Lake Tawakoni Water Supply ProjectConstruction Management – Engineers as Resident Representatives

摘要

Since its formation in 1951, the North Texas Municipal Water District hasrnbeen charged with developing a reliable water supply source for its 13 member citiesrnand 57 other customers (some direct and some indirect), serving more than 1.6rnmillion people in portions of north Texas. The District’s service area covers portionsrnof Collin, Dallas, Denton, Fannin, Hunt, Kaufman, Rains, and Rockwall Counties.rnLong-range water supply planning efforts identified significant increases in waterrndemands that must be met through a corresponding increase in available raw waterrnsupply. Compounding the need for raw water is the fact that the north Texas regionrnexperienced serious drought conditions within the last few years with the District’srnprimary water supply reservoir, Lake Lavon, falling some 17 feet in water surfacernelevation from May 2005 to October 2006. Additional raw water supply was neededrnto prevent extensive water restrictions during this drought and provide for continuedrngrowth of the service area.rnIn an effort to supplement available supplies, the District contracted forrn50,000 acre-feet of water per year from the Sabine River Authority in LakernTawakoni, located approximately 45 miles east of Dallas in October 2005. Therninfrastructure needed to transfer this water from Lake Tawakoni was designed andrnconstructed within an accelerated schedule from January 2006 to July 2008. Therninfrastructure includes approximately 30 miles of 54 and 60-inch-diameterrntransmission pipeline and two pump stations, each with a raw water pumpingrncapacity of 75 MGD at a total project cost of nearly $100 million.rnConstruction management and coordination of the multiple projectrncomponents was critical. The focus of this paper will be a discussion of the majorrnproject components, construction management, and lessons learned duringrnconstruction of the multi-million dollar project on an accelerated schedule. Uniquernproject issues included coordination of 5 construction contracts, equipment preselectionrnand delivery, implementing pipeline corrosion control, technology basedrnmanagement and paperless submittal process, conflict resolution, and specific itemsrnof interest related to engineers as resident representatives. Some of the constructionrnissues to be discussed include addressing failures of pipeline joint bonds andrnconstruction of a 14-foot diameter shaft on the shore of Lake Tawakoni.