Gas leak in University District: Don't go out onto the Ave, officials say

Update: The gas leak was secured around 5:15 p.m. after spewing gas for close to four hours.

Leak isn't the right word to describe what happened in Seattle's University District on Monday afternoon.

More like a white plume shooting into the air.

“When crews arrived on the scene, they saw an excavator that had punctured a 2-inch gas line,” Seattle Fire spokesperson Kristin Tinsley said.

A faint smell of natural gas (technically, the mercaptan added to the gas to give it a smell) was in the air a block away.

A gas line in Seattle’s University District had been punctured.

“When we got here, it was a pretty significant leak, and it is still leaking to the same extent,” Tinsley said around 3:45 p.m., more than two hours after employees at the rooftop bar at the Graduate Hotel spotted a white plume shooting up from the street.

That was at the intersection at Northeast 45th Street and Brooklyn Avenue Northeast, about three blocks from the main University of Washington campus. The leak all but shut down the surrounding area.

“Right now, what people can see in the area is what looks kind of like a vapor cloud or smoke. That is actually the natural gas that is leaking from the pipe,” Tinsley said.

Whether in a pressurized pipe or in the atmosphere, natural gas is invisible. But as it escaped the pipe and suddenly lost pressure, the gas cooled, causing water vapor in the nearby air to fog up.

“My guess is that if it is enough to cause a visible cloud, it must be quite a large leak,” University of Washington atmospheric scientist Nick Bond said in an email.

Seattle's 911 log categorized it as a "gas leak major."

The natural gas leak appears to have come from in the intersection, near the Neptune Theatre.

The I-5 ramps to and from Interstate 5, at Northeast 45th Street, were closed temporarily but have since reopened, according to Washington State Department of Transportation.

Seattle Fire Department and Puget Sound Energy spokespeople did not respond to requests for information on which construction project was doing the excavating.

Seattle Department of Transportation was not involved, according to spokesperson Ethan Bergeson.

Buildings including the University of Washington Tower and the Graduate Hotel were evacuated and officials warned people to avoid the area, including University Way Northeast, known as the Ave.

The evacuation area extended to 15th Avenue Northeast to the east, and Northeast 47th Street to the north.

Last week, a gas leak in Seattle’s Licton Springs neighborhood led to evacuations there. Three Puget Sound Energy workers were injured.

While the leak caused a small amount of short-term cooling in the air right next to it, it will also cause longer-term warming: The main component of natural gas, methane, is a powerful greenhouse gas, at least 30 times more potent than carbon dioxide at trapping heat in the earth's atmosphere.