Olivia Williams, P.E., Solid Waste Engineer, HDR Engineering
Rich Hanson, PE, Senior Engineer, Solid Waste Disposal, City of Spokane

The closed Southside Landfill had a high-maintenance landfill gas collection and flare system that was yielding a limited flow of decent quality. The City of Spokane was looking at options for how to simplify and maintain their system. This webinar outlines the seven-step process the City is currently using to efficiently manage their post-closure responsibilities. These steps include:

1. Landfill Audit
2. LFG Assessment
3. Monitoring Review
4. Notice of Construction
5. Design
6. Construction
7. Follow-up Monitoring

The City conducted a baseline assessment of the 72-acre site in 2010 to evaluate its condition. This included the LFG collection, flare, monitoring systems, engineered cover, and surface water infrastructure. The aging flare struggles with intermittent operation due to poor quality and limited gas generation. Additionally, the City has noted elevated flare emissions due to incomplete combustion. The City has worked with the local regulatory agencies to permit the construction of an LFG biofilter to replace the existing enclosed flare system. The biofilter system will consist of the existing blower conveying LFG to roll-off bins filled with a mixture of organic media and sand to provide treatment of the volatile organic compounds in the gas prior to discharge through a stack.

Generation of LFG at a closed landfill commonly extends well into, and beyond, the 30-year post-closure care period. And LFG management often represents a significant portion of the post-closure care costs. This webinar on the 7-step process employed at the Southside Landfill will be of value to anyone seeking post-closure solutions.