National Dam Safety Program. Magmont Mine Tailings Dam (MO 30917), White River Basin, Iron County, Missouri. Phase I Inspection Report

摘要

Magmont Mine Tailings Dam, Missouri Inventory Number 30917, was inspected. The St Louis District (SLD), Corps of Engineers, has classified this dam as having a high hazard potential. The damage zone length estimated by the SLD extends approximately 19 mi downstream of the dam. Within this estimated damage zone are at least eight occupied dwellings, assorted out-buildings, several unimproved roads, and a school. The contents of a portion of the downstream hazard zone were verified by aerial reconnaissance. Magmont Mine Tailings Dam is in the large size classification based on its maximum height of 135.5 ft. Its reservoir storage capacity is approximately 12,500 ac-ft, including both tailings and water. The large dam classification criteria are: height greater than 100 ft, or storage capacity greater than 50,000 ac-ft. Our inspection and evaluation of available data indicate the dam and appurtenant structures are in generally good condition. No evidence was noted of slope instability such as cracking, slumping or displacement of the vertical or horizontal alignment of the dam crest. No animal burrows, sinkhole development, seepage, or detrimental settlement was noted.