Historic Restoration & Environmental Considerations

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The Posey/Webster Tube is a 70-foot, above-grade structure recognized as both a State and local historic landmark. Due to its historic designation, all seismic, structural, and drainage modifications required careful coordination and special permitting under NEPA (National Environmental Policy Act) and CEQA (California Environmental Quality Act).

A similar approach was later applied to the Caldecott Tunnel for the repair and rehabilitation of Bores 1 and 3. The primary focus of that project was on critical fire safety system upgrades, ensuring compliance with modern safety standards while preserving the tunnel’s structural integrity and functionality.