Ferguson Mayor Allen Dobbs stopped by Upchurch’s home on Friday, and it wasn’t long before the sinkhole was filled in with rock and gravel donated from the railroad.
“The railroad was kind enough to help us,” said Dobbs on Friday. “ ... it seems to be pretty stable right now.”
Dobbs and Upchurch both said the sinkhole actually stretches horizontally back several more feet — which means the ground directly above that chasm was unstable as well.
“We drive our cars over that spot every day,” said Upchurch. “Imagine what would’ve happened if the car had been there when it was like that.”
Dobbs estimated that the sinkhole could’ve been between six and eight feet deep without the loose soil.
By around 4 p.m. Friday — about 24 hours after the sinkhole opened — the area seemed to be more stable. Dobbs even stayed and helped fill the sinkhole in, which left an impression on Upchurch, who had never met Dobbs before Friday.
“I was very impressed with him (Dobbs),” said Upchurch. “He was not leaving until the situation was taken care of.”
Dobbs said the City of Ferguson has dealt with several sinkhole problems, and he said quick action to fill the holes in with debris and rock is the best way to take care of the issue.
“You have to (stabilize sinkholes) for safety’s sake,” said Dobbs. “ ... These things can pop up anywhere.”
Sinkholes, according to the U.S. Geological Survey (USGS), are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by ground water moving through the formations. As the rock dissolves, spaces and caverns develop underground.
The land usually stays intact for a while until the underground spaces get too big. If there is not enough support for the land above the spaces, a sudden collapse of the land surface can occur — as in Upchurch’s case.