The DALC Project - Nelson Tunnel & Commodore Waste Pile
The Nelson Tunnel was constructed in 1899 along the Amethyst vein and is roughly 15,000 feet long. It connected several mines along the vein and made an efficient extraction system. The tunnel served a number of additional purposes to the miners including ventilation and an exit for water. The tunnel functioned until 1920 when it was closed due to failing infrastructure. In 1935, the Emperius Mining Company purchased and reconditioned the tunnel. This investment revitalized the functionality of the tunnel and many mines linked to this transportation system, including the Commodore Tunnel No. 5. The tunnel is now closed, but is a large source of heavy metals within West Willow Creek. Due to the intricate nature and many connecting adits and tunnels, the Nelson Tunnel poses a large challenge for the WCRC.
In December of 2000, the WCRC began underground investigations of the Amethyst Vein Complex, accessed through the Commodore 5 Tunnel. Investigations and water data support a theory that groundwater is entering the mine workings on the Nelson Tunnel level between the Berkshire Shaft and the Amethyst Shaft. Because of absolute flooding, the workings must be dewatered before any characterization can be completed. Thepilot dewatering project is the second step in the plan to determine whether any source controls can be implemented. The final step will include full dewatering and investigation of the flooded workings in the Nelson Tunnel. Check out the Dewatering video here!
As part of the DALC grant, money was allotted to a pilot project to dewater the Nelson Tunnel. CDRMS entered the West Shaft and installed three bulkheads to contain the flow and begin pumping water out of the tunnel. In addition, lime was added to the tunnel floor to raise the pH and in-situ water samples were collected. The project’s goal was to test the design, feasibility and effectiveness of a full-scale dewatering project aimed at decreasing metal loads from the tunnel.
In 2005, a ten-year flood event destroyed much of West Willow Creek near the Nelson Tunnel/Commodore Mine. Cribbing, structures and mine waste were washed downstream and caused fish kills as far as South Fork, Colorado. The USEPA responded to this emergency, and designated the Nelson Tunnel/Commodore Mine a Superfund site in 2008. As such, the WCRC was not able to finish work on the Commodore Waste Pile.