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FAQ'sThe City of Santa Cruz Water Department (SCWD) and the Soquel Creek Water District (SqCWD) formed the scwd2 Task Force to oversee the Pilot Test Plant Program, the Watershed Sanitary Survey, Intake Study, permitting, environmental review and design of the full-scale plant, and to provide a forum for public input on the project and formulate an agreement and governance structure should the decision be made to proceed with a full-scale cooperative desalination project. The scwd2 Task Force is comprised of two Santa Cruz City Council Members and two Soquel Creek Water District Board Members.
What is reverse osmosis desalination? Desalination is any process that separates saline water (water containing salts) into two parts - one that has a low concentration of salt (treated water or product water), and the other with a much higher concentration than the original source water, usually referred to as brine concentrate or simply as ‘concentrate.’ Desalination processes may be used in municipal, industrial, or commercial applications. Available technologies can desalinate water from a variety of sources including: seawater, brackish, river, waste water, pure, and brine.
Both the City of Santa Cruz and SqCWD evaluated their water needs and available sources and determined that a new water source is a necessary component of an overall water plan to meet the demand for water in the community. Desalination is being investigated as a potential new source of supply. Currently, the City of Santa Cruz demand for water exceeds the estimated available yield from its existing sources during drought conditions, even with mandatory curtailment requirements. The Santa Cruz City Council conducted an exhaustive process beginning in 1997 to evaluate several new water source options to protect customers in drought years. From these background evaluations on water demand, conservation, curtailment, and alternative water supplies, the City of Santa Cruz Integrated Water Plan (IWP) was developed and adopted in 2005. The purpose of the IWP is to provide a reliable water supply to meet long-term needs while ensuring protection of public health and safety. The proposed Integrated Water Plan Program Environmental Impact Report (EIR), carried forward from the IWP, consists of three primary components: conservation, curtailment, and additional water supply. The IWP Program EIR identified desalination as the best option for delivering a flexible and reliable water source to meet the needs of the community during drought periods. The City will continue to use conservation and curtailment requirements to maximize efficient use of water resources as outlined in the IWP. Similarly, SqCWD is experiencing shortfalls in water supplies. The current annual water use for the SqCWD exceeds the available water supply by 15% even during non-drought conditions. The SqCWD is entirely dependent on local groundwater, and does not take water from surface water or regional water supplies. The current situation is not sustainable and future deficits will lead to saltwater intrusion. Beginning in the late 1990s, SqCWD began evaluating depressed groundwater levels and saltwater intrusion, long-term water demand, conservation opportunities, the adequacy of water supplies and the preferred options for supplemental water supplies. In early 2006, SqCWD adopted the Integrated Resources Plan (IRP) which recommends a flexible plan to address changing demand and water supply conditions. The IRP-preferred alternative focuses on regional seawater desalination with the City of Santa Cruz as the preferred conjunctive use project to investigate. The IRP also includes implementation of demand and groundwater management to incorporate conservation and recharge protection policies. How are SCWD and SqCWD partnering in the Pilot Program and Full-Scale Plant? The SCWD and SqCWD have developed an agreement for jointly undertaking the multi-layered investigative stage of the project and developing an operating plan. In concept, the Full-Scale Regional Seawater Desalination Project would feature a plant in Santa Cruz, where SqCWD would use the plant to augment groundwater supplies during normal years. Santa Cruz would use the plant during drought periods when surface water sources are limited. The Full-Scale Plant operational strategy would provide water supply during a drought to the City of Santa Cruz service area. During non-drought periods, the plant would provide water supply for Soquel Creek Water District (SqCWD). Key issues include:
What is the scwd 2 Task Force? The scwd2 Task Force is a
Joint Task Force formed by the SCWD and SqCWD to provide direction on the
investigative stage of project, public outreach activities, and
development of an operating plan.
What was the purpose of building a Pilot Plant? A pilot test program is required by the California Department of Public Health (CDPH) for the potential full-scale project to evaluate issues related to public safety, environmental protection and plant operations. The composition of desalination source waters is unique to each site, and therefore each plant requires its own pilot testing to determine site-specific treatment guidelines to ensure public safety. All source waters are under CDPH jurisdiction in order to promote and maintain a physical, chemical, and biological environment that contributes positively to health, prevents illness, and assures protection of the public. CDPH is responsible for permitting desalination facilities and conducts ongoing monitoring as appropriate.
What was tested at the pilot plant? The pilot test program will carefully evaluate operational and environmental issues including:
The Pilot Plant operated from March 2008-April 2009 and utilized source seawater from Long Marine Laboratory’s existing seawater intake. The Pilot Plant pumped and treated seawater up to 50 gallons per minute. What environmental impacts will be evaluated for the potential full-scale plant? Project level environmental review is scheduled to begin in Fall 2009. Impacts evaluated in the Environmental Impact Report (EIR) will include, but are not limited to:
How much could a full-scale plant cost? The capital and operating costs for the potential full-scale plant will depend on several components including:
Several studies are currently underway to evaluate these components for a full-scale plant. scwd2 has not completed a detailed cost estimate since the findings of these studies will determine the scope of work and the corresponding costs.
Where can I get more information? To learn more about the desalination program, the public may:
When will a full-scale plant be built? Construction of a full-scale plant is dependent on the completion of the pilot program, technical review of the data collected, completion of the parallel studies mentioned earlier, and environmental approval and permitting of a full-scale plant design. The preliminary project schedule is:
Where would a full-scale plant be built? Pilot plant evaluations will include a review of potential locations for the full-scale plant allowing use of existing infrastructure and identifying any potential impacts to surrounding properties. Based on the City of Santa Cruz Integrated Water Plan Program EIR, the environmentally superior plant location is within the industrial area of Santa Cruz’s west side. The area is bounded by Mission Street and the Southern Pacific Railroad to the north, Natural Bridges Drive to the west, Swift Street to the east, and Delaware Avenue to the south. The recommendation is not parcel-specific.
What would be the size and capacity of the Full-Scale Plant? The
Santa Cruz IWP recommended a full-scale plant to feature a 2.5 million- gallons-per-day (mgd) desalination facility with two potential future capacity increments of 1.0 mgd each, eventually totaling 4.5 mgd. To meet 100% of demand in all years would require initially building a 5.0 mgd facility and expanding it to 8.0 mgd by the end of the planning period, but the IWP concluded it would not pursue any option that delivered average annual demand in droughts.
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The reverse osmosis process is one type of desalination technology that occurs by forcing a solvent (liquid salt solution) from a region of high solute concentration through a semi-permeable membrane to a region of low solute concentration by applying a pressure to the water.