Client:
Southern Nevada Water Authority
Present Project Value:
$2 billion
Project Duration:
1993-2005
Parsons Services:
Project management, planning, design and construction management, environmental
studies, cost and schedule control, quality assurance/ quality control,
startup assistance
|
Tunneling 240 feet below the surface of Lake
Mead for a new water intake to provide water for the Las Vegas Valley.
|
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 growthin 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.
Pipe was placed across Boulder Harbor by
being lowered down ramps, cradled within a specially constructed
barge, floated into place, sunk, and connected by divers.
|
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 facilitiesthe two treatment plants and the intake
in Lake Meadresulting 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.
|

 |
Large power conduits were laid to carry electricity
to the many new pumping stations.
|
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.
Back
|