Two massive water tanks, almost three stories high and 80 feet in diameter, are slated to be erected along the shore of Lake Winnebago in a $20 million project that is expected to boost local utility rates by 7 to 8 percent.
The project, which has been greenlighted by the Common Council and is now before the Wisconsin Public Service Commission, will have a significant impact on the shoreline’s visual appearance but has attracted little local attention.
The city sent invitations to about 75 neighboring residences for an October public meeting, but only about half a dozen people showed up.
“It’s certainly going to be a big change,” said James Rabe, the city’s director of public works. Construction will go on for about two and a half years, he said.
The new storage tanks will replace three existing tanks that hold purified water after it has gone through the city’s filtration plant. Two of these tanks, called “clearwells,” are over a century old, and the whole setup was identified as “a deficiency” in 2007 by the Department of Natural Resources.
The new tanks will be on the east end of the Water Filtration Plant, near the corner of Washington Avenue and Lake Shore Drive.
The state’s major issue is that the storage system sits below groundwater, which means that contaminated fluids could possibly seep in and mix with water that is headed to household faucets. The state said this situation “has the potential to cause serious health risks or to present long-term health risks to consumers,” according to the city’s application to the PSC.
“What they are really trying to do is prevent groundwater from interacting with treated drinking water,” Rabe said.
The city has selected the most expensive of three construction alternatives to address the problem. Instead of installing above ground storage tanks, the city could have decided to build new clearwells within the existing water reservoirs. Two alternatives that were considered would have meant construction cost savings of at least $2 million, or 20 percent.
But Rabe said the initial cost savings would be offset by increased operating and maintenance challenges.
“You’ve got to do so much secondary containment” with underground storage, he explained. In addition to building double- or triple-wall underground tanks, the city would need to install monitors to see if any water was accumulating in the spaces in between.
If water was accumulating between the tank walls, the city would then need to figure out if water was leaking out or leaking in and then take corrective action. “For purposes of evaluation, that alternative kind of became a wash.”
Project costs are expected to reach $20 million, including new pumping stations and associated piping. The city expects to borrow this amount from the state’s Safe Drinking Water Loan program. The debt will be paid off through sharply higher water rates.
The city has taken some steps to minimize the impact on the neighborhood. For example the new tanks will be prefabricated off site to reduce the number of loads of concrete that would have to be trucked through residential streets.
Most of the truck traffic will use Merritt Avenue rather than Washington Avenue to access the site, and fines will be assessed for violations. The city said it would take steps to limit noise and dust.
The initial exterior design of the tanks is being reconsidered so that it blends in, to some extent, with the architecture of the neighborhood. The new design will have horizontal features that echo the split-stone foundations of nearby houses.
The construction phase will last for about 30 months, and during that time Lakeshore Drive will be closed, limiting access to the lake.
“The new pump stations and reservoirs are tall structures with significant visible impact,” the city told the PSC. “To mitigate the impact on adjacent neighbors, the new structures are designed to match the existing Water Filtration Plant and have roof lines lower than those of some of the existing structures.”
Residents who are familiar with the city’s plans realize that there is going to be a major change in the neighborhood, Rabe said. “But they kind of understand we need to do something.”
Illustration: The city provided this rendering of the completed project at a community meeting in October.