This report summarizes the present version of MWD's 80 Mgd conceptual design and indicates the constraints that have guided it. The MWD board has approved this concept as the basis for the next stage of the program, the design and construction of a 5 MGD Demonstration Plant and associated testing. The performance and cost information from the Demonstration Plant will be essential in decisions for the full scale unit, which could be in operation by 1999.
The Metropolitan
Water District is investigating many possible sources to meet projected needs for large-scale additions to water supply in Southern California. Some of these alternates will be useful and cost-effective, but generally each new increment of supply is more costly than the last. The Pacific Ocean looms as the ultimate, inexhaustible source. Cost and reliability are the factors that will determine when desalting the sea will become the economic choice. The commercially available desalination technology has evolved in parts of the world where small units sited close to special purpose needs are the norm. Such currently available plants are not only very costly, they are ill-suited to the needs of Southern California. This region needs water in very large increments for general use over a large area and at much lower cost. Although the plants as they now exist are unsuitable, our investigation shows that proven elements of this technology can be selected, combined and modified to fit MWD's special needs. Preliminary indications are that the modified process will also meet the target of substantially lower cost. The process modifications involved are derived from several sources, especially the extensive evaporator development program at the Oak Ridge National Laboratory in the 1962-74 period. This work, sponsored by the Office of Saline Water and the Atomic Energy Commission, included both laboratory and large-scale field tests. Research at Berkeley and UCLA in the University of California also contributed.
We have adapted these results to the special conditions of Southern California, making use of newly available materials, and employing operating experience and field results acquired in recent years. The result is a specific process, conceptual design, and plant arrangement to meet the expected needs of the Metropolitan Water District. This conceptual design is described below.