D. RATAs (Relative Accuracy Test Audits)

Regulatory references:
P75 Appendix A, § 3.3 and 6.5, Appendix B § 2.3.1 and P75 Policy Manual Section #8 (Relative Accuracy)


Pre-RATA Activities:

  1. Find and review the in-house RATA procedure prepared for the CEM systems at your facility.
  2. Verify in SV when the last RATA was successfully complete for all of your P75 systems and when the next RATA needs to be completed by. Performing RATAs for HG, HF and HCL systems will be addressed in the OPT’s for P63.
  3. For P75, some systems might require the next RATA to be completed within two (2) calendar quarters or within four (4) calendars. Check the results from the last RATA for each system.
  4. Perform a review of the operating load records recorded in SV for a period of not less than four calendar quarters. Each quarter needs to contain at least 168 operating hours to qualify as a “QA operating quarter”.
  5. Every five years, the flow RATA must be performed in each of the three operating load ranges, so review the existing RATA record to determine when the last three load flow RATA was performed.
  6. During the flow RATAs, their loads need to be separated by no less than 25% of the normal operating range.
  7. The load analysis results need to be reported or updated in the “Load” records of ECMPS.
  8. The RATA for the gas systems is conducted at a single load and must occur in either of the two most frequently operated load ranges identified in the Load Analysis report.
  9. 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, etc.). In many cases, the dates for the RATA need to be scheduled at least several weeks to several months in advance.
  10. Review the records from the most recent RATA. Duplicating those operating conditions should replicate the emission conditions and hopefully achieve successful RATA results.
  11. Make sure all preventative maintenance activities have been completed successfully on the CEM systems which will undergo the upcoming RATAs.

Day of RATA Activities:

  1. Review your in-house RATA procedure making sure you understand it and can answer questions from those whom you will work or interface with.
  2. 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.
    Part 75 (P75) – Lessons Learned from Jon Konings at ESC
    A Starting Point for Developing In-House and Site Specific Procedures and Helpful Tools
    ESC | 10801 N. Mopac Expy, Bldg 1-200 | Austin, TX 78759 | p. 512.250.7902 | f. 512.258.5836
  3. Be sure to discuss with your stack testing lead person the overall strategy of how the RATA will be conducted. Discuss whether the gas or flow RATAs will be performed first, 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.
  4. 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 RA lower if close to 7.0%. Your final relative accuracy results need to be < 7.5%.
  5. You must report the gas cylinders used by the stack testers to perform their calibration checks in the QA EDR file. You need to get copies of the certification sheets for the gas cylinders that the stack testers used in the QA checks on their monitors and enter them into the “Cal Gas Manager” section of SV. Once the certificates are entered in the Gas Manager, they can be linked in the gas RATA records in the RATA Editor for each gas RATA performed.
  6. Be sure your stack testing company identifies who is the “Qualified Individual” for this RATA. You need to have the required information about this individual in StackVision, so it can be linked to the Part 75 RATA results through the RATA Editor. This can be found in the “AETB” tab under “QA and Certificates” in SV.
  7. Exchange the averages recorded for each run for each monitor/system between yourself and the stack testers after every two to three runs.
  8. 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.
  9. The P75 regulations require that at least nine sets of RATA runs be performed and recorded. ESC recommends performing at least ten (10) runs.
  10. Acceptable RATA Relative Accuracy (RA) results are: P75 gas and flow must not be > 10.0%. If RA is >7.5 and < 10.0%, then the next RATA must be performed within the next two (2) calendar quarters. If RA < 7.5%, then the next RATA must be performed within the next four (4) calendar quarters.
  11. Besides reviewing the relative accuracy results, and the duration for when the next RATA must be performed (two or four calendar quarters), look at the Bias Adjustment Factors (BAFs) derived for each of the RATA results. The BAF calculated by the stack testers and in SV need to match.

Post RATA Activities:

  1. When you receive the final RATA report (usually within 2-3 weeks) from your stack testers, 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.
  2. 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.
  3. Review your in-house RATA procedure for updating hourly data based on the RATA results. Reprocessing of hourly data due to a change in a BAF may also trigger the need to accumulate daily, monthly, quarterly or year to date (YTD) totals or averages. Be sure to consult and follow your existing data processing procedures.
  4. When your RATA records are finalized in SV, then generate a QA EDR file and run it through ECMPS. If the evaluation report shows and critical errors, they must be resolved in SV, a new file generated, and evaluated again in ECMPS.
  5. When the RATA is completed, make sure the data and results are saved.
  6. When the RATA is completed, 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 point recorded in each hour for a valid hourly average.

Download the pdf document here.

Jon Konings, Senior Regulatory and Reporting Engineer, ESC    Published: 10/19/2016 5:10:39 PM

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