Plans are heating up to prevent Evanston’s water supply from freezing again.
The Evanston Water Treatment Plant is considering buying heated pipe screens that could prevent the icing problem that limited the city’s water supply Jan. 30. That Friday, especially cold lake water formed ice particles, known as frazil ice, in Evanston’s pipes that link to Lake Michigan. The ice blocked water intake, causing city officials to ask residents, city staff and Northwestern to conserve water usage.
Pipes freeze and block the water supply about three or four times each winter, but usually the pipes are working again by 9 a.m., said Kevin Lookis, assistant superintendent of water production. On Jan. 30, however, the pipes stayed blocked until 12:30 p.m., according to a city press release. To combat the problem, the treatment plant pumped water stored from the previous night, and quality was never compromised, Lookis said.
Frazil ice can form whenever conditions are right. As a precaution, the water department fills all of its storage tanks by 10 p.m. every night during the winter, said David Stoneback, superintendent of the water division.
If the water hadn’t warmed up, the supply scare could have been much worse, Lookis said.
“At some point we would have had to declare a complete emergency, you know, brought in bottled water,” he said. “We don’t like to do (that), but we do if it’s an emergency.”
Fitting heated screens onto the end of intake pipes could prevent frazil ice from forming, Lookis said. He estimated the screen installation would cost upwards of $250,000.
Five other locations on the Great Lakes use similar heating systems, and the results are encouraging, Stoneback said.
“Checking their references, they have indicated that the system has worked,” Stoneback said. “We’re getting cost estimates to have the system installed in Evanston so that we can prevent this in the future.”
The heating system has been on the water department’s capital improvement plan for years. After recent events, Stoneback said he thinks the measure will now be a higher priority. If the city decides to buy a heating system, it would most likely be installed this summer, he said.
The water department discussed options with both the Chicago and Evanston fire departments, Lookis said. One idea involved using Evanston Fire Department pumper trucks to draw water from the lake, he said.
Evanston officials have asked large-scale water consumers to conserve in the past, but Jan. 30 was the first time the city issued an alert to all residents, Stoneback said. The convergence of several factors made the situation particularly hazardous.
“It’s kind of like the perfect storm,” he said. “The wind was out of the west, so it picks up the cold air from the frozen tundra, if you will, with all the snow covering everything, and blows it out onto the lake. There was very low humidity. And under those conditions the lake water can actually supercool.”
