When temperatures plunge, water systems sometimes shudder. Occasionally they develop fissures and cracks, dispersing water in all directions.
Naperville has seen a little more than the normal frequency of those events in recent winters, including the current one, but the city is taking proactive steps to address the problem.
So far, this winter has not delivered the freezing temperatures that the area experienced last year, so the situation doesn’t have Jim Holzapfel, director of the city’s water and wastewater utilities, too panicked. He’s keenly aware that the frost level stretched down about 4 feet last winter, about twice as far as usual.
“When the ground freezes, it heaves. It heaves underground as well, and puts pressure on the pipe wall, (which) will crack,” Holzapfel said. “Once the service line freezes, it’s a plug in the system. You can’t use it.”
The number of water main breaks in the city’s distribution network has increased each year for several years. Mark Straughn, manager in the water distribution and collection division of the city utility, said the annual average has hovered around 75. Holzapfel places the yearly average in the 75 to 100 range. During 2014, the total was 108.
Reported by fiscal year, which runs from May 1 through April 30, the figure for 2013 was 81. There were 99 in fiscal 2014, and the city has tallied about 85 breaks for the first nine months of the current budget year.
“So far this has been a typical winter in terms of frequency of main breaks,” Straughn said by email.
Holzapfel said the city’s prompt attention to the incidents keeps the inconvenience to customers on the system to a minimum. Because the city’s pipes are set up in a way that allows segments to be isolated with valves, an average of 14 households are without water when a main break is being repaired, he said. Residents usually have their service interrupted for no more than a couple of hours when a main ruptures nearby.
A main break invariably leads to water loss, however. When the city utility performed a recent audit for the Illinois Department of Natural Resources, it found just 2.75 percent of the water pumped out by the city was draining away through leaks and cracks — a below-average amount, Holzapfel said.
“Our unaccounted-for water is very good, which means if there is a main break, we’re fixing it timely,” he said.
The numbers aren’t all that precise, however. A recent internal memo puts the water leakage rate for fiscal 2015 so far at 8.9 percent, which represents an increase of about 62 percent over the rate reported two years earlier. Holzapfel said the actual rate of water loss, affected by the timing of the measurement and other variables, is somewhere between the two figures.
The city is in the midst of a multi-year leak study, and that should help, he said. Also done annually is a sonogram-style survey that detects the hissing sound indicating a nearby leak.
“When a water main breaks, the water doesn’t always surface,” Holzapfel said, adding that sometimes it drains into a nearby trench.
The state-mandated audit, a condition required to maintain the allocation permit that allows the utility to continue receiving Lake Michigan water, tracks metered and unmetered water uses, including that pumped out for such purposes as firefighting. But with the IDNR in its final year of allowing any unaccounted-for leakage, Naperville is working to seal up leaks and quickly attend to breaks with the aim of avoiding financial penalties.
“They want us to do a better job of tightening up our systems to use less water, conserve lake water,” Holzapfel said, noting that some of the farther-out counties have begun pushing for delivery of lake water. “It’s a good thing that they’re doing that (the audits). We should conserve lake water. … They’re just trying to spread the good lake water to other communities.”
