Engineering assessment helps identify problem areas of a critical water main to prioritize repairs and prevent failure
Like many fast-growing communities, the Town of Flower Mound, Texas lacked detailed information on the true condition of some key aging assets, including underground pipes and water mains. In 2001, Flower Mound suffered an uncontrolled leak and lost pressure to a third of their system (affecting more than 15,000 customers) for a two-day period due to a valve that could not be located. This led to the development of an asset management program, which resulted in the identification of a 3.5 mile water main that needed urgent inspection.
Water transmission mains are among any city’s most vital infrastructure but inspecting metallic transmission mains has historically been a challenge with few reliable assessment solutions available. Utilities often use indirect methods to assume the condition of the pipeline or they replace pipes based on age rather than actual condition. Flower Mound wanted to ensure their management program was built around quantitative data and using the most accurate methods available. They enlisted Xylem to provide a comprehensive condition assessment of key sections of their steel, ductile iron and bar wrapped pipes in order to make data-driven and accurate decisions and improve the reliability of service within the system.
The assessment was urgent, as Flower Mound planned to widen a major road next to the main and wanted reliable information on the condition of that particular pipeline before the road was built. Any necessary repairs or replacement needed to be completed prior to construction to avoid significant disruption and additional expense.
Flower Mound, in conjunction with Xylem, used a condition-based Engineering Assessment approach that minimizes the risk of failure by identifying damaged pipes using advanced inspection technologies. Work began by performing a PipeDiver inspection using technology to assess the pipe wall condition, including identifying broken bar wraps in bar-wrapped pipe. Identifying areas of wall loss would allow Flower Mound to gain a better baseline understanding of their assets and make targeted repairs where necessary.
Next, the pipeline was inspected using the Sahara leak and gas pocket detection tool. The tethered tool provides real-time video footage of a pipeline as the tool moves along with the flow. Identifying leaks early can allow proactive repairs and provides indicator data on the condition of pipe joints. Air pockets can cause capacity issues within a pipeline and compounds the effects of transient pressure events.
“The knowledge gained from this inspection spring-boarded us to develop an asset management
plan that would give us a good handle on the condition of our high priority assets and reduce risk
- Wes Hubbard, Maintenance Supervisor, Town of Flower Mound
Xylem then used transient pressure monitoring to record pressure in high resolution. Transient events can affect the structural integrity of the pipe because they increase the stress in the pipe wall, causing damage and eventual severe deterioration. Over time, pressure surges can reduce the life of the pipeline and when identified, the source of the surges can be eliminated to prolong the life of the pipeline.
Structural engineering analysis was used to help determine what short-term repair decisions to make by analyzing the condition data collected from Sahara, PipeDiver, and transient pressure monitoring. Finally, finite element modeling provided a detailed analysis of defects on the overall structure of the water main.
By combining these assessment methods, Flower Mound was able to identify multiple problems and act on these sections of the pipeline.
The Xylem team provided the Town’s decision makers with actionable information they needed to proactively manage their metallic pipe assets and create a prioritized program for pipeline repair, replacement and monitoring. Analysis detected 14 pipe sections with losses in wall thickness, and one medium-sized leak on a previously unknown outlet. Twelve (12) joints were observed to contain deficiencies that would need repair. Transient pressure monitoring confirmed that operational practices of the water mains and pump stations were within normal parameters and provided inputs into structural evaluation.
Initially Flower Mound was prepared to raise bond funds to replace the entire pipeline in question, with an estimated cost of over $1 million. As a result of the data provided, Flower Mound avoided taking on new debt. While the assessment identified localized issues in certain pipe segments, it also established that the rest of the pipeline was still in sufficiently good condition to remain in service. Based upon the data and recommendations provided by Xylem, Flower Mound was able to maintain asset integrity at a fraction of the cost, avoid disruption to the community, defer capital replacement dollars, and focus efforts on other priorities.
That’s the power of decision intelligence.