A collapsed culvert running beneath Oxford Township’s Wood Trail, south of W. Drahner Rd., between Watersmeet Drive and Chesnut Court, caused this massive sinkhole to open up over the weekend. As a result, this stretch of Wood Trail is closed to through-traffic, so motorists are asked to please plan accordingly. Photo by C.J. Carnacchio.

The plethora of potholes plaguing the state right now is small potatoes compared to what’s happening on Wood Trail, south of W. Drahner Rd., in Oxford Township.

Until further notice, a portion of this winding road, between Watersmeet Dr. and Chesnut Ct., is closed to through-traffic because it collapsed on Sunday afternoon.

Fortunately, the area was already cordoned off in anticipation of the pavement giving way, so no one was hurt and no vehicles were damaged.

It all started Saturday morning when a sizeable sinkhole was discovered along the east side of Wood Trail, near the Polly Ann Trail, a 16.9-mile non-motorized, recreational path.

A culvert (or corrugated metal pipe) carrying water beneath the road, which leads into the Lakes of Indianwood subdivision, collapsed causing the dirt above it to give way, forming the large, water-filled hole.

What caused the culvert to fail?

“That’s a really good question,” said Craig Bryson, spokesman for the Road Commission for Oakland County (RCOC).

“I think the road was put in in the early 1990s by a developer, so the developer would have put in the culvert (as well) and it should have lasted longer than (it did). So no, we don’t know (why it failed).”

“We’ve got culverts much older than that, (which) are doing just fine,” he noted.

Darryl M. Heid, director of highway maintenance for the RCOC, could only offer some speculation at the scene.

“I just think it was the huge rainfall,” he said. “We had probably a higher level of flow going through there and that probably helped disrupt the (surrounding) earth (causing it to) come down. That would be my guess. But the culvert is old, too. It may have just given way.”

While the portion of the culvert beneath Wood Trail is a corrugated metal pipe, Heid noted that’s not true for the entire culvert

“At a certain point under the old railroad track [which today is the Polly Ann Trail], it’s an old block-and-mortar structure. It’s like an arch structure,” he said.

Paint Creek normally flows through this culvert. The water comes from the Oxford Multi-Lakes Dam, which is operated by the Water Resources Commissioner’s (WRC) Office.

As the hours passed following the sinkhole’s discovery, the dirt packed beneath Wood Trail slowly gave way, causing the asphalt surface above to steadily sag as it lost more and more of its support. Finally, at approximately 12:30 p.m. Sunday, the pavement buckled and fell into the water with a mighty splash, more than doubling the size of the hole.

While all this was happening, water that was no longer able to flow through the damaged culvert had already begun to backup and flood the area on the west side of Wood Trail, adjacent to some homes in the River Walk subdivision. The water in the flooded area was estimated by officials to be about 20 feet deep.

With the water encroaching upon these homeowners’ properties, a decision was made by the road commission to utilize the services of the Davison-based Mersino Dewatering, Inc.

Mersino brought large, diesel-powered pumps to the scene to move the rising water through hoses, which were laid across the road and down its steep side, to the area below where the creek typically flows when the culvert is functioning properly.

Three 6-inch pumps were brought in on Saturday, followed by 8-inch and 12-inch pumps on Sunday.

All five pumps are still 　running and currently situated on the Polly Ann Trail, which is between Wood Trail and the flooded area.

“We got the water level down, which was the most immediate concern,” Bryson said. “I have not been out there, but my understanding is the water level has gone down enough that it’s not a threat to those homes anymore.”

“I would say it’s gone down all of about 4 feet since all the pumps have been up and running,” said Edward Thick, supervisor of construction support and drain maintenance for the WRC. “It’s pretty deep, so there’s (still) a lot of water to come out of there.”

To help keep the water from rising anymore than it already had, the WRC closed the Multi-Lakes Dam over the weekend.

“It was open minimally on Saturday to try to slow things down,” Thick said. “We shut it down completely on Sunday.”

As of press time on Tuesday, the dam was still closed and will remain closed unless the precipitation forecasted for Thursday is enough to necessitate opening it.

“The dam’s holding the water back upstream, so everybody on all the lakes on the upstream side will be flooded out if we don’t let some water out downstream,” Thick explained. “Obviously, with this restricted outlet now (due to the failed culvert), we have to control that. We don’t want to flood out either side, so we’re going to hold it where we can, but if we get too much rain and it starts backing (up) upstream, then we have to break that damn open or we’ll have all those people’s houses under water. It truly is a balancing act.”

Even with the dam closed, some water is still flowing over the top, although Thick characterized the amount as “very minimal.”

“We shut our gates all the way down, but if that (water level) gets too high, it’s going to go somewhere,” he said. “We can only hold it back to a certain height, then it’s going to start spilling over or eroding around the dam, which would be a worst case scenario because we don’t want to have any structure problems with the dam. Right now, it’s just spilling over the top, which is confined (within) the concrete walls. There’s really nothing we can do about that right now. It’s just too high upstream (due to all the recent rainfall and snow meltage).

As for when the failed culvert will be replaced and Wood Trail rebuilt and re-opened, that has not been determined.

“As far as a solution and a time frame, we simply don’t know yet,” Bryson said.

A fix isn’t as simple as it might seem.

“The challenge is this culvert is about 200 feet long and our right-of-way for that road is about 60 feet, so it extends way beyond our right-of-way, which means other people have to be involved, including potentially, the Water Resources (Commissioner’s Office), the Polly Ann Trail (and) the township,” Bryson explained. “We are trying to talk with those other entities and figure out who has responsibility for what and how to replace something that is under multiple jurisdictions.”

“This is a pretty unusual situation for us,” he noted. “Usually, if we have a culvert, it’s completely within our right-of-way and if it fails, we just dig the road up and put a new culvert in. But we can’t do that because technically, we can’t work on property that we don’t own outside of our right-of-way.”

County and township officials gathered at the scene Tuesday afternoon to discuss the situation and how to proceed from here.