Thanks to all who attended our panel discussion on desalination. The public heard from an array of experts including Bill Kocher the Director of the Santa Cruz Water Department,  Shauna Potocky the Visitor Hall and Volunteer Services Manager for the Seymour Marine Discovery Center, Mike Rotkin a member of the Santa Cruz City Council and the City of Santa Cruz/Soquel Creek Water District Desalination Project Committee, Sarah Corbin the Central California Regional Manager for Surfrider Foundation, and Conner Everts the Executive Director of the Southern California Watershed Alliance and Co-Chair of the Desalination Response Group at Environment Now.

Follow up Questions:

In the pilot desalination plant, how will the effect of raised salinity and temperature of the effluent be measured? How will those findings be used? Will the information be made public?

[Bill Kocher]  It isn’t clear you are talking about the raised salinity and temperature of a full-scale plant or the pilot plant, but these factors are of little concern with the pilot plant because of scale.  In the pilot, the permeate (treated water) is blended with the concentrate (reject water with high salinity) and blended with the other water being used on the Long Marine campus for its research uses.  The impacts of temperature and salinity in the full-scale plant would be difficult to determine any other way than modeling, which will be part of the design of the full-scale plant.  It is not expected that either raised temperature or salinity will be an issue because of the project concept of blending the concentrate with the sewer effluent.  The concentrate stream will be fairly low in volume and the disposal of it will be designed in a way that it can be introduced into the wastewater effluent proportionally to allow the production of waste stream that has whatever characteristics it is designed to accomplish.

When will the city and county allow for grey water use on site for irrigation and or reuse in toilets and laundry?

[Bill Kocher] There was a lot of discussion the other evening about why the City is not pursuing reclamation or use of grey water instead of this option.  While it would be easy to spend an entire evening discussing the City’s investigations into how it might use reclaim, it can be simplified into one limiting factor: at this time, the Department of Public Health has some very restrictive rules on the use of reclaim and using it for potable uses is, at this time, not allowable except with a regime of groundwater recharge, blending and storing, all of which are not possible in Santa Cruz because of the absence of groundwater storage.  Typically, the use of reclaim is for one of two purposes: industrial applications or other new construction where “purple piping” is economically feasible, and for irrigation (largely agriculture and bigger acreage such as playing fields, cemeteries, etc.)  While we do have some of the latter, we have virtually none of the former and because the limited applications we do have are spread all over from Davenport to Capitola, it is fiscally impractical to try to pipe reclaim around.  Some day the rules will almost surely change as we all know that wastewater can be treated to a potable standard.  Until the rules change, however, we have a serious drought shortfall that must be addressed.

Can you explain in detail how the mechanics of a desalination plant work, how impacts will be measured?

[Bill Kocher] In the most simple terms, seawater is drawn from the ocean either from a water source in the water itself or under the floor of the ocean or adjacent beaches.  That water is taken to a treatment plant where it is first treated to remove all suspended particles in it (much like the drinking water we now serve is treated).  After it is treated to remove all particulates, it is pressurized and forced through a membrane with pore sizes that are small enough that fresh water can pass but saline water cannot.  The fresh water is of a very high drinking water quality and the reject has about the same amount of salt with half the water, so it must be blended with another source to make it benign prior to reintroducing it to the bay.  Obviously it is much, much more complex than that and I urge anyone who wants to see it firsthand to plan on visiting the pilot plant across from the whale skeleton on the Long Marine campus on the second Wednesday of each month at 10:00 am for a tour with engineering staff who can instruct and answer questions. 

[Sara Corbin] The are various techniques used to desalinate water. A brief overview of desalination technologies and how they work is given in the Pacific Institute report Desalination, With a Grain of Salt (www.pacinst.org/reports/desalination) on pages 13-18.

Impacts of a desalination plant will have to be identified and mitigation planned (if impacts are found to be significant) in an Environmental Impact Report (EIR). The preparation of this document must be publicly noticed—interested parties can request notification by contacting the City of Santa Cruz’s public works department. If and when the facility is built, there will certainly be permit conditions attached to any permits granted from the regulatory agencies (i.e. the Regional Water Board, California Coastal Commission, Dept. of Fish and Game) requiring various monitoring regimes to monitor the discharge (water quality), intake (marine life mortality), etc. If there are impacts that the public feels are important to look at, the public should submit comments during the EIR process and, if the concerns aren’t addressed here, at the public hearings of the appropriate regulatory agencies. Certainly these concerns would be good to share with advocacy groups as well, as they have experience participating in these processes and are an organized voice. General impacts associated with desalination facilities are also outlined in the Pacific Institute Report on pages 59-69.

Further Questions awaiting answers:

Would the power come from the base load beyond the renewable sources output or would that and greenhouse gas emissions be included in the calculation?

What are the three operating desalination facilities in the Monterey Bay area and what is their capacity?

Educational Resources:

www.desalresponsegroup.org

www.cuwcc.org for the California Urban Water Conservation Council

www.pacinst.org for the Pacific Institute