This is a crazy story. I actually remember something similar happening in Georgetown maybe a decade or so ago. Anyone lese recall that?
a non-exploded manhole cover
The article below is from the Washington Post on August 31st, 1889.
A loud report, which was heard for more than a mile around, attracted the attention of several hundred strollers on the avenue yesterday afternoon about 6 o’clock. It was caused by an explosion of gas in the sewer main on D street, between Thirteenth and Fourteenth streets. The cover of a man-hole in front of Hurdle’s saloon, 1222 D street, was thrown into the air half a dozen feet, striking a passer-by on the arm. It did not strike him fairly, however, or he would have been seriously hurt, as the covering weighs about fifty pounds. As it was, his arm was painfully bruised, and he was badly shaken up. Mrs. Hurdle was standing at the side entrance of the saloon with her child in her arms. She fainted and the child became unconscious by the shock.
Washington Post – August 31st, 1889
Every pain of glass in the front windows of the house was shattered, bottles were shaken from the bar and their contents lost, and all the glass-fixtures of the place are a complete wreck. Mr. Hurdle estimates his loss at $200. He wants to know who is going to pay the damages, and if the District does not come forward and do so he says that he intends to commence proceedings immediately.
Superintendent of Sewers McComb was seen at his residence last night by a Post reporter. “I cannot explain the causes of the explosion until I have made a thorough investigation” said Mr. McComb “and tomorrow I shall make a careful study of the matter. The sewer running along that street is more than usually shallow, but this would not account for the explosion. It was, of course, the result of a massing of gas and the only plausible reason for the explosion that I can now think of is, that the ventilators, by some means, which I do not now know, became clogged and the collection of gas was ignited by a spark of fire, or more likely, spontaneous combustion. This is the first occurrence of the kind that I can remember in Washington for a long time and the only reason for it is what I have mentioned. The sewers of the city are better ventilated than in most places, though of course, they may become stopped.
“Is there danger of an explosion from the electrical conduit now being laid?” asked the reporter.
“Yes,” was the reply, “there is great danger. Unlike the sewers, they haven no ventilators at all, and we may look for explosions from that source at any time. We have already had one, you remember about two weeks ago, on New York avenue near Armory Square, and this is sure to be followed by others. Half of the gas in the mains escapes. You can dig into the ground anywhere near a main and plainly detect the odor. It permeates the whole city and collects in every pipe. If it cannot escape to the open air it will explode by spontaneous combustion. These are the causes that led up to the series of disastrous explosions in New York some time ago, and it is possible that they may be repeated with just as fatal results in this city. But the danger is not to be feared from the sewers, it is the electrical conduits. Every basin, every closet, and every manhole connected with the sewers acts as a ventilator, and if these are only left open we have nothing at all to fear.”
Superintendent McComb visited the scene of the explosion late last night, but could make no examination. The matter will have to be investigated by daylight as it would be extremely dangerous to go into the sewer with a lantern.