March 26, 2005
Storm Runoffs May Pose Health, Environmental Risks
San Francisco is one of only two cities in the state – the other being Old Sacramento -- that treat storm water, domestic sewage, and industrial wastewater together. The advantage of having a combined system is that any contaminants present in storm runoff can be treated before they hit the bay or ocean. The downside is that there‘s always a risk of overflows, potentially resulting in the release of virtually untreated sewage.
Under normal conditions, the city’s effluent receives two treatment levels before being discharged. But during a heavy storm, the combined sewage overflow (CSO) receives only primary treatment, excluding bacterial disinfection, before being released from one of 36 overflow structures along the ocean and bay.
During primary treatment waste passes over physical barriers constructed to remove solid material. But these obstacles are not fool-proof -- Jon Loiacono, a senior engineer with the City’s Water Pollution Control Bureau, conceded that if someone threw a dead cat into a storm drain, the animal’s carcass could conceivably make its way into the bay.
But perhaps more troubling, the environmental standards for toxics discharged from treatment plants do not apply to toxic pollutants from overflows, according to the California Water Resources Control Board. That means during stormy weather particularly nasty stuff may go directly into the eco-system.
The City has two waste treatment plants in year-round operation. A third at North Point comes online during stormy weather and only provides primary treatment.
The Oceanside Treatment Plant on Ocean Beach handles waste generated on the City’s west side — mostly domestic sewage. The plant can deal with up to 65 million gallons of combined storm water and wastewater in a single day. It’s only about 10 years old and, located below the City’s zoo, is largely isolated from residential neighborhoods.
When they occur, CSOs along the ocean are discharged via seven overflow structures — including three along Ocean Avenue. Jennifer Clary, chair of the Alliance for a Clean Waterfront, a local coalition, estimates that as much as 180,000 gallons of sewage mixed with a half-million gallons of rainwater might be discharged into the ocean in a 15-minute overflow. “Once it’s in there, it’s in the sand, in the sediment, in the wildlife,” she said.
Because the beaches experience heavy recreational use, city officials pay careful attention to potential bacterial contamination from CSOs. As soon as an overflow occurs, officials post the affected beach with health warnings. Biologists then take water samples. Based on the results, which take up to 24 hours to process, the postings are either left up or taken down.
The city carefully monitors beaches, and health risks from bacterial infection at Ocean Beach are relatively low. According to Sean Gibson, chair for Surfrider’s San Francisco Chapter, “In the water, the currents are the major source of injury and death at Ocean Beach, not water quality.”
Unlike the Ocean Beach plant, the Southeast Treatment Plant -- which is about 50 years older -- treats both domestic and industrial waste generated throughout the city. The Southeast Plant deals with up to 250 million gallons of sewage per day during wet weather, nearly four times what Oceanside can handle.
The Southeast Plant is bordered by the Bayview and Hunters Point neighborhoods. During wet weather, flooding and sewage backups in these communities are not uncommon.
“The overflows come from the fact that all of the sewage is going to one place,” said Clary, also chair of the Wastewater Subcommittee of the San Francisco Public Utility Commission (SFPUC)’s Citizens Advisory Committee. “It just happens to be going to the largest watershed, the Islais Creek watershed, which is where the Southeast Treatment Plant is located. When they have overflows, they have small overflows all around the city, but not surprisingly, the largest overflows are where everything is headed.”
While some have looked to expanding sewage treatment capacity as a remedy, others believe paved surfaces should be replaced with planted areas that would slow surface water runoff.
Islais Creek is lined with old industrial facilities, and as a result storm runoff may contain heavy metals. When the runoff is combined with sewage, there may also be PCBs and high bacteria counts present in the overflow.
According to Clary, it’s not what’s leaving the Southeast Plant that’s causing problems: It’s what never gets there. “It’s the stuff that doesn’t go into the plant that’s creating the most pollution in Islais Creek and the environment,” she said. “The combined storm runoff.”
Not surprisingly, some Bayview-Hunters Point residents are frustrated with the situation. Marie Harrison, a lead organizer at the nonprofit Greenaction, said she’s found city officials uncooperative on issues related to water quality in her neighborhood. “We have to do all the investigating,” she said. “We never get the information from the sources. If you don’t know the right question to ask, they won’t give it to you. They will never volunteer anything.”
But according to Tyrone Jue, outreach coordinator for SFPUC’s Wastewater Master Plan, that may soon change. Jue said the city plans to launch a long-term program this spring or summer that will look at ways to modernize the Southeast Plant and redistribute discharged wastewater.
“We’re going to find out from the public which direction they want to take our wastewater system. We want to bring this out to the public to let them evaluate the alternatives so they can make an informed decision about choices,” he said.