The recently completed drinking water intake constructed to protect Southern Nevada residents from continuing drought has been nominated for the 2016 Outstanding Civil Engineering Achievement Award by the prestigious American Society of Civil Engineers (ASCE).
Listed among six projects selected from around the world, Lake Mead Intake No. 3 is the world’s deepest subaqueous tunnel and is considered one of the most challenging tunneling projects ever undertaken.
Requiring construction of a three-mile concrete-lined tunnel beneath the lake bed, the project required excavation at unprecedented hydrostatic pressure caused by the weight of hundreds of feet of lake water above the tunnel alignment.
As a 1,700-ton tunnel boring machine inched its way through difficult geologic conditions for several years, workers constructed a railroad track in its wake to remove material and deliver supplies.
In December 2014, the machine docked with an intake structure deep within the lake that was secured to the bottom by more than 1,000 truckloads of concrete.
After more than 15,000 feet of underground tunneling spanning three years, the crew carefully mined through the intake’s port within millimeters of the center mark.