25 November 2017 — 1743 mdt

A gas leak in the neighborhood

Around 1900 MST yesterday, a fire truck with lights flashing brightly enough to be seen in Seattle sped past my house, followed by an ambulance with lights just as bright. They stopped a few hundred feet to the north. There were no signs of fire. Eventually, word filtered back informally that there was a gas leak. A while later, there was a strong whiff of a mercaptan odorant.

Initially, I thought the gas was natural gas, methane, CH4, which is lighter than air, but later the gas was reported to be propane, C3H8, which is heavier than air. Which gas makes a difference. Methane dissipates fairly quickly once the leak is plugged, but propane can collect in low areas, such as basements, where it can ignite or asphyxiate. Which gas never was resolved.

The first responders did not conduct a door-to-door canvass of the neighborhood, advising residents of what was leaking and where, and identifying the safety precautions they should take (please stay inside, away from windows, extinguish open flames, don’t use power tools, etc.). That would have been helpful, especially if the canvassers had given residents a half-page check list for dealing with a gas leak. Instead, the firefighters mostly stood around talking to each other. Had the gas gone ka-boom, the fire trucks and the fire fighters were so close to the leak they would have been blown to Kingdom Come.

Thinking back on it, I might have been wise to have stayed inside and away from windows in case the gas exploded. Instead, in the best tradition of disaster photographers everywhere, I stepped outside to photograph the excitement. No one asked me to stay inside, so I assumed I was in little danger.