Dave Phelps has retired as Construction Permitting Section Head effective June 21. Sarah Piziali will replace Dave.

Minor source modeling and permitting for 1-hr SO2 became effective June 3. Non-PSD sources that emit SO2 are now required to demonstrate compliance with the 1-hour SO2 NAAQS.

IDNR has proposed several changes to the PSD and Non-PSD modeling guidelines.

  • Any source that operates on a purely random schedule and is limited to operating for no more than 500 hr/yr can be considered an intermittent source. In addition, any source that meets the 500 hr/yr criterion, but operates on a scheduled basis for testing and maintenance purposes, can be considered an intermittent source if the scheduled testing and maintenance is limited to the time of the day with the most favorable dispersion conditions (between 9 AM and 4 PM). Intermittent sources may be excluded from the 1-hour NO2 and SO2 analyses.
  • When using paired sums data for background concentrations it is important to model the highest-eighth-high averaged over five years instead of the maximum. The data includes several days with the background concentration values exceeding the 24-hr PM2.5 NAAQS. Modeling the maximum will result in background concentrations exceeding the 24-hr PM2.5 NAAQS.