What to do when The City’s primary landfill is full? 

With San Francisco’s primary landfill nearing its capacity for city trash, waste experts are looking at diversion methods, which could include using food scraps for energy, to leave more room for nonrecyclable materials.

The City has deposited almost 12 million tons of garbage at Altamont Landfill in Alameda County since 1988, when it last signed a contract of 65 years or 15 million tons — whichever comes first — with the landfill, according to Department of the Environment officials.

Experts expect that even with current trash-diversion trends increasing — more is diverted away from landfills and recycled — that Altamont will only be able to serve The City until the middle of the next decade, according to officials with the Department of the Environment.

"It appears we’d reach our capacity on the current contract between 2013 and 2015," City Administrator Ed Lee said, noting that The City’s diversion rate is near 70 percent. "The reason it cannot be exact is The City has been quite successful at diverting waste from the landfill."

City administrators today will discuss disposal options and alternatives for The City as well as the remaining capacity on all other landfills used by San Francisco, which is expected will have to purchase more landfill space.

They will also discuss a potential plan for the San Francisco Public Utilities Commission to use methane gas captured from composting food scraps such as coffee grounds from homes and cafes to help power a wastewater treatment plant.

San Francisco residents, restaurants and other food consumers create 79,000 tons of food waste — steak bones, carrot tops, potato skins etc. — annually, and officials have projected that to increase to 400,000 tons yearly by 2020, said John Loiacono, the project director of the SFPUC’s Wastewater Master Plan, a 15-year project to revamp the sewer system and treatment plants.

Loiacono said crews would feed the discarded food into digesters where it’s broken down by organisms, producing methane gas. Norcal Waste Management Services would take the solids left over to be recycled, and SFPUC would use the methane to help generate power for its water treatment facilities.

With existing digesters, the SFPUC creates one-third of its power demand, he added. "Should we get the food waste though, the food waste could double or triple that," Loiacono said.

David Assmann, deputy director with the Department of the Enviroment, said an analysis of The City’s trash showed paper or food made up two-thirds of the total, all of which can be diverted.

Of the potential digester program with SFPUC, Assmann said, "It would demonstrate a technology that could be expanded to take even more trash away from landfills."

dsmith@examiner.com

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