Missoula County is taking its first steps toward removing the last pile of hazardous waste from Bonner’s historic sawmill and plywood plant site.

On Tuesday, Missoula County commissioners approved an agreement with Bonner Property Development LLC, owner of the former Stimson Lumber mill site, to allow workers access to remove a pile of waste that sits in the middle of the property. But a few more months will pass before that actually happens.

The 23-foot-high mound contains soil and debris contaminated with petroleum compounds and polychlorinated biphenyls once disposed of in the cooling ponds of the Stimson mill, and earlier the Champion International and Anaconda Co plywood plant and sawmills.

To protect the nearby Blackfoot River, the Montana Department of Environmental Quality required that the soil be removed to landfills or collected in a repository and capped with 2 feet of clean soil. There it has remained since 2011.

“When they did the cleanup, there was a certain amount that the DEQ said didn’t need to be removed because it met with industrial standards,” said Dori Brownlow, Missoula County development district director. “There was some debate about that, as I understand. Stimson didn’t want to move it; the county wanted it removed.”

Almost a decade ago, cleanup of the last pile would have cost $800,000, Brownlow said. Now, the estimate is almost $3 million.

When Bonner Property Development bought the property, it wanted the pile removed and turned over to the county, which created a Tax Increment District in 2012 to raise funds. The account grew slowly because only new buildings can be taxed. Other than the Kettlehouse Brewing Company development, few new buildings have been built.

But now, the TID fund has enough to allow the county to issue a bond to complete the cleanup and it may be draw money from brownfield funds. Brownlow said Stimson hasn’t agreed to pay for the removal.

“We’re not required to remove it. It’s probably in a gray area. Stimson is still part of it. It’s their pile, they have to sign off on it,” Brownlow said. ““Because we didn’t have the funds before, it wasn’t a serious discussion. Now we’ve got to figure this out. Who are our partners in this?”

Last week, the commissioners approved a contract with Territorial Landworks to do the engineering and be the project manager for the removal work. Now they have to put the project out to bid.

The waste may end up going to the Republic Services landfill, but that’s also still to be determined.

“In a perfect world, we’ll be able to get it done within the next six months. But definitely by next spring,” Brownlow said.