The United Comstock Merger Mill at American Flat (AFM) was built in 1922 to process local gold and silver ore using a cyanide solution and the Merill-Crowe process (a separation technique for removing gold from a cyanide solution). The Mill operated from 1922 to about 1926 and produced $7.5 million worth of silver and gold. Over its short life, the Mill was owned by two different corporate entities, the United Comstock Mines and the Comstock Merger Mines. At the time it operated, AFM was considered the largest, most modern and sophisticated mill of its type in the U.S. The Mill was shut down due to metallurgical problems and the dropping price of silver. When the Mill was closed, all equipment, metal, and wood materials were scrapped and salvaged. During the salvaging process, little care was taken in the removal of equipment and other materials. Concrete structural components were cut and broken as required to facilitate the removal process. The salvage process resulted in a great deal of damage, including large holes and voids left in the concrete, cut reinforcing steel, and broken concrete structural members.
Today the existing structures at the site consist of badly decaying concrete, exposed reinforcing steel, broken structural members, and large holes in the concrete floors; only the deteriorated concrete skeletons of the structures remain. A fatality occurred at the site in 1996 while an individual was ‘crawling’ stairs with an all-terrain vehicle (ATV) inside one of the AFM structures. In response, the BLM officially closed the interior of the AFM buildings to public entry on January 21, 1997 (FR Vol. 61, No. 246, p. 67343). Beginning in 1998, the BLM has repeatedly fenced, gated, and posted closure signs at the mill site, and scarified access roads for public safety. Despite this closure order that remains in effect today, the site attracts the public who use it for unapproved activities including: parties; to post graffiti; and to play paintball games.
An audit of the site by the Department of the Interior, Office of Inspector General in 2008 found the property to be a high-risk liability to the U.S. Government.
To address these issues, the Bureau of Land Management (BLM) Sierra Front Field Office has prepared the United Comstock Merger Mill at American Flat Final Environmental Assessment (EA). The EA has analyzed the potential direct, indirect and cumulative effects to the human environment associated with the Proposed Action, Alternative 2 of the EA, that would result in the complete demolition of all structures at the AFM. Under the Proposed Action, all eight AFM site buildings would be demolished and all building footprints and other disturbed areas would be reclaimed.
On April 3, 2013 the BLM issued a Finding of No Significant Impact and Decision Record for the project (see Documents).