Paul Kilduff

AS IMPROBABLE AS it may seem, the next time you find yourself enjoying a meal in one of San Francisco's many fine restaurants, the veal chop bone you leave behind could end up becoming part of the wine you sip on your next visit. That's because many of the city's restaurants are now participating in a composting program that turns unsavory items such as uneaten Brussels sprouts into a nutrient-rich compost that's used by area grape growers and other farmers.

Called the “Food Scrap Compost Program,” the initiative is run by San Francisco-based Norcal Waste Systems, whose subsidiaries provide collection and recycling services for businesses and residents throughout the Bay Area. The program began as a pilot project in 1997 to help San Francisco meet its goal of a 75 percent landfill diversion rate by 2010. The city's diversion rate is currently 67 percent, the highest of any large city in the country.

Still, of the garbage the city now sends to a landfill, 35 percent is compostable, according to a recent study commissioned by San Francisco's Department of the Environment. The study reported that food waste accounts for 27 percent of the landfilled material and yard trimmings for 8 percent.

“In San Francisco, the single largest component of the waste stream is food waste that's going to landfill,” says Bob Besso, recycling program manager for Norcal. “We can compost that material. If we could just get people to do what we offer today, we'd be at 75 percent, so we are working hard to increase participation.”

Today approximately 2,000 of San Francisco's 5,000 restaurants participate in the Food Scrap program. Norcal subsidiaries also collect food and yard trimmings from residences for the compost.

Each day, Norcal collects about 300 tons of compostable matter — including everything from banana peels and French fries to coffee grounds (including the filter), fish bones and even paper milk cartons — in San Francisco. About 60 percent of the tonnage comes from the city's restaurants.

Nuts and Bolts

Norcal's subsidiaries provide both homes and restaurants with green collection carts for their organic materials. In addition to training restaurant workers, Norcal provides full-color posters for the kitchens and back rooms of participating restaurants. The posters list exactly what is supposed to be thrown in the green carts and give instructions in English, Spanish and Chinese. Because 27 distinct languages are spoken in San Francisco, the posters also contain instructional photos.

“It's not really a big hassle for restaurants,” Besso says. “They just need to make the commitment to do it.” To increase restaurant participation in the voluntary program, eateries pay Norcal 25 percent less to remove the organic materials than it would to carry off regular trash.

Once the organic materials have been collected from restaurants and residences, they are hauled in 18-wheelers to Norcal's Jepson Prairie Organics composting facility, which is located 75 miles north of San Francisco.

Every day, Norcal sends about 14 truckloads containing approximately 24.5 tons of organics each to the facility. One ton of the materials produces approximately one-half cubic yard of finished compost. The facility produces about 50,000 cubic yards of the nutrient-rich soil amendment each year.

Within 24 hours of arriving at the Vacaville plant, the material is inspected, and contaminants such as plastic wrap, bottles, cans and other non-compostable items are removed. The scraps are loaded into an 860-horsepower grinder that turns the future compost into bits no larger than 6 square inches. “You don't want to fall into it,” says Greg Pryor, Jepson Prairie Organic's facilities manager. The bits are then placed into plastic bags, or pods, that are 200 feet long by 10 feet in diameter. California regulations require the future compost to be put in the bags to control vectors and reduce pathogens. The interiors of the bags are hooked up to a blower for aeration using two four-inch diameter pipes.

Inside the bags, microbes eat away at the material creating an internal temperature of up to 135 degrees Fahrenheit that, like pasteurization, kills potentially harmful bacteria. “We get our pathogen kill in that pod,” Pryor says.

After approximately 30 days, the pods are opened up and placed into rows or windrows of immature compost. Every two days, a windrow turner is run over the material for further aeration.

The compost cures outside the bag for another 30 days before it's ready for a final run through a trommel screen that ensures the chunks are 3/8ths of an inch in diameter or smaller. Compost that doesn't make it through the screen is used for erosion control and as an alternative cover for landfills.

Will Brinton, president of Woods End Research Lab, Mount Vernon, Maine, says that placing the organics in bags slows carbon loss and promotes greater nitrogen retention when compared with the traditional composting process, in which the materials are simply placed outside in windrows. Brinton developed Jepson's composting procedures.

The traditional composting process also often produces a product with pH levels that are too high, Brinton says. Typically, Jepson's compost has a pH level of 6, which is acidic and ideal for certain crops such as wine grapes.

Although Norcal's compost is not designated “organic,” as in additive and pesticide-free, it has been approved for use on organic soils by the Eugene, Ore.-based Organic Materials Review Institute (OMRI), a foundation that reviews programs, processes and lab test results. The institute found Norcal's product, called Four Course Compost, has either no evidence of pesticides or inconsequential trace amounts. The OMRI designation means Norcal's compost products are approved for use by organic farmers.

The End Market

For a composting program to be economically viable, somebody has to buy it. “Everybody talks about reducing waste, but we're making a product,” Brinton says. “At the end of the day you've got to move a product and satisfy a customer.” To that end, Brinton has developed a procedure that tests compost samples for 29 traits. Knowing what's in their compost allows companies to market it more effectively. For example, certain traits might indicate that the compost is best suited for home gardening, while others point to use by vineyards.

Northern California vineyards and area farmers who want a product with OMRI approval have been a particularly receptive market for Norcal's compost. More than 100 farms and vineyards that have used Four Course have experienced increases in soil microbial action and crops with thick stems, according to Norcal.

Linda Hale, who manages more than 500 acres of vineyards for farmers in Sonoma County, Calif., has used Four Course Compost for more than three years on half of her acreage. She claims that the resulting grapes are of a higher quality, and the yields have almost doubled — from two to three tons per acre to four to five. “That's the bottom line,” Hale says. “The wineries are happy [and] that makes our clients happy and that keeps us in a job.”

Applying Four Course once a year in the fall also has helped reduce the amount of pesticides and herbicides Hale needs to use on the crops, she says. That's because the compost promotes the natural ability of the vines to combat disease, Hale claims. The compost also feeds the microbes in the soil that break down nutrients, making them available to the plants, she says.

Ultimately though, Hale is influenced most by the compost's contribution to the sustainability of the vineyards they manage. “The idea that it's naturally occurring [and] it's environmentally friendly — those are the things that attract us to using a product like compost as opposed to a chemical fertilizer,” Hale says.

While it's tempting to assume that a composting program will take care of itself, Norcal spokesman Robert Reed cautions that compost is just like a vineyard — they both need to be carefully tended and marketed. “You can't just pick up the food scraps and then pass the football on to somebody else,” he says. “You need to work with the grower — whoever that is — and meet the demands of the marketplace.”

Growing Concept

In the future, it's possible that programs like Norcal's in San Francisco could be more widespread across the United States. In recent years, Norcal itself has begun collecting food scraps for compost in Oakland, Calif., and Los Angeles. To date, 140 Oakland and 100 Los Angeles restaurants participate.

Similar programs run by other operations are either in place or are being established in New York; Boston; Raleigh-Durham, N.C.; Plano, Texas; Toronto; and St. Paul, Minn., among others. Many colleges also have started food-scrap compost programs including Harvard in Cambridge, Mass.; Bates College in Lewiston, Maine; Brigham Young University in Salt Lake City; and the University of North Carolina-Charlotte.

And for those who would like to divert materials from landfills, expanding the universe of successful composting programs is something they can raise a glass of wine to.

Paul Kilduff is a contributing writer based in San Francisco.