FLINT, MI — The city is out of the business of using high-pressure water to excavate service lines to homes — at least until there’s a new protocol in place that will better protect the public, Mayor Karen Weaver has told the state.
Weaver, in a June 22 letter to Eric Oswald, director of the Michigan Department of Environmental Quality’s Drinking Water and Municipal Assistance Division, said the current practice of hydro-excavation “is not sufficiently reliable” for assessing whether service lines are made of lead or galvanized steel, which determines whether they need replacement.
“Most important, adequate safeguards need to be in place to ensure that lead and galvanized steel is removed from residential addresses prior to resuming hydro-excavation,” Weaver’s June 22 letter says.
“This will require additional review and analysis by the city and MDEQ to develop a resolution that establishes a protocol for hydro-excavation to include additional checks and balances when copper is found to confirm that the line is not spliced, leaving lead or galvanized materials” in the ground.
Weaver told the Flint Water Interagency Coordinating Committee earlier this month that she was “putting a pause” on hydro-excavation, a process that uses high-pressure water and industrial-strength vacuums instead of heavy equipment to clear earth away from water service lines.
Although the city is a party to the contract with Martha Brown Custom Builders to provide excavation for this year’s service line removal program, the state is paying the bill.
Flint is in the process of excavating thousands of galvanized and lead lines, which were damaged by corrosive water during the city’s water crisis. Copper service lines are being left in place.
City and state officials have said previously that hydro-excavation is less expensive and faster for line identification than traditional excavation.
Although the DEQ “supports and encourages the use of hydro-excavation,” Weaver said the process is causing some service line materials to be misidentified, resulting in “Russian Roulette” for residents.
DEQ issued a statement Tuesday, June 26, saying “hydro-excavation is an extremely effective and reliable method of identifying service line composition” provided it’s carried out correctly.
“Proper procedures include sending a technician into the home to verify the composition of the material going into the home is the same as the material identified during the hydro-excavation process at the curb-box. DEQ’s understanding is that several communities in Michigan utilize hydro-excavation to identify material type and effectively assist with service line replacement processes,” the statement says.
Weaver told the DEQ that city will use traditional excavation to identify the composition of service lines until “the city staff and MDEQ are able to develop a more rigorous standard” for hydrovac use.
She said the traditional excavation method requires that the length of pipe under observation is extended to 10 feet at a minimum compared to 16 inches of pipe under observation using current hydro-excavation methods.