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Released On: June 30, 2008
The scientific, peer-reviewed risk assessment found that it is highly unlikely that a sudden release of water could occur from either blockage in the Leadville Mine Drainage Tunnel or through the engineered bulkheads installed in the tunnel near the portal.
"The most important and welcome news today is that there is no imminent public safety hazard identified by this risk assessment," said Great Plains Regional Director Michael Ryan. "These findings affirm the appropriateness of Reclamation's actions to date and show that no additional emergency actions need to be taken."
The specific findings of the risk assessment are:
- It is highly unlikely that the blockage near and below the Pendery Fault will have a sudden release of water. If something were to happen to this upper blockage, it would occur over a period of weeks and months.
- Even if the upper blockage failed rapidly, a sudden release of water through the lower blockage and engineered bulkheads is also highly unlikely.
- In the unlikely event that the upper blockage were to rapidly fail, the water levels in the lower portion of the tunnel would rise and dissipate in the surrounding gravel and rocks. There would likely be seeps, similar to what has been occurring in the area for years, and the monitoring wells near the portal could experience an artesian flow.
- The hillside above and around the Leadville Mine Drainage Tunnel portal area is quite stable, even if water levels in the hillside were to increase significantly.
- The Early Warning System around the Leadville Mine Drainage Tunnel portal will provide adequate advance warning to permit the safe evacuation of the residents of The Village at East Fork and Reclamation's Water Treatment Plant staff.
This risk assessment utilized a similar process that Reclamation uses to assess risk at its dams, a model that is a global standard for conducting risk assessments. This process included a peer review by an independent team of Reclamation experts and an external independent consultant review board.
The independent consultant review board has completed its review of the risk assessment and concurred with its findings. The panel also provided comments on the risk assessment that have been incorporated into the final draft of the document.
The risk assessment team made two recommendations that Reclamation has accepted and will implement. They are:
- Add additional water level monitoring instruments to the current monitoring wells in the lower portion of the Leadville Mine Drainage Tunnel and connect them to the existing Early Warning System to provide additional water level monitoring in the portal area.
- Update the Emergency Action Plan to include the new information learned from the risk assessment and establish clear written directions of actions to be taken. The report should then be finalized and exercised.
"Reclamation will continue to pump and treat water from the new well, its other well and what flows though the portal," said Eastern Colorado Area Manager Michael Collins. "We look forward to continuing to work with EPA, the State of Colorado, and Lake County on the long-term issues related to the Leadville Mine Drainage Tunnel."
The risk assessment is in final draft form. The public and government agencies are invited to submit technical comments to Reclamation by July 31, 2008. Comments may be submitted to Les Stone, Bureau of Reclamation, Great Plains Regional Office, P.O. Box 36900, Billings, MT 59107-6900 or email@example.com.
Once the comments are received, they will be reviewed, relevant comments incorporated, and the final report released by the end of September, 2008.
The Final Draft Leadville Mine Drainage Tunnel Risk Assessment will be available at the two informational meetings that Reclamation will host in Leadville at the National Mining Hall of Fame and Museum on July 1 at 1 pm and 7 pm. The documents may also be downloaded from the Internet at www.usbr.gov/gp/ecao/leadville/leadville.cfm.
DOI | Recreation.gov | USA.gov
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