Cowlitz County Landfill Closure

Client: Cowlitz County

Location: Longview, Washington

A former landfill site in Cowlitz County needed to be closed per state and local health jurisdictions’ requirements. Landfill closure requires thorough knowledge of the Department of Ecology closure requirements. The team at MFA provided the necessary understanding of the process and was able to collaborate with the County and various contractors to design and oversee the closure.

The Cowlitz County landfill site was stabilized with minimal environmental impacts and no adverse impact to the public waterways. MFA designed a final cover that employs an alternative cover approach (geosynthetic clay liner), which resulted in more available disposal volume, approximately $1 M savings on material and Construction Quality Assurance testing costs, and a shortened construction schedule.


  • The use of an alternative cap alleviated the need for a two foot soil cap allowing the County to maximize the amount of waste that could be held prior to closure.
  • A long-term monitoring process is required after closure. After that time, the County may be able to repurpose the site as a benefit to the community.


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Cem Gokcora

Cem Gokcora, PE

Senior Engineer