Summitville Mine Superfund Site, Reynolds Adit Rehabilitation

Amid alpine tundra, the Summitville Mine site is located 25 miles south of Del Norte, Colorado, at an elevation of 11,500 feet in the Rio Grande basin near the headwaters of the Alamosa River. The Summitville Mine gained national headlines when the mine operator declared bankruptcy in December 1992 and abandoned the site, leaving behind numerous environmental problems.

The most serious issues were related to metals and cyanide loading to receiving streams from flowing adits, the heap leach pad, waste rock piles, a tailings impoundment, and other mine areas. From 1999 through 2005, Schnabel personnel conducted annual inspections of the Reynolds and Chandler adits to evaluate the condition of the drainage, bulkheads, pipeline, valves, and ground support. In 2005, we rigorously mapped the locations of all supports and evaluated the condition of all timber sets to identify areas in need of rehabilitation.

From 2010 to 2012, we were part of a team evaluating alternatives for rehabilitating the Reynolds adit and bulkhead. Our work included conceptual designs and cost estimates for the various alternatives and then carrying the preferred alternative through to final design, preparing plans and specifications, assisting in preparation of the bid documents and bid selection, providing construction monitoring, and developing as-built drawings. The design included a bulkhead extension, bulkhead rock mass and contact grouting, pipe for mine pool control, cellular concrete pipe protection, adit drainage, ground support rehabilitation, valve layout, and a new portal structure. During construction, we provided a full-time on-site resident engineer.