Pennsylvania Mine clean-up crews look to go underground
July 25, 2011
After extensive surface-level investigations, officials with the Colorado Division of Reclamation, Mining and Safety plan to go underground to seek ways to prevent Pennsylvania Mine water leakage from continuing to pollute waters flowing into the Snake River.
The division’s representative for the project, Jeff Graves, said a drill should arrive today to help him and others eventually get underground in the 20th Century gold and silver mine.
The mine is among nearly 400 others in the area, but is the main target for stream improvements that don’t involve actually treating the water – cost and liability assumed under current law inhibits a third-party treatment system.
“We see a noticeable spike (in zinc concentrations) when Peru Creek runs by the Pennsylvania Mine,” said Ryan Durham, remedial project manager with the Environmental Protection Agency.
He showed graphs that show the presence of zinc and other metals in the creek starting at its confluence with surface and groundwater flowing from the mine area.
“You put two and two together and it points to the Pennsylvania Mine as a primary point for metals reduction,” he said to those gathered for Thursday’s Snake River Watershed Task Force meeting in Keystone.
Some experts contend that the hillsides above Peru Creek are rich with metals that leach naturally, but most officials on this particular project agree that while there may be natural metal deposits occurring to make the creek a consistently uninhabitable place for fish, it’s likely the mine is a big player in sending metals downstream and causing low pH in the water. Downstream, in the Snake River above the Dillon Reservoir, the water is diluted enough by clean stream inflows for fish to live and reproduce.
However, surge events like one in 2007 have sent more than the usual flow pumping out of the mine, meaning more metals heading downstream at once. Increased contamination has caused fish to die downstream, Division of Parks and Wildlife fisheries biologist Jon Ewert said. It’s also unclear if groundwater seepage contributes to downstream contamination.
But despite ongoing water quality sampling, fluorescent dye tests (to see how the water moves through the underground mine network), drilling crosscuts to gather preliminary geotechnical information, installing groundwater monitoring wells and more, project workers still aren’t sure how to help the situation.
The proposed next step should allow further investigation of the amount of water that actually discharges from the mine (including groundwater sources), where and in what condition the water enters the mine, flow paths within the workings, and the accessibility of the mine’s innards. The end goal is finding a feasible control remedy. Proposed solutions currently include building a bulkhead to protect against surge events, sealing entry sources so clean surface water isn’t contaminated and, separating clean water paths from dirty water paths to consolidate the waste.
“Right now, all those options are on the table until we get down there and find out they’re not,” Graves said.
The challenge to verifying the crew’s hypothesis of water flows is the collapse of all portals to the mine’s workings, which is where the drill comes in.
If Graves can complete the plan of boring into the mine, conducting laser and sonar surveys of the historic tunnels and do a visual inspection with a camera, they may find it’s possible to physically get inside. That part of the project, at a cost of about $80,000, should be complete by early August.
With information from the first phase, Graves and his team can consider the feasibility of the rest of the plan next summer, which involves excavating the hillside, draining a pool of backed up mine water into settling pools, building a new portal and finding a safe way to survey the mine’s interior. Depending on the extent of work, the second phase is expected to cost between $450,000 and $800,000.
“We support this approach. It makes sense to us,” said Summit County manager Gary Martinez. The county government is among several agencies collaborating to make the project happen, including the EPA, the Division of Reclamation, Mining and Safety, Northwest Colorado Council of Governments, the Blue River Watershed Group, Trout Unlimited and the Colorado Department of Public Health and Environment.
“We still have to get underground to see if we can control the water coming out,” said Mark Rudolph of the state department.