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Clean Beaches--the S.F. Solution

A single system handles the city's sewer and storm lines, filtering pollution from street runoff. But major rains mean sewage spills into the ocean and bay, despite an extensive network of holding tanks.

March 09, 2000|MATTHEW GOLEC | SPECIAL TO THE TIMES

In the small hours of the morning one day last month, San Francisco was locked in a race against the rain. Storm water spilled into streets, storm drains and sewers. Finally, having absorbed all the water it could, San Francisco's underground plumbing system topped out, spilling its contents.

Millions of gallons of raw sewage and storm runoff--enough to fill thousands of swimming pools--sloshed into the ocean and San Francisco Bay, contaminating city beaches with disease-causing germs and toxic chemicals.

This spill was not an accident; it happened by design.

San Francisco is the only major city on the California coast with a system that is built to overflow during periods of heavy or prolonged rainfall.

As in many older East Coast cities, such as Boston and New York, San Francisco's sewage and storm runoff flow through the same pipes. Waste from sinks and toilets mixes with rainwater running into street drains. And when the rain falls hard and fast enough, the system overflows, dumping raw sewage and runoff into San Francisco Bay and onto Pacific Ocean beaches.

Despite dramatic increases in the volume of waste water San Francisco can hold and treat, sewage overflows remain a matter of course. Over the last two years, raw sewage has overflowed onto beaches and into the bay nearly 30 times.

"Even though [an overflow] always sounds awful . . . probably 90% of the storms are collected," said Arleen Navarret, a senior marine biologist with the city's Public Utilities Commission.

The U.S. Environmental Protection Agency estimates that 40 million people in the United States are served by combined storm and sewer systems like the one in San Francisco.

Most West Coast cities, including Los Angeles, manage their waste separately. Sewage is carefully filtered and disinfected, while storm water is simply channeled out of town to nearby bodies of water--lakes, rivers or the ocean. Cities with separated systems generally don't have to worry about sewage overflows, but their storm water washes oil, grime and other toxic junk directly off the streets and into the lakes, rivers and ocean.

There are trade-offs. In Los Angeles, residents by and large don't have to worry about significant volumes of sewage being dumped onto beaches. But every day, untreated storm water hits some of its best beaches, creating health problems for swimmers and surfers. A recent study at Santa Monica Bay found that people who swam near storm drains were more likely than others to experience colds, ear infections and other minor illnesses.

Giving Treatment Plant Time to Work

So while San Francisco will always suffer occasional overflows on stormy days, government officials and environmentalists alike appreciate its treatment of storm water.

"Only if you do it right is it good," said Wil Bruhns, senior engineer with the Bay Area's Regional Water Quality Control Board. "And San Francisco has spent an awful lot of money to do it right."

In March 1997, the city completed a 20-year, $1.4-billion upgrade of the system. The crown jewel was a pair of new waste-water storage boxes--often described as a moat--buried along the west side of the city.

The boxes hold back water during storms, giving the treatment plants time to process the millions of gallons running off the streets.

City officials estimate that the new system can handle more than 10 times as much rain as would have previously caused an overflow and that the system catches and treats between 80% and 90% of rainy day flows.

"The amount of combined sewage we lose in a year is a small percentage of the total . . . we handle," said Tom Franza, deputy manager for the Water Pollution Control Division of the Public Utilities Commission.

But even small percentages add up: In the course of a year, between 1 billion and 2 billion gallons of untreated overflows spill out of the system and into the bay and ocean.

"It's another source out of many that add up to impair the bay," said Mike Lozeau, executive director of San Francisco BayKeeper, a nonprofit group that monitors pollution threats to the bay. "It limits the ability for us to use the shoreline."

Even if the city were to spend millions more to build additional storage capacity, that still wouldn't guarantee an end to sewage overflows.

"There's no way you can eliminate 100% of all overflows, because there's always going to be a bigger storm," said Chris Phanartzis, a consulting hydrologist with the Public Utilities Commission.

The 600 San Francisco members of the Surfrider Foundation, a nonprofit environmental organization made up largely of surfers, probably represent one of the populations most exposed to viruses and bacteria in San Francisco Bay. Chapter chairman Clay Bennett doesn't like the periodic sewage discharges, but he admits they're preferable to the health problems that come from running storm drains.

Trying to Reduce Risks to Health

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