From EcoWatch:   The Resource War over Pebble Mine in Alaska’s Bristol Bay

(This is just part of the report – see it in full at the above link

Pebble Mine dams to hold toxins forever Credit: EcoWatch

Pebble Mine dams to hold toxins forever
Credit: EcoWatch

The Proposed Pebble Project

While there are at least 16 active mining claims in the headwaters of Bristol Bay, the Pebble Project has gained most of the attention because it is furthest along in the planning process. British mining giant Anglo American and the Canadian firm Northern Dynasty Minerals Ltd. together form the Pebble Limited Partnership that would own and operate the Pebble Project. Anglo American is the second-largest mining company in the world and made $6.2 billion in profits last year.

As noted above, the Pebble Limited Partnership has yet to apply for permits for the Pebble Project, but preliminary reports and government filings provide an idea of its size, scale and specifics. In addition, all large open-pit mines share certain characteristics irrespective of location or owner, which can therefore be expected with the Pebble Project. And an economic-impact study contracted by the Pebble Limited Partnership and released in May based its findings on the extraction of 5.9 billion metric tons of ore, a mine “comparable in size and scale to the plans [the Pebble Limited Partnership] will ultimately submit for approval.”

Even under normal mining operations—free of accidents or natural disasters—the Pebble Project would likely have significant environmental impacts on the natural character of the Bristol Bay headwaters. All of the necessary infrastructure will cumulatively bring tremendous industrialization of a truly unspoiled landscape, destroying streams and wetlands. According to the EPA’s draft watershed assessment of the Bristol Bay region, even without a disaster, mining the Pebble deposit would likely cause the degradation or loss of between 24 miles and 90 miles of streams and between 1,200 acres and 4,800 acres of wetlands, depending on various mine-size scenarios.
The mine itself will likely have both underground and open-pit components, meaning that the rocks, trees and soil overlaying the desired precious metals would all have to be removed. The open pit would consist of a large hole in the ground “up to three miles wide and thousands of feet deep,” according to FRONTLINE. Because the type of ore present in the Pebble deposit is very diffuse, requiring the excavation and processing of vast quantities of earth and rock to be economical, the Pebble Project could be the largest open-pit mine in North America and one of the largest in the world.

Additionally, the Pebble Project could generate up to 10 billion tons of waste, all of which would need to be stored on-site in vast rock piles and tailings reservoirs. These reservoirs, which will hold toxic waste, including the chemicals used to leach out the precious metals from the mined ore, require the construction of large dams and impoundments and then the filling in of previously untouched valleys. Depending on the actual size of the open-pit mine, the Pebble Project will likely require multiple tailings-storage reservoirs, each with multiple dams and earthen embankments.

In addition to the mine, waste rock and tailings piles, the Pebble Project will also require:

• A new road nearly 100 miles long from the mine site to the coast, which will necessitate more than 40 stream crossings that could block fish access to all upstream habitat
Four 86-mile-long pipelines to transport various substances to and away from the mine site, including toxic copper slurry
A new deep-water port to facilitate the transport of concrete, diesel and other materials

And, of course, a major infrastructure project such as this needs energy, but no electricity grid exists in the region. The Pebble Limited Partnership has proposed building a 378-megawatt natural-gas-fired power plant at the mine site and another eight megawatt unit at the port, enough electricity for nearly 300,000 homes (compared to the 311,000 housing units in the entire state of Alaska). Because there are not enough natural-gas resources in the Bristol Bay area, the fuel will need to be transferred to the site via one of the new pipelines mentioned above.

In addition to the likely general operating impacts of the Pebble Project, the legacy of open-pit mining around the world raises serious questions about the potential environmental and economic impacts if a problem does occur. Perhaps the worst-case scenario would be the failure of a tailings dam, which retains the reservoir in which toxic mining waste is stored. These reservoirs not only destroy the valleys in which they are built but also pose grave risks to the waters downstream. Failures in the dams that retain the tailings could cause downstream salmon habitat to be degraded for decades.

While the EPA considers failure of a tailings dam unlikely, one study found that between 1960 and 2000 there were a total of 72 tailings-dam accidents in the U.S. alone. Moreover, this risk would remain for decades or even centuries after the mine has ceased operations. As the EPA wrote in its second draft watershed assessment, “accidents and failures always happen in complex and long-lasting operations.”

The Pebble deposit is also located within the most seismically active region on Earth. While the exact seismicity of the mine site has not yet been studied, one of the strongest earthquakes ever recorded in North America—the 1964 Good Friday Earthquake, measuring 9.2 on the Richter Scale—occurred less than 300 miles away from the Pebble deposit. The tremor permanently shifted surface lands over more than 100,000 square miles and was felt more than 1,000 miles away in the state of Washington.

Another risk with any copper-mining operation comes from the unearthed minerals in the waste rock being exposed to air and water, which can often cause a reaction that forms sulfuric acid. This acidity then releases residual copper from the waste dumps and tailings reservoirs, creating a toxic brew known as acid mine drainage, or leachate. While companies extracting the Pebble deposit would be required to follow regulations for containment and treatment of this toxic waste, the EPA says in its draft watershed assessment that even under normal operations, there is a “realistic expectation that leachate would escape the collection systems” and that leakage of leachates, even in the absence of accidents, is “inevitable.”

Salmon are particularly sensitive to copper and may avoid habitat polluted by the metal, suffer stunted growth, or even die if exposed to high-enough concentrations. EPA preliminarily estimates that copper runoff from mining in the Bristol Bay region—such as what could result from the Pebble Project—could directly impact salmon more than seven miles downstream from the mine and indirectly harm the fish through impacts to their food source as far as 35 miles downstream.
Full report