Arizona State Highways 85 and 86 meet in Pima County in southwestern Arizona. The intersection used to form a “Y” and gave birth to a town name. The unusual name comes from a state law that required town names have three letters, so “Y” became Why. What’s not so unusual is that the town of Why, like many Arizona communities, has high levels of arsenic in their well water that requires treatment.
Arsenic is a naturally occurring element in rocks, soils, and the waters in contact with them. Most arsenic enters water supplies either from natural deposits in the earth or from industrial and agricultural pollution. Long recognized as a toxic element, arsenic today also is a human health concern. Arsenic in drinking water can contribute to bladder, lung and skin cancer, and may cause kidney and liver cancer. Arsenic also harms the central and peripheral nervous systems, as well as heart and blood vessels, and causes serious skin problems. It may also cause birth defects and reproductive problems.
During winter, the town’s population grows with the arrival of snowbirds attracted to the areas’ natural desert setting and average temperature of 70 degrees. Why Utility Company has three water wells to supply the Town’s 1000 service connections and regular population of approximately 400, along with its seasonal visitors. All three wells have arsenic levels that exceed the allowable limit set by the Environmental Protection Agency (EPA) of arsenic of 10 parts per billion. Only one well is currently available with raw water arsenic at 150 ppb.
Filtronics pilot tested the well water at Why Utility Company with a combined flow from two wells. The result of the testing indicated the need for two stage filtration. The primary stage was coagulation and filtration with Filtronics Electromedia® filter. The arsenic in the treated water from the primary stage was reduced to 11 to 18 ppb. The second stage filter was an adsorptive unit that dropped the arsenic to less than 3 ppb.
Design and construction of the full scale facility followed pilot testing. Funding for the project came from Pima County and USDA Rural Development funds. Ultimately, Tres Rios Consulting of Tempe, Arizona was responsible for the final design and start-up phases of the project. The facility has been producing clean, potable water with arsenic levels well below the maximum contaminant level (MCL) of 10 ppb since the summer of 2008.