Lessons Learned from the Multi-Year Assessment of the Homestake Transmission Pipeline

In 2005, a fast-track repair was required for the failed Homestake Pipeline within the 6000-foot long Goddard Tunnel passing under the continental divide in western Colorado. This 66-inch (1680 millimeter) diameter, 56-mile (90-kilometer) long, prestressed concrete and welded steel pipeline traverses Colorado's mountains and provides roughly 60 percent of the raw water for the Cities of Aurora and Colorado Springs. This episode led to a 5-year phased condition assessment on the Homestake Pipeline with the goals of identifying and repairing imminent failure conditions, and producing a 20-year capital improvement plan that the Owner could utilize to extend the service life of this critical facility. An objectives-based program was developed that was revised yearly based upon results, incorporating new technologies as they became operational. In the process our team employed 7 different assessment techniques from 4 separate firms, responded to one catastrophic failure, and developed a risk/consequence decision methodology for prioritizing rehabilitations and improvements. This comprehensive program has revealed several insights for those undertaking condition assessments and contemplating the use of the numerous existing and emerging technologies: 1) The benefit of objective research into the capabilities, limitations, and efficacy of technology tools and strategic use of those tools as part of an overall assessment approach 2) The importance of independent verification of results from high-technology tools 3) Advanced planning to estimate the cost and operational impacts of shutdowns or facility modifications required to perform the assessment work 4) The benefits of phasing an assessment program with subsequent steps based on results of previous work to improve outcomes and manage costs effectively. 5) The benefit of holding a formal "lessons-learned" workshop at the completion of each round of assessment.