Sludge from a dredging operation was spilled Monday on the inside south bound lane of Cline Avenue in Gary between Chicago Avenue and U.S. 20.
The lane was closed immediately and it took three days for it to be cleaned up and reopened.
Working to clean up the spill were the Indiana Department of Transportation, Lake County's Sheriff Police and National Industrial Maintenance, Inc.
"The product contained animal fats and dirt," said Michael Mears, vice president of National Industrial Maintenance. "It is non-hazardous. There was no danger to the general public or environment."
Mears said he does not know which company spilled the product or how the spill happened.
When the spill first occurred, the Indiana Department of Transportation originally believed it to be mud, but later found out it wasn't.
Mears said the reason it took so long was because of how much volume spilled onto the roadway.
The sludge also does not pose any threat to cause contamination in water run off.
"As a matter of protocol, our crews had placed boom around all catch basins in vicinity," Mears said. "The product was mostly solidified, and as a safety precaution we had vacuum trucks removing our wash water as we went. I stress again, this was non-hazardous material."