State of Montana Newsroom
Final Cleanup Activities Begin at Former Stimson Lumber Bonner Mill Site in Missoula County
HELENA—The Montana Department of Environmental Quality (DEQ) announces that work began today on the final phase of removal of an onsite, low-level hazardous waste repository at the former Stimson Lumber Bonner Mill Site in Missoula County, Mont. Though the repository was performing as designed and DEQ did not require removal or alteration, the current landowner, Bonner Property Development (BPD), elected to dispose of the contaminated soils offsite to allow additional space for redevelopment. In the fall of 2021, approximately 40,000 cubic yards of contaminated soils were removed from the repository and disposed of at Republic Landfill in Missoula under a DEQ approved workplan.
The former Bonner Mill site was discovered to have contaminated sediment at the onsite cooling pond in 2006. Stimson Lumber Company, the operator of the lumber mill, completed cleanup actions in 2016 that included disposal of Polychlorinated Biphenyls (PCB) contaminated soils from the old fire pond lagoon, log pond, mill cooling pond and surrounding impacted soils into an onsite repository.
The final cleanup activities include cleaning and testing concrete footings from the kiln building where the former repository was housed, as well as testing soils to confirm that PCB contamination has been remediated to below standards set for industrial properties. Bonner Property Development will reclaim and revegetate the area. Following completion of this work, the 3-acre location of the former repository will be available for redevelopment.