The Dallas water distribution system is one of the largest in the United States, with Dallas Water Utilities (DWU) providing water service to approximately 2.4 million customers within Dallas and the surrounding city limits. The system includes 5,000 miles of water mains, of which 650 miles of which are 20-inches or greater in diameter.
Eleven years ago, the City brought in Xylem as part of their water management program, which started in the late 1990s in an effort to reduce non-revenue water loss and minimize the potential for leaks throughout its transmission infrastructure.
Water transmission mains in Dallas have a higher potential of developing leaks in the summer because of extreme heat and dryness. With expansive clay soils, buried pipes are subject to shifting, causing leaks and water loss. To compound matters, over the last few years, the City has also been hit with excessive rain and flooding, which can lead to washouts, loss of soil bedding, and risk for accelerated pipe failures.
Additionally, the Texas Water Development Board has issued a state decree to the City (and 15 other Texas regions) to update a water plan every five years, with the goal to improve conservation efforts and the responsible delivery of affordable water resources. Compliance allows the regions to receive low interest loans for capital work projects.
“With our aging infrastructure and recent drought conditions, leak detection is one of the most cost-effective ways to improve operational efficiencies, lower water system costs, and reduce unplanned water outage events, and Xylem’s solutions are helping us do this…”
Randy Payton, Assistant Director for Water Delivery, Dallas Water Utilities
Since 2008 DWU has partnered with Xylem to utilize inline acoustic technologies to identify leaks and air pockets in large-diameter water mains using the tethered Sahara® and the free-swimming SmartBall® tools. Sahara is also equipped with a high-resolution CCTV camera that allows for viewing of the pipe interior during the inspection and is tracked in real time, allowing for all leaks and air pockets to be located and marked during inspection.
For longer runs, DWU frequently deploys SmartBall for leak and gas pock detection. SmartBall rolls along with the flow of the pipeline, identifying leaks and gas pockets while the line remains in service, minimizing disruption. It is designed to travel many miles under a single deployment, making it DWU’s choice for transmission mains. Both Sahara and SmartBall have the capacity to identify both large and small leaks (less than a tenth of a gallon per minute) without disrupting service in the water main.
By adopting innovative technologies in support of its comprehensive leak detection program, DWU has located and repaired over 285 leaks on its large-diameter mains. This has led to a substantial decrease in main breaks and an estimated water savings of 7.2 million gallons per day. The gallons saved daily could provide water to an additional 133,000+ new residences (assuming an average use of 5,430 gallons/month per residence).
Since 2008 DWU recognized an almost 50 percent reduction in total water main leaks from 40 leaks per 100 miles to less than 21 leaks per 100 miles today. DWU has been proactive in repairing identified leaks shortly after inspections in an effort to not only conserve water, but understanding that the value of water recovered by fixing a leak becomes recurring revenue for the Utility.
In addition to improving non-revenue water loss for Dallas Water Utilities, Xylem has provided recommendations for ongoing monitoring and maintenance of the City’s pipelines, arming DWU with powerful new insights and empowering them to make the best capital and operating decisions going forward.