US tailings dam wins rehabilitation award

A tailings dam in St. Francois Cty., Mo., has been named National Rehabilitation Project of the Year.

The award, which is given out by the Association of State Dam Safety Officials, recognizes “the use of technology, creativity and economy in the rehabilitation of dams” in the U.S.

The dam’s owner, the Missouri Division of State Parks (part of that state’s natural resources department), was singled out for having rehabilitated a barrier built in the early 1900s as part of a lead operation. Classified as “high hazard,” the St. Joe Park tailings dam had a number of deficiencies, including inadequate spillway capacity, the potential for liquefaction of the embankment and subsequent failure during a moderate earthquake, and excessive seepage through the dam during floods. The dam is situated in what is now a state park.

Rehabilitation work included the construction of stabilizing berms, widening of the crest, and increasing spillway capacity. The berms have a volume of 1.3 million cubic yards. The exterior is made of finely crushed gangue, and the core consists of sand; both materials were waste from the lead mining operation.