Sinkhole Repair

Sinkhole Repair Around Drop Inlet, Williamsburg, Virginia


Asphalt street failed adjacent to a drop inlet in a neighborhood.  Neighborhood maintenance personnel determined that void was “really big” by peering through the hole. Two small sinkholes had formed in the adjacent yard, and tapping on the adjacent driveway indicated that the driveway slabs were not in contact with the underlying soil.

Up to 6 inches of rain was forecasted to start that afternoon.


High density polyurethane grouting to fill the voids around the failed drop inlet, and to seal any leaks in the structure causing the erosion. Because high density polyurethane cures within a few seconds, there were no questions about the ability of the repair to withstand the forecasted very heavy rain.


CJGeo polyurethane grouting crew installed approximately 3 cubic yards of NCFI high density polyurethane to fill the voids under the curbing, asphalt and driveway adjacent to the structure in less than an hour. Injecting foam immediately through the curbing resulted in foam expanding out of the adjacent sinkholes in the yard up to 3 feet away from the injection point. Neighborhood maintenance staff monitored the drop inlet and pipe to ensure no material entered the drainage structures.