California – Composting Rules

California’s regulations are written to encourage the production of high quality compost. Like other composters around the US, operations in California are required to meet certain performance standards of materials management so as to protect public safety and environmental health. California’s Department of Resources Recycling and Recovery’s regulations (Title 14, Division 7, Chapter 3.1) require that compost products meet certain standards that protect public health and safety.

California Composting Rules

Most Californian composting operations are required to apply for a permit; however, there are many exemptions, some of which are listed below. For example, facilities that have less than 500 cubic yards of compost on-site (of which less than 10 percent is food scraps) are exempt from the requirement to obtain a permit. In addition, in-vessel composting of up to 50 cubic yards is allowed without a permit.

Composting operations that are deemed a greater risk are required to either notify the enforcement agency or apply for a full permit. Facilities applying for a permit must adhere to specific site requirements. These include rules on the location and design of the facility, as well as the development of a plan to minimize odors and limit pathogen production.

According to 14 CCR § 17855, on-farm, small-scale food scrap composting operations that are exempt from the requirement to obtain a solid waste permit include the following:

  • Composting agricultural material derived on-site and of which no more than 1,000 cubic yards are sold or given away annually
  • Vermicomposting is exempt; however, handling of compostable material prior to or after vermicomposting composting is subject to regulation
  • Mushroom farming
  • “Handling of green material, feedstock, additives, amendments, compost, or chipped and ground material is an excluded activity if 500 cubic yards or less is on-site at any one time, the compostable materials are generated on-site and if no more than 1,000 cubic yards of materials are either sold or given away annually. The compostable material may also include up to 10% food material by volume”
  • Non-commercial composting of less than one cubic yard of food material produced and used on-site
  • In-vessel composting in vessels with a capacity less than 50 cubic yards


Requirements for Permits, Siting, and Performance Standards

There are many site requirements a compost facility must fulfill in order to receive a permit. Other requirements, such as testing for pathogens and preventing run-off of pollutants, are ongoing. In addition, compost facility operators must consent to inspection by the state enforcement agency.

A few of the major site requirements stated in California Regulations, Title 14, Division 7, Ch. 3.1, Article 6 include:

  • All handling activities shall be conducted in a manner that minimizes vectors, odor impacts, litter, hazards, nuisances, and noise impacts; and minimizes human contact with, inhalation, ingestion, and transportation of dust, particulates, and pathogenic organisms.
  • Random load checks of feedstocks, additives, and amendments for contaminants shall be conducted.
  • Contamination of compostable materials that has undergone pathogen reduction […] with feedstocks, compost, or wastes that have not undergone pathogen reduction […] or additives shall be prevented.
  • Unauthorized human or animal access to the facility shall be prevented.
  • The operator shall provide fire prevention, protection and control measures, including, but not limited to, temperature monitoring of windrows and piles, adequate water supply for fire suppression, and the isolation of potential ignition sources from combustible materials. Firelanes shall be provided to allow fire control equipment access to all operation areas.
  • Physical Contaminants and refuse removed from feedstock, compost, or chipped and ground material shall be removed from the site within seven days and transported to an appropriate facility.
  • An attendant shall be on duty during business hours if the operation or facility is open to the public.
  • Operators shall ensure that all personnel assigned to the operation shall be trained in subjects pertinent to operations and maintenance […] with emphasis on odor impact management and emergency procedures.


Selling Finished Compost

There are additional requirements found in Title 14, Division 7, Ch. 3.1, Article 2, § 17856, for composters who sell finished compost. All agricultural and green material composters must notify the enforcement agency prior to sale of a finished compost product.

  • Once the agency is notified, agricultural material compost can be sold in unrestricted quantities.
  • If less than 1,000 cubic yards of a combination of agricultural material and green material are sold in a year, the enforcement agency will inspect once annually. If the operator intends to store more than 12,500 cubic yards of green material on-site he/she must give advance notice to the enforcement agency, which may determine more frequent inspection is necessary.
  • If more than 1,000 cubic yards are sold or given away per year, operation must not have greater than 12,500 cubic yards of green material on-site and enforcement agency will inspect every three months.



Original post from July 30, 2012
Updated July 30, 2021