A Closer Look At Water Main Break Prediction
To residents, municipalities, and water utility professionals, no calamity is quite like a water main break. Whether a break remains unseen, covertly expending the precious resource and corroding water and wastewater systems, or draws comparisons to Old Faithful in a more public disaster, main breaks represent a huge cost to utilities and tax payers.
Each day, the country suffers 850 water main breaks. The Uni-Bell PVC Pipe Association’s Water Main Break Clock estimates that since 2000, over 4,776,000 water mains have broken resulting in over $47.7 billion in repair costs. A 2002 congressional study found that the costs to U.S. water and wastewater systems associated with corrosion from these breaks exceed $50 billion every year. That’s not to mention the costs in public confidence that utilities suffer every time a break occurs.
But what if utilities could prevent a water main break before it happened? Although outright clairvoyance hasn’t been achieved, there has been recent progress in determining where breaks are most likely to occur. Prioritizing those critical segments for replacement can make all the difference.
Prevention Through Preparation
“Anticipating water main breaks has proved a challenge for water utilities because the conditions and forces that lead to the breaks can be hard to pinpoint,” said Dr. Neil Grigg, a professor of civil and environmental engineering at Colorado State University who has investigated the potential for break prediction.
Instead of predicting breaks, Grigg urges that the best form of prevention is to target the most vulnerable segments of pipeline infrastructure.
“Rather than sit back and try to predict when and where breaks will happen, many utilities are working to identify their critical locations where vulnerable pipe may break,” he said. “By giving these pipe segments high priority to replacement, they aim to reduce their overall risk and improve the performance of their pipeline infrastructures.”
The future of this identification is tied with statistics. Grigg identifies the Washington Suburban Sanitary Commission (WSSC) as particularly adept at mining their system’s data and putting it to use to fight main breaks.
Armed With Data
WSSC is in its eighth year of a comprehensive asset management program designed to prioritize infrastructure investments. 45 percent of its water network will soon be over 55 years old and so selective infrastructure investments, in lieu of complete renewal, has become the focus.
“Like many utilities and other infrastructure sectors, we are faced with the challenges imposed by years of under-investment paired with aging systems,” said Jerry Irvine, public affairs manager at WSSC. “We are addressing these challenges through public awareness efforts, long-term funding plans, and, most importantly, focused programs for preventive and predictive maintenance activities.”
At WSSC, these programs include a geographic information system (GIS), which can track the size, age, material, rehabilitations, and status of pipelines and accessories. When this is paired with a historical database of breaks, leaks, and repairs, the commission can create a “condition score” for each asset, taking into account pipe age, internal and external corrosion rates, repair history, and inspection results. Finally, this “condition score” can be sorted into a “probability of failure” ranking which informs the commission’s maintenance and repair decisions.
“Using our extensive GIS, maintenance records, and modeling tools, we are able to identify those water mains more vulnerable to failure,” said Irvine.
WSSC has another trick up its sleeve. In 2007, it introduced acoustic fiber optics (AFO) to its system to detect the sounds associated with wire breaks on prestressed concrete cylinder pipe (PCCP) sections of its pipeline. The AFO currently monitor 77 miles of PCCP that is 48 inches or larger and provides information to WSSC personnel if it detects potential problems. WSSC is working to add AFO to its smaller diameter pipes as well.
Looking Forward
Even as a leader in prevention techniques with an annual budget of $1.4 billion, WSSC isn’t anticipating a future free of water main breaks anytime soon. The utility averages around 1,700 water main breaks per year and anticipates a dramatic increase as the infrastructure ages. In the next 10 years, the commission predicts twice as many breaks and leaks per 100 miles in its system .
With this dramatic future looming ahead for WSSC and the rest of the nation’s water utilities, Irvine emphasizes the value of technologies and models like the ones implemented at WSSC. He also sees cause for optimism.
“Given the magnitude of infrastructure investment needs and the limits on available funding, innovation and ingenuity are our best allies,” he said. “Fortunately, technology is rapidly advancing to provide the analytical tools to help us optimize the management of our assets.”
Until this next great technological breakthrough arrives, however, a world without water main breaks remains a pipe dream.