The city of Milwaukee may never know why a five-year-old sewer pipe collapsed underneath Locust Street.
Itâ€™s uncommon for combined sewer pipes to collapse. The two most recent cases involved 100-year-old brick sewers that caved in after heavy rain storms, said Martin Aquino, engineer-in-charge at the Milwaukee Department of Public Works. But there wasnâ€™t heavy rain this week, and the 21-inch diameter PVC pipe that collapsed under Locust Street just east of Humboldt Boulevard on Tuesday was installed in 2003, he said.
â€œIt is extremely rare for something like that to fail,â€ Aquino said. â€œSo weâ€™re going to talk to the contractor that put it in and go back to the old as-built plans and try to see if there was anything done that couldâ€™ve caused this or if it was just because of winter cycles –freeze and thaw.â€
MJ Construction Inc., Milwaukee, built the pipe for the city under a $97,323 contract.
Officials from MJ Construction did not return phone calls.
When the city put out calls on Tuesday and Wednesday for pipe to replace the broken sewer, MJ was the only builder that had enough 21-inch PVC pipe for the job in its inventory, said Bob Brooks, Milwaukee sewer service manager.
Brooks said he has no concerns about calling MJ to repair the broken pipe.
â€œWe have many jobs they have done and there have been no problems,â€ he said.
Brooks speculated the collapse may have been because of sandy, loose soil around the pipe.
â€œWe donâ€™t know if it was defective,â€ he said. â€œWe donâ€™t know if itâ€™s because it was so close to the river everything was saturated. We may never know.â€
The Milwaukee Fire Department discovered the problem after a truck hit a two-foot-by-two-foot hole in the road Tuesday afternoon. Aquino said beneath the pavement the hole expanded to be about 20 feet in circumference and 10 to 15 feet deep.
City crews spent Tuesday night and Wednesday morning expanding the hole to reach the pipe. As of press time Wednesday, workers had replaced the pipe and were beginning to repair the road. Crews planned to finish all repair work by the end of the day Wednesday.
Brooks said nearby residents still have sewer service.
Even if crews discover the cause of the collapse, Aquino said the city wonâ€™t be able to seek compensation for the repair work because warranties on city contracts only last one year.
â€œThatâ€™s not something we can go back after,â€ Aquino said. â€œThe problem is: How do you prove something like that, because everything is underground?â€
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