Tunneling

Bay Tunnel

Bay Tunnel

Scope

Michels was the managing partner of a joint venture that constructed the San Francisco Bay Tunnel. As part of a $4.5 billion water system upgrade to provide a reliable clean water source for 2.5 million people, the project included the construction a 5-mile tunnel under San Francisco Bay (the first tunnel under the bay), and launch and retrieval shafts with no intermediate shafts.


The tunnel was excavated using a 14'10" Earth Pressure Balance Tunnel Boring Machine (EPB TBM), and supported by precast concrete segments with an interior diameter of 12'10". A 108" interior diameter steel water carrier pipe was installed in the concrete lined tunnel. The steel pipe segments were joined by a full depth butt weld, and then lined with cement mortar. The annulus was backfilled with cellular grout. Four curves exist in the tunnel's alignment, each with a radius of 1,000'.


The project also included installing two shafts, up to 141' in depth. The 58' diameter launch shaft was supported by a circular concrete diaphragm wall. The shaft invert was 141' deep. The retrieval shaft excavation was stabilized using ground freezing methods with the addition of steel rings and timber lagging with an interior diameter of 22' and a depth of 98'.


The project was located in an environmentally sensitive area between the San Andreas and Hayward faults, both active earthquake zones. The tunnel alignment crosses beneath railroads, large diameter water and gas pipelines, and is up to 110' below the water. The geology of the tunnel excavation included stiff clay, lenses of sand and gravel, and basalt rock. This required the EPB TBM to be designed for interchangeable soft and hard ground cutting tools.


Achievements
The collaborative approach led to many innovations that saved the project owner nearly $13 million, with no construction claims. One of those innovations was using ground-freezing technology for the exit shaft which saved money, reduced risk of water intrusion and prevented damage to the surrounding marshland ecosystem.


The project was also completed seven months ahead of schedule with 0.63 lost work days per 1,000 hours worked by Michels, which is nearly half the industry average. The project received the Tunnel Achievement Award for Project Excellence in 2015 and the National APWA Project of the Year in 2015.

  • Michels was part of a joint adventure that constructed a 5-mile long, 15-foot diameter tunnel under San Francisco Bay.
  • Michels was part of a joint adventure that constructed a 5-mile long, 15-foot diameter tunnel under San Francisco Bay.
  • A view of the route the TBM took under San Francisco Bay.

Projects

Michels constructed secant compression ring launch and receiving shafts for a microtunneling project. The launch shaft was comprised of 46 intersecting 1-meter-diameter secant piles drilled to a depth of 54 feet. The receiving shaft was comprised of 38 intersecting 1-meter-diameter piles drilled to a depth of 52 feet.

Tunneling

Conduit 16 launch and receiving shafts

Colorado

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Conduit 16 launch and receiving shafts

Michels was part of an integrated joint venture responsible for executive management field supervision and engineering on the Central Puget Sound Regional Transit Authority's University Link Light Rail Extension Project.

Tunneling

University Link Light Rail U230

Washington

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University Link Light Rail U230

Michels was construction manager for a project which included construction of the 38th Street ventilation facility, trail track tunnels and cross passages, Grand Central Terminal interlocking caverns, portions of the Grand Central Terminal main station caverns, escalator shaft interfaces and access tunnels.

Tunneling

Manhattan South Structures

New York

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Manhattan South Structures

Michels used microtunneling to build a 485-foot-long, 6-foot diameter tunnel under a major four-lane highway.

Tunneling

Mary Hill Bypass

Canada

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Mary Hill Bypass

Michels is part of an integrated joint venture, responsible for the executive management, areas of field supervision, and heading engineer positions on the Central Puget Sound Regional Transit Authority's Northgate Link Extension Project.

Tunneling

North Gate Extension Light Rail N125

Washington

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North Gate Extension Light Rail N125

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