AWWA ACE62979

AWWA ACE62979 Desalination Water Supply Options for South Central Texas: A Decision Framework Tool
Conference Proceeding by American Water Works Association, 06/01/2006

Graves, Mark

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Like many fast growing regions of the country, rising water demand coupled with increasingpressure on existing water sources is driving the South Central Texas Region (SCTR) to considerdesalination of previously untapped water supplies. Simultaneously, regulatory mandates are set tosignificantly decrease the water available from current fresh groundwater sources. Pursuant tothe requirements of Texas Senate Bill 1 (SB1), the SCTR is one of 16 Texas regions that arecurrently updating their long-term (to the year 2060) water supply plans. The SCTR consists of21 counties forming a band across Texas from the Mexico border through the City of SanAntonio and to the Gulf of Mexico.As part of this planning process, several options to provide a dependable long-term water supplyby desalinating seawater or brackish groundwater are being considered. A unique decisionframework tool is presented that includes major considerations impacting the cost andfeasibility of desalination water supply options. The decision framework tool will be utilized tocompare specific desalination water supply options being considered for the SCTR. Major considerations involved in the decision framework include:Water Availability ¿¿¿¿¿¿¿¿ Groundwater available from brackish aquifers, landacquisition/groundwater lease, competing interests and water rights;Treatment Costs ¿¿¿¿¿¿¿¿ Both pretreatment and desalination system capital and OConcentrate Disposal ¿¿¿¿¿¿¿¿ Cost and permitting requirements for disposal options includingdischarge to surface water, deep well injection, and zero liquid discharge;Raw and/or Finished Water Transmission ¿¿¿¿¿¿¿¿ Pumps, pipelines, and tanks required fordelivery of finished water and integration into the existing distribution system; and,Finished Water Quality ¿¿¿¿¿¿¿¿ Blending and treatment options to meet compatibilityrequirements in the distribution system. Specific desalination water supply options being considered for the SCTR include:brackish groundwater from the Wilcox Aquifer in Bexar County;seawater desalination; and, inter-regional seawater desalination. Includes tables, figures.