Midway Landfill

⚠ Superfund · Ready for anticipated reuse

The site’s long-term remedy included a gas control system; landfill surface filling and grading; stormwater detention, landfill capping and stormwater diversion; groundwater monitoring; and institutional controls. Remedy construction took place between 1990 and 2000. Groundwater monitoring is ongoing.

Location

CityKent
CountyKing County
StateWashington
Coordinates47.38000, -122.29330

Contaminants of concern

Contaminated media

Cleanup timeline

  1. Initial Assessment Completed — 01/01/1983
  2. Proposed to the National Priorities List — 10/15/1984
  3. Finalized on the National Priorities List — 06/10/1986
  4. Remedial Investigation Started — 03/28/1985
  5. Final Remedy Selected — 09/06/2000
  6. Remedial Action Started — Not Yet Achieved
  7. Construction Completed — 09/21/2000
  8. Deleted from National Priorities List — Not Yet Achieved
  9. Most Recent Five-Year Review — 08/20/2025
  10. Achieved Sitewide Ready for Anticipated Reuse — 01/04/2007

EPA references

Other Superfund sites in King County

EPA-regulated facilities nearby

Understanding this Superfund site

Midway Landfill is a federal Superfund site in Washington. The Superfund program, created by Congress in 1980, addresses sites where hazardous substances have been released or threaten release into the environment. EPA scores potential sites using the Hazard Ranking System; those that score high enough are placed on the National Priorities List.

Current status: Ready for anticipated reuse. EPA considers this site ready for anticipated reuse, meaning cleanup has progressed enough for certain land uses. This does not necessarily mean all contamination has been removed — institutional controls like deed restrictions may limit how the land can be used.

Contaminants of concern include 1,2-dichloroethane, chloroethene (vinyl chloride), manganese. Contamination has been detected in groundwater.

If you live near this site and have health concerns, your state health department can provide site-specific guidance. EPA maintains a community involvement program for most NPL sites, and site documents — including the Record of Decision, five-year reviews, and public health assessments — are typically available through EPA's Superfund site profile.