SAWS board goes for expanded desalination project

The San Antonio Water System (SAWS) board in Texas, USA, decided on 10 February 2012 to go for expanded desalination rather than importing groundwater.

The board accepted suggestions from its staff to pursue additional brackish groundwater supplies through a proposed partnership with CPS Energy.

With the availability of brackish supplies in Bexar County and adjacent counties, further expansion of a desalination facility in partnership with CPS Energy could occur on the same site as the currently planned desalination plant, the existing Aquifer Storage & Recovery plant and a third project increasing yield from the local Carrizo Aquifer. This co-location would save money on additional land as well as consolidating management and operation of several water supply projects.

SAWS had a shortlist of three private proposals for imported water, the best of which was from Abengoa Water LLC.

The private proposals would have required annual payments of up to US$ 85 million for 30 years, and a rate increase of approximately 9‑12% in 2019, not including infrastructure integration costs. Also, groundwater conservation districts have the authority to regulate withdrawals of water from aquifers, often with little notice or process for appeal.

SAWS spokesperson Greg Flores said in a later radio interview, “We found that the most interesting proposal was deemed too risky because San Antonio ratepayers would have been required to make payments for that water even if it was not delivered to the city.”

“Our choice was to get desalination as an alternative because it can be phased in over time and therefore spreads that cost and the rate impact over time,” Flores added.

San Antonio’s existing desalination project, being designed by Parsons Corporation, includes 13 raw water production wells, raw and finished water conveyance, residual conveyance, three deep injection wells, a 10 MGD (37,850 m³/d) reverse-osmosis (RO) membrane water treatment plant and a 7.5 MGD (28,400 m³/d) finished water storage reservoir.