Texas Natural Resource Conservation Commission Interoffice Memorandum To: Nonattainment New Source Review (NNSR) Team From: Dr. Kurt Kind, Chemical Section Date: December 4, 1995 Subject: Requirement for NNSR Netting Permit applicants are normally required to perform nonattainment netting for any pollutants that have project emission increases greater than the trigger level for the nonattainment area. If the emission netting results show that the total net project and contemporaneous period emission increases are greater than the applicable significance level, NNSR is required for the project. The NNSR review requires the permit applicant offset emission increases at the appropriate ratio for the county and pollutant. The applicant may choose to offset the total net increase (project plus the contemporaneous period) or only the project increase. If the second option is taken (offsetting the project increases), the netting is used only to determine whether the project is subject to NNSR review. Due to this, the permit engineer does not need to require emission netting if the permit applicant agrees that the project is subject to NNSR and elects to offset the project emission increases at the appropriate ratio. In this case, the permit application will undergo the most rigorous permit review (NNSR) and the netting results would not impact that review. It is important to note that only the project that is offset will be considered relied on in the issuance of a nonattainment permit and thereby excluded from future netting for that pollutant. Note that this does not apply to PSD review as emission netting results are used as inputs to air dispersion modeling performed for that permit review. In this case, all contemporaneous netting is considered relied on in the issuance of a PSD permit and must be excluded from future netting for that pollutant.