As summer quickly approaches, many northern cities are experiencing the after-effects of the harsh winter season. The winter brought record lows and snowfall, but the warmer summer weather is proving to be less welcome than expected because of snow melt runoff and pipe bursts. Some parts of the world experience these issues annually, and have dubbed this time of year “water main break season.” In Prince Albert, Saskatchewan, one such water main break has been flooding the streets for over a month.
Freeze/thaw cycles are common culprits of water main breaks. As warmer weather thaws the frozen ground, differential settlement causes the soil beneath the pipes to shift. A combination of extreme weather and very old pipes (almost a century old, in some cases) is being blamed for the majority of water main breaks this time of year. So far, 19 water mains have broken in Prince Albert this season, and several more are expected over the next few weeks. City officials say that they are working on a plan to address the water main breaks, adding that “the extreme cold last winter has put tremendous pressure on the underground infrastructure system.”
Corrosion of pre-stressed concrete cylinder pipe (PCCP) costs the United States water and waste water systems more than $50 billion a year, according to a 2002 study. In North America alone, there are 850 water main breaks every day, creating an annual repair cost of more than $3 billion. Leaking pipes have been calculated to lose about 2.5 trillion gallons of drinking water every year, which accounts for about 17% of all water pumped in the US, and 90% of this loss has been credited to corrosion-related issues of outdated pipes. In fact, according to a 2012 study performed by Utah State University, 43% of water mains in America are between 20 and 50 years old, and 22% are more than 50 years old.
Unfortunately, nearly half of the one million miles of pipeline laid beneath America’s streets is nearing the end of its serviceable life. Estimations place the cost of replacement at more than $1 trillion over the next 25 years, but considering that funding isn’t available, a solution is needed to extend the life of our PCCP infrastructure. HJ3’s CarbonSeal carbon fiber is one such solution that was used to repair a cracked water pipe at a coal-fired power plant. The internal concrete liner of a 120-inch diameter pipe, used for transmitting water to the plant’s cooling towers, cracked. Water flowing inside the pipe penetrated the cracked concrete, corroding the pre-stressed wires inside. As the pre-stressed wires snapped and failed, the pipe lost its capacity to resist internal hoop stresses. Considering staggering replacement costs, the power plant chose to use HJ3’s CarbonSeal system to repair the 750 feet of pipe instead of replacing it.
After the surface of the pipe was sprayed with an abrasive blast, the leaks were injected with polyurethane foam. The pipe surface was primed prior to installation of the saturated CarbonSeal carbon fabric, and a protective topcoat was applied to the carbon fiber until a pin-hole free surface was achieved and the system was impermeable. It took only 11 days to repair all 750 linear feet of pipe, restoring its full capacity to resist internal hoop stresses. The client saved 50% over other repair methods, 65% over the cost of replacement, and the repair prevented six tons of concrete from going to landfills. Furthermore, the system has been in place for eight years, and “has performed to expectations.” The client is “pleased with the service and performance of HJ3 who provided design calculations, stamped engineering drawings, termination details, and on-site supervision throughout the project.” If you have an underground pipe that needs repair and would like to learn more about HJ3’s CarbonSeal reinforcement systems, contact HJ3 at firstname.lastname@example.org.