2. Regulatory background How these standards could impact the permitting process How is compliance with the standards assessed

3. Original PM2.5 standard was promulgated in 1997 Effective December 18, 2006, EPA ─ Retained an annual PM2.5 standard of 15 μg/m 3 ─ Lowered the 24-hour PM2.5 standard from 65 to 35 μg/m 3 ─ Retained the 24-hour PM10 standard of 150 μg/m 3 ─Revoked the annual PM10 standard On October 20, 2010, EPA established increments for PM 2.5 ─Became applicable on October 20, 2011

4. Effective January 22, 2010, EPA Added a 1-hour NO2 standard at 100 parts per billion (ppb); and Retained the annual average NO2 standard at a level of 53 ppb There is an allowable increment for annual NO2 but EPA has not established an increment for hourly NO2 as of yet.

5. Designed to protect attainment areas by establishing an allowable increment PSD increment - maximum allowable increase above a baseline concentration ─Baseline concentration - ambient concentration at the time the first complete PSD permit application affecting the area is submitted

6. PollutantAveraging Period NAAQSAllowable Increment Class IClass IIClass III PM2.5Annual (μg/m 3 )15 148 24-Hour (μg/m 3 )35 2918 PM1024-Hour (μg/m 3 )150 83060 NO2Annual (ppb)53 2.52550 1-Hour (ppb)100

7. ‣ NAAQS impacts are evaluated as baseline plus all nearby sources ‣ Increment consumption is based on ◦ Actual emission increases at major sources associated with construction occurring after the major source baseline date (October 20, 2010 for PM2.5) ◦ Any increase in actual emissions from both major and minor sources occurring after the minor source baseline date (October 20, 2011 for PM2.5) ‣ Process is dynamic and based on actual emissions – increment can be consumed or can expand

8. NAAQS 35 µg/m3 Background 30 µg/m3 Any New/Modified Source PSD Sources Background 20 µg/m3 20 9 30 5 20 15

9. A new or modified source may have to demonstrate compliance with the ─1-Hour and annual NO2 standard ─24-Hour and annual PM2.5 standards ─24-Hour PM10 Standard A new or modified major source in an area designated as in attainment will have to demonstrate compliance with the increment standard

10. If you are one of 28 listed categories including: ─electrical utilities, ─refineries, ─cement plants potential to emit more than 100 tpy of any regulated NSR pollutant All other sources, 250 tpy

11. The new standards can be challenging particularly those that are short term in nature Increment consumption can be misconstrued ─If all the available increment is consumed, have you limited a region’s ability to support any new projects The complexity of any modeling analysis has increased significantly

12. an assessment of existing air quality ─ambient monitoring data, and predictions, using dispersion modeling, of ambient concentrations that result from the applicant's proposed project and other applicable emissions

13. Model Predictions Direction of travel Where does the plume reach ground Concentrations at ground level

14. Meteorological conditions ─Wind direction ─Wind speed ─Atmospheric stability Source characteristics ─Stack height ─Exit velocity/temperature ─Emission rate The presence of nearby buildings Distance to the fence line Relative location of other nearby sources Receptor locations ─Distance from source ─Surface elevation

15.  General Electric (GE) Frame 7FA natural gas-fired combustion turbine and heat recovery steam generator  Emissions: PollutantEmission Rate g/slb/hrtons/year PM102.31880 NOx2.116.672

16. Wind speed Wind direction Atmospheric stability

19. 44 m 54 m

20. 44 Meter Stack54 Meter Stack

21. 44 m 35 m 27 m

22. 27 Meter Building 34 Meter Building

23.  A lot of factors can have a major impact on dispersion  Any assessment of ambient air quality impacts from a new or modified source must be site specific. We need to know: ◦ The emission rate from the new source ◦ The source characteristics ◦ The source location relative to other sources ◦ The size and height of any nearby buildings ◦ The distance to the facility fence line

24.  The analysis we need is even more complex since: ◦ We need to consider all PM2.5 Sources at the subject facility as well as other nearby PM2.5 sources ◦ We need to average these results over each 24-hour period ◦ We need to do this for every day for the three years in which we have meteorological data. ◦ We need to consider all locations outside the facility fence line

26.  It is a statistically based standard ◦ the 3-year average of the 98th percentile of the daily maximum 1-hour average at each monitor within an area must not exceed 100 ppb  Can be hard to meet particularly when evaluating sources that are low to the ground and near a fenceline (such as a generator)  EPA has had to publish several memos clarifying their approach to demonstrating compliance

27.  Normally, EPA defines a Significant Impact Level (SIL) when it defines the increment  The SIL is important since it is used to determine if a facility contributes to a violation If a facility can demonstrate that its contribution at the point and time of any modeled violation is less than the SIL, the permitting authority has the discretion to conclude the facility did not contribute to the modeled violation  EPA has proposed an interim SIL of 4 ppb

28.  Sources such as emergency generators can have a significant impact on 1 - hour NO2 levels ◦ High hourly emission rates ◦ Short stacks ◦ Close to fencelines  Operation is also infrequent ◦ chances that they will be operating during the hours that produce the worst case NO2 impacts are low  EPA opened the door to excluding intermittent sources from the analysis

29. What is the appropriate method of combining background concentrations with modeled data ─Use the highest one hour concentration measurement – easy but very conservative ─Use the highest 98 th percentile of the annual distribution of daily maximum 1-hour values – easy but also conservative ─Use multiyear averages of the 98 th percentile of the available background concentrations by season and hour of day ─Paired each hour in the monitoring period with each hour in the modeled data - this could require some justification

30. Not all NOx is present as NO2. Conversion depends on many different factors. There is a tiered approach to handling this conversion Tier I ─assume all NOx is converted to NO2. This is the easiest and most conservative approach Tier II – Ambient Ratio Method. ─assume a default ratio of NO to NO2 conversion of 0.80 Tier III – Model conversion with OLM or PVMRM ─This is the least conservative approach. It is also the most complex and requires ozone data, in-stack NO/NO2 ratios. ─Need close cooperation with the regulatory agency