Lake Mead Intake Hydraulic Tunnel, Las Vegas

The Lake Mead Intake Hydraulic Tunnel represents one of the greatest challenges in underground works. The project involved the construction of a system for collecting and transporting the waters of the lake to increase the supply of water, approximately 4.5 million cubic metres per day, for drinking and domestic use in the urban area of Las Vegas.

Lake Mead is one of the largest artificial lakes of the Unites States. It is located approximately 30 kilometres south-east of the city of Las Vegas (Nevada) , where Hoover dam meets the Colorado river. 

The works involved the construction of an access shaft, excavated in the rock on the shore of the lake, approximately 200 m deep and with a diameter of 9 m.  A tunnel was constructed at the bottom of the shaft under the lake bed approximately 4,600 m long and with an excavation diameter of 7.2 m.

The construction of the tunnel was an engineering challenge: the excavation was carried out under extreme conditions. The TBM used to excavate the tunnel was a unique prototype, worldwide. It was designed to withstand unmatched pressure conditions in the history of tunneling. The TBM could advance at a maximum pressure of 15 bar, twice the pressure of the previous world record and five times the average pressure in these kind of works. 

The intake is located at the end of the tunnel, approximately 100 metres below the surface of the lake, made from a structure in reinforced concrete with a pipe-shaped tubular steel structure on top, with a diameter of 6 m, 30 m high and weighing about 1,250 tonnes.
The water, drawn in from the bottom of the lake through the intake work openings, is directed along the tunnel to the access shaft, from where it is pumped to the treatment plant on the surface.

Client: Southern Nevada Water Authority

Awards

In September 2016 Tunnel Business Magazine (TBM), one of the industry’s leading magazines, assigned to the project the “Tunneling Achievement award of the year”. 

In November 2015 the Lake Mead Tunnel was nominated “Project of the Year” by the International Tunnelling Association in Switzerland, and, in December 2015, was awarded the “Project of the Year” prize by the New Civil Engineer (NCE), a prestigious organization of the British Tunneling Society. 

The project also won the Engineering Excellence Award of the American Society of Civil Engineers (ASCE) for the State of Nevada.