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Nevada’s Increment Evaluation Process

Nevada’s Increment Evaluation Process. Greg Remer Staff Engineer Nevada Bureau of Air Quality Planning 333 W. Nye Lane Carson City, Nevada 89706-0851. What are PSD Increments?. Maximum increase in air quality impacts that may occur beyond a baseline air quality level in an area.

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Nevada’s Increment Evaluation Process

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  1. Nevada’s Increment Evaluation Process Greg Remer Staff Engineer Nevada Bureau of Air Quality Planning 333 W. Nye Lane Carson City, Nevada 89706-0851

  2. What are PSD Increments? • Maximum increase in air quality impacts that may occur beyond a baseline air quality level in an area. • Established for sulfur dioxide (SO2), nitrogen dioxide (NO2), and particulate matter smaller than 10 microns (PM10) • Do not exist for other pollutants. • Total impacts cannot exceed applicable Ambient Air Quality Standards (AAQS)

  3. Prevention of Significant Deterioration • PSD increments are typically the most difficult ambient air standards to comply with • Industrial development plans must consider the magnitude and location of potential PSD air quality impacts

  4. PSD Increments • PSD increment is impacted by: • Source changes since the minor source baseline date at: • Minor stationary sources within the triggered planning area • Area sources within the triggered planning area • Mobile sources within the triggered planning area • Source changes since the major source baseline date at: • Major sources within and outside the planning area

  5. Standard EPA Puzzle Book Evaluation Approach • Develop inventory of baseline sources (point, area, mobile) • Develop inventory of current emission sources (point, area, mobile) • Subtract inventory (Current – Baseline, at each source) • Model the difference

  6. Problems with the Standard Approach • Difficult to determine amount of increment expansion • Doesn’t take into account changes in stack configuration • Doesn’t take into account changes in emission location • Doesn’t take into account differences in meteorological conditions

  7. Nevada’s Pre-1979 107(d) Planning Areas

  8. Nevada’s Post-1979 107(d) Planning Areas + =

  9. Nevada’s Increment Evaluation Approach Maximum allowable increase in air quality impacts that may occur beyond a baseline air quality level. Model/Met • Current emissions • (point, area, mobile) Current impact Baseline impact • Baseline emissions • (point, area, mobile) Current Impact - Baseline Impact = Increment (consumption or expansion)

  10. PSD Increment Modeling INPUTS OUTPUT CALCULATIONS (modeling) Source Inventory Meteorological Data Receptors Predicted Impacts At Receptors

  11. PSD Increment ModelingInputs • Point Source Information: • Pollutant Emissions (in general, actual for baseline, potential for current year) • Location • Release height • Temperature • Exit velocity • Stack diameter • Nearby building information • Area Source Information : • Railroad Sources • Mobile Sources • Miscellaneous Sources

  12. PSD Increment ModelingInputs • Planning Area Information: • Includes all stationary point sources in and within 50 kilometers of the planning area • Includes railroad, mobile, and miscellaneous sources across planning area grid • Met Data: • Baseline met • Current year met • Receptors • 500 m grid area-wide • Dense grid around selected points of interest – Additional dense grids can be added for each source, if needed

  13. PSD Increment ModelingOutputs • Binary output files • Post-processed (specially developed software): • Paired in space and time; or • Paired in space, unpaired in time • Post-processed results imported to GIS for plotting • Results are the amount of increment consumed or expanded at each receptor

  14. PSD Increment ModelingPost-Processing • Paired in space, unpaired in time: • Requires baseline met • Model results are evaluated on a receptor-by-receptor basis for the second-highest concentration occurring at each receptor (for each pollutant and averaging time) • Paired in space and time: • Used if no baseline met is available • Current year met is also used for baseline modeling • Model results are evaluated on a receptor-by-receptor and hour-by-hour basis (for each pollutant and averaging time)

  15. PSD Increment Modeling • Lessons Learned • Expensive (over 2 years and more than $0.5 million) • Volume of data creates long model runs • Breaking each model run into pieces makes the number of model runs required hard to manage • Modeling on a facility-by-facility basis provides more refined source contribution information • Once baseline modeling is performed, only current year results need to be re-modeled (if baseline met is available)

  16. Nevada Increment Tracking System Questions?

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