EAST MISSOULA – The last repository of contaminated soil remaining at the Bonner mill is on its way out and will clear the way for another phase of redevelopment and future economic activity, the owners said Tuesday.

Bonner Property Development has contracted Bjorn Johnson Construction to complete the removal. The work will begin this week and must be completed by the end of August.

Missoula County signed the consent form on Tuesday.

“This has been a lot of years in the making,” said Commissioner Dave Strohmaier. “Many of us wish the pile wouldn't be there today and this would have been taken care of many years ago.”

The waste site contains around 60,000 cubic yards of soil and debris contaminated with petroleum compounds and PCBs once used at the former Stimson lumber mill.

The repository stems from cleanup work that occurred at the site back in 2011. The initial cleanup netted more waste material than initially expected, and the extra waste was capped on site as a cost-saving measure at the time.

The material will be hauled to the Missoula landfill.

According to the contract, Missoula County will contribute around $3 million in tax increment funds to finance the cleanup. The remaining amount, which hasn't been disclosed, will be covered by Bonner Property Development.

Removing the waste opens access to a larger segment of property.

“We're excited to get this finally started,” said property co-owner Steve Nelson. “It opens up about 2.3 acres right in the heart of the site.”

Bonner Property Development purchased the Stimson site in 2012 and has retrofitted the former mill with new businesses and hundreds of new jobs, from beer production to bicycle manufacturing.

But the location of the waste repository sits at the center of the larger property, hindering further redevelopment. The repository will be cleaned to industrial standards, giving Bonner Property Development future options.

“We don't have anything planned at the moment, but we are approaching being full,” said Nelson. “The next step would be to build something. There seems to be demand and there's been inquiries. We're all for getting something done so we can create more activity out here.”