July 2, 2008
Vigilance Needed on Leadville Tunnel
By Chris Woodka, The Pueblo Chieftain, Colo.
Jul. 2--LEADVILLE -- A risk assessment study of the danger posed by blockage of the Leadville Mine Drainage Tunnel reveals a path that could head off future emergencies.
For the time being, there's no imminent danger from a blow-out, and several scenarios show failure of huge plugs in the tunnel would create a trickle over time rather than a dramatic burst, according to the study by the U.S. Bureau of Reclamation. Optimum levels of water in the tunnel could relieve pressure without increasing contamination.
However, there's still more work to be done to determine who will ultimately have responsibility for implementing procedures to take care of the problems.
"I don't know what will happen if we have failures in the future," Bureau of Reclamation Great Plains Regional Director Mike Ryan said Tuesday. "One of the questions we'll have to look at in the longer term are what levels we need to maintain the mine pool."
Ryan and other Reclamation officials answered questions from the Leadville community at two meetings Tuesday, one day after releasing a final draft of a risk assessment study on the Leadville Tunnel. The public will have 30 days to comment on the report, and it will be completed by the end of September, Ryan said. Still unresolved is the issue of authority.
"Will the bureau continue to resist assuming responsibility for the mine pool?" asked Lake County Commissioner Mike Hickman.
"We're still trying to figure out the next steps," Ryan replied.
Ryan stressed that the study looked at only the Leadville Tunnel, not surrounding mining districts connected to the tunnel. The scope of the study was limited to human safety and property damage, not levels of contaminants considered harmful to the environment.
Reclamation operates the Leadville Tunnel, which was built during World War II and the Korean War to drain mines for the war effort, and limits its authority to only treating water which comes through the tunnel.
The problem is, there are numerous natural faults, fissures and mine shafts that intersect groundwater and bring it into the 11,000-foot tunnel.
Reclamation considers anything outside the tunnel to be part of the Environmental Protection Agency Superfund sites at Leadville. There are two Superfund sites, but both are connected to the Leadville Tunnel.
Reclamation and EPA have differed for years over issues related to mine drainage tunnel contamination, and while EPA released a report in 2006 detailing how the Leadville Tunnel intercepts mine pools and aquifers, no structural solutions were proposed until Lake County Commissioners declared an emergency in February.
Since then, the EPA launched a $5 million project to drill into the tunnel above the blockage and pipe the water to Reclamation's treatment plant at the mouth of the Leadville Tunnel. It began operating June 18.
U.S. Reps. Mark Udall, D-Colo., and Doug Lamborn, R-Colo., have introduced legislation to allow Reclamation to treat water pooling behind the blockage.
Colorado lawmakers approved legislation that allows state agencies to investigate ways to prevent clean water from flowing into the tunnel.
On Tuesday, Ryan said Reclamation has committed to operate the pump installed by the EPA indefinitely and has included funding requests to do so.
"There was a lot of concern about human life," Ryan said, referring to the alarm of Lake County Commissioners in February over seepage from the mine pool and a growing snowpack at the time. "We will continue to partner with the EPA, the Colorado Department of Health and Lake County."
There are two known areas of major blockage in the Leadville Tunnel.
Around the portal near the Arkansas River, there are numerous sinkholes that began developing in the 1950s and into the 1970s that resulted in a plug about 150 feet long being put in the tunnel beginning at 466 feet from the portal. The upper blockage is 80-200 feet long, about 4,000 feet from the mouth of the tunnel, in an area where some cave-ins were reported as early as 1955.
The result is a mine pool of somewhere between 500,000 and 2 million gallons of water, said Dick Wiltshire, chief engineer for Reclamation on the study.
The elevation of the mine pool -- measured from the highest level of water in monitoring wells compared with the mouth of the tunnel -- has been as great as 119 feet.
"We don't know how high it can get," Wiltshire said.
More study is needed to ascertain what levels should be maintained in the tunnel, and key areas weren't studied in this report, Wiltshire added.
There may be other blockages in the Yak Tunnel, part of the EPA Superfund site, above the Leadville Tunnel, and those blockages may create inflows of contaminated water. There is probably merit to Lake County Commissioners' suggestions to flume clean water from Evans Gulch away from shafts or adits leading into the Leadville Tunnel. At some point, more pumps and pipes may be needed.
"I've lived and worked in the Arkansas Basin for 30 years, and I don't want the Arkansas River contaminated by what's happening in Leadville," Wiltshire said. "I know where the water goes. It goes into Pueblo Reservoir."
Reclamation's study was reviewed and endorsed, with minor recommendations, by engineers Randall Jipson of the U.S. Geological Survey, Bob Elder and John Abel.
While the situation is not completely understood, the engineering used in the report is sound, they said.
"We're analyzing things that are deep underground that have not been observed or photographed," Jipson said. "The critical question is how high can the water level get?"
"I think everyone realizes with the EPA pumping the relief well, it eases the pressure," Elder said. "We have to be able to revise the assessment to reflect changes."
"Bulwarks do fail, but this is a pretty stable situation," Abel said.
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Copyright (c) 2008, The Pueblo Chieftain, Colo.
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