City of San Diego Miramar Greenery Landfill

Composting Food And Yard Waste Atop A Landfill


Environmental Business Journal’s Business Achievement Award

Hear about this award-winning project that is reducing Greenhouse Gas (GHG) emissions by the equivalent of removing 19,015 cars from the road.

Project Details
  • Ownership: City of San Diego
  • Location: Miramar Greenery, CA
  • Start-Up: 2019
  • Product: SG Mobile® System with GORE® Covers
  • Input quantity:  40,000 TPY
  • No. of Heaps: 24 Heaps, 18 covered, 100 ft. x 26 ft. x 12 ft. each
  • Treatment Time: 8 weeks in 3 Phases
  • Aeration: Above ground
  • Control Parameters: Proprietary California Compliant Control mode and Oxygen Control mode
  • Input material: Source Separated Organics (commercial, institutional, residential food waste) / Yard Waste (tree, grass and leaves)
  • Equipment: Pre-Treatment (Grinders) / Front-End-Loader(s) / Electric Powered Winder / Mobile Screen
  • End Product: High Quality Finished Compost

The SG Solution

Pilot Scale Demonstration Project

The City of San Diego (CSD) was composting up to 100,000 tons of green waste material per year using turned windrow technology. As food waste was being added as a new feedstock, and because of the contamination from their automated curbside collection process, the City wanted to evaluate in-vessel technology for the purposes of composting mixed green waste and food waste. After several alternative methods were evaluated, the City chose to implement a SG Mobile® System with GORE® Cover (covered aerated static pile) Pilot-Scale Demonstration Project in 2009.

Goals of the Pilot Demonstration Project:

  1. Food Waste Composting; Compost a new feedstock – commercial, institutional and residential food waste.
  2. Evaluate the ability to produce a high quality finished compost while controlling Odors, GHG Emissions, Leachate, Moisture, and Vectors.
  3. Meet or exceed local, county, and state regulations.
  4. Evaluate the operating capability and simplicity of the technology.
  5. Develop model for the total cost to build and operate the composting technology.

Results Delivered

SG Mobile® Outperforms Existing Windrow Turning Process

Of significant importance to the Pilot-Scale Demonstration Project was that the SG Mobile® System with GORE® Covers process outperformed the existing windrow turning process for quality, time to manufacture and performance. In addition, the demonstration project validated the following:

  • – Waterproof, breathable cover suitable for all SoCal climate conditions
  • – Clear separation of stormwater from leachate
  • – Small footprint (40K TPY on <3 acres)
  • – Low energy costs (<2kw per ton processed)
  • – Oxygen controlled treatment process
  • – Conserve moisture during the composting process
  • – Meet or exceed all government emissions standards
  • – 8-week treatment time

This Pilot-Scale Demonstration Project, along with other positive results of the GORE® Cover’s performance at existing facilities in California, helped CSD to earn a $3 million grant from CalRecycle for this project in 2017.

The IoT enabled Compost Control System is a secure plug and play solution that can be operated from any smart device from anywhere in the world, reducing the cost and complexity of installation and operation.  Of additional note is the fact that Sustainable Generation delivered an all-electric cover winder machine for this project for the first time. Previous generation winders were diesel or gas powered.

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