Federal Highway Administration

Hoover Dam bypass (rendering above) could open new areas for development. Pipeline brings water from central Nevada to Las Vegas.

...first intake at Lake Mead could become inoperable as soon as 2010 based on current drought and consumption projections, spelling potential disaster for Las Vegas. So SNWA is responding with an $817-million, design-build, third water-intake at Lake Mead located about three miles northeast of Saddle Island.

The project has four major contracts, with the largest being a $400-million, 24-ft-dia tunnel and 600-ft intake shaft, with accompanying 33-ft-wide, 36-ft-tall, 232-ft-long forebay. Construction will be by a tunnel-boring machine fitted with a trailer to install precast tunnel liners.

Broomfield, Colo.-based MWH Americas Inc./CH2M-Hill Inc. provided the bridging documents. The project’s three joint-venture finalists are: Kiewit Western Co./Vinci Construction Grands Projects/Frontier-Kemper Constructors Inc.; Impregilo SpA/Taisei/S.A. Healy Co.; and, Traylor Bros. Inc./Obayashi Corp./ Baynard of Nevada Inc. The contract award is expected in January, with completion by 2010.

The third intake, located 860 ft above sea level, also calls for a pumping station, a discharge pipeline from the pumping station to the 600-mgd Alfred Merritt Smith Water Treatment Facility, elec­trical facilities and some modifications to the second intake.
 
“It’s a replacement for intake number one in case it becomes inoperable,” says Jensen. “It’s not going to add to capacity.”

Ramping Up

Phoenix, however, is upping its capacity due to a rapid population growth, which saw it become the nation’s fifth most populous city in 2006, according to the U.S. Census. Phoenix had the largest population increase of any city between 2005 and 2006, adding more than 43,000 residents.

The city’s Water Services Dept. consequently is pursuing capital improvement proj­ects to improve water delivery, including the $228-million, 80-mgd de­sign-build-operate Lake Pleasant Water Treatment Plant that came online earlier this year. Black & Veatch, Overland, Kan., and St. Louis-based McCarthy Building Cos. are the joint-venture de­sign-build contractor, with American Water Services, Voorhees, N.J., as operator.

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The city is also pursuing the $13-million, 200-acre Agua Fria River recharge facility, west of Phoenix. Orlando, Fla.-based PBS&J is providing the project's engineering, planning and management. The undertaking could reclaim up to 60,000-acre-ft from a wastewater treatment plant. A series of lateral pipelines, spaced at one-mile intervals, would divert water from the conveyance pipeline to the Agua Fria River channel for recharge.

The first phase, performed by PBS&J, includes preparation of a consensus plan. Phase two will prepare conceptual design plans, an environmental impact statement, development of alternatives, and a feasibility report that the U.S. Bureau of Reclamation will submit to Congress. The project is expected to finish by 2010.

 “We have substantial groundwater, with rights to a lot more water than we use right now,” says Quay. “Generally, the surface water meets our needs to a great extend. But in times of drought, we are going to have to rely on groundwater supplies.”

SNWA now takes only 10% of its flow from groundwater. It has rights to 40,000 acre-ft of groundwater and has well capacity of 150 mgd to 180 mgd. An agency spokesman says it is unrealistic to expand those resources, although adding more wells could help meet peak de­mand.

Some planners see more demand coming from now undeveloped areas of Arizona near Hoover Dam, where the new Hoover Dam bypass bridge may open up large tracts for home development. Few groundwater rights have been granted so far, but some planners worry about issues emanating from interstate delivery of groundwater. Arizona and Nevada manage groundwater within their borders but if the region continues to grow, there may be need to establish a framework for interstate transfer.