News | September 19, 2007

Marin Desalination Program Receives Industry Recognition

San Francisco, CA — The American Academy of Environmental Engineers (AAEE) awarded Marin Municipal Water District (MMWD) an Honor Award for a program that successfully pilot tested seawater desalination to treat water from upper San Francisco Bay for drinking water. The district has been interested in desalination since 1990 when pilot tests showed that desalination could produce a safe, palatable drinking water. Since then, treatment technologies have improved and desalination costs have declined. However, MMWD had to ensure that operation of a desalination facility could meet new water quality, environmental, and permit requirements and was feasible.

To gather the data needed for comprehensive evaluation of a full-scale desalination facility, MMWD completed a year-long Seawater Desalination Pilot Program to study and pilot recent seawater reverse osmosis (SWRO) and pretreatment technologies. The MMWD Pilot test took source water from northern San Francisco Bay, which presents a number of challenges for water treatment. San Francisco Bay is a complex estuarine water body that is influenced by ocean tides, fresh water from the Sacramento-San Joaquin Delta and local rivers, and bay discharges that shift and change on a daily and seasonal basis.

MMWD hired Kennedy/Jenks Consultants to lead a team of consultants in conducting the Seawater Desalination Pilot Program. Kennedy/Jenks served as the Prime Consultant, assisted by CH2MHill, who acted as technical advisor and led the public outreach program and the cost estimating effort. MMWD Engineering, Operations, and Maintenance staff assisted in the construction and operation of the pilot plant and conducted most of the public tours. URS Corporation, working under a separate contract, assisted with the public outreach seminars and helped prepare the project EIR.

Kennedy/Jenks designed, constructed, and operated the pilot program from June 2005 to May 2006. The pilot program included a water quality test program that is probably the most comprehensive program conducted for a seawater desalination pilot plant. It included extensive environmental testing to support the Environmental Impact Report (EIR) for the project. It also developed substantial analytical evaluations of the pilot data and design criteria and produced a thorough and comprehensive Engineering Report with detailed cost estimates for full-scale project alternatives.

The SWRO Pilot Program used a comprehensive, integrated approach that not only tested the safety and taste of the desalinated water, but also investigated the effects that a full-size desalination facility would have on the water quality in San Francisco Bay, the air quality in Marin County, and the landfill where solid wastes from the desalination process would be sent. The study showed that desalinated water is safe and meets all state and federal requirements. It also demonstrated that brine discharge blended with effluent from the local wastewater treatment plant will not harm the San Francisco Bay environment. The report recommends the best pretreatment process for water from upper San Francisco Bay and presents preliminary design criteria and conceptual costs for a full-scale desalination facility.

Since public perception is very important to the success of implementing a new water treatment approach, the Pilot Program also featured a first-rate public outreach program that included plant tours, information seminars, and public water tasting. In June 2005, Marin County residents were invited to the pilot plant grand opening ceremony, where MMWD customers learned about desalination and took part in water tasting. The Pilot Plant was also toured by water industry professionals in June 2005.

The Pilot Study is an important step toward securing a sustainable water supply for Marin. A SWRO desalination facility would reduce Marin's reliance on imported water and provide a reliable, local, drought-proof water supply for dry and drought years when other water supplies are reduced or cut off. Because the body of work completed as part of the MMWD Seawater Desalination Pilot Program is substantial, it also advances the use of desalination in California and other locations where bay water desalination projects are under consideration.

SOURCE: Kennedy/Jenks Consultants