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February 13, 1981 Baseline Date in Determining Net Emissions Increases 4.15
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4.15
DATE: FEB 13 1981 SUBJECT: Baseline Date in Determining Net Emissions Increases
FROM: Darryl D. Tyler, Acting Director
TO: Allyn M. Davis, Director We have reviewed your January 28, 1981 memorandum in which you request guidance regarding the relevance of baseline date to the determination of creditable contemporaneous increases and decreases under the PSD regulations. Our response is as follows. As you noted, emissions changes can be considered "contemporaneous" only if they occur no more than 5 years before the commencement of construction of the particular changes being considered. 40 CFR 51.21 (b)(3)(ii). There is, however, a limitation on this 5 year period: 40 CFR 52.21(b)(3)(iv) makes any increase or decrease in emissions of sulfur dioxide (SO2) or particulate matter (PM) creditable in this netting process only if it is required to be considered in computing the amount of increment available. This means that no changes in emissions of SO2 or PM commencing prior to January 6, 1975 would be considered in determining net emissions increases. Your question also addresses the treatment of carbon monoxide (CO) emissions changes in determining net emissions increases. The answer is that criteria pollutants other than SO2 and PM, such as CO, are not subject to the limitation contained in Section 52.21(b)(3)(iv); thus, one looks only to the 5 year period proceeding the commencement of construction of the modification triggering netting in determining which emissions changes will be netted. It is possible that the PSD Set II program will develop increments for these pollutants and extend the limitations contained in Section 52.21(b)(3)(iv) to them. Until such time, however, no such limitation exists for CO emissions reductions. I trust that this has been responsive to your request. Please contact Mike Trutna of my staff at 629-5292 if you have any further questions on this matter.
cc: W. Barber |