D. RATAs (Relative Accuracy Test Audits) for Part 60

Regulatory references:
Appendix F to Part 60 – Procedure 1, section 5.1 (Auditing Requirements), Appendix B, Performance Specification 2 for SO2 & NOx, 3 for O2 & CO2 and 4 for CO.
Pre-RATA Activities:

1. Consult the User Guide in StackVision, if needed. Open up the RATA editor first and then click on “Help” at the Main Menu.

2. Find and review the in-house RATA procedure prepared for the CEM systems at your facility.

3. Verify in SV when the last RATA was successfully complete for all of your P60 systems and when the next RATA needs to be completed by.  For P60, the next RATA needs to be successfully completed within the next four calendar quarters, except in the case where the affected facility is off-line (does not operate) in the fourth calendar quarter since the quarter of the previous RATA. In that case, the RATA shall be performed in the quarter in which the unit recommences operation.

4. Review the records from the most recent RATA. Duplicating those operating conditions should replicate the emission conditions and hopefully achieve successful RATA results.

5. For Part 60, the RATA for the gas systems is conducted at a single load, usually at an operating condition of at least 50% of the maximum operating load. This is specified in the Performance Specification 2, but PS 3 and 4 also refer back to PS 2. But, check your operating permit carefully, as it sometimes has other operating conditions specified.

6. Prepare for the RATA itself by selecting the date for performing it and schedule it for that date with the various parties involved (your boss, the operating staff, stack testing team, etc.). In many cases, the dates for the RATA need to be scheduled at least several weeks to several months in advance.

7. Make sure all preventative maintenance activities have been completed successfully on the CEM systems which will undergo the upcoming RATAs.

Day of RATA Activities:

8. Review your in-house RATA procedure, making sure you understand it and can answer questions from those whom you will work or interface with.

9. Be sure to review the testing schedule for that day with the control room operator and the supervisory operating staff. Having steady operating conditions should generate steady or consistent emissions conditions. Give them an estimate for how long it will probably take to complete today’s testing.

10. Be sure to discuss with your stack testing lead person the overall strategy of how the RATA will be conducted. Discuss at what load and how long each run will last. Decide how often results will be exchanged and reviewed, and the number of overall runs you intend to perform. You should compare the RATA results generated by StackVision and the results calculated by your stack testers. The two sets of results should match.

11. After entering the data sets from about six or seven RATA runs, review the projected relative accuracy in SV, and decide if you need to run more than ten runs to allow the opportunity to drive the Relative Accuracy (RA) lower.

12. For P60 systems, there is no requirement to link the certificates for the gas cylinders used by the stack testers to perform their calibration checks in the RATA records.  

13. For P60 systems, there is no requirement to identify a “Qualified Individual” for these RATAs.

14. Exchange the averages recorded for each run for each monitor/system between yourself and the stack testers after every two to three runs.

15. After recording the results for seven or eight runs, compare the relative accuracy results calculated by SV and the results calculated by the stack testers. The two sets of results should match. If the results don’t match, go back and review the results that both parties have recorded in their data systems and correct any discrepancies.

16. Acceptable RATA Relative Accuracy (RA) results are: 
a. SO2 and NOx monitors - must not be > 20.0% of the reference method, or 10% of the emission standard.  [PS 2, section 13.2]
b. O2 and CO2 monitors – must not be > 20% or 1% by volume. [PS 3, section 13.2]
c. CO monitors > 10% of reference method, or 5% of the emission standard. [PS 4, section 13.2]

17. For P60 RATAs, there is no such thing as a “bias adjustment factor”. That only exists for P75 RATAs.

18. In the RATA editor, there is an option to “Optimize” the RATA results. When this option is selected, SV will evaluate all of the data for your RATA data runs and determine which set of nine pairs will give you the lowest relative accuracy (RA) results. If ten runs are recorded, SV will select the nine runs which give the best relative accuracy results. If eleven or twelve runs are recorded, SV will select the best set of nine results and unselect the remaining runs.

Post RATA Activities:

19. When you receive the final RATA report from your stack testers (usually within 2-3 weeks), review and compare each of the averages recorded for each run, the relative accuracy results, and the other results shown on their summary page versus what you have recorded in the RATA Editor. If the two don’t agree, then you need to contact your testing contractor and work out the differences.

20. When the RATA is complete, make sure the data and results are saved in the RATA Editor. Click on the “Locked?” box.

21. When the RATA is complete, it’s a very good idea to review the hourly data for the hours surrounding when the RATA was being conducted. There should be enough data points recorded in each hour for a valid hourly average.

22. Make sure you receive enough copies of the stack testers report to meet your submission needs and have copies available for your records. Some states require you to submit two or more copies of these test results.

23. Make sure you know the submission deadline for submitting these results. Typically, your permit will specify the deadline for making the submission and where and how it needs to be submitted.

Download the pdf document here.

Jon Konings, Senior Regulatory and Reporting Engineer, ESC    Published: 9/17/2016 5:10:39 PM

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