Spokane-based Clearwater Paper Corp. is considering a $160 million upgrade at its pulp and paperboard mill in Lewiston, Idaho.

The upgrade, which would include replacing aging digesters with a single, more efficient digester system, depends on certain contingencies, says Matt Van Vleet, a spokesman for the consumer tissue and paper products maker.

An engineering study is under way to confirm the feasibility of the project, Van Vleet says.

The project would require permit approval from the Idaho state Department of Environmental Quality, he adds.

Clearwater Paper also is seeking tax exemptions from Nez Perce County that Van Vleet says are estimated at $4.2 million.

“If it goes forward, it would be the largest single project at the mill in more than 30 years, and probably one of the largest in northern Idaho in a very long time,” he says.

Van Vleet says the company hasn’t set a timeline for the project, but likely will start it as soon as state, county, and corporate approvals are in place.

“The engineering is moving as fast as we can,” he says, adding, “The permitting process also is going forward well. Each of those pieces takes time.”

Clearwater Paper is seeking a tax exemption under an Idaho incentive that authorizes counties to approve tax abatements for five years of up to 75 percent of the increase in property value resulting from certain facilities upgrades.

“We’re working on an agreement with the county, which has been very positive,” Van Vleet says.

The project would include a continuous digester that would replace 12 batch digesters at the plant, he says. The digester system is the heart of the mill, Van Vleet says. “It’s what turns wood chips into pulp.” 

Pulp is the main component used to manufacture paper products.

The Lewiston facility has 1,370 employees and a total annual payroll of $100 million.

Van Vleet says the project wouldn’t lead directly to more jobs, but the Scandinavian-made digester would produce more pulp for the chip, increasing overall efficiency. The upgrade also would reduce the plant’s power consumption, which would reduce emissions at the plant, he says.

The manufacturing process at the mill relies on steam and electricity generated by burning wood waste, he says.

“More than anything, this is an upgrade to the mill that significantly improves our competitiveness on the global stage in this industry,” he says.

Clearwater Paper, which spun off from Spokane-based real estate investment trust Potlatch Corp. in 2008, employs more than 3,500 people in the U.S. and operates 12 facilities in 10 states, including the Lewiston mill.