Facing the worst drought on record in the Colorado River Basin, the Southern Nevada Water Authority (SNWA) is building a low lake level pumping station to ensure Las Vegas and Southern Nevada maintains access to its primary water supplies in Lake Mead.
Lake Mead water levels have dropped more than 131 ft (40 m) since the drought began in 2000. The new pumping station will allow SNWA to pump water from Lake Mead from an elevation as low as 875 ft (267 m) above sea level into the water treatment facilities and further on to provide water to the city of Las Vegas and neighbouring communities.
Development of the pumping station consists of constructing a 315 inch diameter access shaft at more than 498 ft depth. At the bottom of the access shaft, a 12,379 ft2 underground cavern is excavated. The cavern, known as a fore bay, will connect with 34 vertical shafts, each 498 ft deep and 72 inches in diameter, to accommodate the station’s 34 submersible motor pump sets. 30 of these pump sets will be manufactured and installed by Indar.
Drilled down wells
So far, 20 low lift submersible motor pump sets (LLP) plus 10 high lift submersible motor pump sets (HLP) will be delivered by Indar. Maria Elena Rodríguez, water engineering director at Indar, explains, “The drop of Lake Mead enables wells to be drilled down in order to access those deep water reservoirs…making a traditional vertical turbine solution unfeasible to operate reliably at those depths”.
Each of those 30 Indar pumps is rated at 20,835 US gallons per minute with 433 ft and 695 ft of head, respectively, providing a total capacity at the pumping station of more than 900 MGD (million gallons per day). “These are more than 250 bath tubs every second,” illustrates Dirk Wulf, a project manager at Indar.
The pumps are operated through submersible motor pump sets with 13,800 v motors, ranging from 3,150 HP to 5,200 HP. These pump sets will obtain the required energy right from the hydro power plant at the nearby Hoover Dam. The pumps, motors, riser pipes, and well heads are made of stainless steel 316/316L in order to guarantee a long service life and to reduce the impact of the water.
Testing
In order to test the pumps and motors on full load performance, Indar has built an additional test lab 98.4 ft deep and 158 x 197 inches wide. This $1,8 million investment enables Indar to guarantee the highest performance standards and a lead production schedule in order to fulfil the tight project schedule for SNWA. “Since the motor pump sets need to be ready for start-up by April 2020, we gain now the time which we had invested into the new test lab,” states Jon Alberdi, general manager of Indar Pump Division.
From the fore bay, the water will be pumped to SNWA’s water treatment facilities. The high-volume low lake level pumping station, combined with the recently completed Lake Mead Intake No. 3, will provide the community with continued access to its primary water supply even as lake levels fluctuate as a result of the ongoing drought.
The design and construction cost of the Lake Mead Intake No.3 is expected to total approximately $650 million, and L3PS is on track to be operational by 2020.
“We are aware of our responsibility to enable 2 million people and an uncountable number of visitors to have their shower every morning, to have a reliable source of water and quality of life,” declares Wulf. “We have considered every single detail in order to make this pumping station to be one of the most advanced and efficient pumping station in the world”.
This L3PS pumping station with its huge 30 Indar submersible motor pump sets will be the blueprint for newly-built large pumping stations, and furthermore, for refurbishment of all old-fashioned vertical turbine equipped stations.
With this achievement, Indar reinforces its position as a leading engineered solutions provider for demanding water supply projects. Municipal water authorities, utilities, and engineering companies who have partnered with Indar have received comprehensive support from their 'one-stop-shop', gaining easily installed motor pump sets, efficient pumping, high performance, and more efficient water use.
