How much garbage can you cram into 1.4 square miles?

At least 50 years’ worth, and probably closer to 75, provided you stack the trash hundreds of feet high.

King County has only one active landfill, where the rubbish produced by more than 1.4 million people is hauled, dumped, compacted and layered into a modest trash mountain lorded over by a fleet of semi-trucks, bulldozers and bald eagles. (Eagles love garbage.)

But the Cedar Hills Regional Landfill, located in South King County, between Renton and Maple Valley, is (sort of) filling up.

The landfill has, in fact, been (sort of) filling up for decades.

In 2001, the last time the county produced a comprehensive plan for how to handle its garbage, the landfill was going to be full by 2012.

In 2006, the landfill’s estimated capacity was pushed back to 2016.

In 2013, the landfill’s death date got pushed to 2025.

Currently, the closing date is estimated at 2028. But that could change soon.

On April 1, the Metropolitan King County Council will consider passing a new Comprehensive Solid Waste Management Plan, the first full update to our garbage storage tactics since 2001. The plan proposed by King County Executive Dow Constantine would push the closing date back to 2040 by making up to $270 million of modifications — building a new dumping ground at the landfill site and allowing garbage to be stacked 30 feet higher than is currently permitted.


On the one hand, this forestalls a costlier decision — what to do with the trash when the landfill does fill up.

On the other hand, perhaps you live near the landfill.

“When I first moved here, they said it would close in 2000,” said Janet Dobrowolski, who’s lived in a leafy, idyllic (but for the landfill next door) section of unincorporated King County for 30 years. “Then it’s 2007, then it’s 2012. We believed them. We believed what they were telling us.”

Within a couple of miles of the landfill, in the Renton-Maple Valley area, are the massive Cedar Grove composting facility, the Queen City Farms hazardous waste Superfund site and Cedar Mountain Reclamation, a construction debris recycling and disposal site.

“We are tired of being the dumping grounds of all things toxic and smelly,” said Tammera Widell, who’s lived about 2 miles from the landfill for three decades.

Making the landfill last longer

Each weekday, around 130 tractor trailers arrive at Cedar Hills, carrying with them a total of about 2,500 tons of garbage. They circumnavigate five decades of refuse — a hulking brown mound of patchy grass pierced with piping — to arrive at the summit where their trailers are tipped toward vertical, their contents spilling out, to be bulldozed into rough order.


Eagles flock. Deer and elk frequent the trash-filled hillside below.

The pipes sticking out of the hill collect the methane that decomposing garbage emits. It’s piped to a bioenergy plant, on-site, which converts the gas into usable natural gas that’s pumped into Puget Sound Energy’s grid — enough to power about 19,000 homes a year.

Several factors have extended the landfill’s life. Increased recycling and composting means more refuse gets diverted elsewhere. Heavier equipment compresses more garbage into the finite amount of space available. The landfill used to cover the active disposal site with 6 inches of soil each night, to keep it covered. Now they use a heavy-duty tarp, which saves landfill space.

And the 2008 recession slowed down the economy, which slowed down everything.

“Garbage is a leading economic indicator,” said Pat McLaughlin, the county’s solid waste director. “When the last recession hit, it modified consumer behaviors, it modified package designs.”

Cedar Hills takes the garbage of everybody in King County except for residents of Milton, whose garbage goes to Pierce County, and Seattle. Seattle ships its trash, by train, to a landfill in Arlington, Oregon. Since at least 2001, the county’s plan, once Cedar Hills fills up, has been to mimic Seattle — ship the trash elsewhere.

But the new plan changes that. First, it instructs the solid waste department to “maximize disposal capacity” at Cedar Hills. The landfill already has a new 56-acre Area 8 that will begin being filled with trash sometime this year. The next step would be an Area 9, almost certainly the last possible new trash disposal area at the site, which would extend the landfill’s life until 2040-ish.


Area 9 would be built where the landfill’s current offices and maintenance facilities are located. They would have to be moved.

“That land is permitted for landfilling, it’s a precious commodity if you will,” McLaughlin said. “It’s easier for me to put an administrative trailer somewhere else than it is a landfill.”

The plan also explicitly declines to weigh in on what to do next.

“To account for technological advances, this plan does not specify the next disposal method after ultimate closure of Cedar Hills,” it says.

“We really are just punting the football,” said King County Councilmember Reagan Dunn, who represents that part of the county. “King County has been promising for decades now to close this landfill and pursue alternative methods of processing our county’s waste that wouldn’t place the sole burden on the residents around the landfill.”

Alternatives: Burn the waste or ship it away

The alternative methods likely boil down to either shipping trash, by rail, elsewhere, or building a waste-to-energy plant, which usually burns trash and uses the heat to make electricity. There are 87 waste-to-energy plants in the U.S., including in Portland and Spokane, but only one new one has been built since 1995.


The plants tend to be more popular in places with denser populations — where there’s less room for landfills — like Europe and Japan.

The county estimates the cost of a waste-to-energy facility at $1.1 billion to $1.4 billion.

King County Councilmember Kathy Lambert has been pushing for a waste-to-energy plant for more than a dozen years. She’s visited 13 of them (her favorite is in Hamburg, Germany) and last year led a county contingent, including Constantine to tour a plant in Florida.

“People don’t realize what a modern waste-to-energy plant looks like,” Lambert said, touting their environmental benefits. “The technology’s really, really changed.”

Alex Fryer, a Constantine spokesman, said Constantine is willing to consider waste-to-energy as “a possible future option” but for now supports the plan to keep using Cedar Hills.

The plants reduce the volume of garbage by about 90 percent. The county’s plan estimates a waste-to-energy facility would have a higher greenhouse gas impact than expanding Cedar Hills, but a previous EPA study deemed waste-to-energy plants more environmentally friendly over the life-cycle of the facility.


“Modern waste-to-energy facilities continue to advance toward the goals of sustainability,” a 2017 county-commissioned study concluded, “which include significant reductions in emissions.”

Another study is due in October.

“It keeps other alternatives on the table,” McLaughlin said of the proposed waste management plan. “Because the landfill ultimately has a finite amount of capacity.”