Rotted sewer pipe causes sinkhole on 10 Mile Road

What could have been an infrastructure crisis was averted last week when a rotting corrugated metal storm drain pipe in Warren was repaired after a sinkhole was discovered on 10 Mile Road near Loretta Avenue.

Had the small sinkhole not been discovered and immediately fixed, it could have led to a much larger problem and potentially, a collapse of 10 Mile Road.

“This sinkhole was right up next to the curb. It was already a hazard and could have quickly become significantly worse,” Macomb County Public Works Commissioner Candice Miller said. “In this case, the rotting of corrugated metal pipe installed six decades ago is something we’re seeing more frequently in our inspections or where small sinkholes have occurred.”

Left unattended, the small sinkhole not only could have caused severe damage to the road but to a home on Loretta Avenue located approximately 50 feet away from the site.

An inspection of the storm drain revealed that the bottom of a 30-foot portion of the elliptical, corrugated metal pipe measuring 11 feet wide in the enclosed part of the Bear Creek Drain had rotted.

Storm water got in through those openings and caused some of the gravel and dirt beneath and around the pipe to be washed away, which eventually caused the sinkhole.

In order to fix the pipe, the contractor installed temporary internal bracing inside the pipe to stabilize it, then hydraulic cement was used to fill the holes at the bottom of the pipe and in the sinkhole. The crew working inside the pipe applied a coat of geo-polymer spray on the interior of the metal pipe before installing a carbon fiber grid. That was followed by a second spray coat to complete the rehabilitation of the interior of the pipe which was installed in the early 1960s.

The spray-lining method used by the contractor was efficient with long-term protection of the sewer without the alternative of excavation to reach the rotted pipe, tear it out and replace it with new pipe. Its use by Macomb County in the Bear Creek Drain and an unrelated sewer rehabilitation project along 15 Mile Road is the first of its kind in Michigan.

The project is expected to be completed soon with some grouting on the outside of the pipe, up to the sinkhole.

The total cost for construction and engineering was $230,000.

“It’s a reminder that we need to continue to invest in our aging underground infrastructure by inspecting it, rehabbing it when possible or replacing it when necessary,” Miller said.