Kiewit Construction of Renton, WA selected Condon-Johnson & Associates (CJA) to install drilled shafts on their C700-Sound Transit light rail project. The rail maintenance yards and elevated track structure were located south of downtown Seattle, in an area which had been hydraulically filled to depths of up to 35’.

The Challenge
In order to promote safety in extreme seismic events, the facilities are founded on drilled shafts up to 165’ deep. The shafts were up to 10’ in diameter and in some instances cased full depth with heavy wall casing to provide added shaft stiffness. All shafts were tremied and subjected to non-destructive testing by cross hole sonic logging (CSL) methods.

The Solution
Casings were driven utilizing vibro hammers and off shore impact hammers. The drilling was done using Soil Mec 825’s, IMT AF-25’s and Reed Taurus XL’s. Concrete was placed with boom pumps through a steel slick line. The $ 4.6 million project consisted of twenty-nine shafts.

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Drilled Shafts