NR 502.12(10)
(10)
Minimum operational standards for composting facilities. Unless exempt under sub.
(2) or
(4), no person may operate or maintain a composting facility regulated under this section except in accordance with the following minimum operational requirements:
NR 502.12(10)(a)
(a) Raw materials accepted for composting shall be source separated at the point of generation so that they have not been mixed or otherwise contaminated with nonapproved waste types, particularly materials which are not readily compostable. Prior to incorporation into the composting process, the raw materials shall be sorted as needed to ensure that materials which are not readily compostable are removed unless alternate operational methods are used in conjunction with equipment to produce a compost product virtually free of physical and chemical contaminants.
NR 502.12 Note
Note: Compost product which contains physical or chemical contaminants such as plastic, glass, metal scraps or regulated concentrations of heavy metals or organic compounds, may require controlled disposal under an approved landspreading plan or at a landfill.
NR 502.12(10)(b)
(b) Raw materials in noncompostable bags shall be debagged within 24 hours of receipt at the facility. Raw materials, other than leaves and brush, in compostable bags shall be processed such that the contents of the bags are exposed to air within 24 hours of receipt at the facility. Stored waste shall be managed in accordance with the requirements applicable to the composting process. The following operational standards shall also be met for the wastes specified:
NR 502.12(10)(b)1.
1. Grass clippings and food residuals from canned, frozen or preserved fruit or vegetable processing operations shall be incorporated into windrows or another composting process within 72 hours of receipt at the facility, unless odor becomes a problem at the facility in which case these materials shall be incorporated within 24 hours.
NR 502.12(10)(b)2.
2. Animal carcasses, fish harvesting and processing residuals, manure and food residuals which are not from canned, frozen or preserved fruit or vegetable processing operations shall be incorporated into windrows or another composting process on the same operating day as received at the facility. Upon initial incorporation of these residuals, composting windrows or piles shall be covered with a minimum 6 inch layer of compost, high carbon material such as wood chips, or other suitable material to control odor and vectors.
NR 502.12(10)(b)3.
3. All animal carcasses and food residuals shall be managed to prevent access by dogs and wild animals.
NR 502.12(10)(c)
(c) Compost raw materials shall be size reduced if necessary to provide adequate particle surface area for effective composting.
NR 502.12(10)(d)
(d) Materials within the composting process shall be thoroughly mixed as appropriate to the composting method and aerated as frequently as necessary. Windrow height, structure and porosity shall be designed and maintained to ensure that adequate oxygen is available at all times within the windrow or pile to prevent the process from becoming anaerobic.
NR 502.12 Note
Note: To maintain aerobic composting and prevent odor, aeration is needed whenever the process temperature rises to 150°F or more. Windrows consisting primarily of leaves and wood waste are likely to require turning at least monthly from spring through fall.
NR 502.12(10)(e)
(e) Materials shall be mixed into the composting process to provide a minimum initial carbon to nitrogen ratio of 20:1.
NR 502.12 Note
Note: For aerobic composting, the optimum carbon to nitrogen ratio ranges from approximately 20:1 to 40:1.
NR 502.12(10)(f)
(f) Maximum windrow size and minimum windrow spacing shall match the capability and requirements of the equipment utilized at the facility.
NR 502.12(10)(g)
(g) Material within the composting process shall be wetted as needed to control dust and maintain a moisture content conducive to efficient composting.
NR 502.12 Note
Note: For aerobic composting, the optimum moisture content is 50 to 60% by weight.
NR 502.12(10)(h)1.
1. Stabilized to reduce pathogenic organisms and to ensure that the materials do not reheat upon standing.
NR 502.12(10)(h)2.
2. Free of sharp particles which could cause injury to persons handling the material.
NR 502.12(10)(h)3.
3. Free of toxins and pathogens in amounts or concentrations that could cause detrimental impacts to public health or the environment.
NR 502.12 Note
Note: Pathogens are defined in ch.
NR 204 as “disease causing organisms, including but not limited to certain bacteria, protozoa, viruses and viable helminth ova." Appropriate methods for pathogen reduction during composting are specified in 40 CFR, Part
257, Appendix II, Section B:
NR 502.12 Note
1. For in-vessel or static aerated pile composting, maintain a continuous minimum temperature of 55°C, or 131°F, for a minimum of 3 consecutive days.
NR 502.12 Note
2. For windrow composting, attain a minimum temperature of 55°C, or 131°F, on a minimum of 15 days, which are not required to be consecutive, and turn the windrow a minimum of 5 times during the high temperature periods.
NR 502.12(10)(i)
(i) Compost product storage time shall be minimized to maintain the quality of the compost and the product shall be marketed as necessary to prevent excessive stockpiling.
NR 502.12(10)(j)
(j) The facility shall be operated in a nuisance-free and environmentally sound manner.
NR 502.12 Note
Note: Landspreading of composted leaves, grass, brush and other source-separated compostable material is exempt from department landspreading regulations under s.
NR 518.04 (1) (i) provided the material is applied as a soil conditioner or fertilizer in accordance with accepted agricultural practices and the facility is operated and maintained in a safe, nuisance-free manner. Public distribution of the compost may be regulated by the department of agriculture, trade and consumer protection (DATCP).
NR 502.12(11)
(11)
Minimum design standards for composting facilities. Unless exempt under sub.
(2) or
(3), no person may construct or maintain a composting facility regulated under this section except in accordance with the following minimum design standards:
NR 502.12(11)(a)
(a) Run-off from the composting area shall be discharged to a gently sloping vegetated area of sufficient size to prevent erosion and any discernible confined and discrete discharge of liquids or suspended solids to surface water or wetlands from the composting area.
NR 502.12(11)(b)
(b) Slope, vegetation and surface water containment ditches, retention basins, compost berms or socks and other best management practices shall be used at the facility as needed to minimize erosion, prevent pollutant discharges from storm water runoff and maintain diffused surface drainage.
NR 502.12(11)(c)
(c) Composting shall take place on an area sloped sufficiently to prevent ponding, and measures such as berms or ditches shall be used to prevent storm water run-on.
NR 502.12(11)(d)
(d) If inspections performed under sub.
(15) (a) 4. indicate improvements in storm water controls are needed to meet the requirements of pars.
(a) through
(c), the owner and operator of the facility shall make the needed improvements as soon as practicable and update the storm water pollution prevention plan, if applicable.
NR 502.12 Note
Note: Under ch.
NR 216, new or expanding facilities with one acre or more of land disturbance are required to obtain a construction site storm water permit. In addition, the department may require a composting facility to obtain an industrial storm water discharge permit if it does not maintain compliance with a separate department permit or approval which includes storm water control requirements that are at least as stringent as those required under ch.
NR 216, resulting in the discharge of pollutants to waters of the state or constituting a significant contribution of pollutants to the waters of the state.
NR 502.12(11)(e)
(e) The overall composting facility shall be of sufficient size to allow processing of materials as necessary to avoid nuisance conditions, and shall have adequate room for material stockpiles, windrows of manageable dimensions for maintaining aerobic conditions, curing piles, staging of finished compost, and equipment.
NR 502.12 Note
Note: Composting facilities that accept manure or are located at a livestock operation may be subject to additional state requirements in chs.
NR 151 and
243 and in
ATCP 51, as well as local regulations for manure storage and shoreland and floodplain zoning. Other local ordinances may apply to facilities regulated under this section.
NR 502.12(12)
(12)
Additional operational and design standards for nonexempt composting facilities. Unless exempt under sub.
(2),
(3),
(4),
(5),
(6), or
(7), new or expanded composting facilities regulated under this section shall comply with the following additional operational and design standards:
NR 502.12(12)(a)
(a) All run-off that contacts materials being composted or raw materials staged for composting shall be managed as leachate and shall be directed to either a collection basin or a tank. Leachate may be used in the composting operation for moisture addition. All other leachate shall be treated at an onsite or offsite wastewater treatment facility permitted to accept it.
NR 502.12(12)(b)
(b) All composting, and all storage of uncomposted raw materials other than leaves, clean chipped wood, clean sawdust and other raw materials with initial carbon to nitrogen ratios greater than 30:1 shall take place on a low-permeability pad constructed of asphalt, concrete, recompacted clay or other material approved by the department.
NR 502.12(12)(c)
(c) At a minimum, the leachate collection capacity shall be designed for a 25 year, 24 hour storm event as defined in s.
NR 205.05.
NR 502.12(13)
(13)
Plan submittal requirements for nonexempt and certain exempt composting facilities. Unless the facility is exempt under sub.
(2),
(3),
(4),
(5), or
(6), applicants for all new or expanded composting facilities regulated under this section shall submit a plan of operation report and obtain department approval of the plan of operation report prior to construction of the new or expanded facility. Unless an exemption is granted by the department in writing, the plan shall be submitted in accordance with s.
NR 500.05, except that facilities exempt under sub.
(7) need not comply with s.
NR 500.05 (4). The plan shall provide a design which complies with subs.
(10) and
(11) and, as applicable, sub.
(12), and contain the following minimum information:
NR 502.12(13)(a)
(a) The location of the property where the facility is proposed to be located.
NR 502.12(13)(b)
(b) A brief description of the project, including the area served, an estimate of the annual tonnage and volume of material to be processed and identification of the materials to be used in the compost process.
NR 502.12(13)(c)
(c) A description and drawing of the proposed facility, including location and size of windrows, or other composting process, on site traffic and process flow, the property boundaries, routes to transport feedstocks and finished compost to and from the facility and present land use within 1/4 mile of the facility.
NR 502.12(13)(d)
(d) A description of the procedures for processing the material prior to incorporation into the windrow, or other composting process, such as de-bagging or size reduction.
NR 502.12(13)(e)
(e) For each raw material proposed to be composted, either laboratory or literature data documenting the carbon, nitrogen, and moisture content and pH.
NR 502.12(13)(f)
(f) A proposed raw material mix for composting, with calculations or laboratory data documenting the carbon, nitrogen, and moisture content and pH of the mix.
NR 502.12(13)(g)
(g) A specification of the maximum size, including volume, height and width, for staging piles, composting windrows or other composting processes, curing piles, and finished compost storage. If the materials on site at any one time will exceed 40,000 cubic yards of yard residuals and clean chipped wood, 10,000 cubic yards of source-separated compostable materials other than yard residuals and clean chipped wood, or 5,000 cubic yards of food residuals, an estimate of closure costs shall be provided with the plan of operation report, and prior to licensure, proof of financial responsibility in accordance with ss.
NR 520.06 through
520.13 shall be provided for the closure costs, including the removal, transport and ultimate disposal of all waste material and compost at the site.
NR 502.12(13)(h)
(h) A specification of the methods of measuring critical parameters within the windrow and other composting processes, and a description of methods that will be used to ensure the critical parameters are met. Critical parameters addressed shall include carbon to nitrogen ratio, temperature, moisture content, oxygen content, pH and stability. The specification shall describe methods to be used for maintaining aerobic conditions during the composting process, including turning equipment and frequency for passive ventilation, and equipment and residence time for mechanical ventilation, as well as actions to be taken in response to odors and composting process upsets.
NR 502.12(13)(i)
(i) A description of the type of vehicles used for transporting feedstocks and finished compost to and from the facility, and a description of the type of equipment for turning or mixing and screening.
NR 502.12(13)(j)
(j) A discussion of potential markets for the compost and material specifications necessary to be met for these markets, such as nutrient content, pH, particle size, appearance, moisture holding capacity or other pertinent specifications.
NR 502.12(13)(k)
(k) Identification of any noncompostable waste, such as bags, which will be generated from the composting operation, and the name and location of solid waste disposal facilities at which any waste generated from the composting operation will be disposed of.
NR 502.12(13)(L)
(L) Specification of the design, construction and documentation to be used for the low permeability pad, including materials, thicknesses and testing.
NR 502.12(13)(m)
(m) A description of the planned sampling frequency and testing parameters for the finished compost.
NR 502.12(13)(o)
(o) Identification of local zoning and permit requirements that apply to the proposed facility.
NR 502.12 Note
Note: Under ch.
NR 216, new or expanding facilities with one acre or more of land disturbance are required to obtain a construction site storm water permit.
NR 502.12(13)(p)
(p) Proposed procedures for amending the plan in the event changes to the approved plan are needed.
NR 502.12(14)
(14)
Construction documentation for nonexempt composting facilities. NR 502.12(14)(a)
(a) For facilities other than those exempt under sub.
(2),
(3),
(4),
(5),
(6), or
(7), the department may require owners and operators of new or expanded composting facilities regulated under this section to submit a construction documentation report to the department and obtain department approval of the construction documentation report prior to operation of the facility.
NR 502.12(14)(b)
(b) Unless an exemption is granted by the department in writing, the construction documentation report shall be prepared in accordance with the department's plan approval and the requirements in s.
NR 500.05. The construction documentation report shall be approved by the department prior to obtaining a license and prior to accepting waste at the facility.
NR 502.12(15)(a)
(a) Unless exempt under sub.
(2),
(3),
(4),
(5),
(6), or
(7), owners and operators of composting facilities regulated under this section shall complete monitoring and reporting in accordance with the plan of operation approval and the following requirements:
NR 502.12(15)(a)1.
1. Samples of the finished compost that is ready for sale, distribution or use shall be collected every 2,000 tons or 4,000 cubic yards, with a minimum of one sample per year, or, alternatively, in accordance with the testing frequency specified by the United States Composting Council's Seal of Testing Assurance program, unless a different frequency is approved in writing by the department, and tested for the parameters in Tables 1 and 2.
NR 502.12 Note
Note: Only class A compost under sub. NR 502.12 (16) is subject to the limits in Tables 1 and 2. “Test Methods for Evaluation of Compost and Composting" (2002) and a list of laboratories certified under the Seal of Testing Assurance program are available from the United States Composting Council, 5400 Grosvernor Lane, Bethesda, Md 20814 (301) 897-2715,
www.compostingcouncil.org.
NR 502.12(15)(a)1.a.
a. Samples shall be collected, handled and analyzed in accordance with methods listed in “Test Methods for Evaluation of Compost and Composting" published in 2002 by the United States Composting Council or other methods approved in writing by the department. Samples shall be tested at a laboratory certified under the United States Composting Council's Seal of Testing Assurance program or at another laboratory approved in writing by the department.
NR 502.12 Note
Note: “Test Methods for Evaluation of Compost and Composting" (2002) and a list of laboratories certified under the Seal of Testing Assurance program are available from the United States Composting Council, 15400 Grosvernor Lane, Bethesda, Md 20814 (301) 897-2715,
www.compostingcouncil.org.
NR 502.12(15)(a)1.b.
b. Test results shall be made available upon request to the department, potential users of the compost, and to the general public.
NR 502.12(15)(a)2.
2. Unfiltered leachate samples shall be taken from the collection basin or tank, and tested quarterly for the first 4 quarters and annually thereafter for BOD
5, COD, field pH, field conductivity corrected to 25
°C, nitrate+nitrite-nitrogen, and total dissolved solids.
NR 502.12(15)(a)3.
3. Compost pile turning frequency and temperature readings as appropriate to the composting method used shall be documented and maintained to demonstrate pathogen reduction and odor control activities.
NR 502.12(15)(a)4.
4. The facility shall be visually inspected by the owner or operator quarterly to evaluate storm water discharge quality and performance of discharge controls, and twice per year to identify non-storm water discharges if present.
NR 502.12(15)(b)
(b) Unless exempt under sub.
(2),
(3),
(4), or
(5), the owner or operator of a composting facility regulated under this section shall prepare and submit an annual report to the department by March 1 on forms supplied by the department. The annual report shall include at least the following information:
NR 502.12(15)(b)3.
3. Annual quantities and types of raw materials received and compost produced, in tons. Tonnage estimates may be based on volume records where scale weights are not available.
NR 502.12(15)(b)4.
4. Annual quantity of compost sold, distributed or used, in tons, and quantity of class A compost sold, distributed or used.
NR 502.12(15)(b)6.
6. Any additional information required as a condition of the plan of operation approval.
NR 502.12(16)
(16)
Class A compost. Finished compost may be designated and distributed as class A compost if it meets all of the following requirements:
NR 502.12(16)(b)
(b) The compost is produced by one of the processes to reduce pathogens described in subd.
1. to
3., with temperature and retention time monitored and recorded each day until the temperature and retention time criteria are met:
NR 502.12(16)(b)1.
1. Windrow method consisting of an unconfined composting process utilizing periodic aeration and mixing. Aerobic conditions shall be maintained during the composting process. A temperature of 55
°C, or 131
°F, shall be maintained in the windrow for at least fifteen days. The windrow shall be turned at least five times during the high-temperature period.
NR 502.12(16)(b)2.
2. Mechanically aerated static pile method consisting of an unconfined composting process utilizing mechanically forced aeration of insulated compost piles. Aerobic conditions shall be maintained during the composting process. The temperature of the compost pile shall be maintained at a continuous minimum of 55
°C, or 131
°F, for at least three consecutive days.
NR 502.12(16)(b)3.
3. In-vessel method consisting of a confined compost process utilizing mechanical mixing of compost under controlled conditions. The minimum retention time in the vessel shall be 72 hours with the temperature maintained at 55
°C, or 131
°F.
NR 502.12(16)(d)
(d) The compost does not exceed any of the limits specified in Tables 1 or 2.
Table 1.
Test parameters for nonexempt compost facilities and class A compost
- See PDF for table 
Table 2.
Maturity and stability testing for nonexempt facilities and class A compost
- See PDF for table NR 502.12 History
History: Cr.
Register, January, 1988, No. 385, eff. 2-1-88; r. and recr.,
Register, June, 1996, No. 486, eff. 7-1-96;
CR 05-020: am. (8) (a) 7. and (9) (a) 7.
Register January 2006 No. 601, eff. 2-1-06;
CR 10-128: am. (title), (1) (intro.), r. (1) (a) to (f), am. (2), (3) (title), (intro.), (a), (4) (title), (intro.), (c), (e) (intro.), r. and recr. (4) (e) 1. to 3., cr. (4) (e) 4., am. (5) (title), (intro.), (b), (c), (d), (e), (f) (intro.), 1., 2., (6) (title), (intro.), (b), (c), (e), (7) (title), (intro.), (a), (b), (c), r. and recr. (7) (e), (f), am. (8) (title), (a) (intro.), r. (8) (a) 4., 6., renum. (8) (a) 5., 7., 8. to be 4., 5., 6., r. and recr. (8) (b), cr. (8) (c), r. (9), am. (10) (intro.), (a) to (e), (h) 1., 3., (11) (intro.), (a), (b), r. and recr. (11) (d), cr. (11) (e), am. (12) (a), (b), (13) (title), (intro.), (b), (e), (f), (g), (h), (k), cr. (13) (m), (n), (o), (p), am. (14) (a), r. and recr. (15), cr. (16), r. and recr. Table 1 and Table 2
Register May 2012 No. 677, eff. 6-1-12; correction in (13) made under s.
13.92 (4) (b) 7., Stats.,
Register July 2015 No. 715.
