Yolo landfill turning trash into cash

“The days of the dump are long past,” John Bencomo says.

And the director of planning and public works for Yolo County isn’t kidding.

Because long gone are the days of small landfills and burn dumps scattered around Yolo County, where garbage did little more than accumulate. Since 1975, the Yolo County Central Landfill is where all the action happens, and these days that action is about far more than accepting the garbage produced throughout the county.

Yes, huge garbage trucks still rumble into the landfill all week long, making their way up to the top of an ever-growing garbage heap to dump their loads of food scraps, diapers, packaging and broken and discarded items. Bulldozers and compactors then flatten it all down; and every evening, trucks drop a layer of dirt over all of it in preparation for the next day’s deliveries.

But faced with a state mandate to divert 75 percent of garbage by 2020, as well as the need to pay for operations, the landfill is increasingly looking for ways to turn trash into cash — literally transforming garbage into energy and reducing what’s left over in the process.

“Trash is a commodity,” notes Ramin Yazdani, senior civil engineer for the county. “It’s not just a waste product, especially if you can separate it.”

Currently, the landfill is capturing the methane produced by the piles of decaying trash and turning it into electricity, which it then sells to the Sacramento Municipal Utility District.

But producing solar energy or natural gas would be even more lucrative, Yazdani said. And both possibilities factor into future plans for the landfill.

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Located on County Road 28H east of County Road 102 between Davis and Woodland, the landfill accepts waste from throughout the county, and with the exception of a small transfer station in Esparto, it’s where nearly all Yolo County garbage goes.

Current programs include services for solid waste disposal, liquid waste disposal, hazardous waste collection and agricultural and rural waste collection. In addition to the trash-hauling companies that collect garbage in the cities and deliver it to the landfill, individuals also can bring their garbage to the dump.

There are areas set aside to dump wood and green waste, construction and demolition waste, as well as concrete debris. Recyclables also can be dropped off for free, but any glass, plastic and other recyclables that get tossed in trash bins end up with all the other buried garbage, simply because garbage waste is not sorted at the landfill.

But that could change soon.

Landfill operators envision a sorting center, where items that can be recycled or reused are pulled from the garbage stream that ends up in the dump. There’s even talk of a thrift store on site, where items that the public might want secondhand can be resold — everything from furniture to small household appliances and more. Already, the landfill opens a reuse facility to the public twice a week where household hazardous waste like unwanted paint as well as gardening and cleaning supplies can be had for free.

Increasing the diversion of items could help in the county’s efforts to meet the overall 75 percent goal, says Marissa Juhler, waste reduction and sustainability manager at the landfill.

And the rest of the goal could very well be met with the planned biogreen digester, landfill operators said.
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The Yolo biogreen digester would be a much larger version of a demonstration project already under way at the landfill.

The project grew out of attempts to find ways to make garbage decompose faster. Early efforts found that adding water to organic waste (green waste, food waste, manure and other liquids), covering it up and leaving it to “cook” for a few years enhanced the growth of microbes responsible for breaking down waste.

For many years, adding liquid to trash was against the law because of fears that the leachate would contaminate groundwater and too much methane would be produced. The Yolo County Landfill set out to show that both could be contained, Deputy Director Linda Sinderson told The Enterprise at the time.

Those early efforts showed that compared to “dry-cell” methods — where water is not added and garbage remains mostly unchanged even after being buried for decades — the “wet-cell” approach causes most of the organic material to decompose in about 10 years. What’s left — plastic or glass, for example — can then be pulled out.

A $200,000 grant from CalRecycle in 2007 allowed for a 2,000-ton demonstration project of the biogreen digester. Now, seeing the success of that project, the landfill plans a 50,000-ton version.

The biogreen digester project would be built on 10 acres of existing landfill. In addition to the decomposing benefits, the digester also would produce compost that can be sold, as well as biogas that can be turned into electricity or compressed natural gas.

That gas then could be sold and also used to fuel the county’s fleet of both lightweight and heavy vehicles. Yazdani estimated the proposed digester would produce compressed natural gas equivalent to 298,000 gallons of gasoline per year.

“We can fuel all our vehicles, plus more,” he said. “It’s a great source of fuel, and we can decrease our dependence on fossil fuels.”

Additional energy efficiency — not to mention additional revenue — would come from solar panels that will be placed over closed landfill cells.

All of these efforts are expected to produce revenue while also achieving that goal of diverting 75 percent of garbage by 2020.

The mission won’t end in 2020, of course. Ultimately, the goal for many is zero waste. But at that point, efforts may have to come primarily from manufacturers and consumers.

Standing atop a mountain of buried trash — more than 50 feet tall — as one garbage truck after another rolled up and deposited ever more refuse, Juhler, the waste reduction and sustainability manager, said she doesn’t think zero waste is impossible, “but I don’t know if it’s realistic.”

“If you look, you see an enormous amount of stuff being buried here,” she said. “We have to educate people. We have to deal with how things are packaged.”

— Reach Anne Ternus-Bellamy at aternus@davisenterprise.net or 530-747-8051. Follow her on Twitter at @ATernusBellamy