Composting rules and regulations in Wisconsin

Wisconsin’s composting rules 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. The new rules require most compost sites to turn the piles or windrows and to measure their temperature. Anyone managing a compost site, no matter what the size, should operate in a nuisance-free and environmentally sound manner.

Use of a probe to test compost temperature
Typical probe used to measure windrow temperature.

The DNR regulates sites that compost yard materials or food scraps if the facilities have more than 50 cubic yards of material on-site at any time. For more details, see the sections below. Households, neighborhoods, community gardens and businesses do not need DNR approval for composting yard materials, vegetable food scraps and manure, as long as the site has less than 50 cubic yards of compost at any time. Check with your community to find out if any local regulations apply.

Recent changes to the compost rule

Wisconsin's compost rule, s. NR 502.12, Wis. Adm. Code [exit DNR], has been modified and the changes took effect June 1, 2012. T If you have questions about the changes, please contact Brad Wolbert (608-264-6286) or Jack Connelly (608-267-7574).

Specific compost rules and regulation information

Yard materials

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. New or expansion sites accepting more than 1,000 cubic yards of yard materials must request the DNR conduct an initial site inspection to confirm that the site meets the location criteria. The one-time fee for an initial inspection for sites handling up to 20,000 cubic yards of yard materials is $550. Use DNR Form 4400-209 [PDF] to request an initial site inspection.

Leaf composting
Leaf composting in windrows.

After DNR staff conduct the initial site inspection confirming the site meets the location criteria—for example, not located in a floodplain or too close to neighbors—the prospective operator should complete a Composting Facility Application (Form 4400-282) [PDF]. After the application is reviewed and approved by DNR staff, the DNR will send out a compost facility license application.

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. This includes turning the piles or windrows and taking temperatures. A facility must renew its license each year, but there is no fee for a composting license. See the links below for more information:

Food scraps

Source-separated compostable material composting (includes food)

Source-separated compostable material means compostable materials separated from non-compostable material at the point of generation for use in composting and kept separate from municipal solid waste. These include:

  • food scraps;
  • yard, garden and greenhouse trimmings;
  • farm and non-farm crop residues;
  • aquatic plants;
  • vegetative food processing residues such as from cannery and brewing activities;
  • fish harvesting and processing residuals;
  • farm and herbivorous animal manure, excluding deer and elk manure, and associated animal bedding;
  • clean chipped wood;
  • clean sawdust;
  • non-recyclable compostable paper; and
  • other similar materials approved in writing by the DNR.

This term does not include biosolids, domestic wastewater, sewage sludge or septage, high-volume industrial waste, rendering or slaughterhouse wastes, animal carcasses, other solid waste or hazardous waste.

Composting sites that manage 5,000 cubic yards or less of source-separated compostable material on-site at one time may operate under similar 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 5,000 cubic yards.

Leaf composting
Food scraps prior to being processed and incorporated into windrows.

In addition to complying with the minimum design and operation standards, operators of source-separated compostable material sites must submit a proposed plan of operation describing the site operations, providing a map of the site showing neighboring properties and including a plan for controlling run-on to and run-off from the site.

Source-separated compostable materials composting facilities may also compost food-related 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 their composting process meets the requirements for items such as biodegradable plastic bags and cutlery. These items do not readily biodegrade except under certain conditions and may cause problems with equipment and compost quality.

It may be possible in some cases to combine source-separated compostable materials and yard materials composting operations. Discuss this with your regional DNR recycling specialist for the county where the compost facility will be located.

Large sites

Larger compost sites for yard materials or food scraps

Composting sites designed for more than 20,000 cubic yards of yard materials or over 5,000 cubic yards of source-separated compostable material 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. The DNR has developed a checklist to help develop a plan of operation.

For more details, see Composting Facility Application (Form 4400-282) [PDF]  The application form lists the steps needed to obtain a license and includes a checklist of what needs to be submitted.

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.

Farms

A farm-scale rotating drum composter
A farm-scale rotating drum composter (photo from Washington State University [exit DNR])

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. In most cases a DNR composting license is not needed for on-farm composting of farm materials.

Farm crop residue

Farm sites composting farm crop residue or manure from their operations need only meet minimum requirements including the performance standards s. NR 502.04, Wis. Adm. Code [exit DNR] and operating in a nuisance-free and environmentally sound manner.

If off-site source-separated compostable material other than farm crop residue and manure is accepted, the farm must meet the following additional requirements.

  • meet locational criteria;
  • meet minimum operational and design standards;
  • measure temperature of compost piles and how frequently the pile is turned; and
  • inspect the stormwater control measures used on site during storm events

Farm facilities accepting off-site material must limit the combined volume of off-site material accepted to 10,000 cubic yards unless they obtain a composting license.

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, under s. NR 243.15(8), Wis. Adm. Code [PDF 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 agricultural runoff 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.

Note that manure from deer or elk may not be used as a raw material in farm compost.

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 exit DNR]. Deer or elk carcasses may not be composted at unlicensed farm compost facilities

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:

Yard materials

Farmers doing on-site carcass composting may accept yard materials and clean chipped wood from off-site without obtaining a DNR license 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; and
  • ensure that the site meets the minimum design and operation standards under s. NR 502.12, Wis. Adm. Code [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 composting on-site – that is, materials other than yard waste (described above) are generated by agriculture operations under common ownership or management; materials such as manure and carcasses are not accepted from other farmers;
  • operates in a nuisance-free and environmentally sound manner;
  • meets the performance standards in rule s. NR 502.04, Wis. Adm. Code [PDF exit DNR].
  • landspreads the compost according to rule s. NR 518.04, Wis. Adm. Code [PDF 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

Other solid waste composting

A facility composting materials other than yard materials and source-separated compostable materials is regulated as a processing facility under s. NR 502.08, Wis. Adm. Code [PDF 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 a mixture including any industrial solid waste, such as paper mill sludge, mixed with yard materials or food scraps, is regulated as either a solid waste processing facility by the DNR's Waste and Materials Management Program or under a wastewater discharge permit by the agency's 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 slaughterhouse wastes is likely to have very different design and operating needs than one processing paper mill sludge and chipped wood.

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 recycling specialist assigned to the county where your facility is located 

Last revised: Monday December 09 2013