Minnesota rules require many facilities that produce air emissions to conduct performance testing (also called "stack testing") that:
- Quantifies the facilities emissions
- Determines the emissions' physical, chemical, or aesthetic properties
- In some cases, measures the performance of emission-control equipment
Most performance tests are performed by independent testing companies with testing expertise, unless a permittee has been granted permission to conduct their own testing. A list of testing companies is available from the Source Evaluation Society.
Most permits require recurring performance tests on a set schedule. Before 2019, facilities had to submit test frequency plans to the MPCA, but now the agency sets each facility's test frequency based on factors such as compliance history, previous test results, applicable requirements, stringency of limit, use of emission factor, etc. The frequency is set in the Notice of Compliance or Notice of Verification. The test frequency becomes effective upon issuance of the review letter and is incorporated in the facility’s permit.
Facilities subject to performance-testing requirements must:
- Notify the MPCA in writing of testing and provide a test plan at least 30 days before the scheduled test. A test plan details what will be tested, the test methods, and how equipment will be operated during the test.
- Arrange a pretest meeting with MPCA staff at least seven days before the test. We'll discuss your test plan with you and your consultant to help ensure you'll meet procedural and technical requirements. Pretest meetings are typically held over the phone.
- Submit a test report to the MPCA no later than 45 days after the test.
Note: If you can't meet these deadlines, contact the MPCA to request flexibility. If you have to reschedule a test after the test plan has been approved, please contact MPCA staff.
Your test plan must be complete and accurate, and approved by the MPCA prior to testing. If the submitted test plan is missing necessary information, the MPCA will request a revised plan. The agency will provide written approval of the plan that may include clarifications or modifications to the plan. Use this checklist to ensure you include all required information:
The test plan examples below are designed to meet state requirements and assist companies and test consultants in developing a test plan. All text in italics are suggestions and comments for the test plan writer.
The U.S. EPA's Emission Measurement Center lists the test methods available for emission measurement. Facilities wishing to use the original wet-impinger method to measure condensables must call this out as an alternative test method in the test plan. The MPCA will approve this method in some instances. Minnesota rules also allow for waiving the determination of condensable particulate matter requirement, if previous performance test results or mass balance calculations demonstrate that the emission unit is not a source of condensable particulate matter emissions.
You must submit a complete and accurate test report to ensure it's reviewed in a timely manner. Use this checklist to ensure your report includes all required information:
Submit the appropriate operating data form as part of a complete test report; it provides a summary of the operating conditions during the test. Emission unit and control equipment operating conditions must be recorded for each run and averaged over three runs to provide a final average value for the test. Readings of discrete data from monitoring instruments must be recorded at least every 15 minutes, or other reasonable time interval as approved, during the test. Strip charts or retrieved electronic data from continuous monitors must be included in the test report and summarized on one of these forms:
All performance test reports must be certified using the certification form:
Expedited review request
The MPCA processes test reports on a first come, first served basis. However, for time-sensitive projects where delays may be costly, you can request expedited review:
All periods of noncompliance with emission or other limits – even during engineering tests –must be reported to the MPCA. Operating at a rate other than that allowed by the current air permit must also be reported.
Include the submission date and a brief description as part of the routine report document title:
- Example: 1-28-16, DRF-1, DRF-2, CR-04
- Example: 1-28-16, Pt 60 MM Compliance Report
- Example: 1-28-16, DRF-1 and EU001 NOx
Send routine reports to AQRoutineReport.PCA@state.mn.us
Include the test date, emission unit number, and a brief description of the test as part of the stack test document title:
- Example: 3-1-2016, EU007, NOx and CO
Send stack tests to SubmitStackTest.PCA@state.mn.us
Reporting test results FAQs
Am I required to submit the results of an engineering performance test that I conduct for my own information?
If an engineering test indicates noncompliance with a limit, the company must inform the MPCA. Generally, the pollutant, emissions, and operating conditions can be summarized and reported in place of a complete report, unless a more detailed report is requested. Results of a compliant engineering test need not be provided, unless requested by the MPCA. All periods of noncompliance with emission or other limits must be reported to the MPCA.
If early results indicate a test failure, can I stop the test and try again later?
Each performance test must consist of at least three separate test runs. If after conducting one or more test runs, the company determines that an emission limit has been exceeded, the MPCA should be contacted for further guidance. A detailed description of sampling or other problems experienced during the test should be included in the executive summary of the test report. Regardless of the number or length of test runs, data from an aborted emissions test may be used to establish violations.
What if my test results indicate noncompliance?
The unit must be retested within 30 days of the MPCA notice of noncompliance, unless a compliance plan is submitted and approved by the MPCA. The period of noncompliance begins at the date of the initial noncompliant test. Therefore, you should take immediate measures to minimize emissions without waiting for the formal notification from the MPCA.
Can I use the data from my test report for emission fee inventory purposes?
Yes. Minnesota rules require the calculation of emissions based on an established hierarchy. In the absence of continuous emission monitor data, the next method of calculation, a performance test, must be used. When a performance test for PM, PM10, PM2.5, CO, NOx, SOx, VOC or Pb is conducted and meets the requirements of Minn. R. 7017.2001-7017.2060, the results must be used to calculate emissions, unless specified otherwise by Minn. R. 7019.3000-7019.3100. It is the company’s responsibility to ensure the results of performance tests are accounted for in their annual emission inventory. The final decision to approve the emission factor for any given inventory year will be made by the Emission Inventory Coordinator.
How do I submit confidential information as part of a test report?
Claims of confidentiality for test report information must have a statutory basis and be included in a cover letter that accompanies the test report. See Minn. R. 7000.1300 and Minn. Stat. § 13.37 and 116.075 to determine whether your information meets the criteria. In the cover letter, identify the confidential information and explain the statutory basis for the claim. Provide both a public and a confidential copy of the test report.