EXH0403021824

._., ThirdRunway- EmbankmentFill andWest MSE Wall ExpansionProject Applicant: Portof Seattle Reference: 1996-4-02325 INTRODUCTION Observations of damage to mechanically stabilized earth (MSE) walls and "" extensive liquefaction from the Nisqually earthquakeof 28 February2001 emphasize the seriousness of coneems over the adequacy of these asp_ts of the proposed Third Runway (Third Runway) Expansion Project at Seattle Tacoma International Airport (SeaTac). In a letter dated 16 February 2001, GeoSyntec Consultants (GeoSyntee) provided technical review comments on the investigation, analysis and design relating to construction of the embankment fill and West MSE Wall elements of the Third Runway ' project. GeoSyntee prepared the letter of 16 February 2001 on behalf of the Airport Communities Coalition. On 28 February 2001, following issuance of our comments, the Seattle/Tacoma area was subject to a significant earthquake. In terms of the severity, the ground motions induced by the earthquake of 28 February 2001, now WI.OJSO.OI/SEATACEQ!DOC AR 021824 GzoSY_rzcCo_'t_x_e_rs Terzi and Walker / Kenny March 2001 Page 2 known as the Nisqually earthquake,are best described as moderate. However, despite the moderate severity of ground motions, there were numerous instances of ground failure and structural damage throughout the affected area, including at SeaTac and other regiofial aviation facilities. Furthermore, significant damage was reported to at least two MSE walls. In light of the relatively moderate intensity of the ground motions in the Seattle/Tacoma area due to the Nisqually earthquake, observations of damage to MSE wails and extensive liquefaction and lateral spreading punctuate our concernsover the adequacy of these aspects of…

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Call to order – Roll Call – Quorum Established – Land Acknowledgement We would like to acknowledge that our Agency operates in four present-day counties, which are the traditional lands of the Coast Salish people, past and present. This acknowledgement does not take the place of authentic relationships with indigenous communities in our jurisdiction and [...]