Coal mine fires usually occur in unpopulated areas where they are left to burn themselves out. In 1914, a fire started in an abandoned coal mined under a residential section of Pittsburgh. This wasn't a job that firefighters could tackle-- they needed scientists, engineers. At the time of writing in 1920, the fire was still burning. Engineers at first tried to left the fire burn out, but it soon became clear that wouldn't happen. They then decided to excavate as much coal from the area as possible to remove any fuel from the fire.
Coal became so readily available in the town that people could buy one ton for one dollar.
Read More In Fighting A Burning Coal Mine Under A City.