On May 15th this year, Denver experienced the explosion of manhole covers and smoke rising rapidly in the air. Denver Post reported that the explosions took place shortly before 3:00 a.m. at 18th and Arapahoe. It seems there was a gas leak in the area that potentially caused gasses to build up in the sewers, thus causing the exploding manhole covers. Did you know in 1929 and 1931 Canada’s capital city of Ottawa, Ontario experienced two separate series of sewer explosions as well? Each explosion caused one fatality and several injuries. According to this article, “At least twenty-eight manhole covers were blown in the air, some thirty to forty feet, before crashing to the ground. Clouds of smoke and vivid tongues of flame were reported emanating from the manholes.” The fires actually shot up into people’s homes as well, destroying their plumbing.

Amazingly, the cause was never fully identified. As this article states, “Numerous theories were advanced to explain the explosions, including sewer gas, poor ventilation, an earthquake, or even volcanic action.” The city attempted to blame the Ottawa Gas Company for a gas leak, but they vehemently denied causing it. However, many homeowners described smelling gas in their homes around the time of the explosions.  The article continues, “Although no precisely definitive and singular cause was determined, it was generally accepted that a combination of leaking service station gasoline tanks combined with waste gas and oil being dumped into the sewers by service stations and cleaning businesses, were responsible.”

Unsurprisingly, dumping tons of oil and flammable substances into the sewers has potential for fires to start. The two fatalities are, of course, extremely sad. However, considering fires that blew heavy manhole covers several feet in the air, flames coming into houses, earthquake-level shaking of homes and businesses, and more, it seems the city of Ottawa was rather lucky that the damage and fatality count wasn’t much worse. Denver is fortunate as well that the explosions took place in the middle of the night.

Apex Plumbing has been working on Denver sewers since the mid 1980s. We have seen our fair share of crazy things below the surface while working, but we’re very grateful to say biblical-like flames leaping up from the ground has not been one of them. However, we have dealt with sewers chockfull of oil and grease build up. We don’t expect the sewer to catch fire, but damage can still be done from backups and such. If you are experiencing sewer issues, we would be happy to offer you a free estimate. Contact Apex today!

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