The U.S. Environmental Protection Agency says people living in Flint should be warned of the potential for “high lead release” into their tap water if road work or other physical disturbances to lead and even non-lead service lines occur.
The agency says these physical disturbances “could pose an immediate and acute health hazard” to residents.
EPA released the information late Wednesday in a report sent to Michigan’s Department of Environmental Quality and the city of Flint. It’s the finalized version of an interim report that was leaked to the ACLU over the summer.
This version of the report lays out how a combination of factors may have led to extremely high lead levels at one Flint home. It also says that similar situations could happen in the future.
Regulators say scale would have built up over time inside the distribution pipes in Flint. These scales are described as “protective” because they help prevent water from coming into contact with lead distribution pipes, and leaching lead into tap water in people’s homes.
“Lead service lines are the largest source of lead, when present, and can contribute up to 75 percent of the total mass of lead released into the water,” the report says.
But the scales can pose a big risk too. Over time, lead can accumulate in the scales. Even non lead service lines could be at risk.
“Studies have shown that the scales within galvanized iron pipe downstream of lead pipe segments can be ‘seeded’ with lead from the lead portion of the service,” the report says.
The report says the corrosiveness of the Flint River water without proper treatment “are well known factors that can contribute to high lead release.”
The head of Michigan’s Department of Environmental Quality previously admitted it mistakenly allowed Flint to stop corrosion control treatment when it switched water sources. This week the EPA issued a memorandum to all the agency’s regional directors, clarifying that water systems must study a water source to determine the best corrosion control treatment before making a switch.
Without proper corrosion control treatment, and when road work or other physical disturbances to underground pipes happens, these scales can be “dislodged” into people’s tap water. The EPA says it’s “reasonable to assume” that these disturbances could release lead laden scale into tap water, even if the service line is not made of lead.
At Lee Anne Walters’ home, the iron service line was unusually long; at least 150 feet. The EPA believes the scale on her home’s iron service line was ‘seeded’ with lead. The agency believes the water chemistry and a physical disturbance led to extremely high lead levels in Walters’ home. The report notes two relatively new asphalt patches on the road near her home.
The lack of corrosion control treatment in Flint is now well known. But this is the first time physical disturbance has been mentioned as a big risk.
“The jarring and vibration associated with excavation can dislodge the high lead-bearing scales from with the service line pipes,” the report says.
The report makes several recommendations to prevent the release of “large amounts of scale and sediment that could pose an immediate and acute health hazard to the residents.”
- More data from intact pipes, lead and non-lead, need to be collected. Assessing the scales within these lines in Flint is “essential” to determine the risk to residents, the report says.
- Develop training and public education on potential for “high lead release” from the scales. The report says people should know when utility work is going on and the “potential risk of increased lead levels due to these disturbances.”