By gathering enough information and being creative, we can develop the right treatment approach for each situation.
A Public Approach
In Santa Cruz, CDM Smith executed the design-build-operation of a pilot plant to evaluate treatment options and energy-saving measures for a seawater desalination facility fed by an open ocean intake. The pilot included four different pretreatment processes in parallel, upstream of four different RO systems, to determine the best pretreatment approach to minimize RO fouling.
After a year of pilot operation, CDM Smith is designing a full-scale, 2.5-mgd facility. According to Heidi Luckenbach, Santa Cruz desalination program coordinator, “The pilot project clearly demonstrated that the technologies can successfully meet and exceed state and federal water quality standards to produce a reliable supplemental supply for our community.”
An outreach program grounded in successful pilot results has been vital to engaging and informing the community on the critical need for a new water supply. The program included daily tours of the pilot plant to educate visitors on desalination, energy issues and the local water shortage. Residents and special interest groups also attended informational meetings to learn about the project and ask questions of agency staff and consultants.
In Dana Point, the first slant well desalination project is being developed by the Municipal Water District of Orange County (MWDOC) and other local agencies. Unlike Sand City’s vertical beach wells, the South Orange coastal ocean desalination project uses a slant well—pulling water through a sand and gravel aquifer under the ocean floor. These wells have the potential to draw much higher volumes of water than vertical wells, with minimal impacts to onshore aquifers and no risk of entrainment or impingement of marine life.
CDM Smith is coordinating the 18-month operation of a pilot facility, treating a portion of the water from the 2,200-gallon-per-minute demonstration slant well and leading the evaluation of pretreatment approaches to address the water’s unexpectedly high iron and manganese concentrations. Testing results have been positive, offering MWDOC an approach that is environmentally sensitive, reliable and less costly than a traditional seawater treatment approach.
Case by Case
Coastal communities in California and throughout the world are seeking alternative water supply options as they face drought, population increases and growing environmental challenges. “To make seawater desalination a viable solution, we have to overcome concerns that it is unreliable and unaffordable. We want to help communities develop new, sustainable supplies,” says Wetterau. “By gathering enough information and being creative in our solutions, we can help our clients develop the right, specific treatment approach for each situation.”
Water supply innovation means helping communities develop new, sustainable supplies of potable water.