Compost Rules and Regulations

• Compost Sites with up to 20,000 Cubic Yards of Yard Materials
• Food Scrap Composting
• Large Composting Sites for Yard Materials or Food Scraps
• On-farm Composting
• Other Solid Waste Composting

Composting is the preferred way to manage yard materials and is fairly easy to do properly. Wisconsin's regulations are minimal, including basic operating and location requirements to prevent composting from becoming a nuisance to neighbors and to ensure nutrients are not released to groundwater or nearby lakes and streams. Anyone managing a compost site, no matter what the size, should operate in a nuisance-free and environmentally sound manner.

DNR regulates sites that compost yard materials or vegetable food scraps if the facilities have more than 50 cubic yards of material on-site at any time. For more about site regulations, see the sections below.

Households, neighborhoods, community gardens and businesses do not need DNR approval for composting yard materials and vegetable food scraps (manure may also be added to enhance nutrients and decomposition) as long as they do not have more than 50 cubic yards on-site at any one time. You should check with your community to find out if any local regulations apply to composting.

Compost Sites With up to 20,000 Cubic Yards of Yard Materials

Facilities may compost between 50 and 20,000 cubic yards of yard materials with minimal regulatory requirements. A prospective site operator must provide site location information to the DNR. Staff will then visit the proposed site to confirm that the site meets the location criteria. This step is known as an initial site inspection. The one-time fee for an initial inspection for sites handling up to 20,000 cubic yards of yard materials is $550.

The site owner is responsible for making sure the site is suitable--for example, not located in a floodplain or too close to neighbors. After DNR staff conduct the initial site inspection confirming the site meets the location criteria, the prospective operator can obtain a license. From the time an operator requests an initial site inspection, it may take about one month to get a license.

These sites do not have to submit a formal design and operating plan, but must comply with the minimum design and operation standards described in state rules. A facility must renew its license each year, but there is no fee for a composting license. See the links below for more information:

Composting Facilities Eligible for Exemption, PUB-WA 1025 2006 [PDF 66KB]

Composting and Landspreading Source Separated Solid Waste Rule Summary, PUB-WA 1057 2006 [PDF 86KB]

Food Scrap Composting

Composting sites that manage 500 cubic yards or less of vegetable food scraps (raw or cooked vegetable or fruit scraps) on-site at one time may operate under the same minimal requirements that apply to yard material compost facilities of up to 20,000 cubic yards. Yard waste and clean chipped wood may be added to the food scraps as long as the total amount of material on-site remains under 500 cubic yards.

Food scrap composting facilities may also compost food containers and utensils that meet ASTM International standards for biodegradability (for example, paper cups and plates and degradable cutlery). Facility operators should use caution in accepting these materials, however, and be sure that their composting process will meet the requirements for items such as biodegradable plastic bags and cutlery, as they do not readily biodegrade except under certain conditions and may cause problems with equipment and compost quality.

A 500-cubic-yard vegetable food scrap operation is usually sufficient to compost the material generated by a small community of roughly 2,500 people.

It may be possible in some cases to combine food scrap and yard materials composting operations. Discuss this with your regional DNR composting staff specialist. (To get this contact information, go to the DNR Staff Directory Subject Search and enter "compost" in the search field.)

Larger Compost Sites for Yard Materials or Food Scraps

Composting sites designed for more than 20,000 cubic yards of yard materials or over 500 cubic yards of vegetable food scraps must have both an initial site inspection and a written plan of operation approval from the DNR.

To obtain approval, the prospective owner must prepare and submit to the DNR for review a plan describing how the facility will meet the specified design, operation and monitoring requirements. If critical engineered features are necessary, the plan must also describe how the owner will ensure the use of proper construction methods, and the owner may be required to submit a construction documentation report. For more detail about the requirements that apply, see the publication links provided above.

On-farm Composting

Farmers may compost crop residues, manure and animal carcasses generated on their farm sites. Depending on the material and size of the farming operation, DNR wastewater and/or solid waste rules may apply.

Manure

For manure composting, a livestock operation that is a confined animal feeding operation (CAFO) must have a Wisconsin Pollution Discharge Elimination System (WPDES) wastewater discharge permit, administered by the DNR Wastewater Program, The requirements in s. NR 243.15(8), Wis. Adm. Code [PDF 222KB, exit DNR], apply to manure composting by a CAFO. Smaller farms that combine their manure for composting may be treated as a CAFO, if the combined manure is equivalent to the amount that would be generated by a CAFO.

For information about large-scale farm animal manure or carcass composting, contact your DNR regional animal waste specialist, or Gretchen Wheat, Water Resources Engineer, Bureau of Watershed Management.

For smaller farms not subject to these CAFO rules, composting is regulated by DNR solid waste rules.

Carcasses

All farms, regardless of size, must manage carcasses in compliance with state law that prohibits carcass placement in any stream, lake or swale, and strictly limits the time a carcass may be left accessible to dogs or wild animals (24 hours in April to November, or 48 hours in December to March). All farms are also subject to the agricultural performance standards and prohibitions in subch. II of ch. NR 151, Wis. Adm. Code [PDF 185KB, exit DNR].

While rendering remains the preferred method for handling most routine farm animal mortalities, composting can provide an effective option for disposal and recycling if done properly. See the following publication for a step-by-step description of the process and tips on how to avoid problems such as odors and other nuisance conditions:

• Composting Animal Mortalities [PDF exit DNR]

Yard materials

Farmers may accept yard materials and clean chipped wood from off-site if the following conditions are met:

• Mix yard materials and/or clean wood chips with farm-generated wastes to increase the carbon to nitrogen ratio and porosity.
• Ensure the total waste and compost on-site does not exceed 10,000 cubic yards on-site at any one time.
• Ensure that the site meets the minimum design and operation standards in s. NR 502.12, Wis. Adm. Code [PDF 194KB, exit DNR].

Other requirements

A farm composting operation is exempt from other state solid waste regulations if it meets the following conditions:

• The operation is "on-site" composting--that is, materials (other than yard waste as described above) are generated by agriculture operations under common ownership or management--materials such as manure and carcasses are not accepted from other farmers.
• Operate in a nuisance-free and environmentally sound manner.
• Meet the performance standards in rule s. NR 502.04, Wis. Adm. Code [PDF 194KB, exit DNR].
• Landspread the compost according to rule s. NR 518.04, Wis. Adm. Code [PDF 42KB, exit DNR].

If a farm composting operation does not meet these conditions of exemption, it must follow the requirements of regular composting operations found elsewhere on this page.

Other Solid Waste Composting

A facility composting materials other than yard materials and vegetable food scraps is regulated as a processing facility under s. NR 502.08, Wis. Adm. Code [PDF 194KB, exit DNR]. (This does not include household composting and on-site farm composting.)

This is true regardless of the composting facility size. For example, a facility composting 500 cubic yards or less of food scraps that include any meat would be considered a solid waste processing facility and would need a plan approval from the DNR. A facility composting a mixture including any industrial solid waste, such as paper mill sludge mixed with yard materials or food scraps, is also regulated as either a solid waste processing facility by the Waste and Materials Management Program or under a wastewater discharge permit by the Watershed Program.

The processing facility rule allows the DNR to write a customized permit based on the type of solid waste to be processed, the proposed processing methods and site-specific conditions. For example, a facility composting meatpacking byproducts is likely to have very different design and operating needs than one processing mixed food materials from kitchens or cafeterias.

Just as for large composting facilities, processing facilities must meet location criteria and have an initial site inspection. A facility must get DNR approval of a plan describing how the facility will be designed, constructed, operated and monitored. The facility will also need a solid waste processing license.

For assistance regarding proposed processing facilities, contact your regional DNR composting staff specialist. Visit the DNR Staff Directory Subject Search and enter "compost" in the search field.