On August 23, 2010, the U.S. EPA finalized the new 1-hour primary National Ambient Air Quality Standard (NAAQS) for SO2.  As a result of the new rule, all new or modified major sources will be required to demonstrate compliance with the new 1-hour SO2 NAAQS as part of federal permitting projects.  Many states may also require a similar compliance demonstration for state-level permitting projects.  Additionally, for the first time, U.S. EPA is requiring that states using dispersion modeling analyses to supplement ambient monitoring data in setting nonattainment area designations.

The Illinois Environmental Protection Agency (IEPA) has reviewed ambient air monitoring data for years 2007 thru 2009 and has indicated that sub-county areas in Illinois are not meeting the new 1-hour SO2 NAAQS standard.  IEPA is currently sending letters to SO2 emitting sources requesting specific data that IEPA will be using to conduct dispersion modeling analyses in support of attainment designations with respect to the 1-hour SO2 NAAQS.  IEPA is requesting the following data from facilities:

 - The location, designation, and dimensions (height, width, length) of all buildings and structures at facility.

 - Property boundary locations and the means, if any, by which the general public is preluded access to plant property (e.g., security fences, guard stations, physiographic barriers, etc.).

 - Specific locations for all stacks and release points emitting SO2, along with information pertaining to the manner in which emissions are discharged to the atmosphere (e.g., stack with rain caps, stacks with unobstructed vertical releases, "gooseneck" stacks, lateral discharges, vents, and fugitives.

IEPA is also requesting facilities provide a current plot plan or site map with sufficient level of detail to the data listed above.  In addition, IEPA states that any existing coordinate data related to the locations of buildings, SO2 emitting stacks, and property boundaries would also be helpful to their modeling analyses.  Many facilities, while gathering this data for IEPA, may want to conduct an independent dispersion modeling analysis in case there are concerns regarding the results of the IEPA modeling.

Trinity has served multiple clients with NAAQS analyses and has access to modeling resources across the country.  For further information or assistance in gathering data for IEPA or conducting independent dispersion modeling analyses, please contact a local Trinity office at 800-229-6655.