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Port Of Seattle Letter to Barbara Stuhring: Ethylene Glycol Deicing at Sea-Tac Airport and Wastewater Treatment

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A 1993 letter from the Port of Seattle to a Des Moines resident explains that airline deicing at Sea-Tac Airport uses only FAA-approved ethylene or propylene glycol, and that wastewater from deicing drains to the airport's treatment system before being discharged to Puget Sound — not to Miller or Des Moines Creeks. The Port acknowledged its treatment plant was not designed to handle glycols and was evaluating upgrades. A follow-up 1996 letter challenges a contradictory statement in the airport's Final Environmental Impact Statement, which claimed most deicing fluids were contained and treated by the Port's Industrial Wastewater System.

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Notes

December 22, 1993 letter from Port of Seattle to Barbara H. Stuhring of Des Moines, WA responding to her November 17 inquiry about ethylene glycol and propylene glycol deicing fluid use at Sea-Tac Airport. Letter states FAA requires only ethylene or propylene glycol for aircraft deicing, that deicing areas drain to the airfield wastewater treatment system and discharge to Puget Sound via outfall — not to Des Moines Creek or Miller Creek. Acknowledges Port’s treatment plant is not designed to treat glycols and Port is evaluating modifications. Also includes Stuhring’s March 14, 1996 follow-up letter to David Aggerholm disputing statements in the Sea-Tac Airport Master Plan Update Final EIS (comment R-13-15) as contradicting the 1993 letter, and the Final EIS response to comments regarding glycol concentrations in stormwater runoff, BOD impacts, and effects on Miller and Des Moines Creeks.

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