First U.S. company to use specific strong base ion-exchange to remove chromium-6
California Water Service (Cal Water) completed the final chromium-6 treatment plant in its Willows District. The treatment plant—one of four plants Cal Water has constructed in Willows in the past year—will reduce the amount of naturally occurring chromium-6 from the local water supply.
In July 2014, the state of California set the country’s first regulation for chromium-6, allowing no more than 10 ppb in water provided to consumers. Wells in Cal Water’s Willows District had naturally occurring chromium-6 levels of 16 ppb; however, since the treatment plants came online, the water supply in the Willows District has remained in compliance with the new state standard.
“This treatment plant plays a significant and symbolic part of our efforts to comply with the chromium-6 requirement, as it is the final plant constructed to treat the constituent, and allows us to bring another water source back online to provide better water supply reliability to our customers here in Willows,” said Local Manager Geoff Fulks.
With the state mandate occurring prior to the development of treatment, the Department of Water Resources awarded Cal Water a $5 million grant, and the Water Research Foundation awarded a $175,000 grant for research and treatment, which will help offset the future rate impact for Willows customers.
“If the state establishes a standard to protect health that could be very expensive to meet, the state has an obligation to help make sure that drinking water is affordable,” said State Water Resources Control Board member Steven Moore. “We are here in partnership with Cal Water, Willows and other cities to help make sure that the drinking water is affordable, as well as safe.”
In order to find the most effective solution, Cal Water’s water quality and engineering departments experimented with three types of groundwater treatment options. After taking cost, method effectiveness, waste disposal and raw water quality into consideration, the team selected a strong base ion exchange approach.
“We wanted to use an option that was both cost-effective for our customers and also effective in treating the water supply,” Fulks said. “The treatment plants that we have installed will ensure Cal Water customers continue to have access to a safe and reliable water supply around the clock and has worked even better than we could have expected.”
Cal Water is the first company in the U.S. to use this specific strong base ion exchange to remove chromium-6, and the treatment process now is used as a model for other cities and utilities in their treatment of the contaminant. Cal Water serves about 2,400 customer connections in Willows.