DEQ provides update on UBMC cleanup plans

With cleanup work at the Upper Blackfoot Mining Complex set to resume next week, representatives of the Montana Department of Environmental Quality, U.S. Forest Service and the Natural Resource Damage Program returned to Lincoln Thursday, June 6 to provide the community with an update on the progress of the cleanup.

"We said last winter we'd come back and give an update before construction. They're starting to mobilize now onto the site." Project Manager Dave Bowers told this reporter, the only person to attend the public presentation.

Despite the lack of attendance at the meeting, Bowers went through the presentation, reviewing the progress made and looking ahead at the final phase of the project.

Bowers explained that work should begin June 17 with floodplain back fill in the areas that were excavated last year. Removal of contaminated material in the last stretch of the project area is expected to begin after water levels drop further. Once removals begin it should take about two or three weeks to complete, Bowers said.

Missouri River Contracting will be returning to finish the removal and should finish their work in the UBMC by August.

Work will continue into the fall, however, as Glacier Excavation rebuilds the stream channel and restores the flood plain from the Water Treatment Plant to the boundary of the Engineering Evaluation/Cost Analysis area near the Edith Mine, between Shaue Gulch and Pass Creek.

The EE/CA established the boundary of the cleanup area for the $39 million settlement with ASARCO that has funded work in the UBMC.

Since 2014, the DEQ-led cleanup has removed about 861,000 cubic yards of mine waste and contaminated material from the UBMC. The bulk of it, 542,350 cubic yards, came from the removal of the Mike Horse Dam and tailings impoundment in Bear Trap Creek that was completed between 2014 and 2016.

The cleanup was "paused" in 2017 while the partner agencies sorted through a disconnect on how to best spend the money remaining from the ASARCO settlement, but work resumed last summer. 2018 saw more than 171,000 cubic yards of mine waste removed from the final phase's clean up area that extends from the confluence of Mike Horse and Bear Trap Creeks to the EE/CA boundary.

Only about 86,000 cubic yards of contaminated material remain in the area. Bowers said removals are about 25,000 cubic yards below what they had projected for the final phase.

"We know we're well within budget as were moving forward. Everybody's very encouraged by the outlook of that," Bowers said.

Bowers went on to say the clean-up effort has been awarded a pair of grants from the Montana Department of Natural Resources totaling $800,000.

A $300,000 grant will allow for construction of a bridge and infrastructure protection for the Water Treatment Plant. The new bridge, designed to pass a 100-year flood, will replace the existing culvert and is expected to improve both fish passage and habitat.

"One of the things that makes all of us so excited about that is, this is the year when it should be going in, so the timing couldn't be better." Bowers said. The grant was approved as part of the infrastructure bill signed by Gov, Steve Bullock this year.

A $500,000 grant will allow for the investigation of the wetlands downstream of the EE/CA boundary, to assess the effects of remediation and restoration on contamination there. The DEQ has to find additional support from another stakeholder such as Trout Unlimited or a similar organization before the grant funding will be released.

The wetlands, particularly the upper marsh that lies just west of the boundary, is estimated to hold 46,000 cubic yards of mine waste carried there when the Mike Horse dam broke in 1975.

The 2009 Record of Decision called for removal of the contaminated waste there, but it is on Forest Service land outside the EE/CA area.

The hope is that much of the contamination there will be mitigated through natural processes.

"We're going to have close to 40 acres of floodplain restored, and in the neighborhood of 12,000 feet of stream that have been reconstructed. That's a lot of source area for clean sediment that is going to transport downstream and work its way into the wetland area," Bowers said. "It's a good time to stop and check and see if what was prescribed in the Record of Decision is still indeed what we want to do to move forward"

He said they have the 2009 pre-remediation data to use as a baseline against which they can assess the health of wetlands before deciding on whether removals will be necessary.

"It's going to be a partnered decision that's going to be based on the data that's collected and the complexities of the relationships that exist there. The land ownership is a mix of trust and Forest Service administered land, and (there are) certain environmental regulations and engineering and design considerations (that) have to be weighed against what we find after this study," Bowers said.

The questions about waste removal from the wetlands may impact the final closure of the Section 35 repository as well. For the past four years the repository has been temporarily closed between construction seasons with about six inches of impermeable glacial till to keep moisture out of the mine waste. By contrast, permanent closure would see the installation of a high-density liner to serve as a cap that would be covered by abut 18 inches of glacial till and dirt, and then revegetated. Bowers said it would be cost prohibitive to re-open the repository once it is capped with the liner.

A third option under consideration would be a "long-term temporary" closure for about three years. That would cover the repository with about 12 inches of till and give the DEQ time to complete their investigation into the wetlands.

"It's just a matter of making sure the path we go down is the path we want," Bowers said.

Although waste removal and reconstruction is slated to be completed this year, the final re-vegetation and seeding of the flood plain from the Water Treatment Plant to the EECA boundary won't be finished until the fall of 2020.