Hobart Landfill

Hobart Landfill is a closed municipal solid waste landfill that is regulated under the Minimum Functional Standards for Solid Waste Handling Chapter 173-304 Washington Administrative Code.

The landfill is located within a former sand and gravel borrow area and began accepting refuse since at least the 1950s. The landfill does not have an engineered composite liner beneath the solid waste, which is a requirement for new landfill units constructed after November 1985.

The landfill closed in two phases:

• A low-permeability slurry wall was installed around the perimeter of the entire landfill in 1989. The slurry wall extends from the surface to a low-permeability soil layer beneath the landfill.
• Phase I closure was completed in 1990, which included a geomembrane landfill cover and landfill gas collection system on the northern 15 acres of the landfill. 

• Phase 2 closure was completed in 1994, which included a geomembrane cover system and landfill gas collection system on 20 acres at the southern end of the landfill.

Post-closure care includes periodic monitoring and evaluation of groundwater and landfill gas to confirm the integrity of the landfill containment systems. Post-closure care is required until the landfill generates little or no leachate and landfill gas, landfill settlement has stabilized, and groundwater quality criteria have been satisfied. Reports and investigation reports/letters are located in the electronic document tab on the left side under Site Details-View Documents.

King County Solid Waste Division manages post-closure care for the landfill. 

Public Health – Seattle & King County (PHSKC) is the jurisdictional health department that permits the landfill. Landfill Reports are submitted to PHSKC pursuant to permit. For more information, please contact Jerome Cruz, Environmental Scientist III at 206-450-5833 or email jercruz@kingcounty.gov.

Ecology’s Solid Waste Management Program maintains regulatory standards and provides technical assistance to the jurisdictional health departments.

Permitted landfills are potentially subject to the state’s cleanup law, the Model Toxics Control Act (MTCA) if there has been a release of hazardous substances from the landfill. Ecology has not determined that there has been a release from the landfill that is subject to MTCA.

To report an environmental problem or concern, any time, day or night, use the online reporting form.

Counties: Island, King, Kitsap, San Juan, Skagit, Snohomish, and Whatcom

Email: nwroerts@ecy.wa.gov
Phone: 206-594-0000

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