Board approves additional $6 million in light of sewer fracturing

Another 3,700 feet to be investigated

By: Nick Mordowanec | Fraser - Clinton Township Chronicle | Published May 9, 2017


MACOMB COUNTY — Investigating a decades-old Macomb County sewer has proved to be a monumental effort for engineers, and more surprises continue to appear.

On May 8 at the Macomb County Office of Public Works, the three-member Drainage Board of Public Works Commissioner Candice Miller, Macomb County Department of Roads Director Bryan Santo and Macomb County Commissioner Robert Mijac, D-Sterling Heights, unanimously approved an addition of approximately $6.2 million to the $70 million scope of the damaged interceptor project.

Louis Urban, senior project manager with Anderson, Eckstein & Westrick, said during the Macomb County Drainage Board meeting that more cracks and fracturing have been found in the 11-foot-wide damaged interceptor.

An estimated 3,700 feet of the interceptor, from the east edge of the Fraser sinkhole extending west toward Garfield Road, will need to be improved to prevent a future sinkhole from occurring. Engineers went into the interceptor April 21-25, viewed its condition and documented it with closed circuit TV video.

“It was sewer cracking and fracturing within the first 30 feet,” Urban said. “The pipe literally has failed; it just hasn’t collapsed yet.”

Urban clarified that 130 feet east of the original sinkhole has showed signs of failure. Engineers have expanded the shaft another 20 feet to encompass some of the worst portions of the failure.

He mentioned attacks of H2S, or hydrogen sulfide, in which bacteria eat the gas, excrete acid, and then the acid attacks piping and leads to section loss.

There’s also 2 1/2 to 3 feet of sewage surrounding the present sewer lining. Urban said cracking has occurred at the crown and invert, at the “three and nine” positions.

Since the pipe in question was originally built in the 1960s or ’70s, it’s composed of a primary liner on the outside with steel ribs, while the inside boasts a concrete pipe.

Moving forward, Hobas piping will be used — similar to pipe work done between Eight Mile Road and Interstate 696 on the Oakland Macomb Interceptor Drain, or OMID — which is impervious to hydrogen sulfide attacks.

With the board’s May 8 approval, Urban said “the last stick” of the project should arrive sometime in August. The piping is manufactured out of state, and it’s expensive. Estimates concluded that 1 foot of piping costs $707.

The Hobas lining will feature a 9-foot-2-inch diameter, which is smaller than the current lining.

Two videos were later played for the media and other attendees.

One video taken on April 27 provided a look inside the degraded sewer, emphasizing the “crowning” effect, displaying sanitary trash and acknowledging section loss above the flow line due to hydrogen sulfide attacks.

The other video showed how machines helped engineers apply gel to Hobas liners during the OMID project, from 10 Mile Road to 11 Mile Road.

Urban said gel helps seal leaks, and then grout is pumped to the outer lining of the pipe to prevent soil migration. Stability around the pipe prevents issues like sand silt from invading the piping.

Evan Bantios, an engineer within the Public Works Department, said that as of May 6, 136 of 244 piers had been installed to provide stability to the project, forming a temporary earth retention system.

“It’s not a matter of if (the pipe will collapse), it’s a matter of when,” Bantios said.

Miller said it’s the same exact pipe at the same exact time, buried beneath the same exact soil. She said it’s no exaggeration to believe that another sinkhole could occur if work does not begin immediately on resolving this cracking issue.

“It’s really no surprise,” Miller said in reference to the pipe’s condition. “The sooner we can get this done, the better off we will be.”

Currently, some activities are based on 12-hour and 24-hour operations. Urban said more 24-hour operations might be encouraged in the wake of the pipe’s present state.

The engineers still stayed true to the general timeline, saying the project itself — including water mains, road reconstruction and utilities — should be completed by November.

Chief Deputy Public Works Commissioner Brian Baker stated afterward that the county will receive $5 million in grants and a bond for the other $70 million to pay for this project. The bond will last 25 years, with taxpayers in the 11 affected communities still paying for the last sinkhole from 2004.

However, it’s not expected that these additional repairs will financially impact homeowners.

Also, local retail sewer rates are expected to be rolled out July 1. Baker, who represents Macomb County on the six-person Great Lakes Water Authority board, said a 10 percent increase is expected to be voted on by board members.

The aforementioned videos can be viewed on YouTube by searching for “Macomb County Office of Public Works.”