WAC 173-350-220   Composting facilities.  (1) Composting facilities - Applicability.

     (a) This section is applicable to all facilities or sites that treat solid waste by composting. This section is not applicable to:

     (i) Composting used as a treatment for dangerous wastes regulated under chapter 173-303 WAC, Dangerous waste regulation;

     (ii) Composting used as a treatment for petroleum contaminated soils regulated under WAC 173-350-320;

     (iii) Treatment of liquid sewage sludge or biosolids in digesters at wastewater treatment facilities regulated under chapter 90.48 RCW, Water pollution control and chapter 70.95J RCW, Municipal sewage sludge -- Biosolids;

     (iv) Treatment of other liquid solid wastes in digesters regulated under WAC 173-350-330; and

     (v) Composting biosolids when permitted under chapter 173-308 WAC, Biosolids management.

     (b) In accordance with RCW 70.95.305, the operation of the following activities in this subsection are subject solely to the requirements of (c) of this subsection and are exempt from solid waste handling permitting. An owner or operator that does not comply with the terms and conditions of (c) of this subsection is required to obtain a permit from the jurisdictional health department and shall comply with all other applicable requirements of this chapter. In addition, violations of the terms and conditions of (c) of this subsection may be subject to the penalty provisions of RCW 70.95.315.

     (i) Production of substrate used solely on-site to grow mushrooms;

     (ii) Vermicomposting, when used to process Type 1, Type 2, or Type 3 feedstocks generated on-site;

     (iii) Composting of Type 1 or Type 2 feedstocks with a volume limit of forty cubic yards of material on-site at any time. Material on-site includes feedstocks, partially composted feedstocks, and finished compost;

     (iv) Composting of food waste generated on-site and composted in containers designed to prohibit vector attraction and prevent nuisance odor generation. Total volume of the containers shall be limited to ten cubic yards or less;

     (v) Agricultural composting when all the agricultural wastes are generated on-site and all finished compost is used on-site;

     (vi) Agricultural composting when any agricultural wastes are generated offsite, and all finished compost is used on-site, and total volume of material is limited to one thousand cubic yards on-site at any time. Material on-site includes feedstocks, partially composted feedstocks, and finished compost; and

     (vii) Agricultural composting at registered dairies when the composting is a component of a fully certified dairy nutrient management plan as required by chapter 90.64 RCW, Dairy Nutrient Management Act.

     (viii) Composting of Type 1 or Type 2 feedstocks when more than forty cubic yards and less than two hundred fifty cubic yards of material is on-site at any one time.

     (ix) Agricultural composting, when any of the finished compost is distributed offsite and when it meets the following requirements:

     (A) More than forty cubic yards, but less than one thousand cubic yards of agricultural waste is on-site at any time; and

     (B) Agricultural composting is managed according to a farm management plan written in conjunction with a conservation district, a qualified engineer, or other agricultural professional able to certify that the plan meets applicable conservation practice standards in the Washington Field Office Technical Guide produced by the Natural Resources Conservation Service.

     (x) Vermicomposting when used to process Type 1 or Type 2 feedstocks generated offsite. Total volume of materials is limited to one thousand cubic yards on-site at any one time.

     (c) Composting operations identified in subsection (b) shall be managed according to the following terms and conditions to maintain their exempt status:

     (i) Comply with the performance standards of WAC 173-350-040;

     (ii) Protect surface water and groundwater through the use of best management practices and all known available and reasonable methods of prevention, control, and treatment as appropriate. This includes, but is not limited to, setbacks from wells, surface waters, property lines, roads, public access areas, and site-specific setbacks when appropriate;

     (iii) Control nuisance odors to prevent migration beyond property boundaries;

     (iv) Manage the operation to prevent attraction of flies, rodents, and other vectors;

     (v) Conduct an annual analysis, prepared in accordance with the requirements of subsection (4)(a)(viii) of this section, for composted material that is distributed offsite from categorically exempt facilities described in subsection (1)(b)(vii) through (ix) of this section.

     (vi) Prepare and submit an annual report to the department and the jurisdictional health department by April 1st for categorically exempt facilities described in subsection (1)(b)(vii) through (ix) of this section. Annual reports are not required for facilities operating under the permit exemption provided in (b)(vii) of this subsection if the composted material is not distributed offsite. The annual report shall be on forms supplied by the department and shall detail facility activities during the previous calendar year and shall include the following information:

     (A) Name and address of the facility;

     (B) Calendar year covered by the report;

     (C) Annual quantity and type of feedstocks received and compost produced, in tons;

     (D) Annual quantity of composted material sold or distributed, in tons;

     (E) Results of the annual analysis of composted material required by subsection (1)(c)(v) of this section; and

     (F) Any additional information required by written notification of the department.

     (vii) Allow the department or the jurisdictional health department to inspect the site at reasonable times;

     (viii) For activities under (b)(viii) through (x) of this subsection, and registered dairies where compost is distributed offsite, the department and jurisdictional health department shall be notified in writing thirty days prior to beginning any composting activity. Notification shall include name of owner or operator, location of composting operation and identification of feedstocks.

     (2) Composting facilities - Location standards. There are no specific location standards for composting facilities subject to this chapter; however, composting facilities must meet the requirements provided under WAC 173-350-040(5).

     (3) Composting facilities - Design standards. The owner or operator of a composting facility shall prepare engineering reports/plans and specifications, including a construction quality assurance plan, to address the design standards of this subsection. Scale drawings of the facility including the location and size of feedstock and finished product storage areas, compost processing areas, fixed equipment, buildings, leachate collection devices, access roads and other appurtenant facilities; and design specifications for compost pads, storm water run-on prevention system, and leachate collection and conveyance systems shall be provided. All composting facilities shall be designed and constructed to meet the following requirements:

     (a) When necessary to provide public access, all-weather roads shall be provided from the public highway or roads to and within the compost facility and shall be designed and maintained to prevent traffic congestion, traffic hazards, dust and noise pollution;

     (b) Composting facilities shall separate storm water from leachate by designing storm water run-on prevention systems, which may include covered areas (roofs), diversion swales, ditches or other designs to divert storm water from areas of feedstock preparation, active composting and curing;

     (c) Composting facilities shall collect any leachate generated from areas of feedstock preparation, active composting and curing. The leachate shall be conveyed to a leachate holding pond, tank or other containment structure. The leachate holding structure shall be of adequate capacity to collect the amount of leachate generated, and the volume calculations shall be based on the facility design, monthly water balance, and precipitation data. Leachate holding ponds and tanks shall be designed according to the following:

     (i) For leachate ponds at registered dairies, the design and installation shall meet Natural Resources Conservation Service standards for a waste storage facility in the Washington Field Office Technical Guide.

     (ii) For leachate ponds at composting facilities other than registered dairies, the pond shall be designed to meet the following requirements:

     (A) Have a liner consisting of a minimum 30-mil thickness geomembrane overlying a structurally stable foundation to support the liners and the contents of the impoundment. High density polyethylene geomembranes used as primary liners or leak detection liners shall be at least 60-mil thick to allow for proper welding. The jurisdictional health department may approve the use of alternative designs if the owner or operator can demonstrate during the permitting process that the proposed design will prevent migration of solid waste constituents or leachate into the ground or surface waters at least as effectively as the liners described in this subsection;

     (B) Have dikes and slopes designed to maintain their structural integrity under conditions of a leaking liner and capable of withstanding erosion from wave action, overfilling, or precipitation;

     (C) Have freeboard equal to or greater than eighteen inches to avoid overtopping from wave action, overfilling, or precipitation. The jurisdictional health department may reduce the freeboard requirement provided that other engineering controls are in place which prevent overtopping. These engineering controls shall be specified during the permitting process;

     (D) Leachate ponds that have the potential to impound more than ten-acre feet (three million two hundred fifty-nine thousand gallons) of liquid measured from the top of the dike and which would be released by a failure of the containment dike shall be reviewed and approved by the dam safety section of the department.

     (iii) Tanks used to store leachate shall meet design standards in WAC 173-350-330 (3)(b).

     (d) Composting facilities shall be designed with process parameters and management procedures that promote an aerobic composting process. This requirement is not intended to mandate forced aeration or any other specific composting technology. This requirement is meant to ensure that compost facility designers take into account porosity, nutrient balance, pile oxygen, pile moisture, pile temperature, and retention time of composting when designing a facility.

     (e) Incoming feedstocks, active composting, and curing materials shall be placed on compost pads that meet the following requirements:

     (i) All compost pads shall be curbed or graded in a manner to prevent ponding, run-on and runoff, and direct all leachate to collection devices. Design calculations shall be based upon the volume of water resulting from a twenty-five-year storm event as defined in WAC 173-350-100;

     (ii) All compost pads shall be constructed over soils that are competent to support the weight of the pad and the proposed composting materials;

     (iii) The entire surface area of the compost pad shall maintain its integrity under any machinery used for composting activities at the facility; and

     (iv) The compost pad shall be constructed of materials such as concrete (with sealed joints), asphaltic concrete, or soil cement to prevent subsurface soil and groundwater contamination;

     (v) The jurisdictional health department may approve other materials for compost pad construction if the permit applicant is able to demonstrate that the compost pad will meet the requirements of this subsection.

     (4) Composting facilities - Operating standards. The owner or operator of a composting facility shall:

     (a) Operate the facility to:

     (i) Control dust, nuisance odors, and other contaminants to prevent migration of air contaminants beyond property boundaries;

     (ii) Prevent the attraction of vectors;

     (iii) Ensure that only feedstocks identified in the approved plan of operation are accepted at the facility;

     (iv) Ensure the facility operates under the supervision and control of a properly trained individual during all hours of operation, and access to the facility is restricted when the facility is closed;

     (v) Ensure facility employees are trained in appropriate facility operations, maintenance procedures, and safety and emergency procedures according to individual job duties and according to an approved plan of operation;

     (vi) Implement and document pathogen reduction activities when Type 2, 3 or 4 feedstocks are composted. Documentation shall include compost pile temperature and notation of turning as appropriate, based on the composting method used. Pathogen reduction activities shall at a minimum include the following:

     (A) In vessel composting - the temperature of the active compost pile shall be maintained at fifty-five degrees Celsius (one hundred thirty-one degrees Fahrenheit) or higher for three days; or

     (B) Aerated static pile - the temperature of the active compost pile shall be maintained at fifty-five degrees Celsius (one hundred thirty-one degrees Fahrenheit) or higher for three days; or

     (C) Windrow composting - the temperature of the active compost pile shall be maintained at fifty-five degrees Celsius (one hundred thirty-one degrees Fahrenheit) or higher for fifteen days or longer. During the period when the compost is maintained at fifty-five degrees Celsius (one hundred thirty-one degrees Fahrenheit) or higher, there shall be a minimum of five turnings of the windrow; or

     (D) An alternative method that can be demonstrated by the owner or operator to achieve an equivalent reduction of human pathogens;

     (vii) Monitor the composting process according to the plan of operation submitted during the permitting process. Monitoring shall include inspection of incoming loads of feedstocks and pathogen reduction requirements of (a)(vi) of this subsection; and

     (viii) Analyze composted material for:

     (A) Metals in Table A at the minimum frequency listed in Table C. Compost facilities composting only Type 1 and Type 2 feedstocks are not required to test for molybdenum and selenium. Testing frequency is based on the feedstock type and the volume of feedstocks processed per year;

     (B) Parameters in Table B at the minimum frequency listed in Table C. Testing frequency is based on the feedstock type and the volume of feedstocks processed per year;

     (C) Nitrogen content at the minimum frequency listed in Table C; and

     (D) Biological stability as outlined in United States Composting Council Test Methods for the Examination of Composting and Compost at the minimum frequency listed in Table C;

     (E) The jurisdictional health department may require testing of additional metal or contaminants, and/or modify the frequency of testing based on historical data for a particular facility, to appropriately evaluate the composted material.

Table A - Metals

Metal Limit (mg/kg dry weight)
Arsenic < = 20 ppm
Cadmium < = 10 ppm
Copper < = 750 ppm
Lead < = 150 ppm
Mercury < = 8 ppm
Molybdenum1 < = 9 ppm
Nickel < = 210 ppm
Selenium1 < = 18 ppm
Zinc < = 1400 ppm


1Not required for composted material made from Type 1, Type 2 or a mixture of Type 1 and Type 2 feedstocks.


Table B - Other Testing Parameters

Parameter Limit
Manufactured Inerts < 1 percent
Sharps 0
pH 5 - 10 (range)
Fecal Coliform < 1,000 Most Probable Number per gram of total solids (dry weight).
Salmonella < 3 Most Probable Number per 4 grams of total solids (dry weight).


Table C - Frequency of Testing Based on Feedstocks Received


Feedstock Type < 5,000 cubic yards = or > 5,000 cubic yards
Type 1


or


Type 2		 Once per year Every 10,000 cubic yards or every six months whichever is more frequent
Type 3 Once per quarter (four times per year) Every 5,000 cubic yards or every other month whichever is more frequent
Type 4 Every 1,000 cubic yards Every 1,000 cubic yards or once per month whichever is more frequent


     (b) Inspect the facility to prevent malfunctions and deterioration, operator errors and discharges, which may cause or lead to the release of waste to the environment or a threat to human health. Inspections shall be conducted at least weekly, unless an alternate schedule is approved by the jurisdictional health department as part of the permitting process. For compost facilities with leachate holding ponds, conduct regular liner inspections at least once every five years, unless an alternate schedule is approved by the jurisdictional health department as part of the permitting process. The frequency of inspections shall be specified in the operations plan and shall be based on the type of liner, expected service life of the material, and the site-specific service conditions. The jurisdictional health department shall be given sufficient notice and have the opportunity to be present during liner inspections. An inspection log or summary shall be kept at the facility or other convenient location if permanent office facilities are not on-site, for at least five years from the date of inspection. Inspection records shall be available to the jurisdictional health department upon request.

     (c) Maintain daily operating records of the following:

     (i) Temperatures and compost pile turnings for Type 2, Type 3 and Type 4 feedstocks;

     (ii) Additional process monitoring data as prescribed in the plan of operation; and

     (iii) Results of laboratory analyses for composted materials as required in (a)(viii) of this subsection. Facility inspection reports shall be maintained in the operating record. Significant deviations from the plan of operation shall be noted in the operating record. Records shall be kept for a minimum of five years and shall be available upon request by the jurisdictional health department.

     (d) Prepare and submit a copy of an annual report to the jurisdictional health department and the department by April 1st on forms supplied by the department. The annual report shall detail the facility's activities during the previous calendar year and shall include the following information:

     (i) Name and address of the facility;

     (ii) Calendar year covered by the report;

     (iii) Annual quantity and type of feedstocks received and compost produced, in tons;

     (iv) Annual quantity of composted material sold or distributed, in tons;

     (v) Annual summary of laboratory analyses of composted material; and

     (vi) Any additional information required by the jurisdictional health department as a condition of the permit.

     (e) Develop, keep and abide by a plan of operation approved as part of the permitting process. The plan of operation shall convey to site personnel the concept of operation intended by the designer. The plan of operation shall be available for inspection at the request of the jurisdictional health department. If necessary, the plan shall be modified with the approval, or at the direction of the jurisdictional health department. Each plan of operation shall include the following:

     (i) List of feedstocks to be composted, including a general description of the source of feedstocks;

     (ii) A description of how wastes are to be handled on-site during the facility's active life including:

     (A) Acceptance criteria that will be applied to the feedstocks;

     (B) Procedures for ensuring that only the waste described will be accepted;

     (C) Procedures for handling unacceptable wastes;

     (D) Mass balance calculations for feedstocks and amendments to determine an acceptable mix of materials for efficient decomposition;

     (E) Material flow plan describing general procedures to manage all materials on-site from incoming feedstock to finished product;

     (F) A description of equipment, including equipment to add water to compost as necessary;

     (G) Process monitoring plan, including temperature, moisture, and porosity;

     (H) Pathogen reduction plan for facilities that accept Type 2, Type 3, and Type 4 feedstocks;

     (I) Sampling and analysis plan for the final product;

     (J) Nuisance odor management plan (air quality control plan);

     (K) Leachate management plan, including monthly water balance; and

     (L) Storm water management plan;

     (iii) A description of how equipment, structures and other systems are to be inspected and maintained, including the frequency of inspections and inspection logs;

     (iv) A neighbor relations plan describing how the owner or operator will manage complaints;

     (v) Safety, fire and emergency plans;

     (vi) Forms for recordkeeping of daily weights or volumes of incoming feedstocks by type and finished compost product, and process monitoring results; and

     (xvii) Other such details to demonstrate that the facility will be operated in accordance with this subsection and as required by the jurisdictional health department.

     (5) Composting facilities - Groundwater monitoring requirements. There are no specific groundwater monitoring requirements for composting facilities subject to this chapter; however, composting facilities must meet the requirements provided under WAC 173-350-040(5).

     (6) Composting facilities - Closure requirements. The owner or operator of a composting facility shall:

     (a) Notify the jurisdictional health department sixty days in advance of closure. At closure, all solid waste, including but not limited to, raw or partially composted feedstocks, and leachate from the facility shall be removed to another facility that conforms with the applicable regulations for handling the waste.

     (b) Develop, keep and abide by a closure plan approved by the jurisdictional health department as part of the permitting process. At a minimum, the closure plan shall include methods of removing solid waste materials from the facility.

     (7) Composting facilities - Financial assurance requirements. There are no specific financial assurance requirements for composting facilities subject to this chapter; however, composting facilities must meet the requirements provided under WAC 173-350-040(5).

     (8) Composting facilities - Permit application contents. The owner or operator of a composting facility shall obtain a solid waste permit from the jurisdictional health department. All applications for permits shall be submitted in accordance with the procedures established in WAC 173-350-710. In addition to the requirements of WAC 173-350-710 and 173-350-715, each application for a permit shall contain:

     (a) Engineering reports/plans and specifications that address the design standards of subsection (3) of this section;

     (b) A plan of operation meeting the requirements of subsection (4) of this section; and

     (c) A closure plan meeting the requirements of subsection (6) of this section.

     (9) Composting facilities - Construction records. The owner or operator of a composting facility shall provide copies of the construction record drawings for engineered facilities at the site and a report documenting facility construction, including the results of observations and testing carried out as part of the construction quality assurance plan, to the jurisdictional health department and the department. Facilities shall not commence operation until the jurisdictional health department has determined that the construction was completed in accordance with the approved engineering report/plans and specifications and has approved the construction documentation in writing.

     (10) Composting facilities - Designation of composted materials. Composted materials meeting the limits for metals in Table A and the parameters of Table B of this section, and having a stability rating of very stable, stable, or moderately unstable as determined by the analysis required in subsection (4)(a)(viii)(D) of this section, shall no longer be considered a solid waste and shall no longer be subject to this chapter. Composted materials that do not meet these limits are still considered solid waste and are subject to management under chapter 70.95 RCW, Solid waste management -- Reduction and recycling.



[Statutory Authority: Chapter 70.95 RCW. 03-03-043 (Order 99-24), § 173-350-220, filed 1/10/03, effective 2/10/03.]