Developing an untapped resource for the benefit of the entire region
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Due to the positive developments since 2009 with the Regional Carrizo project, the desalination plant is now scheduled to come on line in 2016.
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 an Antonio Water System is currently developing a brackish groundwater desalination program in southern Bexar County. Brackish groundwater is a plentiful, previously untapped local source of water that will help diversify San Antonio's supplies.
The desalination facility will generate about 10 million gallons of water per day or 11,800 acre-feet per year from the Wilcox Aquifer. The plant will be located at the existing SAWS Twin Oaks Aquifer Storage & Recovery site.
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Making the
Program Possible |
| The 2007 Texas Legislature played a pivotal role in the development of our desalination program. |
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| House Bill 1886 allows Texas municipalities to utilize the Construction Manager at Risk (CMAR) procurement method for water supply projects. Use of CMAR procurement can help reduce construction time and costs, as well as allow greater collaboration between the design, contracting and in-house teams. |
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| In addition, House Bill 2654 provides for a general permit for Class I injection wells that can be used to dispose of brine concentrate from a municipal desalination plant. The new permit process will greatly reduce the time required for the authorization of Class I injection wells. |
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Project Overview
The brackish desalination program is part of SAWS 2009 Water Management Plan, designed to meet the city's water needs over the next 50 years while reducing dependency on the Edwards Aquifer. The Texas Water Development Board has confirmed that a vast supply of brackish groundwater — water too salty to drink — exists in our region and has yet to be developed.
The South Central Regional Planning Group (Region L) has identified brackish groundwater as a supply management strategy to meet future needs.
Initial Investigations
Feasibility studies confirm that there is sufficient quantity and quality of brackish groundwater available in the Wilcox Aquifer to support the SAWS desalination program. Brackish water, which contains dissolved solids, will be treated to drinking standards using a reverse osmosis treatment facility.
Brackish water in the Wilcox is expected to range from 1,300-1,500 mg/L Total Dissolved Solids. Pilot testing confirms that reverse osmosis treatment is suitable for the SAWS program. In addition, SAWS has completed tests and studies to define:
- Well field productivity
- Long-term water quality
- Treatment plant operation
- Pretreatment and post treatment requirements
Program Development
The proposed desalination facility location at the Twin Oaks Aquifer Storage & Recovery site is close to the brackish water source and also near the proposed areas for brine disposal.
The first phase of the program includes development of a production well field, well field collection system, and reverse osmosis treatment plant. Brine disposal will be accomplished through the use of Class I injection wells located on SAWS property in nearby Wilson County. The treatment facility also will be designed to accommodate additional capacity and technology upgrades in the future.
Other engineering and construction components include:
- Geotechnical testing
- Site work preparations
- Administrative building
- Laboratory, treatment and storage buildings
- Well pumps
- Paved access roads
- On-site yard piping
Phase I is expected to be complete in 2016.
Program Update
As the program progresses, SAWS has participated in the following activities to support the future design, construction, and operation of the brackish desalination program:
- Land Acquisition: In 2010, SAWS acquired the remaining property to support production wells for phase I of the program.
- Production Wells:Eight Wilcox production wells are anticipated to be drilled in 2011-2012. These wells will assist in the design and construction of the brackish desalination program by providing additional information such as production rates and water quality.
- Injection Well Testing: SAWS is expected to complete the testing of a concentrate disposal well in 2011. Results from this test well will supply water quality, depth, injection pressures and characteristics of the disposal formation. This information will assist in the permitting, design, and construction of the remaining injection wells.
- Additional Membrane Pilot Testing: In 2010, the Texas Commission on Environmental Quality (TCEQ) approved the first Membrane Pilot Study report. SAWS will continue the pilot study program throughout 2011 to test several membranes that could be used in the full scale plant. Testing and approval of three reverse osmosis membranes by TCEQ will create a more competitive environment for purchasing when the plant becomes operational.
Contracting Opportunities
The brackish desalination program will produce a variety of opportunities for companies to work with SAWS, including small, minority and women-owned businesses (SMWB). Companies may register to be informed of contracting opportunities, as well as availability of plans and specifications for SAWS projects.
Visit our SMWB program page for more information.
* An acre-foot of water is equivalent to 325,851 gallons
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