Installing the Piles

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On Friday morning, October 28th, 2011, the American Construction Company Tugboat Chelan, 140 Ton Floating Crane D.B. Palouse, and Flat Barge Skagit pulled through the passage between Stretch Island and Treasure Island and started work later that morning. 

American Construction Company tug, barge, and crane arriving at Treasure Island

The pile was vibrated in to within 8 feet of the final design depth by the hydraulically powered vibrator; the diesel pile driver was then used to drive the pile to its design depth of 25 feet. The foam around the pile, as seen in the second picture below, is actually bubbles being generated by a bubble barrier, which deadens the sound of the pile driving to prevent damage to any native sea life.

Vibrator being used to set the pile

Diesel-powered pile driver with bubble barrier around pile

As the piles were being driven to their final depth, the Exeltech engineer counted the number of blows per foot required to get the pile to its final depth. The engineer did this for each pile. The "blows per foot" count is critical in ensuring that the pile-bearing capacity is achieved for both load and seismic design capacity.

Exeltech engineer (in yellow jacket) counting and documenting the number of blows per foot

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