From December 1971 up to November 1974 an important and difficult grouting work was executed in the rock• foundation of the Canelles arch-dam.
Leakages and percolations- of water through- the foundations, were around 6 m3 / sec. at the beginning of the works. Once completed the maip curtain, the filtration was reduced to 70' lt/sec.
An impermeabilisation main curtains was developped through drilling and grouting from three tunnels at three different levels in right and left banks and from the toe of the dam, using varied spacing of holes and types of grout mixes. Normally cloy-cement mixes were injected, but in special cases' and in order to cut the flow of water passing through caves and crevices, poliure tone foams and resin-asphalt emulsions were used The average grout absortion was reaching 316 kg. of dry-material for square meter' of grout curtain, at the end of the work.
