NV5 completed a geotechnical and visual assessment of a ground surface depression that developed suddenly in the rear portions of one building at a condominium complex in Tennessee. The depression that formed along the south-central portion of this building were backfilled and emergency underpins were installed along a limited portion of this building, local to the extent of the depression. The ground surface depression and exterior (brick veneer) distress were the primary causes of this claim.
The study included an observation of the depression, distress evaluation of both the interior and exterior portions local to the building and a floor elevation survey of both the first floor and second floor units.
Based on the sudden occurrence, the overall circular geometry, steep-sidedness and depth (about 8 feet deep), as well as the test boring results, it was NV5’s opinion that the ground surface depression is the result of a cover-collapse sinkhole. Formation of the depression caused structural damage to one of the walls. Furthermore, due to its proximity to the condominium’s foundation wall, the sinkhole had the potential to cause more structurally significant damage to the remainder of the building, if left uncorrected. As such, emergency backfilling of the depression was performed, and five emergency foundation underpins were installed along a portion of the foundation wall along the deepest portion of the depression limits.
