Confused about corrosion control? We were too.
In Flint, lead levels in some children's blood have spiked dramatically. Scientists believe the Flint River is part of the problem. Flint switched from Detroit’s water system and started pulling water from the Flint River last year.
We’ve been hearing some conflicting things from state officials about what exactly Flint has been doing — if anything — to cut down on lead in the water.
The confusion
State regulators told federal regulators earlier this year by email that Flint is not using corrosion control.
Corrosion control is important because it helps prevent lead from leaching out of old pipes into people’s tap water.
But on Friday, Michigan Department of Environmental Quality Director Dan Wyant said this:
“Know that when the city switched from Detroit sewer and water, that the city utilized corrosion controls,” he said.
That directly conflicts with what the state said before.
After Friday's press conference, we asked DEQ spokesman Brad Wurfel to clarify. He then said the corrosion control Flint used was lime.
“Flint was trying to address the hardness of the water, so they chose lime to address the hardness,” he said. “That is also a corrosion control agent. It’s a recognized corrosion control agent. It just wasn't, it wasn’t cutting it.”
We ran this by some outside experts.
Daniel Giammar is an expert on lead in water. He's a professor of environmental engineering at Washington University in St. Louis, Missouri.
“Simply claiming to have lime addition as corrosion control is insufficient,” he says.
Giammar told us that you can use lime for corrosion control, but you have to have a plan. You want to make sure your water hits a certain pH range and alkalinity so that you minimize the amount of lead in the water.
“Whether or not you have corrosion control isn’t whether or not you’re adding lime, but it’s rather, are you achieving the target pH that you set out?” he says.
The softening process could be making the situation worse.
Marc Edwards is a civil engineering professor from Virginia Tech University and a nationally renowned expert on water treatment. He was also confused by Wyant’s claim that Flint had corrosion controls in place. So, over this past weekend, he took a closer look at Flint’s data.
He says the water softening treatment Flint is using is actually making Flint’s water more corrosive.
“Even as they’re denying the water is corrosive and it’s causing this higher lead, the pH value is plummeting, it’s becoming more acidic,” Edwards says. “And it led me to wonder, I mean, are they even watching what’s happening to the pH of their water? It’s like flying a jumbo jet without checking your gas tank.”
We requested an interview with someone from Flint's water department, but they did not provide anyone to talk to us for this story by our deadline.
The DEQ's response
The DEQ says they have been keeping an eye on the pH of Flint’s water.
Liane Shekter Smith heads up DEQ’s Office of Drinking Water and Municipal Assistance.
"Absolutely, we've been monitoring the pH data. We monitored it prior to the switch to the Flint River and we monitored it since. And we've compared the pH data and there has not been a significant change."
Shekter Smith says they consider a pH of 7.5 to be acceptable. But both Marc Edwards and Daniel Giammar told us cities should shoot for a pH of 8 or above to minimize the amount of lead getting into drinking water. That's because you want the water to be less acidic to minimize corrosion.
Data available online from the City of Flint show that the pH of treated water leaving the plant has been trending downward - becoming more acidic. Monthly average pH measurements dropped from 8.07 in December 2014 to 7.34 in August 2015.
A key point here: there’s a difference between having some kind of treatment process that might work and having an approved corrosion control plan.
Yesterday, Shekter Smith confirmed that Flint does not have a corrosion control plan.
“At the time they proposed switching to the Flint River and implementing the lime softening treatment method, there was an indication that the pH control provided by that method perhaps would provide optimal corrosion control,” Shekter Smith says.
It’s clear that method didn’t work.
Tomorrow, city, state, and federal officials will get together to come up with some kind of plan to control the corrosion.
*This post has been updated.
