Nevada’s Forward-Looking Public Works Construction Program
Water has always been a key to prosperous communities. In Las Vegas, the fastest growing metropolitan area in the United States, Lake Mead has been there to support this success. The challenge has been to get the water out of the lake, treat it, and distribute it to an area that is experiencing unprecedented growth—in population, in area, and in tourism. To help with this effort, the Southern Nevada Water Authority (SNWA), the water wholesaler responsible for meeting demand, hired Parsons in 1993 as the project manager and construction manager of their Capital Improvements Program.
The $2 billion program is structured to be built in phases, so that the appropriate facilities come into service just before they are needed. Parsons’ first assignment was to develop a capital improvements plan that met this criterion. Because the growth of the Las Vegas Valley has been ongoing, this plan is now undergoing its tenth revision.
Major features in the present plan are: 105 miles of pipeline; 12 pumping stations; 16 reservoirs and forebays; a large new intake in Lake Mead; 3 large hard rock tunnels; a new ozone/direct filtration plant; the addition of ozone treatment to the existing water treatment plant; and turnouts, or distribution points, to the various water retailers. All of this is being supported by a greatly enlarged power system, including 13 substations.
During its 8-year involvement, Parsons has managed over 20 separate design consultants and over 25 separate construction contractors. Sixty contracts are completed and 14 contracts are currently in progress. The largest of the contracts in progress is a $183 million contract to build the new water treatment plant. This is the largest single public works contract in Nevada history and it is approximately 70% complete. Twenty-five more contracts are anticipated.
To meet, and to keep up with, the requirements of such a large and changing program, Parsons developed a unique project control system that tracks, on a daily basis and to the dollar, what is spent on every contract. This control system, combined and linked to an overall project schedule, has withstood a number of audits and received excellent reports from the auditors. SNWA is assured that it not only knows how its ratepayers’ money is being spent but that it is being spent wisely.
Outstanding innovations and accomplishments on this program include:
- Preparing a programmatic environmental impact statement that covered the entire program and shepherding it through the federal agencies. This allowed projects to be built without further numerous individual environmental studies.
- Providing a detailed analysis that determined how best to divide contracts into similar types of work and size. This has resulted in excellent prices.
- Suggesting guidelines for designers to follow as they prepare their designs. This resulted in the design of similar structures and equipment and an estimated construction savings of over $29 million.
- Performing value engineering on three of the major facilities—the two treatment plants and the intake in Lake Mead—resulting in estimated savings of $35 million.
- Special contract provisions in the intake/tunnel contract shared the risk with the contractor. This produced lower bids and avoided disputes and contentious change orders.
- Placing SNWA personnel, each designer, the contractor, and Parsons’ construction personnel in the same field offices, to promote communication and reduce the time needed to resolve issues.
The intake contract is illustrated in the schematic above. The lake tap and intake shaft were sunk in nearly 250 feet of water and another 80 feet into the lake’s rock bottom. A horseshoe shaped tunnel 1,600 feet long was built under Saddle Island leading from the intake to a forebay. Twenty-two shafts were drilled into the forebay and each will house a 3,000-horsepower pump. The discharge from the pumping station will enter a pipeline that extends 2,500 feet along the bottom of Boulder Harbor before it emerges on the mainland. A rate-of-flow control station will enable the Authority to shunt water to its nearby existing water treatment plant in an emergency.
This vast new water system and the upgraded existing system is scheduled to be operational in 2005. It will double the amount of water from 450 million gallons per day to 900 million gallons per day and provide a valuable resource to the United States’ fastest growing metropolis.