A broken holding tank in a Chicago suburb has spilled about 65,000 gallons of oil sludge and contaminated a 3-mile area around the Des Plaines River.

U.S. Coast Guard Petty Officer William Mitchell says about 6,000 gallons of the sludge from a Caterpillar facility seeped into the water near Joliet early Sunday and the rest spilled onto land. He says it poses no risk to human health but puts animals in danger.

Mitchell says the U.S. Coast Guard, the Environmental Protection Agency and local officials are working to contain the sludge. He says authorities have a floating wall in place to keep the oil from spreading in the river.

Calls and e-mails seeking comment from the construction equipment maker were not immediately returned.