About 50 people packed Assembly chambers Thursday night for a hearing on a proposal by Greens Creek mine to expand its tailings facility on north Admiralty Island, about 18 miles from Juneau.
Environmentalists said they are not convinced potentially toxic rock in existing piles is adequately contained. Mine officials are adamant they have taken steps to make sure the waste never hurts the environment.
The company blasts the rock from the underground mine and processes it into a flour-like substance to extract gold, silver, lead and zinc. Roughly half of the leftover material, or tailings, goes back into the mine, located in Admiralty Island National Monument. The other half, up to 270,000 tons a year, is deposited on the surface.
The problem is the company is running out of room. Greens Creek expects to operate the mine at least another 14 years, but the tailings piles, which currently take up about 30 acres, likely will be full in four years.
The company wants to load tailings higher on existing piles and expand the tailings site 84.5 acres to the west and southwest, with 40 acres reserved for new tailings, according to the U.S. Forest Service. The agency is doing an environmental impact statement on the proposal and hopes to make a final decision by December.
Conservationist Buck Lindekugel questioned whether the company is doing enough to ensure acids and heavy metals never seep into the groundwater and streams, where they could harm fish, wildlife and plants. He urged the Forest Service to require Greens Creek to use redundant systems, such as a liner, under the tailings.
"What steps are going to be taken to protect monument values, not only during operation but over the long term?" asked Lindekugel, of the Southeast Alaska Conservation Council.
Company officials bristle at the notion they are risking the environment, saying mine activities have passed muster with environmental regulators. The piles are cradled by thick layers of clay - a natural, dense material more effective at containing runoff than a synthetic liner, they contend. Greens Creek environmental manager Bill Oelklaus said the new site would have the same protection.
The company also is taking steps to stop acids from forming, Oelklaus said. The trick is to keep sulfides in the piles from coming into contact with water and oxygen, which transforms them into harmful agents.
The company dries and compacts the tailings. Although air and water can get in, naturally occurring calcium carbonate in the piles neutralize acids, much as TUMS tablets neutralize stomach acid, said company officials, who figure the piles will stay neutral for many years.
When the piles are full, Greens Creek plans to top them with clay, soil and gravel caps designed to keep out water and air permanently, said Oelklaus. However, Lindekugel, the conservationist, told the Forest Service he wasn't satisfied.
Steve Torok of the U.S. Environmental Protection Agency wanted assurances the tailings wouldn't slide into Hawk Inlet, downhill from the proposed site. A Forest Service representative said seismic specialists would examine that issue, but he downplayed the significance of it, saying the proposed site is a substantial distance from Hawk Inlet.
Kathy Dye can be reached at email@example.com.