Spokane contractor Williams Brother Construction LLC has begun work on the first phase of a wastewater treatment facility update for the city of Coeur d'Alene, says John Williams, project manager at Williams Brother.

Construction at the plant, located at 765 Hubbard Ave., began in August, Williams says. Jim Remitz, capital program manager for the city of Coeur d'Alene's wastewater department, says the project is about 30 percent completed and is expected to be finished in late spring 2014.

The first phase, which will cost just under $8.7 million and is the first of three phases, is known as the initial tertiary membrane filtration and nitrification, Williams says.

"It's an additional level of filtration for cleaning up effluent," he says. "It's being done pretty regularly around here now."

Remitz says the second and third phases of the project could take another 10 years to complete. The total cost for the entire three-phase project, he says, is expected to be about $12.4 million.

The city secured an $8.6 million Department of Environmental Quality loan from the state of Idaho to pay for most of the project, Remitz says, and the rest of the funds will come from the city's wastewater fund.

The project will consist of building new tanks for filtering effluent, a structure to house the equipment needed to run and maintain the tanks, a new secondary waste pump station, modifications to an existing chemical center, a secondary controls building, and piping, Williams says. The tanks will be mostly underground.

The function of the new filtration system is to reduce the amount of phosphorus in the wastewater, says Remitz.

He says the project came about because the U.S. Environmental Protection Agency is in the process of issuing new permits that regulate how much phosphorus can be expelled into the Spokane River from wastewater plants.

"The new permit dramatically reduces the amount of phosphorus that we can discharge into the river," Remitz says. "This phase will give us the initial filtration, and we're hoping that the filtration will be able to reduce the phosphorus enough."

He also says that while the EPA hasn't issued the new permit yet, the city has seen it in draft form, so it would know what the new phosphorus limits would be.

Remitz says that the city did a pilot study of three different systems in 2009 and 2010, and found that this filtration system had the best results.

"This phase is called the initial tertiary membrane filter because we're only diverting a portion of the flow through these filters," Remitz says. "If it performs, we'll be putting all of the flow through the filters."