SCOTTSDALE — Water tainted with a suspected cancer-causing chemical may have entered Scottsdale's drinking water supply for several days in October, federal officials said.
The water, which was pumped from a federal Superfund site into a treatment plant, was apparently introduced into the municipal supply after workers shut down one of two treatment towers and shifted operations to a third, unused tower. Samples taken from that tower's output later showed levels of the solvent trichloroethylene, or TCE, nearly twice the maximum allowed in drinking water.
Water company officials said the water was blended with other sources, which should have diluted it to levels below the threshold by the time it came out of household taps.
Officials with the U.S. Environmental Protection Agency revealed the problem Thursday, during a public meeting where they also disclosed they had rejected a request by the plant's operator to remove air filters that prevent TCE removed from the water from being vented into the air.
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Cell phone maker Motorola operates the Scottsdale Central Groundwater Treatment Facility in south Scottsdale to treat water from the Indian Bend Wash Superfund site, one of the largest groundwater cleanup projects in the nation, covering 13 square miles in Scottsdale and Tempe.
TCE was widely used as a solvent to wash circuit boards and other electronics starting in the 1950s and was dumped down dry wells, sewers and into leaching beds for three decades until it was discovered in five wells serving Scottsdale in 1981.
Three companies, Motorola, GlaxoSmithKline and SMI Holding, formerly Siemens, are responsible for most of the more than $100 million in cleanup costs.
Motorola wanted to remove the air filters preventing about 6 pounds of TCE from being vented each day, arguing that operating them actually pumps more pollutants into the air because of increased energy use.
The release of TCE into the water supply happened during eight days the backup tower operated in mid-October, officials said. The tainted water was sent to a facility run by the Arizona American Water Co., where it was blended with water from several other sources before being sent to customers.
Company representatives asserted that in the blending, the TCE was diluted to within federal guidelines.
"Based on what the company has told us, we do not believe anyone was exposed to levels of concern," said Sheryl Bilbrey, chief of the EPA's Superfund Private Site Section.
Many residents at Thursday's meeting were incensed that they were not told to avoid drinking the water during that time.
"I don't care about the average," said Hannah Goldstein. "I care about how much my coffee is poisoned in the morning."
