The state of Michigan is seeking more information from Flint Mayor Karen Weaver about why she has suspended the use of hydroexcavation to identify lead service lines for replacement.

According to a report in the Flint Journal, Eric Oswald, director of the Michigan Department of Environmental Quality’s Drinking Water and Municipal Assistance Division, wrote a letter to Weaver dated July 23. Its questions include:

• Did the city carry out inspections inside homes to confirm the composition of entire lengths of service lines?

• Why is excavation by traditional digging more protective of the public health than a properly performed hydroexcavation?

• How did the city identify some service lines that were found to contain lead material after they were hydroexcavated and identified initially as copper?

Hydroexcavation has been heavily used in Flint as the city works to eradicate lead pipe from its water distribution system. But Weaver put a stop to it in mid-June, citing concerns that hydroexcavation had identified some pipes as copper that later turned out to be lead.

“Hydrovacing is missing lead and galvanized service lines. I’m not going to be a part of putting profit over people or having cost savings more important than life-saving,” Weaver told members of the Flint Water Interagency Coordinating Committee in June.

According to Oswald, there is no state mandate that a certain type of excavation method be used. However, the state has leaned toward the use of hydroexcavation over traditional excavation in Flint’s identification of its remaining lead service lines, especially emphasizing it when federal or state funds are backing a project. When Flint paid two contractors earlier this year to excavate sites at 124 homes without hydroexcavation, the Michigan DEQ questioned the spending, noting that the average cost of a traditional excavation was $1,660 compared to $228 for hydroexcavation.

Beyond the expense, Oswald noted in his letter to Weaver that traditional excavation can be more disruptive to existing utilities and potentially disturb or damage service lines.

Source: Flint Journal