On December 31, 2003, a major break was reported in the Dallas Water Utilities' (DWU) LakeTawakoni 84-inch diameter raw water pipeline. This single break started a chain of events whichpresented DWU with the possibility of losing almost 30 percent of the system capacity to meetpeak summer demands. Although DWU immediately repaired the break, a subsequent physicalinspection of 15.4 miles of the pipeline identified 465 sections of pipeline experiencing varyingamounts of distress and damage. If additional repairs on the 84-inch line were not completed byJune 2004, when peak summer demands began, DWU customers would be faced with significantwater restrictions or water rationing during the summer months, and DWU would lose a majorportion of the annual revenues necessary to operate and maintain the water system. This paper describes the unique design and construction challenges faced during this $18 Mproject that included: using patented, innovative technology for physical inspection;using DWU's "Special Needs" authorization to procure engineering and surveyingservices, obtain replacement pipe and repair materials, and award multiple constructioncontracts;accelerated design, manufacture, and delivery of pipe repair materials;developing special design details to accommodate removal of distressed pipe sectionsand provide efficient connection of repair sections;using GPS surveying techniques to locate repairs along the remote alignment;and, utilizing up to 10 separate construction crews working simultaneously to accelerate theconstruction schedule and meet the fast-track deadline.
