Cut-Off & Containment

Blu Harbor Deep Soil Mixing Wall

Redwood City, CA
October 2015
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Project For
Contractor
B&B Hughes Construction
Engineer
Engeo, Inc.
Owner
The Pauls Corporation
Maximum Protected Height
Maximum Exposed Height
Maximum Sheet Length
Max Depth
20 ft (6 m)
Max Retained Height
Length
15 ft (4.6 m)
Project For
Wall Lengths
Number of Sites
Max Depth
20 ft (6 m)
Max Retained Height
Length
15 ft (4.6 m)

Features

Shipping Details

Background

Blu Harbor is a luxury apartment development in Redwood City, California, located on a peninsula on San Francisco Bay. The site was once a marina with an old tide “wall” made of asphalt, wood pilings, concrete rubble, laced tires and gravel. The plans required the removal of old debris and raising the entire peninsula a few feet. A new, mostly buried, 40-50 ft Deep Soil Mixing (DSM) wall would cut-off bay water, stabilize the soft soils, and supply scour protection during storms.

Why CMI

The DSM wall located 10-15 ft from the water’s edge would be in a corrosive saltwater environment. Engeo, Inc. needed a solution for protecting the top 15 ft of the soil-cement wall from saltwater decay. Due to this, Engeo rejected steel sheet piling. Instead, they specified CMI’s highly corrosion resistant ShoreGuard® vinyl sheet piling. The vinyl sheets, in 15-20 ft lengths, were driven down 12-15 ft on the bay side of the DSM wall, leaving the top 3-5 ft exposed.

Performance

The contractor was thrilled to finish ahead of schedule. The developer, The Pauls Corporation, was extremely happy to see the designers’ gently curving walls take form. Eventually, a promenade 12 ft wide will cap the wall, covering all but 2 ft of the sheets.

Installation

A DSM machine created the soil-cement wall and had cured before B&B Hughes Construction came to install the sheet piling. Unfortunately, the Blu Harbor Community high pressure of the DSM process caused the soil-cement mixture to fill various voids in the soft soil. This hardened “over pour” created root-shaped obstacles where the vinyl sheet piling needed to be driven. B&B Hughes, an experienced ShoreGuard® piling installer, expected potential buried obstacles.

Products Used

Product Used

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