Treated Water Will Irrigate Poplars

Inland Empire Paper Co. plans to begin irrigating an experimental plot of year-old poplar trees with treated wastewater.

Trying to find a new source of pulp for its Millwood newsprint mill, the paper company planted four acres of fast-growing poplars on its property off Empire Way east of Argonne Road.

After getting the trees started on cooling water, the company will begin irrigating the plot with wastewater this summer.

The paper mill was granted a permit by the Washington Department of Ecology to irrigate with the wastewater. Inland Empire Paper Co. is owned by Cowles Publishing Co., which also owns The Spokesman-Review.

Though the thrust of the project is the trees, it has the benefit of reducing the volume of wastewater the company discharges into the Spokane River, said Wayne Andresen, Inland Empire Paper Co. vice president and general manager.

Each day, the company discharges about 3.5 million gallons of water into the river.

However, only a fraction of that 3.5 million gallons is waste and the company actually discharges far less waste than it could under its state permit, Andresen said.

Inland Empire has permission from the state to discharge up to 2,400 pounds of waste per day in the summer, said Pat Hallinan, with the Washington State Department of Ecology.

Though the company can discharge 2,400 pounds of waste, it only puts out 340 pounds per day on average, Hallinan said.

When planted last spring, the hybrid poplars were only two inches tall. By the end of last summer, their average height was six to eight feet, Andresen said.

Some of the trees have already grown a foot this year. A few are around 10 feet tall.

The poplars are not only fast growing, but they are also tough. Over the winter, none died, even though a devastating ice storm destroyed thousands of other trees in the area.

The company expected some of the trees to die. Since none did, crews will thin the poplar stand this summer, removing nearly half of the trees, Andresen said.

The trees should be ready for harvest in six to eight years. By then they will be about 50 feet tall and 10 inches in diameter.

Whether the company plants more poplars depends on the supply of pulp. “If fiber continues to be available, I’m not sure we would (plant more poplars),” Andresen said.

The poplars need expensive sprinkler systems, and unless the pulp becomes more expensive, such an operation isn’t economically feasible, he said.

The state is planning to significantly lower the maximum amount of waste Inland Empire will be allowed to discharge after it completes a major plant expansion in the next few years, Hallinan said.

The poplar trees are one alternative the company could use to reduce the amount of waste it puts into the river, Hallinan said.

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