Cedar Grove Composting Process and Impact

  • Cedar Grove Composting Overview

    • Local family-owned business dating back to 1938 in Seattle.
    • Key player in Puget Sound recycling and sustainability efforts.
    • Diverts over 350,000 tons of yard and food scraps from landfills each year.
    • Operates two main facilities in Maple Valley and Everett, creating green jobs in King and Snohomish Counties.
    • Produces nutrient-rich compost for various consumers including businesses, agriculture, and governments.
    • Everett Facility
    • Established in February 2004, implementing European technology.
    • Covers 28 acres and is among the largest composting facilities globally.
    • Processes approximately 350,000 tons of organic waste yearly; produces about 130,000 cubic yards of compost annually.

  • Composting Process Overview

    • Step 1: Waste Collection
    • Food and yard scraps collected from restaurants and homes by local haulers.
    • Weighing of trucks upon arrival to the facility.
    • Step 2: Tipping Building
    • Waste is dumped into the tipping area; maintaining a clean wood stockpile is essential.
    • Step 3: Aerobic Composting Requirements
    • Requires airflow for microbes; must maintain a balanced carbon-to-nitrogen ratio.
    • Example: During grass season, wood chips are added to balance ratios.
    • Step 4: Negative Air System
    • Controls odors with a negative air system and biofilter that eliminates 90% of odors.
    • Step 5: Grinding
    • Material ground to allow air passage necessary for effective composting.
    • Front loaders adjust material for optimal carbon-to-nitrogen ratio.
    • Step 6: Conveyor & Moisture Adjustment
    • Ground material moved on conveyor belt; recycled water is added for moisture.
    • A magnet removes metal contaminants (e.g., forks) from the mix.

  • Composting Phases

    • Phase One (21-28 days):
    • Material piled to a specific heap size (164 ft long, 26 ft wide, 10 ft high) and covered with Gore cover fabric (provides biosphere for warmth and airflow).
    • Maintains temperature between 165-170°F with airflow monitored by COMP Master Control system.
    • Phase Two (14 days):
    • After initial phase, material is placed in a new heap for further organic decay.
    • Phase Three:
    • Moisture content and temperature lowered; material prepared for screening.
    • Final screening removes plastics ensuring purity of finished compost.

  • Final Product & Community Impact

    • The finished compost is dark, clean, and has an earthy smell; ideal for yards or landscapes.
    • Cedar Grove creates a local recycling loop, supporting the sustainable economy.
    • Celebrates transformation of organic waste into valuable compost enriching the community and environment.