Zoning and Land Use Rules that Address Composting in San Diego County Jurisdictions


Compostables are not "Garbage"

Compostable materials, including food scraps, pose significant public health and sanitation challenges when treated as a solid waste material. Yet compostable material is an enormous agricultural resource when it is directed to more sustainable outlets like farms and compost facilities. 

Definitions of high-value compostable materials common to California and San Diego County municipal codes include “garbage,” “waste,” “solid waste,” “refuse,” and “putrescibles.” Kitchen and table food scraps, leftovers, and any unconsumed foods is referenced. All of these definitions direct how materials are disposed. Several, and in some cases, all of these classifications are included in various sections of San Diego County jurisdictions' municipal codes. This leads to confusion about what materials are recoverable under California's new rules and initiatives. This toolkit identifies local barriers to composting, develops recommendations to improve planning, and helps local jurisdictions comply with state mandates.

Large-Scale or Centralized Composting

Challenges that affect the siting of large-scale, centralized facilities include NIMBYism, expensive real estate, and ambiguous or non-existent policies. Despite these issues and need for infrastructure to meet state mandates and greenhouse gas emission reduction goals, only three jurisdictions address commercial composting facilities, defined as an industrial use. Outdated definitions of feedstocks are limited to green materials, wood wastes, and/or manures. Commercial and residential-based food materials are not defined in compost feedstock or facility type definitions, which represents ambiguity for development of emerging uses and facilities. 

Barriers and Opportunities for Small to Mid-Scale Composting

The majority of jurisdictions do not differentiate between the various scales and technologies of composting activities, nor the variety of feedstocks that can be processed. Most jurisdictions would require development of small to mid-scale composting projects, including in-vessel composting, to go through the same level of rigorous permitting as large-scale facilities. The permit costs and obstacles present formidable challenges, and are often immediate deal breakers. Jurisdictions in San Diego County are slowly becoming more aware of and responding to these challenges. For examples of local best practices, visit the Rules We Like! section. 

"Generated Onsite, Used Onsite"

It is generally accepted that materials generated onsite and used onsite are exempt from a permit, especially backyard and agricultural composting. Six jurisdictions expressly provide this exemption, though interpretation in a few codes is unclear due to size limits and permit requirements mentioned elsewhere in their respective codes. Interest in onsite composting is rising, although sites including restaurant rows and commercial strip malls might not have a use for all the finished product, nor produce the bulking agent required to compost the materials they generate efficiently. Existing codes are not in sync with state initiatives to allow businesses, schools and other entities to self-manage their compostables.

Composting in Zoning Codes

None of the 19 jurisdictions in San Diego County thoroughly address composting through their municipal codes, and no codes are written to address the range and scales of organics processing options. Jurisdictions with  established codes require modification to address statewide regulations and changing regional dynamics. As mentioned in the section, Composting - Benefits, Siting and Methods, composting is generally viewed as a solid waste or industrial activity, if addressed in municipal codes at all. While some jurisdictions mention composting in their health and sanitation code, composting as a use and the permitting process required is not necessarily defined in their respective zoning code.

Decentralized and Agricultural Composting

Farms, community gardens and sites where agricultural uses are permitted all serve as logical recipients of organic materials to produce soil amendments, if regulations allow them to import such materials from commercial and residential generators. Most San Diego jurisdictions with community garden ordinances limit composting to material generated onsite or provided by active garden members. Regulators have expressed concerns about opening up commercial or industrial composting activities to agricultural sites and whether the character of the agricultural use would be preserved. Composting, though historically a common agricultural activity, is generally not defined as an agricultural activity in county jurisdictions' municipal codes, nor is it specified as a use or accessory use in agricultural zones. Under current rules, importing or maintaining small composting volumes onsite would trigger a Use Permit, an expensive and lengthy process, even if the composting activity remained accessory to the property’s primary use. 


Vermicomposting/vermiculture is of emerging interest because the vermicompost and earthworms produced provide two streams of value added products. The activity does not require a composting permit from CalRecycle (though collection/transfer of feedstocks could require a transfer permit, and pre-composting of feedstocks may depend on the volume and temperatures of the piles). Vermicomposting is typically classified as a backyard composting or educational classroom activity, and it is undervalued for its commercial potential. Only three jurisdictions specifically address vermiculture in zoning and land use codes, though others encourage it in backyard and educational settings.  When defined, the codes include limits on activity size and/or source of materials in residential applications. Commercial vermiculture is not addressed well, and in most codes, not at all.

Composting for Manure Management

Onsite composting of manure is an established best practice recognized by four of the seven jurisdictions that address manure management in their codes. One jurisdiction effectively suppresses both onsite and offsite manure management options by explicitly requiring a Minor or Major Use Permit for most animal waste processing. A small percentage of horse manure is composted in San Diego County jurisdictions and the majority is landfilled or mismanaged by dumping it in back lots or open spaces.