Alcoa utility leaders are set to invest in a safer environment for workers by contracting two studies to prevent injuries from electrical explosions, this only a month after an unexpected explosion caused a 7,000-customer outage in January.
Alcoa commissioners voted unanimously Tuesday to approve two task orders with Patterson & Dewar Engineers for arc flash hazard assessments for the both electric department and the public works and engineering department.
“The electric department is basically updating processes and procedures they’ve already had in place,” City Manager Mark Johnson told commissioners and department heads during a January briefing in which he introduced the studies. He explained electric has already undergone similar studies but this is a new development public works facilities.
Explosions and precautions
Arc flashes are sudden and dangerous electrical explosions, often caused by a damaged piece of equipment.
“Our linemen are exposed to that potential all the time, but they’re extremely well-trained,” Johnson said, “But it also can happen ... inside, and it frequently does.”
Alcoa Electric Director Ryan Trentham explained engineers are coming to show each facility how it can better protect its workers through training and with protective gear.
“It’s not prevention, it’s protection,” he explained after Tuesday’s vote. “They’ll come in, we’ll provide them our model, they run different scenarios and they can calculate what potential energy is available for some sort of arc explosion.”
Based on the study’s recommendation, each department will be able to ascertain whether it has the right equipment for people who work in high voltage situations and whether that’s protective gear or proper labeling.
The study will also recommend necessary training for employees who deal with certain kinds of equipment that could put them in the path of an explosion.
“On the power side it’s a lot more common for utilities to do (this study),” Trentham said. “But it’s a little bit ... newer on the public works side.”
He said public works facilities like lift stations and pump stations are mostly low voltage, similar in strength to residential electricity.
But that doesn’t mean there are no risks.
Though Johnson said the the studies were in the works before 2020, in early January the electric system suffered a significant arc flash when Tennessee Valley Authority metering equipment at the Duncan Substation malfunctioned.
“It wasn’t during a storm,” Trentham said. “When that piece of equipment failed, that’s a good example of an arc flash happening.”
Thankfully, no one was there, but when the equipment failed, it exploded.
“I mean, there was shrapnel everywhere,” Trentham said. “If somebody was there? If they didn’t have the proper (protective equipment), they could have been ... “
The failure not only caused an outage for thousands, it also forced a second outage when TVA to came to make repairs.
Trentham said the department had done a study internally years ago, but it was time for an update, and the January incident made that all the more clear.
The study is set to cost no more than $15,000 for the electric department and a total $35,000 for the service center, the water treatment plant and raw water intake and the lift and pump stations.
Public Works & Engineering Director Shane Snodderly noted during the January briefing that funds for the study for the public works side of the study was not necessarily in the budget, but there was enough money available to move forward.
Notes on the task order show the studies may be complete by June.