Greens Creek Mine
The Greens Creek Mine is an operating, underground mine near Hawk Inlet on northern Admiralty Island within the Tongass National Forest. The mine is the largest producer of silver in the United States, but also produces smaller quantities of zinc, lead, and gold. It is located approximately 18 miles southwest of Juneau, Alaska, within the Admiralty Island National Monument. Greens Creek is the only active mine inside a United States National Monument. In 1980, Congress provided for mining at the Greens Creek site, then called “The Big Sore”, in the Alaska National Interest Lands Conservation Act (ANILCA).
Full-scale development of Greens Creek began in 1987. The mine, currently owned and operated by HECLA Mining Company from Coeur d’Alene, Idaho, is the second largest producer of toxic waste in Alaska. The mine's tailings and waste rock are currently stored in a 100 acre dump at the head of Tributary Creek, an anadromous salmon stream. Contaminated water from the tailings pile and elsewhere is treated and dumped into Hawk Inlet. Greens Creek has a history of underestimating the acid mine drainage potential of its tailings and waste rock. There have also been numerous water quality violations and spills.
The Greens Creek Mine produces three main types of toxic waste. The first type is the waste product of the mine's mill, which takes ore-bearing rock and processes it into a concentrated product. The process produces very high amounts (well over 95%) of waste, which is known as "tailings." The tailings are finely ground, exposing sulfates within the rock to the environment, which leads to production of sulphuric acid. In addition, the tailings contain heavy metals as well as chemicals used to concentrate the ore, such as diesel fuel, xyanthrate, and cyanide. The mine produced 318,000 tons of tailings in 2011.
The second main type of waste produced by Greens Creek mine is acid producing waste rock that does not go into the mill because of low ore content. Waste rock can still contain high amounts of sulphates and must be disposed of in a tailings dump to reduce acid contamination of surface waters. About 41,000 tons of waste rock was deposited into Greens Creek's tailings dump in 2011.
The third--and most significant from an ecological standpoint--type of toxic waste produced by the mine is contaminated water. This water comes from a variety of sources, including water pumped out of the mine, water removed from tailings prior to dry stack disposal, and water that perculates through the tailings pile. These waters contain a wide variety of toxic metals (lead, mercury, cadmium, arsenic) as well as other contaminants. All of these waters are pumped to a collecting pond and treated by a special facility prior to disposal into Hawk Inlet.
An average of 1.5 million gallons of contaminated water is dumped each day into Hawk Inlet. These waters, even after treatment, contain contaminants many times the state standards designed to protect aquatic life. Under state law, mines are granted an exemption from state water quality standards, allowing them a mixing zone designed to dilute the contaminants to safe levels. However, dilution does nothing to prevent the build up over time of these toxic metals and chemicals in Hawk Inlet.
Proposed Tailings Expansion
Currently, Greens Creek is in the process of applying for a permit to expand their tailings pile by 15 million tons, covering 60 additional acres. The current tailings system was permitted in 2003 to last until 2025, but now is estimated to fill to capacity by 2014.
The requested new expansion will, according to the mine, will be adequate for 30-50 years, which is the new estimated life of the mine. The mine has the right under its lease agreement to continue mining until 2095, so further expansion beyond 50 years is probable.
These additional tailings would, of course, lead to vastly increased amounts of contaminated wastewater which would have to be treated for hundreds of years if not forever.
Exhibits and Background Information