Sewer gas could eat into village's resources

Unexpected underground repairs could prove costly

Oct. 23, 2013

Thiensville — Recently discovered damages to a shared sewer main could necessitate pricey repairs, Public Works Director Andy LaFond told the Village Board on Monday.

While examining manholes recently, Mequon public works staff found significant deterioration of a shared sewer main that runs along Cedarburg Road from Mequon Road south to County Line Road.

Several inches from the walls of the 36-inch diameter main, which was built in 1987 and serves all of Thiensville and part of Mequon, have been eaten away by hydrogen sulfide, a corrosive agent commonly referred to as "sewer gas."

A series of photos from inside the main, taken recently in the first visual inspection of the main since 1987, shows corrosion deep enough to expose the first of two metal support "cages" around which the concrete pipe was poured.

"This has to be repaired," LaFond said. "We're working on finding out how (quickly)."

So far city workers have inspected about 1,700 feet of the roughly two-mile-long main, said LaFond, and have found the deterioration to be less severe the further down the main they go. Still, at least 420 feet of the main needs to be relined, preliminary inspections have found.

At most, it would cost an estimated $250 per foot to reline the inside of the main with a hard-set epoxy, he said. If the whole main has to be relined it would come at a total pricetag of roughly $3 million, though LaFond said he expects much less of the pipe to need the extensive repair.

The cost-sharing agreement between Mequon and Thiensville requires Mequon to pay two-thirds of any repair and maintenance costs.

LaFond said he and city engineers are working to find find alternative ways to fix the main at a lower cost. If the project can wait, he said it may be preferable to bundle the work with an upcoming state Department of Transportation reconstruction of Cedarburg Road.

Such a partnership, he said, could save both Mequon and Thiensville money and minimize impact on Cedarburg Road neighbors.

"We're trying to be creative with our plan, so we can do it as affordably as possible," LaFond said.

The Village Board will receive future updates on the condition of the main and possible fixes at upcoming meetings.


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