San Francisco's Palimpsest Sewer

Sewers are kind of a miracle. You get the feeling that if the leaders of the current American political system had to build one in every city, we'd all just get used to septic tanks and trenches along the streets. The sewer is the kind of infrastructure that's hard to build and finance, even though everyone knows it is necessary and a damn good idea. Constructing one takes vision and dedication to the long-term good of a place.

And even once you do get a sewer built, usually the early iteration can't handle a growing population and the system must be amended or erased and rebuilt.

This whole story is lovingly told on the Streetsblog for my beloved town of San Francisco. Apparently, some sewer lovers took a group of interested locals on an aboveground bike tour of the city's underground sewage geography. The writeup is tidy, oddly compelling history, particularly if you've ever spent some time in the Mission. It is the undisputed epicenter of sewer activity in the city, which is yet another reason to love the place in my book.

"In order to understand the sewers of San Francisco, you have to be a historian," said Greg Braswell, an expert on San Fransico's sanitation facilities, during a recent sewer tour called Fathoming.

The workshop and bike tour were organized by Think Works artist Miles Epstein, whose interest was piqued a year ago when the facility was flooded during heavy rains.

Epstein, local water historian Joel Pomerantz, artist and geologist Judy West, and Braswell combined their unique knowledge to illustrate some of the more interesting parts of the current and historical system.

On the tour, Braswell and the others explained that as the settlement around the Mission and Potero Hill grew, pollution in the estuary became unbearable. Early experiments with wooden box sewers were a failure, unintentionally creating highly fertile, highly unsanitary compost chambers.

The first brick sewers appeared from the 1860s through the 1880s, in a hodge-podge that emptied into creeks and marshes that smelled worse and worse over time.

Finally in the 1890s, Carl Edward Grunsky developed plans for an innovative gravity-based sewer that would carry waste all the way to North Point, where the rapid current would sweep it out to the Golden Gate, or back towards Oakland, depending on the time of day. It took years before the city built the pipeline, finally realized during the construction boom after the 1906 quake and silver industry lulls during which there was an excess of unemployed miners.

That pipeline is still in place today, draining all the way from Daly City. It was a giant leap forward in sanitation, which persisted unchanged for decades, despite clear problems. For example, the system couldn't handle large storms and during moderate rain and about sixty times a year it would overflow and dump raw sewage into the bay.

Though it would seem terrible to us today to have so many overflows, this was consistent with most cities' practices up until the 1950s.

In 1972, the Clean Water Act changed everything. San Francisco was the first city to experience an EPA enforcement action, which was all due to sewage. "They said, 'you gotta stop pooping in the bay,'" Braswell explained.

Modifying the sewer system would be expensive and the city initially balked. Ultimately, with significant state and federal assistance, a ring of underground chambers was built around the city. Those chambers function like waiting rooms, detaining stormwater until the treatment plants have time to process it all. They're massive, some as big as 25 feet wide by 45 feet tall.

Read the full story at Streetsblog San Francisco.