Engineering & Mining Journal

SEP 2015

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portal work and treat the discharge water, so they backfilled the No. 7 Level portal site to prevent a blowout during the winter. That is what we believe led to the blowout in August. They were doing the right thing, but like the Titanic, a combination of minor problems culminated in a major incident." The Debate Over the Sunnyside Mine Pool The Silverton Caldera is also home to the historic Sunnyside gold mine, which had about 100 miles of mine workings. According to Hennis, the mountain, Bonita Peak, is fractured, folded, fissured, and filled with exploration drill holes, and it's unreasonable to expect bulk-heading to work in these geologic conditions. The problem lies inside of Bonita Peak, according to Hennis, and it started when Sunnyside began the bulk-heading process on the American Tunnel between 1996 and 2003. He believes the head on the mine pool is much higher than anyone anticipated. "The pressure on the lower- most bulkheads has to be extraordinary," Hennis said. "If a seismic event were to occur with that much hydrostatic pressure and faults lubricated with water, the dis- charge will be much greater than this one." Discharges from the Mogul mine (anoth- er mine in the region he owns) began to increase in 2000–2001. "Despite everyone being cognizant of what was happening, the state of Colorado allowed Sunnyside to fin- ish bulk-heading the mine and walk away," Hennis said. "The state signed away any ability to regulate the Sunnyside mine pool." By carefully and incrementally lowering the Sunnyside mine pool, Hennis believes all of these peripheral UA discharges will return to minor amounts or zero, which was the pre-existing conditions prior to the bulk- heading of the Sunnyside mine. He also wants to see a processing facility installed at Gladstone near the American Tunnel por- tal that could treat Cement Creek. At the time Sunnyside was bulk-heading the mine, the mine was owned by Echo Bay Mines. In 2003, Kinross Gold purchased Echo Bay Mines. After the Gold King spill and in response to Hennis' allegations, Sunnyside Gold Corp. issued a statement explaining that it is not involved whatsoever with this situa- tion; it never owned or operated Gold King and did not take part in work being done there. The company said the following: "The Sunnyside mine workings have no physical connection to the Gold King and such a connection never existed. Sunnyside is not the cause of the water buildup at Gold King. "In fact, Sunnyside, with oversight and approval of all relevant agencies, installed a series of bulkheads to isolate its mine work- ings from other workings in the area and to prevent water flow from the Sunnyside mine workings to the Animas Basin. The bulkheads installed at Sunnyside are engi- neered concrete structures. While the state- approved bulk-heading was always expect- ed to return the local water table toward his- toric natural levels, it did not cause the water buildup at Gold King. "As the EPA has taken responsibility for the discharge, it is unfortunate that the representative of Gold King mine is trying to deflect responsibility from what has clearly been the location of the incident, which is Gold King mine. The spurious allegations made against Sunnyside are not based on fact." What's the Solution? From an engineering standpoint, Newmont's Idarado gold mine provides a great regional contrast. It closed in 1976. In the 1980s, as they were performing reclamation, they looked at all options, rejected bulk-heading and implemented hydrological controls above the portals to prevent inflows into the old workings. The Red Mountain and Treasury tunnels are still open today and water is flowing from those tunnels, but the water quality is good. Mark Gibson, an environmental specialist with Kyklos Engineering, worked on the Idarado reclamation project and said the results speak for themselves. "It was a state- directed Superfund site," Gibson said. "There was a dispute on how to deal with zinc contamination and provide an aquatic life habitat on all sides of the drainages." He has since been involved in several dozen Superfund site disputes and as many hard rock mine cleanups. When they were originally looking at reclaiming the Idarado mine, the regulators proposed a $150 million mitigation strategy that involved a series of dam impoundments and active treatment systems. "If they would have been allowed to do that, the Idarado property would have been turned into a huge dam impoundment, creating liabilities for- ever," Gibson said. "That's not solving the problems. They are treating the symptoms." SEPTEMBER 2015 • E&MJ; 67 www.e-mj.com G O L D K I N G S P I L L

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