Project Information

MON-1-6.7- Grey Slip
(REINFORCE RETAINING WALL)

PROJECT DESCRIPTION:

This proposed project includes placing approximately 20,000 cubic yards of material at the toe of the retaining wall at this location. The material will be transported from the temporary site developed at the old Willow Creek slide. The fill will slope from approximately 170 feet from the base of the wall to a height of approximately 15 feet on the wall. Larger boulders will be placed at the outer edge of this fill. A continuing maintenance strategy will be needed to place additional buttressing boulders along the toe of this fill as the slope continues to settle and migrate. In addition, the area will be re-graded to close the many cracks that have formed. This work is necessary to reduce the amount of water saturating the slide mass. Grading will not occur any closer than 10 feet of the outer edge of the slide where the slope line breaks to the ocean.

ESTIMATED TIMELINE:

• Construction Complete: Winter 2001

TRAFFIC CONTROLS:

N/A

PROJECT BACKGROUND:

The retaining wall is adjacent to a landslide known as Grey Slip. As the landslide continues to move, so does the ground below the wall which provides support in the manner of a buttress the proposal is the only viable strategy to restore the structural compromise of the wall caused by the slide movement over the past few years. A permanent repair strategy has not been determined, as no methods are available to arrest the movement of slides of this magnitude.

SPECIAL CONSIDERATIONS:

Marine Sanctuary: The Monterey Bay National Marine Sanctuary has expressed high levels of concern with the migration of the landslide towards the shoreline and intertidal habitat below. Close coordination with the sanctuary has been important towards developing an acceptable approach to protect the roadway at this location.

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