About 20 gallons of oil spilled into a tributary of the Youghiogheny River in South Huntingdon Township Monday evening, according to the Pennsylvania Fish and Boat Commission.
A heating-oil tank officials thought to be empty was in the basement of a home being demolished along Fitz Henry Road, said Mike Parker, communications director with the commission.
During demolition, a slow leak started from a pipe of the tank, causing oil to spill into the tributary.
A small amount of oil also flowed to the Youghiogheny shortly after 7 p.m., leaving a strong odor and oil sheen visible on top of the water, he said.
Officials from the Turkeytown-South Huntingdon Township Volunteer Fire Department, the Westmoreland County Hazardous Materials Team and McCutcheon Enterprises, a cleanup company, responded to the scene and were able to stop the leak by removing the compromised pipe.
More oil was found in vegetation along the stream banks after a heavy rain Tuesday pushed oil from contaminated soil into the water, Parker said. Officials were able to remove the soil from the property to stop further contamination.
Dead aquatic life was not observed and warnings were not issued for people downstream, Parker said, adding a slight sheen might still be visible after a rain.
The Pennsylvania Fish and Boat Commission and the Pennsylvania Department of Environmental Protection are investigating the leak.