<p><p><div class="grayed-title"></p><p><figure id='attachment_3521' style='max-width:790px' class='caption aligncenter'><img class="wp-image-3521 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of the mechanically stabilized earth wall on the Third Runway project at SeaTac Airport. The tallest MSE wall in the U.S." width="790" height="562" /><figcaption class='caption-text'> SeaTac wall. (Photo courtesy of Tony Allen)</figcaption></figure></p><p><strong>Location:</strong> Seattle, WA</p><p></div><h2>Project Summary/Scope:</h2>The tallest MSE wall in the U.S. to date, the wall has an exposed height of 138 feet (42 meters) at its tallest section and was constructed to limit encroachment on adjacent creeks and wetlands and increase the land use area for the Third Runway project at SeaTac Airport. The West MSE wall was one of several walls constructed for the runway extension and is approximately 1,430 feet (436 meters) long, has four tiers formed by 8-foot (2.4-meter) setbacks, and had a constructed height of 150 feet (46 meters). The wall supports a ~15-foot (~4.5-meter) high, unreinforced 2H:1V slope. The MSE wall used steel reinforcing strips with concrete facing panels. In the lower tier, up to twenty-five 2-inch (50-mm) wide by 0.24-inch (6-mm) thick strips with a length of 116 feet (35.4 meters) were connected to the 5 by 5-foot (1.5 by 1.5-meter) panels.</p><p>A full discussion of project background, design aspects, and instrumentation of these MSE walls are provided by Sankey et al. (2007) and Stuedlein et al. (2007).<br><h2>Project Technical Papers:</h2>Sankey, J.E., Bailey, M.J., and Chen, B. (2007). “SeaTac Third Runway: Design and Performance of MSE Tall Wall,” New Horizons in Earth Reinforcement, 5th International Symposium on Earth Reinforcement, IS Kyushu 2007, Fukuoka, Japan.</p><p>Stuedlein, A.W., Mikkelsen, P.E. and Bailey, M.J. (2007). Instrumentation and Performance of the Third Runway North MSE Wall at Seattle-Tacoma International Airport, Field Measurements in Geomechanics 2007, GSP No. 175, ASCE, J. DiMaggio and P. Osborn (Eds.), pp 1-14.<br><h2>Date Case History Prepared:</h2>November 2012</p></p>