WAUKESHA COUNTY, Wis. (CBS 58) -- An investigation is underway after a salt dome collapsed in Waukesha County Tuesday, Jan. 23. 

The collapse happened around 3:40 p.m.at Highway Operations located off Woodburn Road. 

Authorities say no one was inside or loading salt at the time of the collapse, and there were no injuries. 

Waukesha County DPW says the dome was 37 years old, the oldest of the county's three salt domes. The two other domes at this location have more than 15,000 tons of salt available, and the department says the collapse will not impact the public or salting operations.

There are also several other domes at substations throughout the county. 

“First and foremost, we’re very grateful no one was in or around the salt dome at the time of the collapse and that there will be no impact to operations for our County residents,” County Executive Paul Farrow said.

The department estimates about 1,600-2,300 tons of salt were in the dome. The cause of the collapse is unknown, however DPW says there was snow on the roof from the recent snowfall. 

They say a contractor with the Department of Transportation inspected the structure last year.

DPW says they hope to repurpose and salvage the salt that was in the collapsed dome.