An excavation digging into sinking pavement at Third and California streets has revealed hand-made brick infrastructure dating back to a century ago when Columbus’ sewer system was first installed.
Workers from Culy Contracting in Winchester excavated the sinkhole on Wednesday, creating a 10-foot by 10-foot hole, about 12 feet deep, in Third Street, one of the main arteries heading westbound into downtown Columbus.
Workers were somewhat surprised to find that below the pavement was open space and a crumbling brick manhole, with a criss-crossing of various conduits, some operational electrical conduits for the streetlight and others of unknown origin, said Scott Dompke, Columbus City Utilities executive director.
“There was just an enormous void under the pavement,” Dompke said. “The brick structure (manhole) holding it up had a hole in its side … this could have been a much worse situation.”
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Columbus street department workers blocked off the far left lane leading to the sinking pavement last week, with arrow directing traffic to the right two lanes as an investigation began into why the pavement was buckling.
Dave Hayward, Columbus executive director of public works/city engineer, said city workers had identified the area as a potential problem for the past several weeks, but when the slight dip in the pavement was noticed, that part of the street was blocked off from traffic.
Culy workers blocked another lane of Third Street on Wednesday and Thursday, which limited motorists to one lane heading westbound into downtown Columbus as repairs continued. They are hoping to have it done by mid-morning Monday, Dompke said.
Work temporarily paused on Wednesday when the various conduits running through and next to the brick structure were found. Workers are not sure which were live electrical connections and which were abandoned ones from earlier projects, Dompke said.
“There’s some pipe running through there that no one knows what it is,” Dompke said. Utility workers were scheduled to be on site along with the Indiana Department of Transportation to mark live utility connections before work could continue.
The collapse of the crumbling brick manhole, concealed under the pavement, will cost about $75,000 to repair, which is coming out of the city utilities budget for emergency repairs, Dompke said.
When Mayor Jim Lienhoop asked earlier this week if there would be any more service interruptions in the area of the sinkhole, Dompke said, “No, unless something else breaks,” which caused Columbus Board of Works members to chuckle at his deadpan response.
Dompke said the failing infrastructure appears to be part of Columbus’ original sewer system, with the tipoff being that the manhole is made of brick. The brick work was probably done by hand a century ago by unknown city employees when the city’s sewer system was being built, Hayward said.
The city engineer said it is possible there are other brick manholes similar to the one that is collapsing around the city sewer system, but it’s unknown what their condition is.
“There are always more,” he said. “But some of them might not be quite as deep, and they wouldn’t create quite as big of a hole if they failed,” he said.
Earlier this month, the city entered into an agreement with Christopher Burke Engineering for a Stormwater Program Assessment for the city.
Hayward said while the city has completed an assessment of street pavement and funding needs for upgrade and maintenance for streets, and a similar, but less detailed assessment of traffic signals, the city did not have an assessment for maintenance and repairs for its stormwater infrastructure.
“Stormwater repairs and improvement projects are getting more expensive and more difficult (more infrastructure competing for the same underground space, more regulations etc.), Hayward told the city’s Board of Works on Feb. 5. “An assessment and plan is needed to consider current and future funding needs and sources.”
The city’s agreement with the engineering company is for a total cost not to exceed $42,000.
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Two lanes of Third Street at California Street heading westbound into downtown Columbus remain closed as repair work continues on a sinkhole at the intersection.
Workers hope to have the repairs completed by sometime today, or Saturday if further delays occur.
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