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Picture this: It’s a beautiful late spring day in Sandy Hill just after noon. You are in your house preparing lunch and you go down to the cellar to grab some potatoes.

Suddenly the earth beneath you begins to move! Flames begin shooting out of one of the sewer connections! The cellar fills with flames and choking smoke! Miraculously you escape with your life. This was the exact scenario for Lilian Pettapiece during the Ottawa sewer explosion on May 29, 1929^[1].

There have been at least two sewer explosions in Ottawa’s history, the first occurring on May 29, 1929. These began in the Golden Triangle neighbourhood at 11:50am, continued on to Sandy Hill at 12:10 and reached New Edinburgh and Montreal Road around 12:15^[1].

The worst property damage occurred in Sandy Hill and New Edinburgh where windows were blown out on many buildings, some of which were even lifted off their foundations. One church in New Edinburgh, St. Martin’s Reformed Episcopal Church, lost all its indoor contents due to the explosions^[2][3].

Along with property damage, it was reported that 56 manhole covers were blown into the air, some as high as 40 feet. Witnesses described the explosions as sounding like a small cannon being discharged^[2].

About 9 people were injured by flying glass and many suffered severe burns. Mrs. Hannah Hayden, aged 73, was the only person who died from burns sustained during the explosions^[3].

Although the cause was never officially determined, it was suspected the explosions were the result of homeowners disposing of gasoline in the sewer and leaking service station tanks or a leak from a gas main. The gas might have ignited from a match, an automobile backfiring or a spark from a trolley wheel^[4].

Another set of explosions occurred on January 28, 1931 at around 4:50pm^[5].

Once again, the explosions started in the Golden Triangle, continued through Sandy Hill but stopped just east of Cummings Bridge, sparing New Edinburgh due to the City of Ottawa having installed ventilators throughout the system after the 1929 explosions^[6].

Property damage was not as severe this time and the most significant damage occurred to the City’s infrastructure. As in 1929, manhole covers at more than 40 intersections were launched into the air, some as high as 60 feet. Some of them landed on powerlines, causing severe damage to the power grid. Windows were blown out in many residences and some minor structural damage occurred as well^[6].

Days before the explosions, the City received many complaints from residents saying they’d smell gas within their houses. However, these reports were ignored^[7].

Injuries were less severe than 1929 and no fatalities occurred. However many people who experienced the 1929 explosions were left in shock. One harrowing moment occurred to a 12-year-old boy who was skiing with a group of friends on Somerset St. He was launched into the air by an explosion but fortunately landed on a snowbank^[6].

The cause of the 1931 explosion again came down to seeping gasoline entering the sewer system^[6]. Initially it was suspected that the gas was ignited by a plumber's assistant at a house on the corner of Robert and Lewis streets. However this was never officially determined.

As for Lillian Pettapiece, she was riding a bus near her Somerset home when the explosions occurred. She received medical aid for shock but this time was not seriously injured by the explosions^[6].

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