MORE STUDY NEEDED
Because of the potential for treatment changes to affect lead levels in distribution system, utilities need to understand what comprises the scale that occurs in their pipes, said Michael Schock, a chemist in the EPA's Office of Research and Development. When pipes or lead service lines are removed from service, they can be analyzed by X-ray diffraction or other techniques to determine the nature of the scale in the system. In this way, Schock said, utilities have information to help predict what might become destabilized and enter the finished drinking water following certain kinds of treatment changes.
The complicated nature of the problem and the difficulties inherent in studying it mean that utilities are “learning the science after the fact,” said Marc Edwards, professor of civil and environmental engineering at Virginia Polytechnic Institute and State University. Because so much is unknown about how different treatment changes can exacerbate the leaching of lead, drinking water providers should plan after any treatment change to monitor their systems for increased lead levels beyond what the LCR requires, Edwards said.
Water providers typically rely on customers to perform the sampling, which introduces another variable that can complicate efforts to comply with the LCR, said Kathy Moriarty, water quality manager for the Bangor (Maine) Water District. “You have to have the cooperation of your customers to do this for you,” said Moriarty. “Sometimes [customers] can't or they don't want to” cooperate, she said.
To ensure that customers continue to cooperate with sampling efforts, the water department in Cedar Rapids, Iowa, samples more often than required by the LCR, said Shelli Grapp, the department's administrative affairs manager. Because its lead levels do not exceed the action level, the department is allowed to sample every three years. However, Cedar Rapids monitors annually to help retain its current pool of sample sites, Grapp said. “We're concerned that if we only contact people once every three years, we are going to lose continuity,” she said.
Moreover, if Cedar Rapids were to experience high lead levels, Grapp said, “we really don't want to wait three years down the road to determine that.”
— Landers is a freelance writer and editor based in Austin, Texas.