Live Oak —
A professional geologist from Bracken Engineering, Andrew Glasbrenner, said he and his crew had conducted a test of the soil a few feet from the condemned buildings on Warren Street. Their investigation revealed that there were five different types of soil found and it was determined there was a subsidence, or shifting of the soil, that was caused by the sinkhole.
“Just off the curb, we placed one of our borings,” said Glasbernner. “It was 160 feet to rock there. Very deep sinkhole, very broad.”
It was in his professional opinion that the circumference of the sinkhole encompassed the greater part of the buildings. Glasbrenner said the sinkhole is a “zone of loose, weak soils that are moving down and will continue to move down. The sinkhole diameter is large, but not like an open void.”
He said that the sinkhole was more like an hourglass that over a long period of time would eventually keep settling. He explained that the sinkhole was not a cover-collapse sinkhole, but a cover-subsidence sinkhole.
He concluded that it was of his opinion there was no real danger for the demolition crew that would be tearing the buildings down.
“The remediation plan we developed consists of a process called compaction grouting,” said John Greis, project manager and professional engineer with Bracken. “We have designed for a contractor to install basically steel pipes in the ground, two or three inches in diameter.”
He went on to explain that these pipes would be placed on a grid and that grout he described as being like cement, or mortar and under pressure would be injected into the areas to densify.