MANSFIELD — A century of street construction history was on display on Sturges Avenue early Thursday.
Actually, it would be more accurate to say it was on display beneath Sturges Avenue.
Bricks, stones and concrete were left exposed after a large sinkhole on Sturges Avenue occurred early Wednesday morning over a corrugated steel culvert that is 84 inches in diameter.
As a result, the busy street has been closed between Ohio and Mendota streets while crews investigate the cause of the sinkhole and determine needed repairs, according to City of Mansfield engineer Bob Bianchi.
The aging culvert, part of the city’s storm sewer system, begins just west of Sturges Avenue and carries water under Ohio Street, Glessner Avenue and Mulberry Street and ultimately into the Ritter’s Run tunnel that flows through the downtown, according to Bianchi.
The engineer said an excavator will be brought to the site Thursday. Sturges Avenue will likely remained closed for a couple of weeks, though Bianchi said it’s too soon to tell exactly what will be needed.
Bianchi said records show an improvement was made to the culvert in 2000 that involved pouring a concrete invert over the bottom of the pipe.
“This kind of improvement is done to protect the pipe from corrosion. Corrosion in these types of culverts can lead to soil loss around the outside of the pipe,” he said.
“At first glance, it appears that soil loss from the corroded culvert formed formed a cavity deep under the pavement around the outside of the pipe.
“The cavity collapsed and created the sinkhole in the pavement,” he said.
(Photos taken Thursday morning at the site of a sinkhole on Sturges Avenue in Mansfield. The story continues below the gallery.)
“This is only my opinion at this point, until we excavate the area so we can further investigate the cause and make the necessary improvements,” Bianchi said.
A major concern is the condition of the corrugated steel culvert, which is likely at least six decades old. These kinds of pipes are not used these days, replaced by PVC pipe or reinforced concrete pipe in today’s construction projects, Bianchi said.
He said the expected lifespan of the older corrugated steel culverts is around 50 years, though they can last longer.
“It just depends on how active the corrosion is in the pipe. So I can’t tell you, though the lifespan can vary. I believe that certain conditions can lead that pipe to live a lot longer or shorter,” the engineer said.
He said recent video of the pipe “appears to show some flattening, though that has been recorded for years.”
“We’re going to further investigate the condition of the pipe to see what may need to be done to further improve it,” Bianchi said.
“I am hoping we do not need to repair the pipe. That’s my hope.
“If this was just a cavity, and I want to be careful with the word ‘just,’ but if this was just a cavity that formed around the pipe that collapsed, it’s a matter of excavating and then backfilling a road with structural backfill and then paving the area,” he said.
(Below is a video recorded at the Sturges Avenue sinkhole early Thursday morning.)
