Malcolm Drilling Working on Seattle’s Second Tallest Tower

Malcolm Drilling at Rainier Square in Seattle
Malcolm Drilling at Rainier Square in Seattle

Malcolm Drilling is currently working on shoring for the foundation excavation of a new tower at Rainier Square in downtown Seattle.  The structure will be a 58-story mixed-use skyscraper topping out at 850 feet, which will be the second tallest in the City. The site encompasses almost an entire city block, and currently contains the iconic Rainier Tower, designed by Minoru Yamasaki- architect of the World Trade Center.

The foundation excavation will extend to a depth of 87 feet below grade.  Shoring consists of 85,000 square feet of soldier beam shoring with 135-foot long tiebacks.  Soil conditions consist of 15 feet of fill over 30 feet of silty sand and 50 to 60 feet of clay with slickenside, which is characteristic due to the nearby Seattle fault zone, and glacial till.  Secant pile shoring with tiebacks will be used where the excavation is deepest to mitigate potential settlement of the nearby Rainier Tower.

Image credit: Malcolm Drilling

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