BOARD00535

• Board Meeting Date: 5/22/2000
• Description: Colorado River Basin Issues - Colorado River ‎(Mainstem)‎ Director's Report
• Board Meetings - Doc Type: Memo

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rent surplus of unallocated Colorado River water, now brim-
ming from several recen t wet years.
For now, the construction 'Just barely" keeps up with
increases in local demand for water while providing needed
back-up operational redundancy, says Marc M. Brown, a vice
president at Montgomery Watson, which has a 50(50 joint ven-
ture with CH2M Hill as the project's lead designer. The two
firms expect an $80-million fee, including $70 million so far.
OZONE Even with MW/CH2M Hill setting system-wide design
criteria, that still left work for a 50/50 team of Carollo Engi-
neers and Black & Veatch. The latter two firms added 200 mgd
of capacity to the Smith plant in 1997, but its operation still
relies on relatively inexpensive anthracite media filtration.
Now ozone units must be added. SNWA selected ozone rather
than "potentially more effective" granular activated carbon fil-
tration or membrane filtration to avoid higher costs and tech-
nical uncertainties, SNWA's Jensen explains.
Southern Nevada spent $13 million on what SNWA officials
describe as the world's largest single purchase of ozone units
for the 600-mgd Smith and 150-mgd River Mountains plants.
Carollo Black & Veatch had designed an ozone treatment plant
in Tucson in 1991 that city officials mothballed over alleged
design and construction flaws (ENR 2/28 p. 14). But Ivan L.
Waggoner, Carollo's chief resident engineer at the Tucson
plant and its site engineer at the Smith plant claims that,
"Here, you don't have any of the same situations." Tucson,
located at the end of a $4-billion, 335-mile aqueduct from the
Colorado River, received hotter water than expected after
farmers passed on the costly water. The heat encouraged bio-O.
logical growth, placing costly demands on the ozone system in
unanticipated ways, Waggoner says.
At the Smith plant, Waggoner's team took pains to increase
the contact time for ozone. Carollo Black & Veatch designed II
custom-formed 30-ft-high baHIes with f1ares-called hydraulic
foils-to help water flow smoothly over and under the walls.
"They're architectural in that they're a pain to build," says Ed
Calo, project manager for J.R. Jacks Construction Corp., Boul-
der City, Nev. It holds the $61-million contract to add ozone to
the plant by 2002. Carollo officials expect operational savings
from the walls, but an SNWA official dismisses that as "opinion."
For Calo's crew, the biggest challenge came last December
while cutting into southern Nevada's water lifeline, a 10-ft-dia
concrete pipe that delivers lake water. Shutting off its flow for
20-hour stretches, subcontractor TDW Services Inc., Signal Hill,

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Calif., cut two holes into the 11- ~
- in.-thick pipe. "It's the largest ~
'hot' tap we're aware of," Calo i
says. The 8.5-ft-dia holes divert .
water to ozone contactors; a 600- ~
ft-Iong cut-and<over tunnel leads 3:
g
to an existing aeration basin. ~
Next October, for the first time, '
crews plan to draw water into the
basin using the new lake intake.
INTAKE The intake's controver-
sial siting takes advantage of
good geologic conditions, accept-
able water quality, minimal envi-
ronmental impacts and optimal
operational logistics, SNWA offi-
cials say. Surrounded by geologi-
cally youthful volcanics, the site
overlies a weathered block of Pre-
cambrian metamorphic rock. "To
me, it was probably the best selec-

INTAKE WORK
Intake Oeftlleads to tun-
nsl under Island. Well
shafts (top) Intersect
tunnel(below); fissures
and seepage complicated
work In tunnel and wells.

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APRtL 24, 2000/ENR 65