'Diggings East' Superfund work slated to begin in August

The Diggings East site in Butte contains just about everything except the kitchen sink, and that’s likely in the mix too.

Along with mine tailings, contaminated soils, municipal wastes, timbers, household wastes, construction debris and more.

Josh Bryson, Atlantic Richfield’s project manager in Butte, said the 30-acre Diggings East site along George Street likely became an unpermitted landfill when people were working to fill in a wetlands near Silver Bow Creek. The earliest dumping might have occurred in the early 1900s.

The Diggings East site is one of several locations within the so-called Silver Bow Creek Corridor that is being remediated under federal Superfund guidance.

The riparian corridor for Silver Bow and Blacktail creeks is near where Uptown Butte transitions to the Flats. And it is a legacy of the decades when Silver Bow Creek became an industrial sewer.

Other sites in the corridor include the Butte Reduction Works, Northside Tailings, Buffalo Gulch, Blacktail Creek and Grove Gulch.

Work has been underway on Grove Gulch and at the Butte Reduction Works. Grove Gulch is nearly complete and a second round of demolition is planned for the Butte Reduction Works off Montana Street. That work, which will remove more slag and foundations, will begin in February.

Atlantic Richfield has also created the Lexington Wetlands recreational area, a site that has not included removal of contamination.

The work at Grove Gulch has included, among other things, construction of a sedimentation bay and vegetated swale — a type of channel — to reduce the amount of contaminated sediment and metals that reach Blacktail Creek and thereby improve the quality of water in the creek.

Atlantic Richfield has expressed support for using the Butte Mine Waste Repository to begin dumping wastes hauled from Diggings East. Bryson said Atlantic Richfield anticipates about 345,000 cubic yards of wastes will be excavated from the site and trucked to the repository. One cubic yard is roughly equivalent in size to a conventional washing machine.

Bryson hopes the excavation will begin in August.

He said most of the material excavated will go in the Butte Mine Waste Repository. There will be exceptions, including large items like refrigerators, which will likely be disposed of at the Butte-Silver Bow Municipal Landfill.

The initial work will begin with “dry digging,” excavating materials above the groundwater level, he said, with dewatering to begin later.

“The dewatering will support deeper excavations and initial site reconstruction, for items like the liner system, permanent pools and structural footing,” Bryson said.

The Diggings East project will likely require four years to complete.

When it’s done, the acreage could become a park and join similar parks in the corridor that emerge after remediation.

On Wednesday night, Bryon briefed the Butte-Silver Bow Council of Commissioners about the projected use of the Butte Mine Waste Repository.

Bryson described how a repository siting committee had considered several alternatives before concluding the existing Butte Mine Waste Repository could be expanded to handle the estimated 1.1 million cubic yards of wastes from the Silver Bow Creek Corridor sites.

He said work in the Silver Bow Creek Corridor could require five to seven years and that during busy periods there could be 300 truck trips a day to haul wastes to the repository.

Bryson said truck drivers would receive rigorous training and that Atlantic Richfield and its contractors will monitor how and whether the truck traffic is damaging public roads before the trucks reach the property of Montana Resources.