The Bureau of Reclamation (BOR) released its risk assessment of the Leadville Mine Drainage Tunnel (LMDT) on June 30, which determines that Lake County is in no danger of a tunnel blowout or flood.

The report states that it is highly unlikely for the blockages within the two mile long tunnel to cause the sudden release of water, which could flood the surrounding area and endanger the lives of residents nearby. That possibility of disaster was enough cause for the Board of County Commissioners (BOCC) to declare a state of emergency back in February, and has brought Leadville into the national limelight in recent months.

"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 the BOR’s actions to date and show that no additional emergency actions need to be taken."
At a public informational meeting July 1, the BOR presented it’s report and answered questions.

The BOR highlighted findings that it is highly unlikely that the blockage near and below the Pendery Fault will have a sudden release of water, and that any release would occur over a period of weeks and months. Furthermore, if the upper blockage failed rapidly, a sudden release of water through the lower blockage and engineered bulkheads is also highly unlikely.

In the event that the upper blockage were to rapidly fail, the findings state that water levels in the lower portion of the tunnel would rise and dissipate in the surrounding gravel and rocks, creating seeps that are similar to what has been occurring in the area for years. The monitoring wells nearby could experience an artesian flow.
The assessment also found the hillside above and around the LMDT to be quite stable, even with potentially significant increases in water levels in the hillside.
This risk assessment was done by a corps of BOR engineers, using a standardized assessment model, and included a peer review by an independent team of BOR experts and an external independent consultant review board. This board was composed of a research geologist for United States Geologic Survey, a professor from the Colorado School of Mines, and two independent engineers.

“We felt the report did a good job of making reasonable and sound interpretations,” said Robert L. Elder, an engineer, “and the conclusions were generally supported by sound analysis.”

The independent consultant board reccommended that the BOR add additional instruments to the current monitoring wells in the lower portion of the LMDT and connect them to the existing Early Warning System. They also recommended updating the Emergency Action Plan. The BOR stated in its report that it intends to implement these recommendations immediately.

"The BOR will continue to pump and treat water," said Eastern Colorado Area Manager Michael Collins. "We look forward to continuing to work with the EPA, the State of Colorado, and Lake County on the long-term issues related to the Leadville Mine Drainage Tunnel."

The public and government agencies are now 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 lmdtra@gp.usbr.gov. The final report will be filed and adopted by the BOR by the end of September.

Kay Doan is the reporter for the Leadville Chronicle. She may be reached at kdoan@leadvillechronicle.com.