NO2 analysis: Aircraft operations and NOx emissions discrepancies in DEIS, FEIS, and SEIS

A commenter challenges the air quality analysis in the Draft, Final, and Supplemental Environmental Impact Statements for Sea-Tac Airport expansion, arguing that NOx pollution totals were manipulated to stay below regulatory thresholds. Despite aircraft operations increasing significantly from roughly 384,000 to as many as 585,000 per year across the three documents, the reported tons-per-year of nitrogen oxides remained nearly flat or even decreased, which the commenter contends defies logic and contradicts the DEIS's own statements that newer, larger aircraft produce higher NOx emissions. The commenter also highlights a discrepancy between the DEIS claim that 525,000 annual operations would occur with or without a new runway and the SEIS claim that the airport is capped at 460,000 operations without one.

Open full document

Notes

A commenter argues that aircraft operation numbers used in air pollution modeling for the Draft, Final, and Supplemental Environmental Impact Statements for Sea-Tac Airport have been manipulated to obtain predetermined results. The document presents tabular comparisons showing that despite significantly increased aircraft operations in the SEIS (445,000 in 2005 and 474,000 in 2010), NOx emissions in tons per year are the same or lower than in earlier documents with fewer operations. The commenter calculates what NOx increases should be based on consistent per-plane emission rates and concludes the SEIS analysis is biased and falls below de minimis levels through manipulation.

Notes

Message