A closer look at the city’s sewage system and upgrades

Not many folks think about their local sewer system, but for Grady Jenkins, taking care of the city’s wastewater is a full-time job for himself and his crew.

Last week Jenkins gave a tour of the treatment plant, which takes the foul brown water and turns it crystal clean in about 24 hours.

The city is looking at about a $5.5 million upgrade to the plant, both increasing its capacity for future growth and adding redundancy to its systems. The project will be paid for with about $4.357 million in federal grants, with the remainder coming from sewage fund reserves. The city won’t have to borrow money to finish the project.

Redundancy is an important aspect of treating sewage — the plant has multiple pumps and various stages of treatment. For example, if a pump goes down, the entire operation can stop if there’s not a secondary pump that kicks in, Jenkins noted.

The upgrades will increase the size and capacity of the bioreactor and add redundancy to its other systems, Jenkins said,

The sewage system isn’t just about the plant itself, either. The city also has nine lift stations. About 70% of all the city’s sewage has to be pumped up into the plant, which sits in a nondescript site along the Flathead River, just out of the flood plain.

A treatment plant mimics natural processes, using bacteria to clean the water of nutrients. It all arrives through two pipes — one is gravity flow, the other is pumped in. It then goes through a bioreactor, where the water is either exposed to oxygen or deprived of it. That process, which also adds ammonia sends the nitrogen in the effluent back into the air.

The solids are then removed through a process called DAFT — short for dissolved air flotation. It’s a clarification process that utilizes air to remove suspended matter from the surface of treated water.

The process allows the dissolved air bubbles to adhere to a suspended matter within the water, causing it to come to the surface to be skimmed away.

The solids are then put through a machine that squeezes water out of it to the point where it can then be loaded onto a dump truck and hauled away to the landfill.

The water, which is crystal clear by this point, is then disinfected with UV lights and then discharged in the Flathead River.

Crews at the plant make four trips to the landfill a week, Jenkins noted.

The county, however, is exploring the idea of using the solids to create compost. The city has agreed preliminarily, to be involved in that.

Right now the plant sees about 450,000 gallons of sewage a day. It’s rated for about 510,000 gallons per day, which is another reason for the upgrades.

The upgrades should serve about 9,000 residents, when completed.

There are some things the average user can do to help the plant. For one, don’t dump grease into the drain. It gunks up the works and eventually has to be removed manually. Secondly, flushable wet wipes do flush, but they also plug screens, Jenkins noted.

They became more popular during the pandemic.

Jenkins said the engineering for the project will take several months and work would likely begin sometime next year.