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Green bonds: Duvall Landfill

Duvall Landfill – Landfill Gas Control & Cover System Improvements

King County Green Bonds

Duvall Landfill tree cover
Duvall Landfill tree cover

The 13-acre landfill closed in 1981 with clay and tree cover, a passive leachate collection system around the perimeter, and a flared, passive gas (no vacuum) monitoring system. No bottom liner. Groundwater treatment, groundwater and landfill gas monitoring, and a poplar tree landfill cover are all in place. An emergency radio tower is located on the property.

Project goals

  • Reduce low-level groundwater contaminants in an area where refuse is prone to saturation;
  • Improve the grass and tree cover to reduce water infiltration and improve carbon sequestration;
  • Evaluate wastewater control system improvements to improve groundwater quality;
  • Installation of a gas collection and control system to reduce greenhouse gas emissions completed by 2026;
  • Conclude improvements and provide property for secondary beneficial use.

Key environmental attributes

  • Groundwater quality improvements to meet regulatory compliance that are protective of human health and the environment, through installation and 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;
  • Achieving the above goals in order to minimize or terminate post-closure activities.

Project info

Green Bonds: 2017-Series A

$0.8m Green Bond Proceeds spent

In progress GHG emissions MTCO2e/yr

In progress water quality metrics

CICERO independently rates King County Green Bonds.
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