TagSea-Tac Airport(2025)

Letter dated March 21, 2001 from Maggie Corbin, Sr. Environmental Program Manager, Port Of Seattle Seattle-Tacoma International Airport, to Ann Kenny at the Washington Department of Ecology Northwest Regional Office, transmitting a synthetic minor permit. Background: Puget Sound Clean Air Agency (PSCAA) issued Order dated September 21, 1999 (Construction No. 7777, Registration No. 21408) limiting

Following the Nisqually earthquake of February 28, 2001, GeoSyntec Consultants wrote to the U.S. Army Corps of Engineers and Washington State Department of Ecology raising serious concerns about the seismic safety of the proposed Third Runway expansion at Seattle-Tacoma International Airport. The letter highlighted that the earthquake caused damage to mechanically stabilized earth (MSE) walls and widespread liquefaction despite being only a moderate event, reinforcing earlier warnings about flaws in the project's seismic design criteria and ground motion analysis. GeoSyntec argued that the airport's role as a regional emergency lifeline demands higher safety standards than those applied to ordinary residential structures.

Two 2001 Seattle Post-Intelligencer articles raise safety and environmental concerns about SeaTac Airport's proposed third runway. The first warns that a planned 15-story, 1,450-foot retaining wall built on weak, earthquake-prone soils could catastrophically fail in a seismic event, threatening wetlands and salmon-bearing streams. The second reveals that state officials approved a key water-quality permit for the runway without following their own attorney's advice to secure a water right, prompting the Airport Communities Coalition to appeal the permit and allege political pressure was driving the project forward.

This internal engineering memo from Jamie Beaver to Mike Bailey, dated March 9, 2001, outlines the process used to determine subgrade improvement zones for a 3R embankment stability project. The analysis focused on liquefaction risks, using post-liquefaction undrained residual shear strength (PLURSS) values derived from seismic reanalysis, ultimately recommending improvement zone widths of 100–120 feet depending on location. The memo notes that factors of safety for the liquefaction and pseudo-static cases generally ranged from 1.0 to 1.2 across various zones.

Port of Seattle SEPA addendum (POS SEPA No. 01-05, AR 049967) dated March 6, 2001, for the Seattle-Tacoma International Airport North Electric Service Upgrade project. Documents a revised proposal for the North Main Service Point site location and 12.5 kV cable route connecting to the Bow Lake Substation via International Boulevard near South 176th Street.

Draft memorandum dated March 5, 2001 from Douglas Lindquist E.I.T., Barry Chen PhD P.E., and Michael Bailey P.E. of Hart Crowser Inc. to Jim Thomson P.E. of HNTB, project J-4978-30. Presents revised methods and results of liquefaction analyses for the SeaTac Third Runway embankment, based on revised probabilistic seismic hazard analysis (PSHA) and one-dimensional site

Draft Conceptual Reclamation Permit Package for Borrow Areas 3 and 4 at Sea-Tac International Airport, City of SeaTac, Washington. Prepared by Hart Crowser for Port Of Seattle for presentation to the Washington Department of Natural Resources (DNR), March 1, 2001, project J-4978-62. Document covers site preparation activities, mining practices, operating plan, conceptual reclamation plan, revegetation

Letter dated February 22, 2001 from Pam Bissonnette, Director, King County Department of Natural Resources, to Ann Kenny, Senior Permit Specialist, Washington State Department of Ecology Northwest Regional Office, regarding King County’s technical review of the Port Of Seattle’s Comprehensive Stormwater Management Plan (SMP) for Master Plan Improvements at SeaTac International Airport. The letter references

Letter dated February 22, 2001 from Pam Bissonnette, Director of King County Department of Natural Resources, to Ann Kenny, Senior Permit Specialist at Washington State Department of Ecology (DOE) Northwest Regional Office, regarding King County’s technical review of the Port Of Seattle’s Comprehensive Stormwater Management Plan (SMP) for Master Plan Improvements at SeaTac International Airport.

In February 2001, engineering firm GeoSyntec Consultants submitted a technical review letter on behalf of the Airport Communities Coalition, raising serious concerns about the proposed Third Runway expansion at Seattle-Tacoma International Airport. The review identified significant deficiencies in the geotechnical investigation and analysis supporting construction of the embankment fill and West MSE Wall, including insufficient soil strength data and inadequate seismic safety assessments. GeoSyntec warned that the proposed design — which would result in the world's tallest MSE wall built over weak, potentially unstable soils in a seismically active region — could fail under earthquake conditions, threatening both airport operations and nearby natural resources.