King County study narrows post‑Cedar Hills options to rail export or mass‑burn energy

King County staff told Renton council members that a long-term disposal study found two feasible options for managing solid waste after the Cedar Hills Regional Landfill reaches capacity around 2038–2040: exporting waste by rail to out‑of‑county landfills, or building a mass‑burn waste‑to‑energy facility paired with rail export for ash. The presentation, given by Brian, a county presenter, summarized three tonnage scenarios and the study’s environmental, logistical and cost comparisons.

The study examined three tonnage scenarios: a status‑quo case, a mid‑range “repress” case that assumes implementation of policies such as extended producer responsibility and increased organics diversion, and a high‑diversion case that assumes reaching the county’s “zero waste of resources” goal by 2030 (which would divert roughly 68–70% of material now sent to the landfill). Under the study’s low‑tonnage scenario, the county would send about 333,000 tons per year; the county sent roughly 840,000 tons to Cedar Hills in the most recent year cited in the presentation.

Why it matters: Cedar Hills is the only active landfill in King County; its scheduled closure window drives a multi‑decade planning need. The county has begun the State Environmental Policy Act (SEPA) scoping process and expects a draft environmental impact statement (EIS) by the end of this year, with a final EIS targeted for late 2026 and advisory‑committee recommendations in early 2027. Any policy choice will go through the King County comprehensive plan adoption process and then to city adoption.

Key findings presented

- Of five…