Steam Rises From Some San Francisco Streets. Why?

The boilers, fueled by either natural gas or diesel fuel, create steam, which then travels along a 71,540-foot distribution network to about 180 different buildings, providing heat for more than 37 million square feet of office space in the Tenderloin, Union Square, the Financial District and parts of SoMa.

According to a Department of Public Works newsletter, feeder pipes run steam from the network into radiators that heat San Francisco City Hall. When the loop opened in 1915, a powerhouse at Larkin and McAllister streets supplied its steam until the mid-1990s.

These days, crews with the Bureau of Building and Street Repair handle that part of the network under the four main streets that surround City Hall: Grove, Larkin, McAllister and Polk streets.

“We simply feed it from our system. We kind of treat it like a service, like any other building,” Eurkus told The Standard.

Eurkus said about 95% of the network’s steam comes from the 460 Jessie plant, using not just the groundwater piped from the Powell BART Station but also another source: “The other part is we actually return condensation.” After the buildings use the steam, some of it condenses, converts to water and gets pumped back to the Cordia Energy Plant, he explained.

The network’s oldest working parts date back to 1913 and are used to draw on multiple boiler plants. The Meacham plant in the city’s Tenderloin came online in the 1960s, offering additional boilers to supplement steamy needs.

“When there’s a problem now, 99% of the time we’ll get a call from, whether it’s DPW or even the fire department, a lot of times because it’s something that’s happened. If it’s abnormal, it’s an excessive amount of steam coming out of the ground,” Eurkus said.

“We can respond within an hour, and we address it. Normal operation, you’ll see it popping, floating a little steam, but if it’s an abnormal situation where it’s an excessive amount and you know, we’ll get the call, we’ll go address it.”