Cedar Hills Regional Landfill (CHRLF) Area 8 Development

About

CHRLF receives municipal solid waste (MSW) from most municipalities and unincorporated areas of King County except the City of Seattle. The Area 8 Development Project is a 34-acre horizontal expansion that provides capacity for an additional 6 years of MSW. The project also included significant site work to modify environmental control facilities serving the new Area. BHC lead significant elements of the Area 8 Development including overall project direction as well as design of lining systems and leachate and contaminated surface water management facilities.

Features:

  • 34-acre MSW landfill horizontal expansion with relocation and processing of refuse from a previously-closed area to make room for environmental control facilities
  • A successful regulatory demonstration that the proposed alternative lining system is equivalent to the prescriptive system under WAC 173-351
  • New contaminated surface water and stormwater detention, treatment, and storage lagoons
  • Leachate pumping facilities and leachate pre-treatment lagoon hydraulic improvements
  • Hydrogeologic and Geotechnical Engineering Reports

 

Cedar Hills Regional Landfill (CHRLF) Area 7 Staged Closure

About

CHRLF receives municipal solid waste (MSW) from most municipalities and unincorporated areas of King County except the City of Seattle. The Area 7 Staged Closure is a 64-acre MSW landfill closure constructed in 5 Stages. Each stage was a separate design and bid package to close as much of the area as feasible each year. The project also included significant site work to modify environmental control facilities (Landfill Gas(LFG), stormwater and contaminated stormwater, and leachate) serving the new Area. The project included several updates to the Area 7 Plan of Operations. It also included significant collaboration with the Area 8 Development design team.

Features:

  • 64-acre MSW landfill Closure constructed in 5 stages
  • Final MSW landfill closure sections compliant with Subtitle D requirements
  • Design of both a 20-year and 8-year design life interim cover sections for slopes that will be covered subsequently by more refuse
  • Design of LFG, Stormwater, and Leachate control facilities
  • Four updates to the Area 7 Plan of Operation