For a Sustainable Sonoma County
The creation of a new organics processing facility, which includes composting and anaerobic digestion, is being explored by the public agencies Zero Waste Sonoma and the City of Santa Rosa, with the private developer/operator Renewable Sonoma. A thorough environmental review must be undertaken for this project, which will address community concerns about possible environmental impacts. During that analysis, there will be several opportunities where formal community input and comment will be facilitated and encouraged. Informal public input is welcome at any time during the planning and development process.
Since there is currently no large-scale, industrial organics processing facility within Sonoma County, all collected green material and food scraps are 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. This new proposed organics facility would make out-hauling unnecessary and bring back valuable compost to the community. Farmers and residents alike will once again have access to high quality, locally produced compost at an affordable price.
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.
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 create compost, which is a nutrient-rich soil amendment. 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.
In 2015, Sonoma County’s local organics processing facility was permanently closed. Zero Waste Sonoma has since been working to re-establish the processing facility for organic 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 2018, 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.
Organics processing facility timeline
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. The proposed organics facility will accept residential curbside green bin materials, commercial food scraps, and self-hauled yard debris.
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.
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.
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.
For more information, please visit Renewable Sonoma: renewablesonoma.com
A robust environmental review of the proposed project will be conducted pursuant to the California Environmental Quality Act (CEQA). There will be opportunities for the public to participate, review findings, and provide formal comments through public meetings and hearings.
The proposed location was selected because it is centrally located within the County and is already operating as a facility to compost biosolids from the Laguna Treatment Plant, thereby reducing environmental impacts. The proposed location also provides easy access for businesses and residents to drop-off green materials and purchase high quality soil amendments. Additionally, locating the proposed organics facility next to the Laguna Treatment Plant creates synergies associated with the capture and treatment of process water and storm water from the site, which will result in a zero discharge facility.
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.
ZERO WASTE SONOMA