Seattle-Tacoma International Airport, WA

Seattle-Tacoma International Airport, WA


Sea-Tac Airport - 3rd Runway, WA
Reinforced Earth MSE precast retaining wall
Location: 
Seattle, WA
Owner: 
Port of Seattle
Contractor: 
TTI Joint Venture (Tri-State Const., Gary Merimo Const., Scarcela Bros. Construction)
Consultant: 
HNTB
Engineer: 
Hart Crowser

Expansion of the SeaTac International Airport in the State of Washington (USA) included construction of a third runway, which required installation of a series of single face and multi-tiered Mechanically Stabilized Earth (MSE) wall structures.  The tallest of these MSE walls consisted of a four-tier structure with a total exposed height of approximately 43 meters (45 meters with wall base embedment

The significant height of the retaining walls for the project left few viable options from engineering and economic standpoints.  The design team made a preliminary evaluation of more than sixty retaining walls and slope geometric relationships before selecting steel-reinforced Mechanically Stabilized Earth (MSE) walls for the three main retaining walls.  It is notable that a comparison of wall technologies provided by FHWA (1995) indicates that steel-reinforced MSE walls are a stand alone selection for heights exceeding 20 meters.  On this basis, a qualifications-based selection process by the Port of Seattle (Owner) and HNTB (A/E) found that Reinforced Earth ® technology had a reliable international track record with regard to retaining walls exceeding 30 meters in height.  The technology for tall Reinforced Earth walls typically consists of cruciform facing panels connected to discrete steel reinforcing strips in a select granular fill matrix.  The design of the panels and the material components that make up the Reinforced Earth volume needed to be based on a combination of internal, external and compound stability evaluations.