Alvin was walking down 6th Street on a hot sunny day when he saw smoke coming out of the street. He could smell the smoke, and it was getting thicker. It was coming out of a storm drain. Alvin used his cell phone to call the fire department.
"The storm drain is on fire!" he said. The fire department asked for his whereabouts and he said he was near 6th and Main. They said they'd be right there to investigate the situation. Alvin didn't have to be anywhere, so he waited for the firemen to arrive. He was curious himself as to what could possibly be burning beneath the street. As far as he knew, there wasn't anything beneath the street except concrete. And everyone knows that concrete doesn't burn.
A fire truck arrived a few minutes later. "Are you the man who called?" asked the driver. Alvin said yes. By now Alvin could hear crackling sounds, like wood burning. The firemen didn't seem to consider it an emergency.
"What do you think it could be?" Alvin asked the driver.
"Oh, we know what it is. We have to take care of a problem like this every few months. It's the homeless people in their houses."
Homeless people have been living under the streets for years. Using their knowledge of the storm drain system, they set up their own "bunkers" beneath the streets. These living areas frequently contain tables, mattresses, chairs, and sofas. The residents often "borrow" electricity by connecting to a live wire above ground to power their own lamps and even TVs underground. Either this borrowed electricity or a discarded cigarette causes an occasional fire.
Alvin watched as a couple of firemen lifted a manhole cover and descended beneath the street with a fire hose. A few minutes later, the black smoke turned white. Shortly afterward, the firemen reappeared with a homeless person who seemed to have just been woken up.