King County Navigation Bar (text navigation at bottom)

Landfill gas–to–energy facility at Cedar Hills Regional Landfill
Privately owned facility converts landfill gas to pipeline quality natural gas and reduces greenhouse gas emissions

Project description

In 2008, the King County Solid Waste Division contracted with renewable energy company INGENCO (external) – doing business as Bio Energy (Washington) LLC, (BEW) (external) to generate usable energy from methane gas produced by decomposing garbage at Cedar Hills Regional Landfill.

In early 2009, BEW completed major construction of the landfill gas processing facility on about two acres of land leased from King County at the 920-acre Cedar Hills Regional Landfill in Maple Valley. BEW owns and operates the facility, which includes a quarter-mile pipeline for transporting the processed landfill gas to Williams Northwest Pipeline and on to Puget Sound Energy's natural gas-fired power plants. The facility operates 24 hours a day, seven days a week and also generates supplementary electricity for use on site.

In September 2010, the BEW facility continues to operate in the commissioning stage, which involves testing equipment and operating systems. The current gas processing efficiency varies between 80-92 percent based on the volume of gas collected.

Once the commissioning stage is completed and the facility is operating at full capacity, BEW expects to deliver about 5.5 million cubic feet of gas per day, which is enough to power about 24,000 homes.

Major benefits

  • Waste reduction - Prior to this facility, landfill gas was burned off through the landfill gas flare system. Now, instead of being wasted, landfill gas is converted into pipeline quality gas and is being used to generate power.
  • Reduction in greenhouse gas emissions - Because the converted landfill gas replaces an equal amount of nonrenewable natural gas, this project will result in a 63 percent overall reduction of greenhouse gas emissions at the landfill.
  • Revenue - proceeds from the sale of the gas will help keep solid waste disposal rates low and will provide approximately $1 million annually to the Solid Waste Division.

Project schedule – major milestones



February 2008

King County signed contract with INGENCO, Inc. - doing business as Bio Energy (Washington) LLC, (BEW)

January – June 2008

The State Environmental Policy Act (SEPA) environmental review was completed in June 2008 and no further mitigation measures were required.

June 2008

The Solid Waste Division issued a Notice of Action (PDF, 110 K) for BEW to proceed with building the landfill gas processing facility, provided they obtain all required permits.

July 2008 – March 2009

BEW received required permits from the responsible regulatory agencies. BEW began constructing the facility.

March 2009

Major construction of the landfill gas processing facility was completed.

Facility commissioning began, including testing equipment and operating systems and delivery of a limited quantity of gas to the adjacent natural gas pipeline.

March 2010

BEW received a final Certificate of Occupancy

September 2010

BEW facility is operating in the commissioning stage; the current gas processing efficiency varies between 80-92 percent based on the volume of gas collected.

Nov. 16, 2010

A community meeting was held by the Solid Waste Division and Bio Energy Washington in response to neighbor concerns about noise from BEW’s landfill gas-to-energy facility. View a written summary of the Nov. 16 meeting. (PDF, 88 K)


Bio Energy Washington
If you have any questions or comments about BEW’s landfill gas processing facility or would like to schedule a facility tour, call the BEW comment line at 425-392-3918 or visit BEW (external).

King County Solid Waste Division
If you have questions or comments about the operation of the Cedar Hills Regional Landfill, or would like a tour of the landfill, call 206-263-1000, TTY Relay: 711. This phone line is answered 24 hours a day, seven days a week. You can also use our online comment form.

top of page

Public comment line:

Bio Energy Washington’s Public comment line is 425-392-3918. Please provide detailed information including your name, phone number, and the date, time, and description of your comment. BEW's plant manager will follow up with you.

[+] EnlargeCedar Hills Regional Landfill with Mt. Rainier in the distance

Methane gas is a by-product of decomposing garbage.

[+] Enlargeflare system at Cedar Hills Regional Landfill

Prior to processing landfill gas, it was burned off through the landfill gas flare system.

[+] Enlargepipes at the Cedar Hills landfill gas-to-energy facility

The Solid Waste Division collects landfill gas through a network of pipes.

[+] EnlargeLandfill gas-to-energy facility at Cedar Hills

Landfill gas is processed to separate methane gas from other unwanted gases and destroy harmful emissions.

[+] EnlargeLandfill gas-to-energy facility at Cedar Hills

The processed pipeline quality gas is conveyed to the nearby natural gas pipeline.

[+] Enlargehouses like this are powered by reclaimed landfilll gas

This reclaimed resource supplies energy to thousands of homes in King County.

Updated: Jun. 3, 2014

King County | News | Services | Contact | Search

Links to external sites do not constitute endorsements by King County.
By visiting this and other King County Web pages,
you expressly agree to be bound by terms and conditions of the site.
The details.