Maine – Composting Permit Exemptions

In 2009, Maine adopted significant changes to its compost facility rules in an effort to advance the practice of composting. The revision of Maine’s composting rules was mandated by Chapter 139 of the 2007 Legislative Resolves, which directed the Departments of Agriculture and Environmental Protection to collaborate to 1) ease the regulatory burden on agricultural composting operations and 2) revise the volume and types of materials that may be composted without a permit from the state.¹ 

Current Regulations

The Resolve resulted in the adoption of new composting rules, including new permit exemptions, changes to regulatory thresholds, and feedstock classification. State composting rules were separated into a new chapter of solid waste regulations (CMR 410) in order to differentiate municipal and agricultural composting facilities. Maine’s current composting rules can be found in 06-096 Chapter 410 of Maine’s Department of Environmental Protection rules. 

Feedstock Classification

Maine developed a classification system for different types of compost feedstocks, based on the ratio of carbon to nitrogen (C:N) in the given material. Materials with a higher proportion of nitrogen (i.e. a lower C:N ratio) have greater potential to produce odors or leachate, while others have far less risk and thus fewer required regulatory restrictions. 

• Type IA residuals consist of leaves, vegetative matter, and other residuals with a carbon-to-nitrogen (C:N) ratio exceeding 25:1.
• Type IB residuals include food and other residuals with a C:N ratio ranging from 25:1 to 15:1.
• Type IC residuals include fish and other residuals with a C:N ratio less than 15:1.

Permit-exempt Facilities

A composting operation is permit-exempt if, in a (30) consecutive day period, the facility accepts less than: 

• Ten (10) cubic yards of Type IA residuals
• Five (5) cubic yards of Type IB residuals
• Five (5) cubic yards of Type IC residuals
• Composts 10,000 cubic yards of residuals or less of animal manure per year

Solid waste composting during a Department-supervised remediation, emergency response, or research project is also exempt from permitting requirements.

On-farm Composting Exemptions

Agricultural Composting Operations that carry out the following activities, as detailed in Chapter 410, are also exempt from requiring a permit: 

• In any thirty (30) consecutive day period, compost a total of between (5) and sixty (60) cubic yards of Type IB and IC residuals;
• Compost any volume of Type IA, Type IB, or Type IC waste provided that at least 70% of the finished compost product is used at appropriate agronomic rates on the farm that produced the compost within two (2) years after it is produced;
• Use leaves as an amendment to compost manure;
• Compost offal; or 
• Composts domestic animal and poultry carcasses from routine events pursuant to the Maine Department of Agriculture, Food, and Rural Resources’ “Rules and Regulations Relating to Disease Control of Domestic Animals and Poultry,” 01-001 CMR 211.

Although the Maine Department of Environmental Protection issues solid waste management rules for composting, it is stated that the exempt facilities above should still comply with the Department of Agriculture, Food, and Rural Resources’ Best Management Practices. Operations must still develop and implement a Compost Management Plan in accordance with the rules found in Section 01-001-565-8 of the Rule Chapters for the Department of Agriculture, Conservation and Forestry.

Composting Resources in Maine

Maine Composting School

The University of Maine Cooperative Extension (UMCE), Maine Department of Agriculture, Food and Rural Resources (DAF&RR), Maine Department of Environmental Protection (DEP), and Maine State Planning Office (SPO) offer a regularly scheduled Maine Compost School. This school provides training to people interested in or involved with medium and large-scale composting operations. This course is offered as a certificate program and trains people to be qualified compost site operators.

More Information

• Maine Solid Waste Management Rules, Chapter 410: Composting Facilities (June 2018)
• Maine Dept. of Env. Protection – Guide to Recovering and Composting Organics (March 2016)
• Maine Dept. of Agriculture, Conservation, and Forestry – Composting Program

¹ Note: A “Resolve” is defined in Maine as “Laws having a temporary or limited purpose that do not amend the general public laws.”

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Original post from July 30, 2012
Updated April 18, 2024