Berkeley Pit
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The Berkeley Pit is a gigantic former open pit copper mine located in Butte, Montana, and is the one of the largest Superfund sites. It was opened in 1955 and operated by the Anaconda Mining Company and later by the Atlantic Richfield Company (ARCO), until its closure in 1982. When the pit was closed, the water pumps at the bottom were also turned off, which caused groundwater from the surrounding basin to leak into the pit. The water seeped through metal deposits, causing it to become heavily acidic and laden with heavy metals and dangerous chemicals such as arsenic, cadmium, zinc, and sulfuric acid. The water has a pH level of 2.5. Toxic water was filling up the pit at a very fast rate after its closure until it was a mile wide and over 900 feet deep, but it was not until the 1990s that serious plans were devised for solving this problem.
The water is so loaded with metals (up to 187 ppm Cu) that "mining" of the water has been done. However, fluctuations in power prices have made this difficult.
In 1995, a large flock of migrating snow geese landed on the Berkeley Pit water and were killed, most likely by the high concentration of acid. 342 carcasses were recovered. Their livers and kidneys had bloated, and many had eroded esophaguses. ARCO, the current custodian of the Pit, denied that the toxic water caused the death of the geese, instead blaming their deaths on their diet. They maintain that the Pit is safe and environmentally sound.
Nearby residents are also concerned about the fog produced by the pit and are wondering what it is doing to their health. The most recent development in the clean-up was the construction of a treatment plant on Horseshoe Bend. This facility is intended to treat and divert water coming from the Horseshoe Bend flow. In addition, it will be able to treat the existing Berkeley Pit water in 2018, or whenever the water level hits the critical point of 5,410 feet above sea level. This number was set by Federal order and is intended to protect the ground water from being contaminated by the water in the pit.
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[edit] Extremophiles
A few new fungal and bacterial species have been found to have adapted to the harsh conditions inside the pit. Intense competition for the limited resources caused these species to evolve the production of highly toxic compounds to improve survivability; natural products such as Berkeleydione, berkeleytrione [1] and Berkeley acid [2] have been isolated from these organisms which may kill cancer cell lines.
[edit] Early history and development
The underground Berkeley Mine was located on a prominent vein extending to the southeast from the main Anaconda vein system. When pit operations began in July 1955, near the Berkeley Mine shaft, the older mine gave its name to the pit. The open-pit style of mining superseded underground operations because it was far more economical: even very low-grade ore could be recovered using shovels and trucks, which were also less dangerous than underground mining. Within the first year of operation, the pit extracted 17,000 tons of ore per day, much of it averaging only 0.75% copper, meaning that only about 127 tons of copper was produced from the 17,000 tons of material moved. Ultimately, about 1,000,000,000 tons of material was mined from the Berkeley Pit [1]. Copper was the principal metal produced, together with subsidiary amounts of silver and other metals.
[edit] External links
- Berkeley Pit Photos from the Montana Department of Environmental Quality
- PitWatch
- Berkeley Pit and Butte Mine-Flooding Operable Unit
- A Photo of Berkeley Pit from an aerial viewpoint
- A famous former resident of Berkeley Pit
- ISS image of Berkeley Pit (dated August 2, 2006)
[edit] References
McClave, M.A., 1973, Control and distribution of supergene enrichment in the Berkeley Pit, Butte District, Montana: in Guidebook, Butte Field Meeting of Society of Economic Geologists, p. K-1-K-4.
Shovers, B., Fiege, M., Martin, D., and Quivik, F., 1991, Butte and Anaconda revisited: Montana Bureau of Mines and Geology, Special Pub. 99, 64 p.
Weed, W.H., 1912, Geology and ore deposits of the Butte District, Montana: U.S. Geological Survey Professional Paper 74, 262 p.
