Month: October 2025
THE DIRT: The history of roads in the Silver Valley Pt. 2
As noted in part one of this series, the Silver Valley’s mining legacy runs deeper than its mountains—it is built right into the roads beneath our feet. For decades, mine waste was routinely used to build and maintain local roadways, rights-of-way, and driveways. Though this practice is long behind us, its impact can still surface today, especially for the road crews, utility workers, and contractors who continue to work in these areas.
Due to the widespread depth and distribution of contamination throughout the Bunker Hill Superfund site, complete removal of these waste materials was not economically feasible, nor logistically possible. As such, only partial removals of contaminated materials could be completed. Remediation depths vary, but most clean barriers will be either 6 or 12 inches deep, creating a clean protective layer over the remaining contaminated waste.
Roadbeds and rights-of-way are common places to run underground utilities such as fiber, gas, water, and sewer. This means most of the utility lines found within or adjacent to roadbeds throughout the Silver Valley were placed in contaminated materials. When utility, roadway, or ditch maintenance is needed, our local contractors are faced with the task of performing necessary repairs while also maintaining and restoring any remediated barriers they may encounter. This can be a big challenge, taking more time and effort than working in unremediated areas. To ensure this work is done properly and safely, contractors are encouraged to take the ICP class before working within the Superfund site.
Crews must protect remediated barriers by excavating and separating the clean barrier materials, then separating and isolating any of the deeper contaminated materials. Mishandling of contaminated materials during excavation can result in recontamination of clean areas and expose children and those near construction sites to lead and other metal contaminants. The responsible handling and disposal of these materials ensures that public health and the safety of the surrounding environment are protected. When all work is complete, contractors must ensure that the remediated barriers are restored to their original condition. While this process adds a layer of complexity to their everyday tasks, our local construction crews have mastered the methods needed to complete their work while protecting the remediation barriers that prevent accidental exposure to the contaminants that remain in our area. We thank them for their hard work and continued efforts to work safely and protect us all!
The Dirt is a series of informative articles focused on all aspects of cleanup efforts associated with the Bunker Hill Superfund Site. Our goal is to promote community awareness of contamination issues, to provide tools for protecting public health, and to keep the community informed of current and future cleanup projects. The Dirt is a group of committed and local experts from multiple agencies, including the Basin Environmental Improvement Project Commission, Panhandle Health District, Shoshone County, Silver Valley Economic Development Corporation, and the Idaho Department of Environmental Quality.
THE DIRT: The history of roads in the Silver Valley
The Silver Valley’s history is deeply rooted in mining. What started with a few mining claims quickly exploded into an industry that was created and remains the backbone of our community.
From 1886 to 1997, it is estimated that Silver Valley mines processed and concentrated approximately 130 million metric tons of metal-bearing materials, generating 109 million metric tons of mill tailings as waste byproducts. The topography of the region provided limited flat land for stockpiling and saving tailings and this became problematic for most of the mills throughout the region.
While the most convenient and common method of tailings disposal was to directly discharge them into local streams and creeks, some of these materials were used for more productive means.
One of the most common uses was the construction of local freeways, roads, railroad ballast, and driveways. For example, during the early 1900s, the City of Wallace procured and maintained a stockpile of tailings from the Standard-Mammoth Millsite. For years, the city used horse-drawn buggies and manual labor to dump and spread tailings throughout town for new roadways and for the maintenance of pre-existing roads.
In the 1960s approximately 2.6 million tons of tailings were removed from the Bunker Hill Mine’s impoundment pond and were used to build the roadbed for Interstate 90 through the Smelterville and Kellogg areas. Approximately one million tons of tailings were also used to create the Interstate 90 roadbed near Cataldo using dredge material placed between two parallel dikes. In addition to large-scale road projects, it was also common for homeowners and contractors to use these materials on smaller projects, such as to build and improve driveways, as fill materials, or for use as a base for concrete slabs, and sidewalks.
While these materials were utilized for their convenience and practicality, they unintentionally became a major exposure source of lead, arsenic, and other metal contaminants for both humans and the environment.
The abundance of these cheap, or often free, materials naturally encouraged their widespread use. This caused contamination to be spread to areas that would not have been impacted by mine waste.
When the Bunker Hill Superfund site was established in 1983 and cleanup efforts began, road shoulders, rights of ways, ditch lines, and driveways were a major consideration for the cleanup remedy.
Since cleanup began, thousands of driveways and hundreds of miles of road shoulders have been remediated to remove surface contaminants and replaced them with clean materials, creating a protective barrier between us and the contaminated materials underneath. The next time you are out for a drive, consider what you might find below the asphalt under your tires.
The Dirt is a series of informative articles focused on all aspects of cleanup efforts associated with the Bunker Hill Superfund Site. Our goal is to promote community awareness of contamination issues, to provide tools for protecting public health, and to keep the community informed of current and future cleanup projects. The Dirt is a group of committed and local experts from multiple agencies, including the Basin Environmental Improvement Project Commission, Panhandle Health District, Shoshone County, Silver Valley Economic Development Corporation, and the Idaho Department of Environmental Quality.
