San Ramon Canyon Storm Drain Repair

These tunnels were constructed to provide a conduit for storm water to be more efficiently transported to the ocean in areas known to be prone to landslides initiated by water inundation. This work was performed just south of the Portuguese bend area of Rancho Palos Verdes, CA. The tunnels were constructed using modified SEM techniques supported by TBM equipment.

Drill Tech constructed the smaller slant drain tunnel using a digger shield supported by continuous driven steel casing, and the longer rib and lag tunnel using an open face TBM supported by steels rib and lagging through sandstone and siltstone. Both tunneling machines were 7’ diameter and consisted of an open shield with a carriage mounted roadheader attachment. Additional work included constructing the inlet and outlet structures. After the tunnels were excavated, 60″ diameter welded steel conveyance pipes were installed in the tunnels and the annuluses were filled with cellular grout.  

Ranchos Palos Verdes, CA

Contract Value:

$4.8M

Delivery Method:

Design-Build

Property Owner:

City of Ranchos Palos Verdes

General Contractor:

L.H. Woods & Sons, Inc.

Project Overview

  • 7′ dia. Open Shield / Roadheader Tunneling
    • 2,000′ tunnel at 13% upgrade
    • 350′ tunnel at 32% downgrade
  • Additional Scopes
    • Soldier Piles
    • Tiebacks
    • CIDH Piles
    • Soil Nails
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