Village set to drain pond to check dam

Barrier hasn't been inspected in 15 years

May 4, 2010

Menomonee Falls — ill Pond Park might not be the best spot for wedding photos this summer.

The Lepper Dam, north of Main Street in the park, has not been inspected in 15 years. This summer, the village will draw down the pond to inspect the facility and repair hopefully minor issues.

However, if major problems, like a buildup of sediment requiring excavation, are found, the Village Board would have to decide whether to fund the project in the capital improvement budget.

Village engineer Thomas Hoffman said no cost estimates are available for what it could cost to fix a major problem. If only minor issues are found, the village can fund the repairs with the Public Works maintenance budget, he said.

The state Department of Natural Resources recommends dam inspections every three to five years, but does not require it, he said.

"It's only a recommendation," Hoffman said.

The DNR currently is working on a policy mandating dam inspections.

Several problems discovered

The dam was built in 1953. About 37 years later, the village fixed some deterioration. And in the mid- to late-1990s, a teenager opened the dam gates, which was the last time the dam was open.

Last year, the Department of Public Works noticed a leak, so the village hired a firm, which checked the dam in September. That company found vegetation too close to the dam that could be ruining the mortar, rusted gates, cracks around the gates, broken seals and a flow of water seeping under the gates.

A complete inspection will include a hydraulic and dam break analysis as well as a maintenance plan.

A dam break analysis, or dam shadow, results in a hazard rating. As far as Hoffman is aware, the dam has never been rated.

The analysis, or shadow, calculates the downstream impact of a dam break. A high hazard rating means loss of life and businesses while a low hazard rating means light flooding, he said.

Work set to begin June 7

But before the inspection can be completed, the village must draw down the pond.

The draw-down is expected to start June 7, depending on the weather, and last about two weeks. The DNR allows a rate of 6 inches every 24 hours. Also, heavy rains could lengthen the draw-down period.

Village officials had initially picked August for the draw-down, but the DNR raised concerns about aquatic species preparing for winter. So the date was moved to June.

The village will place sandbags around the base of the gates and then start be raising the gates 2 inches. The pond will be drawn down to mud. Newly established fish hatcheries likely will be washed away, Hoffman said.

Once the pond is drained, the inspection will begin. Village staff will deal with minor problems and bring major issues to the board.

Because it is unknown what the inspection will yield, Hoffman doesn't know how long the pond will be down.

The DNR prefers the water to stay down until all work is completed, he said.

Village President Randy Newman asked for some sort of public notice or signage about the draw-down, especially since the gazebo at the park is used for wedding photos.

Board members raised concern about the pond being back to normal in time for the Big Pig Gig in September.

"We are going to try to get it back up as soon as possible," Hoffman said.

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