California Gulch NRDAR Canterbury Tunnel Restoration
Dates
End Date
2012
Start Date
2012
Summary
Background information. The original Canterbury Tunnel began as an idea in 1922 as a way to remove excess water in the mines that honeycomb the mountains near Leadville, Colorado. The objective of reducing the volume of water in these mines was to increase the opportunity for ore extraction. The project’s original plans were never fully realized because of technological limitations and increasingly dangerous conditions that confronted workers, and so the 4,000-foot-long Canterbury Tunnel sat dormant until the early 1960s. Historically, Leadville relied on the nearby Big Evans Reservoir as the primary source of municipal water. The reservoir’s elevation of 10,200 feet above sea level has been particularly problematic for Leadville during [...]
Summary
Background information. The original Canterbury Tunnel began as an idea in 1922 as a way to remove excess water in the mines that honeycomb the mountains near Leadville, Colorado. The objective of reducing the volume of water in these mines was to increase the opportunity for ore extraction. The project’s original plans were never fully realized because of technological limitations and increasingly dangerous conditions that confronted workers, and so the 4,000-foot-long Canterbury Tunnel sat dormant until the early 1960s. Historically, Leadville relied on the nearby Big Evans Reservoir as the primary source of municipal water. The reservoir’s elevation of 10,200 feet above sea level has been particularly problematic for Leadville during the cold Colorado winters because the cold water regularly caused pipes throughout the town to freeze.
In 1962, Leadville learned that the water draining out of the Canterbury Tunnel was not only clean, but it was also at a temperature of more than 50 ºF. The town decided to invest in piping and a pump station so the relatively warm water flowing from the Canterbury Tunnel could be used to supplement the town’s municipal water system and help reduce the problem of frozen pipes.
By the early 1990s, the original Canterbury Tunnel began to show signs of stress. The timbers used as support structures for the tunnel’s original construction in the 1920s began to rot and collapse causing cave-ins and blocking the water flow. By 2003, the water source flowing from the tunnel could no longer be used, which resulted in water shortages and a stressed distribution system during the winter months. In response to these shortages, the Parkville Water District in Leadville elected to re-drill and intersect the original Canterbury Tunnel above the collapsed areas that were restricting the flow of the warm water. Funds for the project came from the Colorado Department of Local Affairs, the settlement from the California Gulch Superfund site, and the Parkville Water District. Components of this project included drilling and intersecting the passageway above the tunnel’s blockage, building a new pump station, and laying an additional 8,200-foot pipe to the Big Evans Water Treatment Plant, which expanded the distribution of the relatively warm water to other parts of the municipal system that were historically bypassed by the tunnel’s original design. The project was completed in November 2012, and resulted in an average increase of 10 ºF in water temperature throughout the distribution system. As a result of this project, 2012 marked the first year on record where Leadville’s water distribution system did not experience frozen lines during the winter months.
Background information on the Canterbury Tunnel project was obtained from Laura Archuleta, U.S. Fish and Wildlife Service, and Greg Teter, Parkville Water District, written commun., 2015; and from California Gulch Superfund site Natural Resource Damage Assessment and Restoration case documents at
http://www.cerc.usgs.gov/orda_docs/CaseDetails?ID=37.
Economic impacts. The Canterbury Tunnel project was conducted in 2012, and had a total cost of more than $1,674,000 (2014 dollars). Approximately 52 percent of project funds was spent locally, which supported an estimated 8.6 job-years; $516,000 in labor income; $769,000 in value added; and $1,702,000 in economic output within the local economy near the project site. Expanding to include both local and nonlocal expenditures, this project supported an estimated total of 21.6 job-years; $1,461,000 in labor income; $2,325,000 in value added; and more than $4,462,000 in economic output in the national economy.