically refurbishing every motor and every moving part,” Helling said. “The screw pumps, clarifiers, any portion of it that’s a moving part is being replaced. The cement structures will stay in place, but basically everything else is being refurbished. We’ll take it down one at a time because we have to keep the plant functional.”
Other things being added are new braceways for control module wiring, replacing drives, adding a larger sludge tank on the north side of the plant grounds, as well as bringing in a new generator to increase energy production.
Construction crews were filling a large cement pad for the new generator to sit on.
“We’re building a new generator pad, replacing the old generator. We hope to have that generator in next week. It’s two times the physical size of the current one which is a 500-kilowatt generator. The new one will be 1 million kilowatts. They’ve also drilled pilings down 40 feet underneath the pad to give it good support because we’re close to the river and the ground could settle. This entire plant is built in the river, basically on land that’s been brought in over time,” Helling said.
So how does the sewer treatment plant prepare the water for release into the river? In a nutshell, the water flows down to the treatment plant and is pumped into “primary clarifier holding areas”. Helling said the water sits in those areas for about 2 to 3 hours to allow the heavy sludge to settle and suspended sludge to rise to the top. Then heavy sludge at the bottom gets separated and the suspended sludge then gets pumped into aeration tanks where ‘bugs’ in those tanks start digesting the suspended solids. They get heavy and the sink to the bottom where they are scraped off and some are even put back into the tank to keep a good bug population base.
Then the water is sent through a chlorination tank where regulated amounts of chlorine are added to decontaminate the water, the water is then again pumped through a holding area where sodium bisulphate is added to clean up the chlorination. Federal and state guideline dictate minimum levels of chlorine that can be present in the water before it is put into the river.
New levies are also being built on the river side of the property. Helling said those are being built up to protect the facility for flooding. He said the floods of 1993 and 2008 were hard on the plant and the new levies should solve that problem as well.
“Parts of this facility are almost 50 years old. It’s been a good facility and has taken care of us for a long time,” Helling said.