Cedar Falls Landfill – Landfill Gas Control Improvements
King County Green Bonds
The 12-acre landfill closed in 1990 with a composite geomembrane cover, passive gas collection and bio-berms for gas treatment. Groundwater, surface water, and landfill gas monitoring are ongoing. Improvements are being made to the landfill gas collection and treatment systems to improve water quality.
- Continue evaluation of installed enhancements for landfill gas collection, control, and treatment (2019);
- Conclude improvements and provide property for secondary beneficial use.
- Ongoing evaluation of installed enhancements to improve gas collection and treatment. (Approx. 80% complete);
- Evaluation being performed to determine if improvements to the cover and landfill gas control and treatment systems will facilitate the improving ground-water quality to meet regulatory requirements (Approx. 100% complete).
Key environmental attributes
- Groundwater quality improvements to meet regulatory compliance;
- Be protective of human health and the environment, through improvements to the environmental control systems;
- Reduce the potency of GHG emissions to the greatest extent feasible, through the collection and treatment of landfill gases with bio-filtration technology;
- Achieving the above goals in order to achieve post-closure of landfill facility.
Green Bonds: 2017-Series A
$1.3m Green Bond Proceeds spent
Evaluation of passive (bioberm) and active (biocannister) treatment systems determine to continue with an active system to improve water quality.
Biofiltration treatment methane efficiency reduction is 74.5 – 80%.
200 MTCO2e/yr reduced.
2021 annual review of groundwater data demonstrates key water quality parameter and trends each year are continuing to stabilize.
Initial 20% improvement in ground water quality parameter can be seen in our short term trends.
There is indication for the groundwater data of natural attenuation occurring in many of our groundwater wells.