CLINTON — An agreement between Archer Daniels Midland and the City of Clinton could lower residential sewer rates, but not before 2025.
Bob Milroy, director of Clinton’s regional water reclamation facility, shared initial plans for the project with the Clinton City Council last week.
The RWRF is responsible for the collection, transport, and treatment of wastewater for the cities of Clinton, Camanche and Low Moor. According to a city report, ADM approached the city last year about accepting wastewater from ADM’s corn plant.
ADM has to meet new nutrient removal requirements by December of 2023, Milroy said Thursday, and, according to Clinton City Administrator Matt Brooke, ADM doesn’t have the space build the infrastructure needed to meet those demands.
“Several months ago, the council approved us to go forward with a facility plan to work with ADM on the possibility of taking all their wastewater, Milroy said Thursday. ADM and the City split the $80,000 cost of a feasibility study on the proposal.
ADM will incur the entire $93.7 million in capital cost to expand the City’s wastewater facility to handle the additional waste, Milroy said. “I think they freaked out when they heard that number.”
The facilities plan calls for the City to borrow $5.8 million for 20 years at 1.75%. ADM will cover the loan, the cost of increased plant operations and maintenance and pay a base sewer rate and capital reserve and rates sufficiency costs.
“We had to really zero in on the cost,” said Milroy. “Theres a lot of things and rumors flying around,” he said.
“And then we’ve talked about a take-or-pay contract that would be in place with ADM before we spend any money at all,” Milroy said.
A take-or-pay agreement will make ADM, rather than Clinton taxpayers, liable for all the costs, said City Administrator Matt Brooke.
“They were very forthright in saying that … one of the biggest pieces when you’re working something of this scale is basically the public perception,” Brooke said, “so they wanted to make sure from the get-go that this was a good deal for the city, first and foremost, and then of course for ADM.”
The City already has the basic facility, said Brooke. “The costs that are being saved by adding on to the city’s plant is what’s really a benefit for ADM,” he said.
“But also at the same time, we’re going to benefit back for having that increased flow, and increased revenue that will come in from this project.”
Officials used three years of data from ADM to plan additions to the City’s wastewater facility, said Milroy. ADM produces a minimum of 74,000 pounds of wastewater per day. The City’s plant is designed for 18,000 pounds per day.
“Our average flow right now is probably 4 1/2 million, and their daily flow over that three-year period is 8.1 million, so it’s pretty substantial,” Milroy said.
The City will have to build a new pump station to handle the AMD flow, Milroy said. Additional pipe will be installed to get the waste from ADM to the treatment plant and back to the effluent in at Beaver Channel.
The pipeline will follow easements the City already has, much of it through Alliant Energy property. “But we already have easements. We’re just going to have to expand those easements a little bit,” said Milroy.
ADM will discharge its wastewater into its F-tank and send it to the City from that, “in case they have an upset in the plant or something,” Milroy said. “They can stop it before it gets to us.”
To treat the additional wastewater, the City will install two ADI-BVF reactors. They’re essentially covered sludge lagoons, Milroy said. “This is designed to handle high-strength waste.
“What will happen in here, through … micro biology, is it will go in high-strength waste. It will come out basically domestic waste, so the rest of the … treatment plant can handle it,” Milroy said.
“We’re low on BOD (biochemical oxygen demand) in the main plant,” said Milroy. “About 10% of what comes in from ADM can be sent right to the front of the oxidation ditches to improve our BOD numbers.”
The rest of the waste will be split off to go through ADI-BVF reactors before going back to the main pipe.
The main plant is at 50% capacity hydraulically, said Milroy, and about 20% organically. It has plenty of capacity.
“I don’t want to get into a huge business of it, because you never know what you’re going to get, but we can take some high strength waste hauled in and run it through there for another revenue source,” Milroy said.
From the reactors, the waste goes into oxidation ditches. For the hydraulics, the City will have to add two more oxidation ditches and two more final clarifiers, Milroy said.
Then the waste goes through disinfection and then back out to the pump station.
David Haugen, of Veenstra and Kimm, who assisted with the facility plan, said the pipes in use right now won’t handle the new volume. “Right now there’s two 18-inch pipes coming out to the plant. There’s one 24 going back for discharge. In the future, in addition, there’ll be another 24 coming back to the plant and then another 24 going out for discharge,” he said.
“In addition, once you get back to Beaver Channel, theres an F1 pipe that goes out into the Mississipppi. that will have go be upsized,” Haugen said.
One 36-inch pipe handles the discharge now, but the City will add a second 36-inch pipe in the upgrade.
The City will also have to get rid of ADM’s solid waste, Milroy said. “About 60% of the solids are going to settle out in those reactors,” he said. “Our solids are going to increase by 40%. … so we’re going to have to get rid of those the traditional way.
“What I decided that I wanted to do is put a sludge dryer in,” said Milroy. That saves having to expand the sludge storage pad.
“The other advantage of drying it, it’s going to be over 90% solids,” said Milroy. “It’s more like a dust. And that’s caused by class A sludge. I can sell it. I can give it to you guys to put in your garden. Legally.”
Milroy said he’s constantly approached by contractors looking for solids. “Contractors are always asking me for our biosolids so they can help … seed properties. … I can’t give it to them the way it is now. Or sell it. This stuff I can sell it to them.”
Milroy said he barely has room to store solids now. “This way, from what I”m being told by the engineers, even with ADM, that building will be half full.”
The City will add a septic drop-off for septic haulers, port-a-potty services and recreational vehicles, said Brooke.
“We wanted to that to begin with as a customer service thing, and that was going to help with our BOD,” Milroy said.”
ADM will pay $2.80 for each unit of 748 gallons, according to the City’s plan. Total yearly cost to ADM will be $10.92 million, Milroy said.
That cost is based on a minimum of eight million gallons, Brooke said, but the take-or-pay agreement isn’t based on gallons. ADM will have to cover the cost of the debt service and increased plant operations, regardless of volume.
They will have to pay $900,000 a month no matter their flow, Brooke said. “They’re paying a lot more today,” he said.
If the flow is greater than eight million gallons, ADM will pay more, but it won’t ever play less, Brooke said. There’s no chance that residents will have to make up the difference. “We didn’t even want to get into this discussion of there was,” he said.
Officials expect to submit plans to the DNR in March and approve a contract with ADM for engineering fees in April, Milroy said. “We would like to award the contract in roughly March of ‘23. That gives us about a year and a half or so for design.”
“A lot of things have to happen for that. That’s what we’re shooting for,” Milroy said.
Construction would likely begin in June of 2023 and finish in 2025, Brooke said. After processing ADM’s waste for a few quarters, the City would examine data to see if residential sewer rates could be decreased.
“It’s not like we’re going to drop residential rates tomorrow. We need time and space,” Brooke said.