Tailings dam remedial works

The author describes his experience in 1929 with a tailings dam being built in Spain by the traditional upstream method. Tailings from the Rio Tinto mines in southwest Spain were transferred to the dam in 0.3 m timber launders constructed with a 4-5% slope to prevent the solids from settling out. The authorities insisted that no tailings whatever should enter the Rio Tinto. With 30 million tons of mineral lying in tips on the hillsides, much of it being sprayed systematically to leach out the copper, the mine management considered that their experience justified using an impervious starting dam for the tailings dam. When the crest of the dam was about 6 m high, and the lagoon not far from the face, the face showed signs of weeping. The author details the remedial measures carried out to restore the imperviousness of the starting dam.