Lake Tawakoni Water Supply Project Construction Management—Engineers as Resident Representatives

Abstract

Since its formation in 1951, the North Texas Municipal Water District has been charged with developing a reliable water supply source for its 13 member cities and 57 other customers (some direct and some indirect), serving more than 1.6 million people in portions of north Texas. The District's service area covers portions of Collin, Dallas, Denton, Fannin, Hunt, Kaufman, Rains, and Rockwall Counties. Long-range water supply planning efforts identified significant increases in water demands that must be met through a corresponding increase in available raw water supply. Compounding the need for raw water is the fact that the north Texas region experienced serious drought conditions within the last few years with the District's primary water supply reservoir, Lake Lavon, falling some 17 feet in water surface elevation from May 2005 to October 2006. Additional raw water supply was needed to prevent extensive water restrictions during this drought and provide for continued growth of the service area. In an effort to supplement available supplies, the District contracted for 50,000 acre-feet of water per year from the Sabine River Authority in Lake Tawakoni, located approximately 45 miles east of Dallas in October 2005. The infrastructure needed to transfer this water from Lake Tawakoni was designed and constructed within an accelerated schedule from January 2006 to July 2008. The infrastructure includes approximately 30 miles of 54 and 60-inch-diameter transmission pipeline and two pump stations, each with a raw water pumping capacity of 75 MGD at a total project cost of nearly $100 million. Construction management and coordination of the multiple project components was critical. The focus of this paper will be a discussion of the major project components, construction management, and lessons learned during construction of the multi-million dollar project on an accelerated schedule. Unique project issues included coordination of 5 construction contracts, equipment preselection and delivery, implementing pipeline corrosion control, technology based management and paperless submittal process, conflict resolution, and specific items of interest related to engineers as resident representatives. Some of the construction issues to be discussed include addressing failures of pipeline joint bonds and construction of a 14-foot diameter shaft on the shore of Lake Tawakoni.