Intake tunnel construction at Lake Mead

摘要

Saddle Island on the west shore of Lake Mead is the site of two water intakes for the Southern Nevada Water Authority system serving the Las Vegas valley. The first system was completed in 1970 and the second will be completed in 2002. Both tunnels were driven by the drill-and-blast method in fractured and faulted metamorphic rock. Grouting ahead of the tunnel face was essential in the construction of both tunnels. Hydrostatic pressures were about 40 m in the first tunnel and 100 m in the second tunnel. This paper summarizes the tunnel excavation and water-control grouting in both tunnels.