S.F. seeks a solution to spewing sewage 

The filth and stink of sewage spills into streets and the Bay may be stanched by reconstructed pavements lined with trees and gardens, water-absorbent asphalt and other rainwater-catching tools.

A thousand miles of subterranean sewers carry 80 million gallons of raw sewage every dry-weather day to waterfront treatment plants, according to San Francisco Public Utilities Commission figures. The system combines untreated sewage with rainwater that flows into curbside drains.

An unknown amount of untreated sewage spewed out after the ravaging storms earlier this month, according to PUC spokesman Tyrone Jue. He said problems were compounded by storm-related power outages at pump stations.

Problem hot spots after rainstorms include Cayuga Street, which used to be a flood-prone stream, and areas around Lake Merced, according to PUC wastewater planner Rosey Jencks.

"It’s an issue of the pipes not having enough space, and too much water getting into them," Jencks said.

The City’s plan includes recommendations for rooftop gardens that trap rain for plants, thirsty trees planted in special spongelike soil, water-pervious asphalt, vegetated run-off channels and underground tanks that trap rainwater for irrigation.

During a recent inspection of the city’s sewers, inspector Raymond Mattias showed The Examiner just how foul the subterranean conditions are.

"This one’s still in good shape," Mattias told The Examiner recently as he squatted in a 5-foot-high brick sewer below Ellis Street in the Tenderloin. A sheet of cockroaches shuffled above the PUC worker’s hard hat as he spoke. "It’s over 100 years old but it’s still functional," he said. "It’s still working."

Nearby, a side-sewer spouted steaming water: Somebody was probably taking a shower, Mattias said. Between his gumboots raced a foot-wide stream of liquid filth, which can become a torrent of muck when it rains.

Jencks, who has been working for two years on a plan to help reduce and slow the flow of rainwater into sewers, said she is working with other city departments to draft developer guidelines to ensure new projects are built in a way that reduces storm-water runoff, and she’s working on a citywide effort to draft new standards for streets and roads, she said.

A handful of demonstration projects were finished last year. A rooftop garden was included on the rebuilt Summit Pump Station near the Sutro Tower, and 3.5 acres of vegetated basins were built into the eastern shore of Lake Merced, according to PUC reports.

Such projects are expected to take pressure off The City’s aging underground sewer system.

jupton@examiner.com

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