Filling a sinkhole doesn’t take too much time for Agency of Transportation crews. But making sure it doesn’t open up again can be more time consuming.
That’s what VTrans workers were trying to ensure Wednesday after a sinkhole swallowed part of the breakdown lane on I-89 southbound just north of exit 17, closing one lane.
The sinkhole was filled by noon and the traffic lane was reopened by 3 PM.
“We’ve pretty much achieved the first objective today which was squaring off the hole, cleaning it up, filling the hole back in with proper materials,” VTrans District 5 administrator Dave Blackmore said.
But the work is so much more than just filling the gaping hole.
“Each time one of these happens we actually dig deeper to find where the problem is,” Blackmore said.
VTrans hired a contractor to inspect the culvert underneath the road with a remote control camera. Engineers will analyze the video to determine if the sinkhole was caused in anyway by a deficiency that structure.
If it's not found there VTrans could hire another contractor to take infrared readings of the stability underneath the road.
“This cost will increase if there's something wrong with that structure,” Blackmore said.
The cost is already estimated at $10,000 to fix this one sinkhole.
VTrans does not keep a specific budget for fixing sinkholes but says it’s part of the pothole budget, which has seen a significant increase.
In fiscal year 2007 fixing potholes cost Vermont $1.02 million. In FY 2012 $2.57 million and in FY 2013 it was $2.03 million.
The last sinkhole on I-89 that Blackmore remembers was in Bolton in April of 2013. Burlington residents remember the Battery Street sinkhole last August.
Blackmore says he hasn’t seen an increase in sinkholes on state roads but when he does see one he makes sure it’s patched up perfectly.
“So that when were all said and done we have a good road back again,” Blackmore said.