By Travis Gulbrandson
Due to issues with its current boiler, representatives from the wastewater treatment plant are asking city officials for funds to purchase a backup.
They made their case during a special city council meeting held July 1, where they said the entire project would cost approximately $231,000.
According to wastewater superintendent Paul Brunick, it will cost $190,000 for a backup boiler to be installed in an existing garage of the digester building, with an additional $41,000 to install pipes that will bring natural gas to the treatment plant.
Problems began with the plant’s digester boiler late last year.
“We’re getting to the point where we’re starting to dump quite a bit of money into that dual-fuel boiler,” said assistant city engineer Jason Anderson.
To keep the boiler up and running, approximately $18,000 in maintenance has been performed over the past two years already, he said.
“It’s a dual fuel boiler that runs on methane and propane, so the methane that’s created through the process is burned, and when that methane’s not available we use propane,” Anderson said.
Unfortunately, the boiler “does not run optimally on either fuel,” according to a document supplied to the city council members.
“If the digester is down for an extended period of time, we may need to adjust how we dispose of the biosolids.”
Brunick said if the digester is down for too long, it could become “unhealthy.”
“They have microorganisms in there, and they produce methane gas,” he said. “If you throw it out of balance, they don’t produce the gas, and then what happens is, they get – like we do – an upset stomach. You either just have to take your sludge and put it out to the pond, or you just try to baby it to get back healthy again.”
Instead of methane, the new backup boiler would run on natural gas.
“Right now you run on methane. When it gets cool it kicks on and it burns down. When it runs out it switches to propane,” Brunick said. “This would be the same thing, it would just be natural gas. When it would fill up and get to a certain height (and) pressure, then it would kick back over to methane, burn down, kick back and forth.”
A backup boiler was originally planned for the Wastewater Treatment Plant Phase I improvements, but was removed from the plans due to budget overruns.
The city consulted with Banner Associates to put together cost estimates, and Brunick said the natural gas boiler seems like the best option.
This way, the system can be optimized by setting the existing boiler to burn methane and the backup for burning gas, he said.
If the project is bid out now, a new boiler probably would not arrive until next year, Brunick said.
“It’s going to take probably 60 days to get the plans all finalized, and by the time you set it out to bid … it’ll be Nov. 1 and it’s going to take 12 weeks, 14 weeks for a boiler,” he said. “In a way, it’s not bad because it gets us into March, April. The weather’s a little nicer. You can maybe burn the methane so you’re not switching back and forth.”
The city council members plan to discuss the issue further at their next meeting, which will be held July 15.