Stack Configuration Changes caused by the addition of Scrubbers/SCR

1. Stack Configuration Changes caused by the addition of Scrubbers/SCR Louis Nichols EPRI CEMS User’s Group Cleveland May 12, 2010

2. New Scrubber Additions 2004-2009

3. New SCR Additions 2004-2009

4. Types of Configuration Changes • Conversion of common stack reporting to individual unit reporting • Adding SO2 scrubber to individual unit (with or without bypass stack) • Adding SCR to individual unit on (with or without a common stack) • Combining individual units into a common stack • Combinations of any or all of the above

5. Timing of Configuration Changes • Best time to change configurations is at end of the reporting year • 2nd time is best at the quarter boundary • Worst time to change configurations is in the middle of quarter (most common) • CAMD Analysts know that Environmental Managers do not control the timing of unit outages or the scrubber/stack start-ups

6. Specific Timing for Removing Units from Common Stack • When the first unit that leaves the common stack goes on outage, separate that unit’s reporting from the common stack reporting if you can use that to separate at a year or quarter boundary • If possible convert as many units as you can to individual reporting at that time or do away with common stack if no units need to report as common stack • A unit must not report at a common stack the next quarter if no other units are reporting at that common stack

7. The Good News is: • Separating individual unit reporting from common stack reporting is easier under ECMPS reporting than the old system • ECMPS has a unit stack configuration record for linking units to a specific stack ID. This link can be ended by entering an end date for the relationship. • ECPMS also has stack retirement dates that can be used when the stack is no longer active

8. Using ECMPS to make configuration changes • When you change a configuration, do so by editing the existing monitoring plan • If the change represents a split, report all emissions for that quarter in a common quarterly report through the end of the last quarter that the units exhaust at the common stack • EPA will aggregate emissions from the different configurations (previous and new) during reconciliation • For the Acid Rain Program, SO2 mass compliance is at the facility level • For Acid Rain Program, NOx emission rates are still at the unit level, but if there is an averaging plan it may not appear to be at the unit level • For CAIR, the NOx mass compliance is at the facility level

9. Summary Record • Heat input must be reported at the unit level for entire year (always true) • Report pollutant emissions at the monitoring level (unit, common stack, or multiple stack) consistent with the location for which the emissions are monitored during the quarter • For a quarter in which there is a configuration change during the middle of a quarter, the emissions will be reported in at least two monitoring locations (e.g., at a common stack and at the unit level)

10. CAIR Annual NOx Program Summary Record • Report heat input for entire year at unit level • Report NOx Mass emissions at common stack summary record prior to separating unit from common stack • Report NOx mass emissions at unit level summary record after separating unit from common stack

11. By-Pass Stacks • Bypass stacks should only be defined as locations if monitored • Adding and Removing by-pass stacks • Use the Bypass Indicator in the Monitoring Location Attribute Data record • Uses a multi-stack (MS) designation when bypass stacks are defined as monitoring locations • Add and remove these stacks using the appropriate activate and retire dates in the Stack Pipe Data record

12. Part 75 Guidance • Chapter 15 of the Revised Part 75 Policy Manual provides guidance on requirements for recertification and diagnostic tests required for newly installed add-on SO2 and NOx emission controls on units or stacks with previously certified CEMS • Check ECMPS reporting instructions for additional guidance on reporting

13. Question 15.4 (old 16.14) • Provides timelines for recertification and diagnostic testing • References section 75.4(e) • Sets testing deadline to 90 operating days or 180 calendar days after emissions first exit to the atmosphere through a new add-on SO2 or NOx control that is operating • Provision for individual units on a common stack with separate controls to have different timelines (e.g., SCR on individual units)

14. Question 15.5 (old 16.15) • Recertification and diagnostic test requirements for add-on SO2 and NOx controls • Recertification requirements in section 75.20(b) • Examples of recertification events caused by installation of add-on controls – relocation of a CEMS, replacement of an analyzer, installation of a new CEMS, change in critical orifice with different size orifice, and dual-span monitor requirement met with an additional analyzer

15. Question 15.5 (continued) • Events that require diagnostic test are cases where the installation of add-on controls do not involve the relocation of the existing CEMS, replacement of an analyzer, installation of a new CEMS, or a change in dilution ratio • Only involves adding the low-scale measurement range

16. Question 15.7( old 16.16) Provides for data validation and reporting requirements for units that install add-on SO2 and NOx controls • For monitoring systems that require full certification or recertification • For monitoring systems that only require diagnostic testing

17. Question 15.7 (continued) • For monitoring systems that require full certification or recertification: • Use the substitute data • Use data from EPA reference Methods • Use conditionally valid data from the newly installed CEMS as described in section 75.20(b)

18. Question 15.7(continued) • Note: conditional data validation may be used for the entire window of time allotted to complete testing • If a certified high range monitor is available to record emissions data, the start of conditional data validation for the low measurement range may be delayed for 60 unit operating days after the emissions pass through the control device

19. Special Considerations • Some units may combust natural gas to dry stacks prior to combusting coal which starts clock and may require substitute data • Make sure that the probationary calibration is performed as soon after the unit starts to combust natural gas as possible • Use option under section 75.11(e) to account for SO2 mass (this includes equation F-23) • Use CEMS to account for NOx mass or fuel specific substitute data