Lesson plan
Berkeley Pit
The Berkeley Pit is a former open pit copper mine in the western United States, located in Butte, Montana. It is long by wide, with an approximate maximum depth of . It is filled to a depth of about with water that is acidic (4.1 - 4.5 pH level), about the acidity of beer or tomatoes. As a result, the pit's water is laden with heavy metals and dissolved metals that leach from the rock in a natural process known as acid rock drainage. The pit's water content includes (but is not limited to) dissolved copper, arsenic, cadmium, zinc, and sulfuric acid. The mine was opened in 1955 and operated by the Anaconda Copper Mining Company, and later by the Atlantic Richfield Company (ARCO), until its closure on April 22, 1982. When the pit was closed, the water pumps in the nearby Kelley Mine, below the surface, were turned off, and groundwater began to slowly fill the Berkeley Pit, rising at about the rate of per month. Since its closure, the water level in the pit has risen to within of the "protective water level", above which the polluted water might flow into a nearby creek and other local water sources. As a result, a water treatment plant has been operating at the site since October 2019. The Berkeley Pit can be visited by tourists, with a viewing stand and small visitor center.
Article summary
The Berkeley Pit is a former open pit copper mine in the western United States, located in Butte, Montana. It is long by wide, with an approximate maximum depth of . It is filled to a depth of about with water that is acidic (4.1 - 4.5 pH level), about the acidity of beer or tomatoes. As a result, the pit's water is laden with heavy metals and dissolved metals that leach from the rock in a natural process known as acid rock drainage. The pit's water content includes (but is not limited to) dissolved copper, arsenic, cadmium, zinc, and sulfuric acid. The mine was opened in 1955 and operated by the Anaconda Copper Mining Company, and later by the Atlantic Richfield Company (ARCO), until its closure on April 22, 1982. When the pit was closed, the water pumps in the nearby Kelley Mine, below the surface, were turned off, and groundwater began to slowly fill the Berkeley Pit, rising at about the rate of per month. Since its closure, the water level in the pit has risen to within of the "protective water level", above which the polluted water might flow into a nearby creek and other local water sources. As a result, a water treatment plant has been operating at the site since October 2019. The Berkeley Pit can be visited by tourists, with a viewing stand and small visitor center.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.