The Cedar Hills Regional Landfill is the only active landfill in King County. It will operate until at least 2028. It has been in operation since the 1960s. Aaron Kunkler/staff photo

The Cedar Hills Regional Landfill is the only active landfill in King County. It will operate until at least 2028. It has been in operation since the 1960s. Aaron Kunkler/staff photo

Waste study puts numbers behind King County trash alternatives

County has one remaining landfill located near Maple Valley, and it’s nearing capacity

An environmental study has been released detailing several ways King County could handle its trash in coming years and lays out options ranging from a waste-to-energy power plant to expanding the current landfill.

The environmental impact statement (EIS) will provide the first major update to the county Solid Waste Division’s management plan since 2001, and deals with a range of issues including recycling levels and whether the county should build a waste-to-energy (WTE) plant. The King County Council is scheduled to select its preferred alternatives early next year — decisions that will have widespread and prominent effects.

The most critical decision will be how the county deals with trash. King County has one remaining landfill located near Maple Valley. The Cedar Hills Regional Landfill is currently building its eighth and final cell, which will be filled until it reaches a maximum height of 800 feet above sea level in 2028. Once that happens, the EIS lays out five alternatives. The first would be to emulate what the city of Seattle does in its contract with Waste Management, where all solid waste is packed onto train cars and shipped to another landfill, likely in eastern Washington, Oregon or Idaho.

This option assumes the landfill will hit capacity as expected and the county would then contract with BNSF or Union Pacific to handle the 1.3 million tons of waste it generates annually. This would account for around 2 percent of all freight traffic in the state and run around $5 million to $7 million in capital costs. However, a 2014 study from the Washington State Department of Transportation shows some parts of the rail system could be over capacity. While trash from King County would account for around 2 percent of all freight, King County Councilmember Kathy Lambert has said in previous stories that she is worried hauling trash will be low on the list of priorities for railroads.

The second option would further develop the Cedar Hills landfill and begin shipping waste to another landfill when it reaches its new limit. The landfill height could potentially be increased to 830 feet in some places, extending its life until 2040. This would cost the county between $240 million to $270 million in capital expenses.

A third option, and one which Lambert has been advocating for, is to build a waste-to-energy power plant and use the landfill to deposit residual solid waste and ash. This leftover waste could also be shipped by rail to other landfills. The EIS finally puts some figures on this option, saying it would create around 2,000 metric tons of carbon dioxide (CO2) annually over a 50-year lifespan, slightly less than .01 percent of the total current greenhouse gas emissions in King County.

The final two options involve using aerobic or anaerobic digestion processes to create methane, which can be siphoned off and refined by Bio Energy Washington, which already has a facility at the landfill. The difference between the final two options is whether processing would be done off-site by a private company or at the county’s landfill.

Using digestive technologies would also create new greenhouse gas emissions, but the facilities could reduce emissions more than landfilling the same material by keeping it at landfill instead of moving it, according to the study. The EIS said both the digestive and power plant options would likely decrease greenhouse gas emissions, but the aerobic and anaerobic methods are thought to lead to lower emissions than a power plant.

The cost between the final three options will inevitably factor into the county council’s decision. The digestive options cost between $34 million and $190 million, depending on which variation the county could pick. Building a new WTE plant will cost between $1.1 billion and $1.4 billion to construct.

Improvements to several transfer stations are also being considered. The county could close the Algona and Renton transfer stations when replacement capacity is made available. The Houghton transfer station in Kirkland would remain, and a new South King County transfer station could be created.

The Algona, Houghton and Renton transfer stations were all built before existing zoning laws were implemented. These stations are in areas where they are not permitted and require a special land use permit before any major improvements are made. The county has proposed citing the new South King County station at 35101 West Valley Highway South next to the existing Algona station, which it would replace. Construction is planned to begin in 2020 and last around two years.

The county also has the option of maintaining and improving existing transfer stations — without closing older stations — and not develop new facilities. It could also keep existing stations and develop new capacity, or create new resource recovery centers at existing and new recycling and transfer stations.

Recycling was also explored in the EIS. The county and its partner cities recycle at a rate of around 52 percent, which hasn’t changed much since 2007. The county is hoping to increase its recycling rate to 70 percent. The report lists three alternatives of varying levels of education and regulation to get there. The most restrictive would increase education and recycling incentives and increased collection standards. It would additionally put a ban on throwing recyclables, yard and food waste in the garbage.


Talk to us

Please share your story tips by emailing editor@kentreporter.com.

To share your opinion for publication, submit a letter through our website https://www.kentreporter.com/submit-letter/. Include your name, address and daytime phone number. (We’ll only publish your name and hometown.) Please keep letters to 300 words or less.

More in News

t
33rd Legislative District sets Telephone Town Hall for April 29

District includes part of Kent; call hosted by Sen. Orwall and State Reps. Gregerson and Obras

Kent Police officers will carry the latest Taser 10 model produced by Axon Enterprises. The gun can fire more shots and at a longer distance than the older model. COURTESY PHOTO, Axon Enterprises
Kent Police add latest Taser model to officers’ equipment

Taser 10 can shoot more shots at a longer distance; department also adds dash cameras

t
Kent crime numbers drop dramatically in first quarter of 2025

All categories down compared to first three months of 2024; commercial burglaries drop 62%

t
Kent Police arrest man in stolen vehicle after short pursuit

Seattle man, 36, taken into custody April 14 at apartment complex near Kent-Meridian High School

t
Kent church reaches $1 million milestone for assistance program

Kent United Methodist Shared Bread Program helps people pay rent, utilities

Atena, part of a Kent Police K-9 unit, helped locate a man who reportedly fired three to five shots from his motorcycle at another vehicle April 12 in Kent. COURTESY PHOTO, Kent Police
WSP plane, Kent K-9 unit locate man who fired shots at teen

Motorcyclist fled drive-by shooting on West Hill during April 12 incident

A house in Issaquah was damaged by fallen trees during November’s bomb cyclone. (Courtesy of King County Councilmember Sarah Perry’s office)
FEMA denies funds to WA for damage caused by 2024 ‘bomb cyclone’

Gov. Bob Ferguson says federal funds are needed to address $34 million in damage caused by the storm, and that the state will appeal.

Kentwood High School, 25800 164th Ave. SE., in Covington. COURTESY PHOTO, Kent School District
Person who made Kentwood High social media threat tracked down

‘Had no means to carry out the threat,’ according to King County Sheriff’s Office

A man places his ballot into the drop box outside Federal Way City Hall. Bailey Jo Josie/Sound Publishing
SAVE Act could disenfranchise millions of voters

Congressman reports law could cost Washingtonians over $361 million just to register to vote.

t
Judge dismisses petitions to recall 2 Kent School Board members

Group wanted to recall Meghin Margel and Tim Clark

t
Kent Police Blotter: March 25 to April 6

Incidents include attempted bank robbery, cable wire theft, DUI arrest, parking lot robbery

Courtesy Photo, Kent Police
New 3-year contract gives Kent Police officers pay boost

Hikes of 16% and 17% in 2025 compared to 2022; beginning salary at $96,306 with annual increases