ReSSA Major Update and MSEW Update

The much anticipated LRFD update to the MSE Wall and Reinforced Soil Slope Manual is now available for download from the FHWA’s website. The full title of the document is Design of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes and it was authored by Ryan R. Berg, P.E.; Barry R. Christopher, Ph.D., P.E. and Naresh C. Samtani, Ph.D., P.E. Find the abstract and download link below. As time permits, I’ll try to post more about some of the changes in this important geotechnical publication.

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[Correction] Whoops, I think it’s North America’s tallest MSE Wall, not the world’s. Anyone know what the World’s tallest MSE wall is? [/Correction]

TheNewsTribune.com has an interesting article on the Sea-Tac third runway project and how it is nearing completion and an overview of the hurdles faced. This was a unique project from a geotechnical perspective because in order to construct the runway, North America’s tallest MSE retaining wall at 130-ft high was built. One thing I didn’t know is that the 13 million cu-yd of fill needed to construct the runway needed to pass careful inspection to make sure it was free of contaminants and similar in mineralogical composition to the on-site materials. The implications and reasoning are explained in this quote from the article:

“We had to find gravel that originated in the same place in Canada and that was transported here by the glaciers as the gravel that was here on the site,” said King.

The reasoning behind such a requirement is that water that leached through the fill would pick up minute traces of the minerals in the fill, drain into the creeks and confuse or damage native salmon returning to those creeks.

By way of ASCE SmartBrief. 

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The ARES wall system is a geosynthetic reinforced MSE wall with a concrete panel facing. Most concrete panel systems use metallic reinforcement. On this project, the on-site backfill soil did not meet electrochemical requirements for […]