Subsurface Intakes for Desalination

Pioneering Desalination Intake Systems

In the face of increasing pressure on water supply, water agencies and coastal communities are increasingly considering the viability of seawater desalination to meet their water supply needs.

GEOSCIENCE developed, and is a leader in slant well subsurface intakes for seawater reverse osmosis (SWRO) desalination plants. For more than a decade, GEOSCIENCE has led the major projects looking at this very important alternative water supply issue throughout California. As part of its role as an industry leader, GEOSCIENCE is a founding member of CalDesal, the only professional association dedicated to ocean, groundwater and salinity management in the state.

GEOSCIENCE designed and drilled the first successful artificially filter packed slant well near Dana Point for the Metropolitan Water District of Orange County, a project now being managed by the South Coast Water District. The test showed consistent high efficiency pumping for nearly two years with very low silt density index.

How Slant Wells work:

Slant wells are drilled at an angle, which allows for the slant well to pump water from below the ocean surface. The sea water obtained by this method contains fewer impurities and has silt density indices that are below current SWRO feedwater supply standards, which reduces the need for pretreatment. The subsurface intake approach also reduces issues related to impingement and entrainment, thus eliminating impacts on the ocean ecosystem that occur from open ocean intakes.

We have continued to be involved in numerous projects and feasibility studies throughout the state, including:

  • California American Water Monterey Peninsula Water Supply Project
  • South Orange Coastal Ocean Desalination Project
  • City of Oceanside – Seawater Desalination Feasibility Mission Narrows
  • Water Authority -Camp Pendleton Desalination Project
  • SCWD2 Seawater Desalination Facility – City of Santa Cruz Water Department and Soquel Creek Water District
  • Monterey County Water Resources Agency –Monterey Bay Regional Desalination Water
  • Cambria, Cambria Community Services District and US Army Corps of Engineers
  • Poseidon and ECO Water Systems — Huntington Beach
  • San Diego County Water Authority – Desalter Well Design in the City of Oceanside
  • City of San Diego — San Pasqual Brackish Temporary Desalination Facility
  • Vista Serena Hotel Desalination, Mexico
  • Cabo Hacienda Hotel Desalination, Mexico
  • California American Water Coastal Water Project – Moss Landing


Monterey Bay Desalination Project

GEOSCIENCE is using slant well technology to help alleviate pressure on the local aquifer and contribute to local water supplies.

Client: California American Water Company
Date: 2010-present
Services Performed: Groundwater Modeling, Subsurface Intakes for Desalination


Doheny Ocean Desalination Project

Municipal Water District of Orange County (MWDOC) has conducted detailed investigations to determine the feasibility of providing an ocean water desalination supply source in south Orange County utilizing slant well technology.

Client: Municipal Water District of Orange County, SCWD
Date: 2005-present
Services Performed: Groundwater Modeling, Subsurface Intakes for Desalination