Overlooking the massive, tiered hole in the earth near where the Parrot smelter once stood and where a fleet of heavy equipment was rapidly moving dirt, clay, slag and tailings on Friday morning, Water and Environmental Technologies Senior Engineer John Trudnowski explained the scene below in the most understated of terms: “What you’re seeing right here is more or less a backfill operation.”
That might technically be true, but what was actually happening was a major environmental cleanup that has been in the works since at least 2006, when the state of Montana began pushing the Environmental Protection Agency to remove the buried contamination to protect Blacktail and Silver Bow creeks.
When excavation finally began on Aug. 7 of this year, engineers for the Parrot Tailings Waste Removal Project weren’t sure exactly what they would find as they started digging into the site. But now that crews from the Lewistown-based MK Weeden Construction have been moving and removing huge amounts of dirt as part of the first phase of the two-phase project, a more complete picture of the extent of the site’s contamination is coming into view.
On Thursday evening, Jim Ford, the project manager for the Montana Natural Resource Damage Council, presented an update on the removal work at a meeting of the Butte Natural Resource Damage Restoration Council (BNRC). There, Ford described the various layers that exist between the surface and the groundwater on the site. He also told attendees that groundwater contamination at the site is more extensive than many experts had previously believed.
“Everywhere we’re digging down to the groundwater, we’re finding blue water," Ford said Thursday.
That unnaturally blue color is the result of copper contamination. According to Nick Tucci, a WET hydrologist who is the project manager for groundwater, the contamination being found in that water is an “order of magnitude higher” than what is found in the Berkeley Pit.
And Tucci’s “working theory” is that copper is “wicking back and forth” between a layer of highly contaminated clay and the groundwater, through a thin strip of alluvial soils.
A complete understanding of the soils, contamination and groundwater at the site is still developing, but Ford explained that it is coming into focus, with five distinct layers having been identified between the surface and groundwater.
On top, he said, is about 110,000 cubic yards of overburden—a layer of clean soil that will be set aside and reused at the site.
Next is about 130,000 cubic yards of slag, a byproduct of smelting that contains a slight residue of metals. While these metals could leach some small amount of contamination if exposed to water, Ford explained that the slag will also be kept on site, beneath an ET (for “evapotranspiration”) cover that will prevent infiltration of water, which would be the pathway for moving contamination from the slag to the groundwater.
According to Trudnowski, the slag will be placed against the side of an existing railroad berm on the site to “kick out” the slope so it will be gradual enough for soil and vegetation.
Below the slag, Ford said, is some 40,000 cubic yards of black clay that “picks up contaminants” due to its high amount of organic matter. Testing indicates that the clay has very high concentrations of copper, which are up to 4 percent in spots, according to Tucci.
The final layer of earth is a thin strip of alluvial soils, some of which is contaminated and some of which is not. While the contaminated soil is being sent to Montana Resources, where the mining operation will leach metals from all of the site’s contaminated waste and take responsibility for its final disposal, the clean soil is being retained at the Parrot site.
Below the 400,000 cubic yards of soil is the groundwater. As it has been uncovered and more fully understood, Ford said a plan has taken shape to pump the contaminated water off site, to MR’s nearby process pond. That, he said, will represent a “huge savings” over having to deal with the contaminated water some other way. According to Trudnowski, pumping could begin as early as next week.
While MR’s willingness to take contaminated tailings, soil, clay and water from the site has helped reduce cost for the project, Ford said Thursday that the greater-than-expected volume of contamination at the site will likely increase the cost of having to remove it.
Though he said during the meeting that such increased costs could threaten the project’s budget, Ford added afterward that project managers have “that risk pretty well managed.”
Project managers have also been surprised by how thick, hard and rough on equipment the layer of slag has proven to be.
“It’s really difficult to get through, but the good news is, we’re getting through it,” Ford said.
If crews remain on schedule, phase one of the project should be complete by the winter of 2019. As for phase two, its start is dependent on Butte-Silver Bow moving the county’s vehicle and maintenance shops from the site. That move has been delayed repeatedly, but at Thursday’s meeting, Eric Hassler, the county’s Superfund Operations Manager, indicated a new plan is in the works.
According to Hassler, the county submitted a revised proposal to the state on Wednesday. That proposal would still involve moving the facility to property owned by Bill Hollow off Beef Trail Road, a location the county’s Council of Commissioners approved last year. However, Hassler said the new plan would involve reusing some existing buildings and realigning how the buildings would be positioned on the site. That, he said, would reduce the amount of earth that needs to be moved at the Hollow property, which would bring costs down “much closer” to the $12.5 million price tag that the state originally budgeted for the shops' relocation.
Hassler said the county’s new proposal also offers another, unnamed location as a “fallback” option.
But Hassler was reluctant to divulge too many details, as it has not yet been brought before the commissioners. That is expected to happen Tuesday, at a special council meeting, he said.