Drilling continues in Commerce to discover the cause of two mining subsidence sinkholes that opened up back in January.

COMMERCE - The ground in Commerce surrounding two substantial mining subsidence sinkholes that opened back in January is being drilled to help determine the depth of the issue and safety of the area.

The discovery of the sinkhole in January and cracking on the nearby roadway caused the closure of Commerce Main Street and Newman/East 60 Road, from East 60 to State Highway 69. Barricades were put up, and traffic has been detoured around the area since the beginning of the year.

The complete cause of the issue is still undetermined at this time and a timeframe for when or even if the roadway will be reopened to traffic is uncertain.

“At this point, your guess is as good as mine,” Commerce City Engineer Jack Dalrymple said. “We still lack pure scientific evidence to make a strong calculated decision. Best to err on the side of public safety even if it means inconvenience to some. My advice to the public is to avoid that area.”

“The City of Commerce requested I close the road, so I did,” Clarke said.

The first round of drilling this past week Letts & Demery Pump and Drilling of Neosho, Missouri has been at the site drilling exploratory holes to attempt to determine the depth, stabilization and what lies beneath the roadway.

“They're not finding anything solid to drill through,” Ottawa County District 1 Commissioner John Clarke said last week while out overseeing the drilling underway. “The problem is all this loose chat and material they're drilling through is falling back into the drilling hole.The chat was running in there as fast as they could drill.”

The costs of this round of drilling was $400 to set the rig up each time and about $20 per foot, according to Clarke.

The sinkholes have been under evaluation for any further movement or cave-ins, but appear to be stable.

Both the Oklahoma Department of Environmental Quality (ODEQ) and Environmental Protection Agency (EPA) were notified in January and have left the issue and responsibility in the hands of the Ottawa County Commissioners and the City of Commerce. Financing for the work also falls with the County.

Clarke, Dalrymple, and Commerce City Administrator Tommy Long have all been part of monitoring the site and working toward a solution. The road is maintained by the County and is bordered by Commerce and North Miami.

No substantial structural rock has been found in this round of drilling to support the roadway.

“What I was hoping we would find with the drilling was a solid structural rock formation that would give me that warm and cozy feeling that something more than loose subgrade materials were supporting the driving surface,” Dalrymple said.

All the chat and tailings that should be coming up in the drilling process at the site are falling downward indicating there is nothing substantially supportive below, according to the Commerce engineer.

“In both holes, we were never drilling in a solid material. It looked like all chat even to the depth of the first hole which was the deepest, almost 60 feet,” Dalrymple said.” As the drill tool went down, very little materials came up. In both cases, the materials disturbed by the drilling operation disappeared somewhere underground. I can only assume into a void under the road. Operating in the drill hole closest to the larger subsidence disturbed the water in that subsidence and made it undulate. Assumption again is that the subsidence and the drill hole must be attached to something in common like a large void full of water.”

The next step in the process is more drilling with bigger rigs with better drilling capability for such conditions.

“What John's going to try to find is somebody with a drill rig that actually can push the casing down as the drill bit goes down at the same time,” Dalrymple said. “Then the casing will keep that material from caving onto the drill stem. I need to know there's something solid there. It's just like building a house – you've got to have a footing.”

Melinda Stotts is the associate editor of the Miami News-Record. She can be emailed at mstotts@miaminewsrecord.com or followed on Twitter @MelindaStotts1.