Water’s newest frontier
North America’s largest inland desalination project has recently been completed in the arid Southwest, on the United States-Mexico border where drinking water supplies are scarce. El Paso Water Utilities and the U.S. Army at Fort Bliss have tapped brackish water reserves beneath the desert floor to stock the 27.5 million-gallon-per-day (mgd) Kay Bailey Hutchison desalination facilities.
The project — developed through a public-private partnership involving the Department of Defense and the utility — provides a new source of water to the area and will supplement fresh groundwater supplies when the Rio Grande proves inadequate during droughts. It also is needed to protect El Paso’s and Ft. Bliss’ fresh groundwater supplies from brackish water intrusion. El Paso draws some of its water from the Hueco Bolson aquifer, as do other nearby communities, but the amount of brackish water in the Hueco Bolson exceeds the amount of potable water by approximately 600 percent. To tap into that supply, the city contracted with a team that included the locally based engineering firm Moreno Cardenas and Cambridge, Mass.-based CDM to plan, investigate, design and manage construction for a facility that would treat and deliver the water using two-stage reverse osmosis membranes, a technology that has been used for coastal desalination.
Disposal of the facility’s 3-mgd waste concentrate, made up of salts and other pollutants, was challenging, though, because the plant is too far inland to discharge waste flows to the ocean. So, designers chose deep-well injection — commonly used in the petroleum industry — in which concentrate produced by the treatment process is pumped 22 miles across a buried pipeline in the desert to a remote area of Fort Bliss property. Three solar-powered injection wells convey the concentrate 4,000 feet below ground with enough capacity for the next 50 years.
The plant opened in August 2007, and, supported by the new drinking water supply, the Army increased personnel and operations at Fort Bliss. “This project not only provides a critical water supply, but was instrumental in convincing the Pentagon that El Paso had sufficient water resources to support the expansion of Fort Bliss,” says Edmund Archuleta, utility president and chief executive officer.
Among other honors, the project won the 2008 Superior Achievement Award from the Annapolis, Md.-based American Academy of Environmental Engineers.
Inland desalination plant
El Paso, Texas
El Paso Water Utilities
Cambridge, Mass.-based CDM; Locally based Moreno Cardenas