Compost Facility Permitting Guide for Solid Waste, Air and Water

A compost facility usually needs three separate kinds of approval: a solid waste permit for handling the material, an air permit where the local air agency regulates compost emissions, and a water approval for process water and stormwater. Local land use approval sits on top of all three. The agencies, thresholds and names differ by state, so the first task is to map which approvals apply to your feedstock, volume and site, and in what order.

Key takeaways

  • There is no single federal composting permit. EPA states that composting policies and regulations are set at the state and local level. Biosolids composting must also meet 40 CFR Part 503.
  • Permit level is usually driven by feedstock type and volume on site. Food material, biosolids and digestate push a project into higher tiers than green material alone.
  • In California, solid waste (CalRecycle and the local enforcement agency), air (the air district) and water (the Regional Water Board) are three separate tracks with separate applications.
  • Rule requirements differ inside one state. An 80% VOC control tier in an air district rule is a top tier that applies to specific operations, not a blanket requirement.
  • Measured data from a pilot (temperatures, emissions, water behavior) answers many of the questions regulators ask of a new technology or feedstock.
  • All rules cited here are as of October 2026. Check the current text before you apply.

The three permit families

Family What it regulates Typical agency What triggers a higher level
Solid waste Feedstocks accepted, volumes, operations, pathogen reduction, product testing, records, odor plans State solid waste agency, often through a county health or enforcement agency Food material, biosolids, digestate, mixed materials; more volume on site
Air VOC and ammonia emissions, odor nuisance, engines and grinders Local or regional air agency Feedstock type, annual throughput, location in a nonattainment area
Water Process water (leachate), pad and pond construction, groundwater protection, stormwater discharge State or regional water quality agency Feedstock type, volume on site, shallow groundwater, permeable soils
Land use (local) Zoning, conditional use, environmental review City or county planning department Any new site or major expansion

EPA confirms the general picture: composting policies and regulations are set at the state and local government level. One federal rule matters directly. If you compost sewage sludge (biosolids), the process must satisfy 40 CFR Part 503, whose Appendix B defines composting as a Process to Further Reduce Pathogens: 55°C or higher for three days in a within-vessel or static aerated pile system, or 55°C or higher for 15 days or longer with a minimum of five turnings in a windrow. EPA does not certify compost or composting systems; the operator demonstrates compliance with records.

California worked example

California has three separate tracks plus local land use, which makes it a useful template for asking the right questions elsewhere.

Solid waste: CalRecycle tiers under Title 14

CalRecycle’s compostable materials regulations (Title 14, Division 7, Chapter 3.1) place each activity in a tier. The local enforcement agency (LEA) processes the paperwork and inspects. CalRecycle’s tier placement table reads as follows:

Tier Composting activities placed in it Section
Excluded Activities listed in the exclusions 14 CCR 17855
Enforcement Agency Notification Agricultural material composting operations (all); green material composting operations (under 12,500 cubic yards); biosolids composting operations at publicly owned treatment works (all); research composting operations (5,000 cubic yards or less) 17856, 17857.1(a), 17859.1, 17862
Registration Permit Vegetative food material composting facilities (under 12,500 cubic yards) 17857.2
Full Solid Waste Facility Permit Composting facilities (all), for example biosolids, digestate, food material, mixed material; green material composting facilities (over 12,500 cubic yards); vegetative food material facilities (over 12,500 cubic yards) 17854, 17857.1(c), 17857.2

For green material, the 12,500 cubic yard figure counts feedstock, compost, or chipped and ground material on-site at any one time. What changes from tier to tier is the level of review. The notification tier carries no site-specific terms and conditions. A registration permit is issued by the LEA without prior CalRecycle concurrence. A full permit follows the Title 27 application process, requires the LEA to give notice and hold an informational meeting, and goes to CalRecycle for concurrence or objection.

Every tier must meet the state minimum standards. CalRecycle lists, among other things, a Report of Compost Site Information, an Odor Impact Minimization Plan, environmental health standards for sampling, metals, pathogen reduction and physical contamination, and (since the SB 1383 regulations took effect on January 1, 2022) measurement and quarterly reporting of organic waste in residuals sent to disposal. SB 1383 itself is a diversion and procurement law, not an air rule (see the key SB 1383 requirements).

Air: district permits and compost rules

California’s local air districts issue stationary source permits. CalRecycle’s list of other agencies with permitting authority names the air quality management districts and air pollution control districts alongside the LEA and the water boards. In the San Joaquin Valley, Rule 2010 requires an Authority to Construct before building or altering a source of air contaminants and a Permit to Operate before running it.

The two districts with the best-known compost rules do not regulate the same way:

  • South Coast AQMD. The Rule 1133 series, amended September 5, 2025, includes Rule 1133.2 (co-composting: any biosolids, or more than 20% manure) and Rule 1133.3 (all other composting). In Rule 1133.3, the 80% VOC and ammonia control requirement applies only to the active phase of piles with more than 10% food waste at sites processing more than 5,000 tons per year of food waste.
  • San Joaquin Valley APCD. Rule 4565 covers biosolids, animal manure and poultry litter operations. Rule 4566 covers organic material composting, with requirements that step up at 200,000 and 750,000 wet tons per year. Only operations at or above 750,000 wet tons per year must demonstrate at least 80% VOC reduction.

Read the rule for your district and throughput before you assume a control level. The VOC reduction list goes further.

Water: the State Water Board composting general order

The State Water Resources Control Board regulates discharges from composting through the General Waste Discharge Requirements for Commercial Composting Operations: Order WQ 2015-0121-DWQ, adopted August 4, 2015, as amended by Order WQ 2020-0012-DWQ on April 7, 2020. The Regional Water Boards administer it.

  • Tier 1: Tier 1 feedstocks only (such as green materials, vegetative agricultural materials and vegetative food materials), less than 25,000 cubic yards of materials on site at any given time, and site percolation rate and depth to groundwater that meet the order’s Table 3.
  • Tier 2: any Tier 2 feedstock (non-vegetative food materials, biosolids, digestate from those feedstocks), or 25,000 cubic yards or more on site, or site conditions that miss the Tier 1 standards. Tier 2 adds hydraulic conductivity limits for working surfaces, ditches and detention ponds.
  • Exempt: among others, composting within a fully enclosed vessel, operations with less than 500 cubic yards at any given time, and chipping and grinding.
  • How to enroll: a new operation must submit a Notice of Intent, the filing fee and a technical report to the Regional Water Board not less than 90 days before starting. When the package is complete, the board issues a Notice of Applicability that confirms the tier and monitoring method.

The order also prohibits composting within 100 feet of the nearest surface water or water supply well unless the board allows less, and requires containment sized for a 25-year, 24-hour peak storm. Stormwater discharge may need separate NPDES coverage from the Regional Water Board.

Land use and CEQA

CalRecycle lists the county or city planning department as responsible for CEQA compliance, conditional use permits, zoning and siting. It also cautions that operations cannot begin on a solid waste permit alone if other approvals are still required.

How other states differ

Washington. Composting is regulated under WAC 173-350-220. The solid waste handling permit comes from the jurisdictional health department, not directly from the state. Small volumes can be conditionally exempt, for example 25 to 250 cubic yards on site with a notice of intent filed thirty days before operation. Permitted facilities need engineering reports, plans and specifications prepared by a professional engineer registered in Washington, an approved plan of operation with odor prevention measures, and an annual report by April 1.

Oregon. Oregon DEQ uses a risk-based system. A permit is needed above 100 tons of feedstock per year for Type 1 and 2 feedstocks (yard debris, crop residues, vegetative food waste, manure) and above 20 tons per year for Type 3 feedstocks such as mixed food waste and meat, or 40 tons with an in-vessel system. DEQ then screens the site, and lower-risk facilities operate under a different type of permit than higher-risk ones. Exempt facilities still have to meet the performance standards.

Typical sequence

  1. Define the project in regulators’ terms: feedstock types, tons per year, maximum cubic yards on site, method, site hydrogeology.
  2. Hold pre-application meetings with the planning department, the solid waste agency, the air agency and the water agency. California’s general order encourages early consultation with Regional Water Board staff.
  3. Start land use and environmental review. It is usually the longest item.
  4. Prepare the technical documents: site plan, operations plan, odor plan, water management plan, engineering design.
  5. File air and water applications on their own clocks (for example, the 90-day Notice of Intent in California).
  6. File the solid waste application once the design is stable.
  7. Build, commission and operate to the permit: monitoring, records and reports.

Choosing a permitting route

Route Fits when Does not fit when
Start in a lower tier (smaller volume, limited feedstocks) You can begin with green material and grow later The business case depends on food material or biosolids from day one
Research or pilot authorization first The feedstock or technology is new to the regulator and data would settle questions The project is a standard design the agency already permits
Full permit from the start Tonnage contracts and funding require full capacity and all feedstocks Feedstock supply is uncertain and the review cost cannot be recovered
Modify an existing permit You already operate a permitted site and are adding feedstock or changing method The change is large enough that the agency treats it as a new facility

What an application needs, and how pilot data helps

Across agencies, applications ask for the same core information:

  • Feedstock types, sources and quantities, and maximum volume on site
  • Site plan with pads, drainage, ponds, setbacks and surrounding land uses
  • Process description with time and temperature monitoring for pathogen reduction
  • Odor management plan
  • Emission estimates and controls, with the test data behind them
  • Water management plan, pad and pond design, soil and groundwater data
  • Operations plan, recordkeeping and closure

A pilot answers a regulator’s questions about your feedstock on your site. Sustainable Generation’s pilots and demos program uses the SG MOBILE® System to run batches of a client’s own feedstock and generate data for permits, grants or board approval. SG’s Mid Valley Disposal profile describes a pilot in the San Joaquin Valley that shaped the full-scale design, including the discovery that the hot, arid site needed water addition.

When you rely on vendor emission data, ask how, where and on what feedstock it was measured. SG reports greater than 95% VOC control in third-party testing of its covered aerated static pile under a GORE® Cover, and describes its systems as tested against air district rules. Its SG COMPOST CONTROL™ System exports temperature and oxygen records for regulatory reporting. SG’s consulting page says its team assists with documentation for solid waste, air quality and stormwater permits; see also its permitting and engineering support page.

FAQ

Is there a federal permit for composting?

No general one. EPA says composting policies and regulations are set at the state and local level. Federal rules still reach specific cases: biosolids composting must meet the pathogen and vector requirements of 40 CFR Part 503, and stormwater discharges may need NPDES coverage administered by the state.

Which California tier applies to a food waste composting facility?

Vegetative food material facilities with less than 12,500 cubic yards on site fall in the registration permit tier, and larger ones need a full permit. Facilities taking other food material, biosolids, digestate or mixed material need a full solid waste facility permit regardless of size, according to CalRecycle’s tier table.

Does every California compost site need 80% VOC control?

No. That figure is a top control tier in specific district rules. In South Coast AQMD Rule 1133.3 it applies to the active phase of higher food waste piles at sites above a food waste tonnage threshold. In San Joaquin Valley APCD Rule 4566 it applies at 750,000 wet tons per year and above.

How does a pilot help with permits?

It replaces assumptions with records. Several weeks of logged temperatures show pathogen reduction, emissions sampling supports the air application, and observed drainage informs the water plan. It also gives regulators a working process to inspect before they rule on the full-scale application.

Next step

List your feedstocks, annual tons and maximum volume on site, then book pre-application meetings with each agency. If measured data would strengthen the application, talk to SG about a pilot or demo, or ask the consulting team how similar projects were documented.

Related guides

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