Carlsbad Desalination Plant

The Project.

Even before California’s historical drought, plans were being drawn for a desalination plant on the Coast of San Diego County. The privately financed project will produce enough drinking water to serve 400,000 San Diegans and aimed to provide the County with approximately 7% of its total water supply by 2020.


Tetra Tech for Poseidon Water


Carlsbad, CA


  • Geotechnical
  • Geotechnical Testing

Project Fact:

The plant is the first water infrastructure project in the state to have a zero net carbon footprint.

The Leighton Solution.

The $1 billion desalination project includes three main components: the desalination plant which includes pretreatment filters, a post treatment facility, chemical storage area, a solid handling building, a 3.4 million gallon (MG) product water storage tank, a booster pump station, a reverse osmosis building, and associated improvements including retaining wall, screen walls, road widening, parking area, and landscaping; a 10-mile pipeline that connects to the Water Authority’s regional distribution system; and upgrades to Water Authority facilities for distributing desalinated seawater throughout the region.

Leighton provided geotechnical reports for both the desalination plant and the backbone pipeline. Challenges of the project include the coastal location, bedrock and alluvial conditions, below grade facilities, and significant differences in soil properties across the site.

The backbone water pipeline crosses Carlsbad, Vista, Oceanside, and San Marcos connecting to Vallecitos, Olivenhain, and San Diego Water Authority pipelines. The pipeline consists of 20-, 36-, and 54-inch-diameter Cement-Mortar Lining (CML) and Coating steel pipes with invert depths generally ranging from 10 to 25 feet below the existing grade.