DES MOINES, Iowa -- After calling the massive opening in the ground outside City Hall a sinkhole for the last 24 hours, Des Moines city officials are now calling it something else.
The city now calls it a "subsidence," or gradual caving in of ground. They say years of water erosion slowly eroded the dirt around a sewer box under the ground, which eventually collapsed and caused the bigger cave-in.
City crews have been working to repair the ground all day Tuesday, and put up temporary stabilizers as a precaution against the stairs near City Hall caving in.
Engineers say they are now working to get the situation under control and there is currently no concern about the concrete wall collapsing. The Army Corps of Engineers has slowed the Des Moines River's current to allow for crews to assess the damage. Engineers have not said if other sewer boxes are placed along the riverfront.
They say one silver lining to the collapse happening now is that City Hall is closed for renovations, so there was no interruption of other city work.
Crews hope to determine a final cost and end date for this project by next week.