Monday, May 13, 2013

Construction Update: Pile-driving Work Underway in Preparation for Water Pipeline Installation

If you use Mission Blvd. in Warm Springs or drive by our work area on the I-680, you might have noticed the arrival of some new, tall machines. These machines aren't bulldozers or excavators. Instead they’re being used to help drill holes for cement pillars in the earth – called secant piles – along the pathway of the new BDPL3 water pipeline.

The purpose of this secant pile work is to ensure that our regional water delivery pipelines are protected during an earthquake in the following ways:
  1. The secant piles will serve as the pipeline’s first line of defense against earthquakes. Their existence around the newly installed BDPL3 pipeline will lessen the impact of soil movement on the pipeline’s own seismically-designed casing and joints. 
  2. Secondly, these piles are necessary to serve as foundations for the temporary raised bridges which will soon replace the I-680 on-ramps and allow construction workers to access pipelines underneath Mission Blvd.
  3. Finally, the piles act as barriers to shore up soil on either side of the project area, ensuring workplace safety during the project’s next phases.
To see more images by SFPUC photographer Robin Scheswohl of the secant pile drilling, watch our video below:

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