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Providing Reliable, High-Quality Drinking Water for San Diego

108” Horseshoe Tunnel crossing under the Agua Hediona Lagoon for the 54” Steel Conveyance Pipeline
Tetra Tech used our Leading with Science® approach and expertise in desalination plants to design a drought-proof drinking water solution for the Claude “Bud” Lewis Carlsbad Seawater Desalination Project in San Diego, California.

Tetra Tech was a key design partner in the Western Hemisphere’s largest, most technologically advanced and energy efficient seawater desalination plant. The project provides a new source of fresh drinking water—desalinated seawater from the Pacific Ocean—to serve the demands of San Diego residents.


  • 400,000 San Diego residents have a new supply of fresh drinking water
  • Constructed the pipeline through three cities while minimizing traffic disruptions in high-traffic, urban areas
  • 78-inch diameter tunnels were designed to protect a sensitive wetland and eliminate disruption to Interstate 5 and a major commuter railroad
  • 52,000 total linear feet of 54-inch welded steel water conveyance pipeline was designed, permitted, and constructed within 30 months from award of contract

As part of the Poseidon Resources team, Tetra Tech prepared the 30 percent design drawings for the 54 million gallons per day seawater desalination plant and the 10-mile, 54-inch conveyance pipeline. The plant was designed using the latest technology, including use of fish-friendly intake pumps, a pretreatment system to remove seawater contaminants, and energy recovery devices to reduce pumping at the reverse osmosis system. As part of the Kiewit Shea team, Tetra Tech also provided final design and construction engineering services for the conveyance pipeline and new intake pump station.

The pipeline was separated into six packages to enable construction to progress on multiple headings while the design and approvals were completed. Tetra Tech was challenged to complete, permit, and obtain approval for the initial design package three months after receiving notice to proceed.

Claude "Bud" Lewis Carlsbad Seawater Desalination Plant Reverse Osmosis Racks
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