Organics Facility
Turning Sonoma County’s Organic and Green Material into Compost, Mulch, and Biogas Energy
Senate Bill 1383 became State law in 2016. This legislation requires that the amount of organic materials put into landfills be reduced by 75% by 2025, based on 2014 baseline levels. Cities and counties could incur strict penalties for non-compliance.
It’s the Right Thing to Do, and Helps Comply with Increasingly Rigorous State Law
Diverting these materials from the landfill reduces methane and other greenhouse gas emissions, which has community-wide benefits. This new facility will provide biogas energy and will create a nutrient-rich soil amendment — compost. This can be used by home gardeners and the agricultural industry to enhance crops, gardens, and landscapes; increase plants’ resilience to pests, disease, and other environmental stressors; save irrigation water and money; and reduce the use of commercial fertilizers and soil amendments.
Proposed New Organics Processing Facility —
a Multi-Year Project
In 2015 Sonoma County’s local processing facility was permanently closed. Zero Waste Sonoma (Sonoma County Waste Management Agency) has since been working to re-establish the processing facility for organic /green materials in the County. This large-scale facility is an important aspect of local sustainability and community resilience, helping divert organic materials from landfills and reduce greenhouse gas emissions.
In August 2019, after a competitive selection process, Zero Waste Sonoma chose to enter into exclusive negotiations with the company Renewable Sonoma for organic material processing — the first step toward securing an agreement to provide these services.
It will be a complex, multi-year process to develop, build, and open a new facility. Renewable Sonoma must apply for various permits, complete environmental analyses and mitigation, and build the facility, which is proposed to be located on property owned by the City of Santa Rosa. Meanwhile, Zero Waste Sonoma needs to secure agreements from the 10 jurisdictions in Sonoma County for their organic/green materials to be directed to this project.
The proposed organics processing facility will accept green materials from Sonoma County communities and turn them into compost, mulch, and biogas energy.
Organic Materials
Green materials and food scraps — also called organics, organic matter, yard debris, or organic materials — may include leaves, grass clippings, untreated wood, vegetable/fruit peelings, meat, bones, and unlined paper products like napkins and pizza delivery boxes.
For more information about what to put in your green curbside compost/yard trimmings container, please visit zerowastesonoma.gov.
Organics Processing
Receiving and Processing
The organic materials will be delivered inside a large building with a state-of- the-art odor control system called a biofilter. The materials will be sorted to remove any contaminants or non-organic matter. Finer organic materials will be processed to a liquid slurry and sent to the anaerobic digestion system. Coarser organic materials will be sent to the composting system.
Anaerobic Digestion
In the anaerobic digestion system, the liquid organic materials will be digested by bacteria in large tanks — a process very much like a cow’s stomach.
Methane-rich biogas is produced, which will be conditioned for use as an energy source. The remaining solid materials (digestate) will be returned to the large building and blended with the materials to be composted.
Composting
The materials to be composted will be put into long concrete bunkers, covering a network of air ducts in the floor. This state-of-the-art system, called a Covered Aerated Static Pile (CASP) system, will push air up through or pull air down through the solid materials to maintain ideal composting conditions and control odors. Air flows will be exhausted through a biolayer or the same biofilter as air from the receiving building to maximize efficiency of the odor control system.
To view the Proposed Organics Processing Facilities flow chart, click here. For more information, please visit Renewable Sonoma: renewablesonoma.com
Selection of the facility’s location will go through a rigorous and transparent public review process.
Since there is currently no organic material processing facility within Sonoma County, all collected green material and food scraps are currently transported to compost facilities in Napa, Mendocino, Marin, and Contra Costa counties. Sending material out-of-county comes with significant costs, and putting trucks on the road for longer trips contributes to greenhouse gases.
Potential Location of the New Facility
Various sites are being evaluated. Renewable Sonoma is currently negotiating with the City of Santa Rosa to lease City-owned property near the Laguna Treatment Plant. The preferred location in that area, on Llano Road, is currently used by the City for its biosolids composting facility.
As a separate matter, the City is exploring other, more cost-effective solutions for the beneficial reuse of biosolids produced by the treatment plant (biosolids are not an approved material for use in organic compost, and cannot be utilized by the new organics processing facility).
If all goes as planned (which depends on permitting, environmental review, construction, and many other factors), it’s anticipated that the new facility could open as soon as 2022.
(Aerial view of Laguna Treatment Plant and vicinity)
Anticipated Schedule 
Projected schedule for locating and implementing the new facility.
Funding
Renewable Sonoma and its partners will fund the development, construction, and operation of the new organics processing facility. They currently estimate the construction costs at over $50 million, and expect to recover those costs through the tipping (disposal) fees for green material that is brought to the facility.