County of Mariposa // Mariposa, CA

County of Mariposa // Mariposa, CA



    Client Needs:


    Mariposa County needed a composting technology vendor to design and provide equipment for a new Municipal Solid Waste (MSW) composting facility with:

    • A preprocessing line for separating the organic fraction from the incoming unsorted waste;
    • An in-vessel system for primary composting and an ASP system for curing; and
    • Proven odor control for location on an odor sensitive site.



    ECS Solution:


    The team of ECS and DA Construction (of Montana) completed the design and construction of the Mariposa MSW in-vessel composting facility. This facility is designed to receive 50 tons of unsorted MSW per day. The waste passes through pre-processing equipment including picking lines, bag breakers, and a debris-roll screen for removing recyclables and contaminants and separating the organic from the non-organic wastes.

    Primary composting takes place in our In-Vessel Tunnel system, an automated compost system. This installation includes eight (8) concrete vessels that are 14’ wide by 50’ long. The In-Vessel Tunnel features include, automated aeration control and monitoring; reversing and recirculating process aeration; in-floor plug-resistant aeration; leachate and condensate collection; and, biofiltration of all exhaust air. ECS supplied process equipment includes a heavy-duty compost mixer, specialized conveyors, and a negatively aerated ASP system for extended curing.


    Following 16 days of primary in-vessel composting the biomass is cured on an ECS ASP. When ready, the compost is mechanically screened and made available for alternate daily cover on the County’s landfill. Future facility plans include composting source separated organics for making Grade A compost.


    Capacity (tpy)



    Municipal Solid Waste

    ECS Technologies Employed

    In-Vessel Tunnel System

    CompTroller™ Automated Control & Monitoring System

    Low-Friction Aeration Floor

    Reversing Aeration System

    Negative Aeration System

    Suspended Floor Biofilter

    Vertical Auger Compost Mixer

    Start-Up Year



    Mariposa County, CA


    Visit the County of Mariposa's Composting Facility online.