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Desalination projects ranging from 3 MGD to 14 MGD have been studied at various locations (Carmel to Moss Landing). Reverse osmosis is primary desalting technique. Facilities include intake, pretreatment, desalination plant, posttreatment, brine discharge, and conveyance pipelines. New Cal-Am facilities needed to receive water from northern end of system. Operations can be full-time, seasonal, or standby use. Full-time use is needed to maximize compliance with Order WR 95-10. Roughly twice the amount of potable water produced is processed by the plant.
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Annual yield is 90% of daily rating (MGD) for full-time use; 60% if seasonal use. Projects producing about 2,000-14,000 af/yr have been studied. |
Capital costs for 3-MGD project at Sand City is $29.2 million plus $9.0-13.4 million for Cal-Am facilities (roughly $38-43 million total). For 6-MGD project, $53.2 million plus $12.7-17.9 million for Cal-Am facilities (roughly $62-67 million total). For 7-14 MGD at Marina or Moss Landing, costs range from $72 million to $171 million for desalination plant plus $13.4-19.4 million for Cal-Am system (approximately $85-191 million total). O&M costs ranges from $2.1 million to $2.8 million per year for 3 MGD; $3.9-5.4 million per year for 6 MGD; $4.6-12.9 million year for 7-14 MGD; varies with type of use. These are initial costs, and do not include facility replacement costs. |
Up to 3 years needed for environmental review and to obtain permits. 1-3 years for final design and construction, depending on size and site. Project life estimated at 20-25 years before major facilities need replacement. Membrane replacement every 5 years is included in O&M costs. |
Major Benefits: Produces water to replace Carmel River diversions and reduces impact of diversions. Only 14 MGD provides streamflow similar to dam. Plant footprint covers small area; can be built in industrial area. Major Adverse Effects: Collectors and pipelines in coastal dunes, wetland areas; brine discharge effects on marine life and dispersal of sewage (if outfall used); air quality effects of high energy use. |
Desalination plants have been shown to be technically feasible worldwide. Questionable feasibility identified for projects over 6 MGD on Monterey Peninsula due to limitations on intake and outfall facilities and other factors. Advantages include rapid construction, modular expansion, flexible operations, "drought-proof" source of supply, no inundation effects. Disadvantages include high O&M and energy use, need for major facility replacement, potential impacts on coastal dune and marine life, and competition for sites among agencies. |
* "Feasible" means project is a reasonably foreseeable means to provide lawful supply for Cal-Am water system. See text for further discussion.