Montana Mining Era Offers Rich Historical and Contamination Legacy

Montana mining and historical contamination

By Duane Craig

The recent announcement that the Environmental Protection Agency had scheduled the cleanup at an old copper refinery near Great Falls, Montana, culminates a year long process of getting it on the Superfund National Priorities List. Cleanup will begin this summer.

Historical Contamination in Montana

The cleanup surrounds three different hot spots that have elevated amounts of lead and arsenic, along with other heavy metals. The contamination is at sites that form a rough triangle with one leg extending from the 15th Street Bridge to the Moose Lodge, another leg extending from the Moose Lodge to the Memorial Park and the third leg returning from the Memorial Park to the 15th Street Bridge. An old railroad line is also included. Back in 1891, according to this old perspective map, the Boston and Montana Smelters sat on higher ground and across the river from current day 20th street.

The EPA shows the Boston & Montana Consolidated Copper and Silver Mining Company building the first smelter in 1892 and beginning operations in 1893. In 1910 the Anaconda Copper Mining Company bought the facilities there and renamed them the Great Falls Reduction Department. Throughout a large part of its history the refinery casually dumped tailings and slag into the Missouri River using a tramway along the edge of the river. Just in 1907 alone it was estimated 905,000 tons of contaminated slag and tailings were dumped into the river there.

A secondary polluter was the 502 foot tall smokestack that delivered a steady stream of contaminants over a wide area. That famous landmark was dropped to the ground by explosives in 1982 to the thrill of 40,000 spectators. Dubbed the Big Stack, its demise was heralded by T-shirt sales with catchy slogans, and “blow your stack” tavern parties. But the stack didn’t go easily. The first attempt dropped everything but a 250 foot tall splinter. So, more explosives had to be packed into an additional 80 holes to finish the job.

Another report cites historical records that detail “the sluicing and dumping of granulated slag, slimes, ash and tailings directly into the Missouri River.” Montana’s Department of Environmental Quality reported an estimated 27 to 31 million cubic yards of waste being dumped into the river until 1915. Onsite containment began that year. Arsenic trioxide has been reported in the soils at concentrations between 5 and 40 pounds per acre in downwind areas.

There is a great number of heavy metals found in the sediment of the Missouri River, in the surface water and beside the old rail line. A 2003 study documented antimony, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, silver, sodium and zinc. The soils mostly have high levels of arsenic, lead and cadmium.

At the peak of its production the refinery employed 2,000 mostly union workers and delivered ever increasingly higher wages. At the end of its life in 1980 it employed 500. From 1981 to 1999 the latest owner of the site, Atlantic Richfield Company, tore down buildings, backfilled basements and buried flue dust, granulated slag, asbestos material, demolition debris and other waste as part of the site’s closure. There was no oversight of those activities by any regulatory agency.