Situation
Located 20 miles southeast of Seattle, the 920-acre Cedar Hills Regional Landfill is one of the largest solid waste processing facilities in the Pacific Northwest. Since opening in 1965, the landfill has grown to serve all residents of King County, receiving more than 800,000 tons of solid waste annually.
As the region continues to grow, so does the demand for landfill capacity. King County’s Solid Waste Division faces the ongoing challenge of managing increasing waste volumes while meeting evolving environmental requirements and long-term sustainability goals. To support the County’s solid waste strategy, Goodfellow Bros. has partnered with King County on a series of critical landfill infrastructure projects, consistently delivering complex work safely and successfully.
Solution
The Cedar Hills Area 8/9 project encompasses two major work areas that are essential to extending the operational life of the landfill.
Area 8 – Landfill Closure
Area 8 focuses on the closure of an existing landfill cell (Cell 8). The work includes installation of approximately 300,000 square yards of landfill liner, more than 10 miles of HDPE piping ranging from 4 to 30 inches in diameter, and the drilling of 17 gas extraction wells to depths of up to 150 feet within the landfill mass. The project also includes placement and grading of approximately 200,000 cubic yards of screened embankment material to establish the final cover system and prepare the site for long-term closure.
Area 9 – Demolition & Excavation
Area 9 represents one of the most significant landfill expansion efforts currently underway in King County. Goodfellow Bros. was contracted to demolish existing landfill facilities and excavate approximately 1.4 million cubic yards of native material to create the footprint for a new landfill cell, Cell 9.
Once completed, Cell 9 will provide critical disposal capacity, allowing Cedar Hills Landfill to continue serving King County through approximately 2040 and providing additional time to develop future waste management solutions. In addition to the mass excavation effort, the project includes screening roughly 350,000 cubic yards of material and constructing several key infrastructure improvements, including a cast-in-place retaining wall, 10-inch waterline relocations, electrical system upgrades, and stormwater improvements.
Notable
The Cedar Hills Area 8 Closure and Area 9 Development project is the fifth—and by far the largest—project Goodfellow Bros. has delivered for King County’s Solid Waste Division. With a contract value exceeding $50 million, construction began in May 2025 and is expected to continue through 2028.
Over the years, Goodfellow Bros. has built a strong partnership with King County, becoming one of a limited number of contractors qualified to perform highly specialized landfill construction work. This expertise has positioned the company as a trusted partner in delivering critical infrastructure projects that support the region’s long-term waste management needs.
With significant future landfill work anticipated at Cedar Hills, Goodfellow Bros. looks forward to continuing its successful partnership with King County and helping deliver solutions that serve the community for generations to come.
