Located in Bayview Hunters Point, the Southeast Treatment Plant (SEP) is found in the midst of a mixed industrial, commercial and residential area. Brought online in 1952, many parts of the SEP facilities represent 1940’s technology. The plant expanded several times after it was built. This neighborhood holds just five percent of San Francisco’s population but a third of its industrial and toxic sites.

Back in 2002 an SFGate article cited Don Birrer, the city’s engineer in the late ’70s, as saying the southeast plant was built at its current site because of topography and the contours of creek and storm water flows. “Two of the city’s largest sewer pipes had been constructed along former creekbeds — along Army Street and Alemany Boulevard — which converged near that spot, so it was a good place to put the plant,” Birrer said.

At the time that Congress adopted the Clean Water Act, in 1972, the Southeast Plant handled 20 percent of the city’s sewage. At the same time a North Point Plant at Bay and Embarcadero handled 60 percent, from the northeastern section. And a Richmond-Sunset plant near the Golden Gate Park soccer fields treated the 20 per cent flowing from the west end.

In response to Clean Water Act requirements, the city revised its existing sewage treatment formula largely by expanding the southeast plant in the late 1970s. So now it handles 80 percent of the city’s sewage. On an average day, it treats 80 million gallons of wastewater. However, in the rainy season when storm water also passes through the system, that number can rise to an incredible 575 million gallons.

As pictured above, the Southeast Plant originally and currently has 10 2-million-gallon digesters. After completion of the plant upgrade, just one of the projects under the SSIP program, there will be six 1.33-million-gallon digesters. New technology will improve efficiency and increase the production of methane gas, which is in turn used to power the plant. To help control odor emissions, the six new structures will be 65 feet tall and have fixed roofs, as opposed to the current floating covers.

The new digesters will also be relocated from the original site on Phelps Street. They are now less than 100 feet away from the nearest residences, and after the move will be 1,000 feet from the closest home. The new facility is being sized for future wastewater flows for the population anticipated in 2045.