Guaranteeing Zero Leakage on a New 20 Mile Pipeline: TRWD's 350 MGD Eagle Mountain Connection Project

As aging water infrastructure and increasing water supply demands become a fact of life across North America, attitudes towards leakage from water mains are changing. Water leaking from pipelines creates a slew of problems, such as cross-contamination, corrosion, and degradation of bedding soils, which can lead to pipeline failures. Water utilities and districts have gone through a learning curve of the key role leakage plays in pipeline failure mechanisms, and are becoming increasingly proactive. One target of the growing concern about leakage is the allowable leakage standard on new pipelines. A hydrostatic pressure test is essential to test structural and mechanical properties. While it was once the best tool available to test for leakage, allowing a certain amount of leakage was unavoidable; hydrostatic tests cannot detect the smallest leaks, and even if detected such leaks can be impossible to locate. Contractors facing a failed hydrostatic test spend enormous resources trying to find leaks, and suffer penalties for extending the length of the contract schedule. The Sahara® Leak Location System is a tethered inline sonic leak location (TISLL) technology that has the proven capability of pinpointing leaks of under 1G/hr, allowing for rapid repair of even such tiny leaks. Tarrant Regional Water District (TRWD) and Freese and Nichols Inc. (FNI) have chosen to take advantage of this proven technology on the Eagle Mountain Connection Pipeline, requiring that the pipeline be surveyed for leaks before the hydrostatic pressure test. This paper describes this project, including the approach and advances used to allow for full testing of the pipeline under hydrostatic pressures, and results to date.