Notes
GeoSyntec Consultants, retained by the Airport Communities Coalition (ACC), provides a technical review of the Port of Seattle’s Low Flow Analysis for the Third Runway Expansion Project at Sea-Tac Airport. The letter identifies critical deficiencies in the Port’s analysis, including failure to account for initial years of operation water requirements, unreliable long-term flow predictions, and unvalidated assumptions. GeoSyntec concludes that the current vault sizes may be substantially under-designed and that insufficient water will likely be available to mitigate impacts to low stream flows during the initial post-construction period.