San Francisco residents and businesses have contributed more than 620,000 tons of compost since the city began its collection program in 1996, according to the latest figures from the city’s recycling company.

The company, Recology, made the announcement Tuesday in advance of the Thanksgiving holiday, a prime opportunity for residents to contribute all their leftover food scraps under the city’s new mandatory composting program, which went into effect Oct. 21.

According to Recology spokesman Robert Reed, the city now collects an average of 500 tons of organic material for composting each day, a 25-percent increase over last year.
Recology estimates that since its inception, the program has prevented the release of 137,000 tons of methane gas into the atmosphere.

The U.S. Environmental Protection Agency considers methane a more potent greenhouse gas than carbon dioxide, with the largest contributor coming from decomposing waste in landfills.

San Francisco has goals of diverting 75 percent of its waste from landfills by 2010 and of achieving zero waste by 2020.

Recology said its program has also allowed 18,400 metric tons of carbon dioxide to be returned to the soil, the equivalent of keeping 3,600 cars off the road.

Reed said San Francisco’s program has become a model of conservation and sustainability, with the city’s food leftovers returned to Northern California vineyards and farms in the form of nutrient-rich compost for their soil.

“We make probably one of the very best composts in America,” Reed said, noting the city’s “diverse feed stock.” He said the hundreds of different kinds of foods served in city restaurants, from crab shells at Fisherman’s Wharf to pasta in North Beach, are a good stimulant of microbial activity for the compost.

The food scraps are taken from residents’ and businesses’ green carts to the city dump in the Bayview District and then delivered by truck to a compost facility outside Vacaville.

Reed said the location provides a relatively close source from which vineyards and farms, most of them in Napa and Sonoma counties, can purchase custom blends of compost–designed to match the nutrient needs of each farm’s soil–for between $9 and $15 a cubic yard.

The facility produces a finished compost in about 60 days, Reed said.

“But some of the vineyards like us to age it” until 90 days, he said.

“This program has become part of the environmental culture in San Francisco, and it’s also being replicated in dozens of other cities and universities across the United States,” Reed said.

Composting is credited not only as a reducer of landfill disposal; it also returns nutrients to the farmland, helps soil retain rainwater to reduce the need for irrigation, and gives farms an alternative to chemical fertilizers.

Residents are also encouraged to do their own composting in their backyards, to take the transportation component out of the equation, according to Reed.

“When you start to add them all up, these programs are extremely effective at protecting the environment,” Reed said.

San Francisco chefs and restaurant workers have also enthusiastically received San Francisco’s composting program, according to Reed.

“That’s role reversal,” he said. “Historically farms have served cities. Now you have people in cities sending nutrients back to farms.”

Please make sure your comment adheres to our comment policy. If it doesn't, it may be deleted. Repeat violations may cause us to revoke your commenting privileges. No one wants that!