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Sulfur Dioxide Dispersion Modeling for Navarro County

Air dispersion modeling methods, files, and data to support the Navarro County sulfur dioxide attainment demonstration for the State Implementation Plan (SIP) revision.

A portion of Navarro County does not meet the 2010 Sulfur Dioxide (SO2) National Ambient Air Quality Standard (NAAQS) . TCEQ has developed a plan to demonstrate how the area will meet the SO2 standard. Below is TCEQ's dispersion modeling that was used for developing the plan, including a description of pollution sources and the surrounding area.

If you have about these files, please email with "Navarro County SO2 Dispersion Modeling Files" in the subject line.

Area Overview

The Streetman Plant owned by Arcosa LWS, LLC has one SO2 emissions source within the Navarro County 2010 SO2 NAAQS nonattainment area, outlined in blue on the map. The Richland Southeast 1220 Road monitor, or Continuous Ambient Monitoring Station 1081 (C1081), is required under the Data Requirements Rule and was sited (green triangle on the map) in 2016 to monitor SO2 concentrations near the facility. The National Weather Service monitor (purple plus sign on the map), located at the Corsicana Municipal Airport, provided the surface meteorological data input for this modeling.

A map showing the area in Navarro County, Texas where the Streetman Plant is shown as a smaller area outlined in blue, within the larger Navarro 2010 SO2 NAAQS nonattainment area outlined in red. A Data Requirements Rule monitor, the Richland Southeast 1220 Road monitor, is shown as a green triangle in the middle of the Streetman Plant area. The National Weather Service monitor used for surface meteorological data, located at the Corsicana Municipal Airport, is marked as a purple plus-sign north of the Navarro nonattainment area.

Larger Map

Model Configuration

The source in the Navarro County 2010 SO2 NAAQS nonattainment area was modeled with the standard practices outlined in Appendix W, Guideline on Air Quality Models.

Air Dispersion Model: AERMOD version 21112

AERMOD Preprocessors:

  • AERMET version 21112 to generate meteorological data files.
  • AERMINUTE version 15272 to include measured one-minute wind averages.
  • AERSURFACE version 20060 to determine the surface characteristics for the meteorological station.
  • AERMAP version 18081 to gather elevation data for sources and receptors.
  • The Building Profile Input Program for PRIME (BPIPPRM) version 04274 to calculate building downwash effects.

Meteorological Years Modeled: 2015 through 2017, and 2019 through 2020. 2018 did not meet the US Environmental Protection Agency’s data completeness requirements.

Background Concentration: The background SO2 concentration used for this modeling was 6.0 parts per billion, taken from the 2020 design value from the Midlothian Old Fort Worth monitor (C52).

Modeling Data Files

You may view and download the model runs and control file inputs described below from the TCEQ Air Modeling secure FTP site . To download a large quantity of modeling files, please use an FTP client software, such as FileZilla , to access our secure FTP site:

Data available includes:

  • Ancillary inputs (downwash, meteorology, and receptor input data).
  • Run directories containing control files and model output.
  • Postprocessing script to calculate the five-year design value with the split years used due to incomplete data in 2018. 

AERMOD and its preprocessor source code and executables are available on the US Environmental Protection Agency's website .  

If you would like to request additional data related to the modeling for this SIP revision, please email with "Navarro County SO2 Modeling Files - Data Request" in the subject line and specify which data you are requesting.

SIP Revision and Related Appendices 

Documents for the SIP revision and appendices related to this modeling are below:

For more on this SIP Revision, visit the Air Pollution from Sulfur Dioxide webpage.