Improving Groundwater Taste and Odor: The Cypress WPF

Client: City of Lomita
Location: Lomita, CA

The Cypress Water Production Facility Off-Line Testing Plan was created in an effort to address concerns expressed by the residents of the City of Lomita in regards to hardness, alkalinity, taste, and odor. Hazen and Sawyer created a comprehensive testing plan to evaluate the treatment at the well and blending with Metropolitan Water District imported water.

One method of managing water quality at the Cypress WPF is to blend the treated well water thoroughly with MWD water at the plant and in the tank. Two blends of well and MWD water (60/40 and 50/50) were tested.

Lomita residents taste blends of local well water with imported water, in addition to 100% imported water. Over 97% of participants found the appearance of the blended water acceptable and nearly 67% preferred some form of blended water to 100% MWD imported water.

Hazen and Sawyer carefully tested and analyzed the well water to consider the causes of complaints and to evaluate possible adjustments to operations of the existing treatment and production facilities to improve the water quality.

Project Outcomes and Benefits

  • Conducted flavor profile analyses to help identify the possible causes of taste and odor.
  • Resolved all community issues with hardness, taste, and odor.
  • Developed an economical blend of local groundwater and imported surface water, saving the city almost $500 per acre-ft. of water.
  • Removed methane and sulfide by adjusting existing aeration and oxidation.
  • Integrated treatment processes to optimize groundwater quality for iron, manganese, and calcium.

For more information on this project, or to discuss a similar project in your area, contact Lynn Grijalva at