Nearly 4,000 gallons of an oil-based drilling mud spilled from a tanker truck after it overturned early Wednesday on the Mon-Fayette Expressway in Carroll Township.
State police said the trucker, Stephen Addleman, a driver for Keister Miller Investments of Mahaffey, suffered minor injuries when the vehicle crashed in the southbound lanes shortly after 2 a.m.
The mud reached a storm drain and stormwater retention pond, as well as an unnamed small stream, said Lauren Fraley, spokeswoman for the state Department of Environmental Protection in Pittsburgh.
She said the exact amount of the spill was undetermined, but that crews were there to remove hydrocarbons from the stream.
The DEP was working with the trucking company, state Turnpike Commission and Washington County on a plan to fully remediate the spill, Fraley sad.
A Washington County hazardous materials team was summoned to the spill that closed the southbound lanes, police said.
Southbound travel was still limited Wednesday afternoon to one lane between the exits to Route 136 and Coyle Curtain Road because of the cleanup efforts.