An impressive sinkhole that opened up Sunday at an Uptown Minneapolis intersection was caused by a collapsed clay sewer pipe that's been in use since 1903, officials said Monday.
Curtis Stallings, general foreman of sewer construction for the city, said the sewer pipe — already stressed by age — fell apart following this year's high-frequency freeze-thaw cycle and abrupt snowmelt.
Stallings said a temporary bypass was expected Tuesday, a permanent new PVC pipe would be installed by Wednesday, and that the street should be patched up by April 21.
The sinkhole, roughly 10 feet deep and 5 feet wide, opened in the middle of the intersection of W. 27th Street and Girard Avenue S. Workers on Monday were diagnosing the hole from within, descending beneath the street and working from inside a trench shield, a reinforced box designed to protect them in the event of a cave-in.
Meanwhile, residents of the surrounding neighborhood were still able to flush their toilets because the city was running a rotation of vacuum trucks that can collect two blocks' worth of wastewater at a time.
"We have invested into the vehicles and things to make sure people can continually live their daily lives," said Stallings, who was less fazed by the girth of the sinkhole than by all the people with cameras swarming it. He's seen bigger sinkholes in his 18 years with the Public Works Department, he said.
CenterPoint Energy workers were also at the site checking the condition of the nearby gas main.
"And yet another terrifying landmark on my way to work," wrote Frances Kittery on Facebook, referring to the sinkhole.
Others also commented on the sight, which became a mini tourist attraction Sunday.
"Close to my apartment," Olivia Hope Matteo posted on social media along with photos of the crater. "A big huge sinkhole in the middle of the street."
Minneapolis City Council Member Aisha Chughtai said Monday that residents should watch for crumbling asphalt around manhole covers as the snow continues to melt. And send in photos , so Public Works can try to catch potential sinkholes before they form.
Another large sinkhole, about 6 feet wide, caved in a trail near 57th Avenue on the Brooklyn Center side of North Mississippi Regional Park early last week.
Danny McCullough, regional trail system manager for the Three Rivers Park District, said the trail was immediately closed in preparation for repair work scheduled to begin Monday. The sinkhole is located in an area of the park that was closed and left unplowed for the winter but was about to be reopened, he said.
The cause of that sinkhole was not yet known, but McCullough suspected a break in the storm drain culvert that runs beneath the trail.
"If there's any kind of a failure of that culvert, water gets outside of it and starts flowing on the outside," he said. "Then that washes away soil. And that's probably what's happening there. ... We won't really know exactly until we dig it all out."
Staff writer Tim Harlow contributed to this story.