The Montana Department of Environmental Quality is considering whether a more intensive effort is needed to clean up arsenic contamination at Arrowstone Park in Deer Lodge.
The park was built on top of toxic mine waste in 2001. In the decades since, erosion and weathering have caused arsenic and other metals to become exposed on the surface.
Jessica Banaszak is DEQ’s project manager at the site. At a public meeting Tuesday, she said more cleanup may be needed to protect people from arsenic in the soil.
"We’re working really hard to find the best path forward to ensure that we’re protecting human health and doing a cleanup that’s going to be enough for the park going forward. "
During the park’s construction more than 20 years ago, officials established a threshold for acceptable concentrations of arsenic in the ground. The Clark Fork Technical Assistance Committee, a citizen-led group, says that threshold is likely too high to protect human health long term. Repeated arsenic exposure over many years can increase cancer risk, according to the EPA.
State officials say the park is safe for public use in the short term. DEQ will maintain temporary soil caps placed over exposed areas and has posted warning signs around the park.
The agency had initially planned to start a permanent cleanup last fall. Banaszak says the reevaluation of the arsenic threshold is the main reason for the delay. DEQ will conduct additional soil sampling at the park this summer but does not have a firm timeline to begin cleanup.
