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<br />Las Vegas Area Taps Lake Mead to Satisfy A Growing Thirst (4/24/2000) <br /> <br />Page 6 of7 <br /> <br />Morgantown, W.V., helped keep the shafts' steel casing~ iHJJS-ll 2 in. of <br />plumb. <br /> <br />From the lake, pipelines wend across the River Mountains over grades as <br />steep as 22i. Concerned about possible flash flooding, snwa insisted on using <br />"controlled low-strength material" as backfill to protect buried pipes from <br />scour. The 100-psi cement slurry costs about $22 per cu yd to make and <br />install, compared to $13 or less for conventional granular backfill. Forced to <br />use the costly slurry, contractors tried not to make trenches wider than 212ft. <br />Blasting makes the trenches too wide, notes Bill Bevilacqua, project <br />superintendent at Las Vegas-based Contri Construction Co., whose crews <br />switched to rock saws before laying 3 miles of9-ft-dia pipe for $15 million. <br /> <br />NEW PLANT The mountains also made the siting difficult for a new plant. <br />The II-acre Smith site, wedged in the Lake Mead National Recreation Area, <br />seemed too small. Turning to the Las Vegas Valley, snwa repeatedly ran into <br />plans for new subdivisions, before settling on an alluvial fan within I 4 mile <br />of homes in Henderson. With memories of industrial accidents nearby, <br />neighbors worried about chlorine gas wafting down the hill, so Montgomery <br />Watson/CH2M Hill designed the new River Mountains plant to use less <br />dangerous liquid chlorine. Using ordinary salt, a record-sized, on-site facility <br />will produce sodium hypochlorite to make the chlorine. "It's innovative and <br />almost unheard of in treatment plants of this magnitude," says mw Project <br />Manager Charles O. Bromley. . <br /> <br />The plant's controversial plan calls for an initial capacity of 150 mgd plus <br />construction of shells for a later 150-mgd expansion. With seven cranes and <br />30 major structures under construction on just 15% of the 415-acre-site, <br />Kiewit received the $3 I-million change order in February to build shells for <br />eventual filters, flocculation, ozone contactors and equalization basins. The <br />change saves $7 million in soft costs, keeps others from getting in the way <br />and forcing delay claims, and minimizes future disruptions of neighbors, <br />snwa officials say. And given Kiewit's command of the site, it made no sense <br />to advertise a "phony bid," Mulroy says. <br /> <br />Some critics say the entire plan makes no sense; to use the second 150- <br />mgd shells, snwa needs more water. Besides banking river water now and <br />lobbying for permission to use current river surpluses, snwa proposes <br />"taking" flows from Colorado River tributaries in Nevada but wheeling the <br />water through the river-a plan opposed by the Los Angeles-based <br />Metropolitan Water District of Southern California and others. But even <br />MWD's expert on Colorado River matters, former U.S. Bureau of <br />Reclamation Commissioner Dennis B. Underwood, commends Mulroy as a <br />"dynamic" leader with "a lot of initiative." <br /> <br />Mulroy, 47, and a self-described "big mouth," once dreamt of working as <br />an overseas diplomat, then quit a Stanford University doctoral program in <br />German literature. Now as she takes a gamble, she hopes to convince <br />Colorado River interests to buoy the Las Vegas Valley's continuing growth. <br /> <br />... CLICK HERE FOR PAST COVER STORIES AND FEATURES <br /> <br />@ 2000 Engineering News-Record <br /> <br />http://www.enr.comlnew/c42400.asp <br /> <br />05/1512000 <br />