Monday, May 19, 2014

CA flounders on desalination, TX moves forward

I have constantly read articles and posted some of the sputtering in CA regarding the use of desalination to supply water to parched cities and areas.  However, in TX we see progress moving forward:

On April 29 2002 Texas Governor Rick Perry visited San Antonio and announced his intention to push for construction of a 25 mgd desalination plant on the Texas coast. He said "Though it may be many years, if not decades, before ocean water is a prime source of water for Texas to use, we must begin the groundwork today so that future Texans have an abundant, drought-proof supply of water."

In November 2002 the South Central Texas Regional Water Planning Group endorsed a proposal by the San Antonio Water System, the San Antonio River Authority, and the San Patricio Municipal Water District to build and operate a desalination plant that could produce eight million gallons per day by 2006. The project would include a plant to purify brackish groundwater in San Patricio county and another plant to purify ocean water. Initially it would not deliver water to San Antonio but would free up surface water in the Nueces River Basin now used by the city of Corpus Christi, thereby reducing pressure on the Edwards to meet those needs. Corpus Christi has it's own competing proposal to build it's own desalination plant and then sell surface water rights to San Antonio. SAWS indicated it is not interested in a customer relationship with Corpus.

In April of 2004, the city of Brownsville dedicated its new Southmost Regional desalination plant, which is designed to turn brackish groundwater from the Gulf Coast Aquifer into drinking water. The plant cost $21.1 million and has a capacity of 7.5 million gallons per day. It is the city's first drought-proof source of water. By 2004, there were more than 100 desalination plants in Texas, all of them treating either brackish groundwater or surface water. Some of the larger facilities are in Sherman (26.4 mgd), Lake Granbury (14.2 mgd), and Fort Stockton (12.7 mgd). El Paso Water Utilities is planning a 29 mgd facility, and the San Antonio Water System is also studying the feasibility of withdrawing and treating saline water from the Edwards Aquifer.

In August of 2004, Governor Rick Perry gave the concept of desalination another shot in the arm by delivering a speech in which he claimed that membrane technologies "will change the world forever". He suggested that Texas should lead the nation by building the country's first large-scale desalination plant.

In April of 2006 the city of Brownsville began construction on a pilot-scale ocean water desalination plant that will produce about 100,000 gallons per day. The main purpose of the facility will be to determine how to develop a full-scale plant and what financial incentives will be needed.

Also in 2006, the San Antonio Water System began tests at several sites to evaluate the feasibility of constructing a plant to desalinate brackish water from the Wilcox Aquifer. One site in Atascosa county seemed especially promising, and SAWS set a goal to have an operating facility by early 2011 that could produce up to 25 million gallons per day.

In August of 2007, the city of El Paso opened the Kay Bailey Hutchison Desalination Plant, which will eventually supply 27.5 million gallons of drinking water daily. Officials said it is the largest desal plant outside of a coastal area. Constructed at a cost of $87 million, it draws brackish groundwater from underneath Fort Bliss. Costs were expected to be about $1.65 per thousand gallons.

In October of 2007, under intense local pressure from area residents, the board of the Evergreen Underground Water District voted to rescind an agreement it had made with SAWS to regulate and permit the production and export of brackish Wilcox water. Under the agreement, the district was to have issued permits to SAWS after the utility showed the water was available and production was not likely to effect freshwater supplies from the the overlying Carrizo aquifer. If an impact occurred, SAWS would have to limit or stop production. In return, SAWS agreed to abandon plans to pump fresh water.

In January of 2008, a citizens panel endorsed the San Antonio Water System plan for desalination, but it noted that local opposition may turn out to be a bigger obstacle than any technological challenges. SAWS Board Chairman Alex Briseno said SAWS had not been proactive in doing outreach to the communities involved, but "We don't intend to just go to a place and take its water. The goal is to have a win-win situation." Some of the benefits to the local community could include providing treated water or economic development funds.

In July of 2008 Atascosa residents were upset by news that SAWS had donated $10,000 to help sponsor their annual Cowboy Homecoming festival. Many considered it a "bribe" to quell opposition. After much public outcry at a packed City Council meeting, officials said they would not accept the money (14). In response, SAWS interim CEO Robert Puente said the contribution was misconstrued and said "I give you my word as a fellow Texan that our gestures were made in good faith and reflect our sincere attempt to respect your natural resources and be a contributing member of your community."

In February of 2009 SAWS unveiled a revised 50-year water supply plan, and the desalination component was scaled back to 11,800 acre-feet per year, or about 10.5 million gallons per day. Originally the project was envisioned to produce up to 25,000 acre-feet per year. The SAWS desalination wellfield will now be entirely within Bexar county on the Twin Oaks ASR site; previously, it was a multi-county design. The current goal is to have the project online by 2016 (16). SAWS began testing a pilot well on the Twin Oaks site to confirm the treatment requirements for the brackish water and to evaluate whether brackish water could be produced without affecting the stored Edwards water in the Carrizo sands. Brackish water will be produced from the Wilcox Group, which is deeper than the Carrizo sands and separated by the Calvert Bluff formation, which has very low vertical permeability, so waters in the formations above and below do not mix. All the tests produced excellent results and SAWS went ahead with design of a full-scale project at Twin Oaks. By mid-2012, drilling had begun and SAWS indicated it was on track for a 2016 startup.

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