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The Texas Commission of Environmental Quality (TCEQ) is requesting information from sites that reported > 10 tons per year (tpy) of sulfur dioxide (SO2) emissions in the 2009 TCEQ point source emissions inventory questionnaire (EIQ). This information will assist the TCEQ with State Implementation Plan (SIP) development for the one-hour SO2 National Ambient Air Quality Standard (NAAQS).

The initial requests are being sent to sites via certified mail and include an Excel spreadsheet listing the SO2 emitting sources reported in the 2009 EIQ. Sites are asked to correct errors in the spreadsheet, provide missing data, and ensure SO2 emissions from all sources on-site are listed regardless of being included in the 2009 EIQ. The emissions data must include all one-hour and annual permit allowable emission rates including certified emission limits and any registered or unregistered permit by rule actual emissions from the most recent year. Sites are also asked to update stack parameters and locations for sources. Responses are due to the TCEQ within 30 days of the date of the letter.

On June 2, 2010, the EPA strengthened the NAAQS for SO2 by issuing a new 1-hour primary NAAQS for SO2 of 75 parts per billion (ppb) calculated as the three-year average of the 99th percentile of the annual distribution of daily maximum 1-hour average concentrations. As required by EPA, the TCEQ must demonstrate attainment of the SO2 NAAQS using refined air dispersion modeling (e.g., AERMOD Modeling System) as well as ambient monitoring data. If there are any sources or groups of sources that may cause or contribute to a violation of the NAAQS, as demonstrated by the model or ambient monitoring data, they must be sufficiently controlled to ensure timely attainment of the standard. TCEQ must submit maintenance SIP revisions for attainment and unclassifiable areas by June 2013 and attainment demonstration SIP revisions for SO2 nonattainment areas by February 2014.

Therefore, the TCEQ is requesting SO2 emissions data from sources with site wide SO2 emissions > 10 tpy in order to perform air dispersion modeling using AERMOD. If sites are not screened out during the initial TCEQ modeling, they may be contacted in the future by TCEQ to provide more detailed information for modeling including property lines, building downwash data, and hours of operation.

If you are a site that has received a Special Inventory request letter from the TCEQ, Trinity Consultants can assist with data collection, verification, and preparation of a response to the TCEQ. If you need assistance or have any questions, please contact one of Trinity’s Texas team: 512-514-6600 (Austin), 337-493-3301 (Beaumont-Port Arthur), 361‑883‑1668 (Corpus Christi), 972-661-8100 (Dallas) or 713-552-1371 (Houston).