• facebook
  • twitter
  • YouTube
  • RSS feed
  • 651-201-6000
  • 800-967-2474
  • 711 TTY

NodeFire Save Document
Home > Plants, Pests & Pest Control > Pest Management > Emerald Ash Borer Program > EAB Compliance Agreement Guide for Regulated Articles > Heat Treatment Guide for Firewood

Firewood Heat Treatment Guide


EAB is commonly spread by firewood, and firewood from any hardwood (deciduous) tree is considered a regulated article. No regulated articles are legally allowed to move outside of a quarantine (untreated or treated), unless they are accompanied by a MDA certificate. MDA Certificates are only available when a Compliance Agreement (CA) is signed between the Minnesota Department of Agriculture and the a company, city, county, agency, or organization interested in moving the regulated article. For more information on EAB quarantines and Compliance Agreements, see Guidance Documents 1 and 3.

Heat treatment is an approved treatment for EAB. The treatment must occur in a private heat treatment facility (facility) that is certified by either a qualified United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine (USDA APHIS PPQ )official or a qualified Minnesota Department of Agriculture (MDA) official (agency officials). For clarity, “certification” and “re-certification” will both be referred to as “certification” in this document.

Certification tests by agency officials must be carried out prior to sale of treated firewood, or whenever a malfunction or alteration in the facility system warrants a certification test. Firewood treatment in this manner will allow the movement of firewood from the current EAB quarantine areas. Certification will be granted by agency officials on the basis of the ability of the facility chamber to meet treatment requirements, in addition to the extent of the facility’s export safeguards to prevent re-infestation of treated wood and safety conditions.

Current heat treatment standards follow the protocols of United States Department of Agriculture protocols core temperature of 60.0 degrees Centigrade (140˚F) for 60 minutes. (T314-a treatment schedule in USDA Animal and Plant Health Inspection Service, Plant Protection and Quarantine Treatment Manual (PDF: 4.57 / 862 pages))

In order to obtain certification from the MDA for heat-treated firewood, there are five main components:

  • A completed application (PDF: 200KB / 2 pages)
  • An operational work plan
  • Certification treatment test/thermal mapping
  • Calibration of the temperature sensors
  • Compliance Agreement and permits and/or certificates

Operational Work Plan

Prior to the start of the heat treatment certification process for a new or existing facility, a detailed work plan of the facility’s physical characteristics and a written, step-by-step description of all the processes related to treatment must be approved by the agency officials.

At a minimum, work plans must include a description of all processes related to the heat treatment of firewood. These descriptions should reference diagrams with numbers where appropriate. A facility requesting a heat treatment certification must submit a work plan to the agency official for approval. See Appendix A for an acceptable work plan outline.
The process of reviewing the work plan may take as long as sixty (60) days and subsequent requests for additional information may further extend this time. Facilities should take this time constraint into account when developing a project timeline. Work plan approvals expire one year from the approval date, if the facility has not been certified.

Certification Treatment Test

Following work plan approval, facilities seeking certification must be tested by an agency official to ensure the facility can meet all treatment requirements. If deviations from the approved work plan are necessary, the certifying agency must approve these changes in the work plan prior to testing. Testing may take as long as thirty (30) days and subsequent testing requirements may further extend this time. A certification treatment test must be completed for each chamber load and volume configuration.

The required number of permanent sensors for normal operation of the facility depends on factors such as the chamber size, chamber dimensions, and air flow patterns. See Table 1 in Appendix B to determine how many permanent temperature probes are needed.

All sensors should be placed in the largest firewood piece in a portion of the load. The sensor portion of the probe should be fully embedded in the pre-drilled holes to measure internal wood temperature (See Figure 1 & 2 in Appendix B). Sensors are to be sealed into each hole with non-hardening putty to prevent reading ambient air temperature (See Figure 2 in Appendix B). Other recording arrangements may be considered if approved by the certifying agency.

The agency official will use the agency -owned portable sensors, in addition to the facility’s permanent sensors to conduct the certification treatment test. Because this test also detects the coldest area in the chamber, this process is also referred to as thermal mapping. The agency official will place portable temperature sensors throughout the chamber and the treatment is conducted. A tamper resistant seal will be placed on all doors by the agency official. The tamper resistant seal(s) shall not be removed, altered, or mutilated in any way except in the presence of the agency official. Breaking the seal and tampering with the treatment chamber will invalidate the test treatment. After the treatment has completed, the company will notify the agency official. Temperatures are automatically recorded at a specified time interval.

The sensors that require the longest time to record the approved treatment temperature represent colder areas of the chamber. The certification treatment test must be conducted with the kiln loaded the way the facility plans to use it, as stated in the approved work plan. The agency official chooses which pieces of wood to place the probes into, and where to place those pieces of wood in the kiln.

In certain situations, the thermal mapping may be conducted separately from a certification test treatment.

These certification test treatments should test the ability of the treatment chambers to heat a standard load of wood according to the treatment guidelines. The company’s facility sensors must be located in the areas specified by the certifying agency. The company must maintain the placement and monitor sensors in these locations for all certified heat treatments. Bent sensors may not read properly and must be replaced. All damaged sensors must be replaced with temperature sensors from the manufacturer or a temperature sensor that had been NIST certified within the last 12 months.

If the data shows that the test treatment failed, then any problems or deficiencies found in the facility or with the treatment must be corrected by the facility, and the facility must modify their work plan to reflect these corrections. Then the agency official will run the test treatment again, until all treatment requirements are met and the facility passes.

A certification test performed by an agency official is required once a year, and/or whenever the system has a malfunction, breakdown, or other failure that required modifications that alter the manner in which the system functions. This excludes the replacement of a faulty temperature sensor if either: the replacement temperature sensor is new from the factory, or the replacement temperature sensor had been NIST certified within the past 12 months.

The facility shall be considered certified only after the state is paid in full for certification services.

Calibration of the Temperature Sensors

All facility temperature sensors must be calibrated annually, at the discretion of the certifying agency, or whenever any part of the temperature recording system fails or is replaced. Calibrations must be performed by the temperature sensor manufacturer’s trained technicians to National Institute of Standards and Technology (NIST) standards. The MDA may request the NIST certificates for the facility at any time.

Compliance Agreement and Certificate

Once the facility is approved, the facility is required to sign a compliance agreement with the certifying agency, with the work plan attached as an addendum. See Guidance Document 3 for more information about Compliance Agreements.

For compliance agreements with the State of Minnesota, a certificate will be included in the compliance agreement, which must be used in the manner described below.


All use of the MDA issued heat treatment certificate must be thoroughly documented including:

  • Date(s) of treatment
  • Printed name of person certifying treatment
  • Signature of person certifying treatment
  • Destination of treated firewood*
    Date(s) of shipment of treated firewood**
  • Certificates must be accompanied with the point of origin and final destination clearly indicated on the bill of lading or other shipping documents

All firewood sold by an MDA certified company must be clearly labeled with the following information:

  • Company name
  • Business address or website
  • County and state of harvest
  • Net quantity in volume or weight
  • All firewood labels must be in compliance with Minnesota Statute 239.092 and 239.093 as applicable.

*The destination of treated firewood may by coded by the company using a unique identifier. However, in the event of a failed heat treatment, failed inspection, or revocation of the certificate, the company must supply the MDA with a complete list of unique identifiers and corresponding company information.

**In the event of a failed inspection or revocation of the certificate, the MDA reserves the right to request information regarding the destination and shipment dates of all firewood, regardless of whether it was heat treated or not.

Appendix A

Work Plan Suggested Outline

  1. Business name
  2. Business owner name
  3. Business phone number(s)
  4. Email address or addresses
  5. Website
  6. Business address
  7. Heat treatment facility address (if different)
  8. Storage facility address (if different)
  9. GPS coordinates for each address, or locations marked on a USGS Topographical map with identifying labels.
  10. Heat treatment facility make and model (if commercially built or designed)
  11. Temperature probe and data logging equipment make and model (required if heat treatment facility is not commercially built
  12. A description of crates, bins, racks, etc. used to hold firewood during treatment, including total volume and projected capacity
  13. A description of the process used to calibrate the temperature sensors, and how the calibration will be documented
  14. A description of the post-treatment packaging
  15. Procedures to prevent re-infestation of the treated wood
  16. Treatment chamber including heating system, arrangement within the chamber, and air flow
  17. Map of facility, with all landmarks uniquely labeled. Map should include at least:
    1. North arrow
    2. Scale if available or statement that map is not to scale
    3. Heat treatment facility
    4. Arrival and storage of untreated wood
    5. Storage of treated wood
    6. Delivery pickup area for treated wood
    7. Delivery pickup area for untreated wood
    8. Any other relevant landmarks
  18. Copy of label on firewood bundle, which must be legible; follow all state labeling requirements in Minnesota Statutes Sections 239.092 and 239.093; and allow space for a certificate shield (1.5 inches by 1.5 inches).
  19. Specified location for record storage
  20. Template record for each firewood treatment
    1. Business name
    2. Business phone number(s)
    3. Business address
    4. Date of treatment
    5. Unique lot number assigned
    6. Volume treated in lot number
    7. Treatment record showing time and temperatures
    8. Storage area before shipment
    9. Date of shipment
    10. Receiver of shipment, including name and full address.

Appendix B

Certification Treatment Test Requirements

  <500 ft3  5001 - 7000 ft3 7001 - 9000 ft3 9001 - 11,000 ft3 11,001 - 13,000 ft3 13,001 - 15,000 ft3 15,001 - 17,000 ft3 17,001 - 19,000 ft3 19,001 - 22,000 ft3
Minimum # of core sensors required 3 4 5 6 7 8 9 10 11
Minimum # of air sensors required 1 1 1 1 1 1 1 1 1

Table: The number of temperature sensors required per load will vary with the internal size of the treatment chamber. The minimum requirement is four (4) sensors – one (1) for measuring air temperature and three (3) for measuring internal wood temperature. For loads greater than 5,000 ft3 (142 m3) of wood, a minimum of one additional sensor for measuring internal wood temperature must be provided for each additional 2,000 ft3. For example, a load of 9,000 ft3 would require a total of six (6) sensors (one ambient air temperature sensor and five [3 + 2] additional sensors).

Probe for testing temperature in firewod compared to a pen Firewood Heat Treatment Test with Probe
Insert temperature sensor to where the arrow points Seal the temperature sensor with non-hardening
putty to prevent reading ambient air temperature.