Nelson Tunnel Bypass Adit

The Nelson Tunnel/Commodore Waste Rock Pile is an EPA National Priorities List (Superfund) site located in the Creede Mining District in Mineral County, Colorado. Constructed between 1893 and 1902, the Nelson Tunnel was developed to access and dewater underground mines along the highly productive amethyst vein, and to serve as a haulage route for ore. Since mining ceased in the 1970s, underground conditions have deteriorated, characterized by timber rot, roof falls, and several major collapses. Schnabel was brought in to develop a feasibility plan for remediation of the site, and to design solutions for rehabilitation.

With the Wooster and Humphries extensions included, the Nelson Tunnel stretches approximately two miles. It serves as the lowest drainage tunnel in the vein system, collecting water from connected underground workings. The original portal, now collapsed, lies on the west side of West Willow Creek, about one mile north of Creede. Current access is through the higher elevation Commodore 5 Tunnel.

Ground collapses due to deteriorated underground conditions have impounded millions of gallons of water that now seep into West Willow Creek as heavy metal-laden mine-influenced water (MIW). The uncontrolled seepage and potential for a sudden uncontrolled release pose risks to the City of Creede and the surrounding ecosystem.

Schnabel was part of a team hired by the EPA to develop a focused feasibility study to identify remedial alternatives to reduce these risks. In conjunction with the Colorado Division of Reclamation Mining and Safety, Colorado Department of Public Health and Environment, and the EPA, the team developed and evaluated five alternatives, assessing risk, effectiveness, and cost.

Building on this work, Schnabel helped design a rehabilitation plan including a bypass adit, bulkhead with valved piping, and drainage ditch to control flows. In 2019–2020, Schnabel completed a Failure Modes and Effects Analysis for the preferred alternative and supported public meetings for the interim record of decision.