PITTSBURGH — State officials hope to extinguish an underground coal waste fire burning near Pittsburgh International Airport.

The fire has been burning for several years and sits less than a quarter mile from a runway.

The state Department of Environmental Protection says the fire has the potential to threaten visibility for air traffic, and poses a risk to an airport radar facility and an underground gas pipeline.

The $1.4 million project is expected to start next month and take about a year, and involve firefighting foam and millions of gallons of water.

Workers also will remove more than 400,000 cubic yards of coal waste from the underground pile. The pile dates to the early 20th century.