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Las Vegas Area Taps Lake Mead to Satisfy A Growing Thirst (4/24/2000) Page 4 of7 000784 anticipated, says Jesse L. Yoder, deputy project director for Parsons Infrastructure & Technology Group Inc., program and construction manager. "The client did everything right, in my estimation, on a large program like this," he says. Parsons' fees now amount to $75 million of$119 million expected. OVERBillL T? While critics continue to question the project's scope and expense, SNW A claims that local water demand will exceed capacity by no more than 114 mgd by 2002, and then catch up by 2023. "I don't think we've overbuilt our system," says Marcus R. Jensen, SNW A engineering director. With completion of the initial 150-mgd capacity at the River Mountains plant in 2002, the system's treatment capacity will total 750 mgd. With seasonal variations in use, 750 mgd equates to 526,000 acre-ft annually- more than Nevada's river allocation of 500,000 acre-ft including return-flow credits, Jensen concedes. At first, he expects to make up the difference with groundwater. As demand warrants, SNW A plans to install another 150 mgd of capacity in building shells now under construction with the $3 I-million change order. And to use the extra capacity, Jensen expects SNW A to obtain a federal entitlement to the current surplus ofunallocated Colorado River water, now brimming from several recent 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 50150 joint venture 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 50150 team of Carollo Engineers 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. SNW A selected ozone rather than "potentially more effective" granular activated carbon filtration or membrane filtration to avoid higher costs and technical uncertainties, SNW A's Jensen explains. Southern Nevada spent $13 million on what SNW A 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 ofa $4-billion, 335-mile aqueduct from the Colorado River, received hotter water than expected after farmers passed on the costly water. The heat encouraged biological 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 baffles with flares--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., Boulder 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." http://www.enr.com/new/c42400.asp 05/15/2000