MLGW updates Lakeland on ‘catastrophic failure’ of substation
Editor's note: This version of the story, updated as of July 22, contains details about the potential toxicity of a mineral oil fire — details that replace our original story's reference to mineral oil as harmless. MLGW is currently reviewing a Bartlett Express request for information on whether the destroyed transformer's oil did or did not contain contaminants and if the substances created in the fire presented any health risks to nearby residents.
Six Memphis Light Gas & Water leaders stood before the Lakeland mayor and board July 14 to shed light on the July 11 substation explosion and how recovery will temporarily strain electrical resources to Lakeland and Arlington. (See a citizen's video of the massive fire here; more videos here, here and here.)
Jerry Collins, president and CEO of MLGW, said three substations went down within minutes of each other the night of the explosion. One of them was an unrelated incident, when a Shady Grove substation went down briefly because a short-lived racoon crawled on top of the transformer.
But Substation 68 in Lakeland had a “catastrophic failure — an explosion the likes of which we probably have never seen at Memphis Light Gas & Water,” Collins said. That explosion also temporarily took down nearby Substation 85 on U.S. 64.
It also happened at the worst possible time for customers — the middle of summer, when power demands are at their peak, he said.
The cause of the fire has not yet been released, but an MLGW spokesman has promised more information once they complete an investigation. Meanwhile, members of the public have also voiced concerns about health and safety, property damage, transparent communications, and possible installation of new safety features at substations.
The extent of the damage
If a substation's equipment fails, it's usually confined to just one piece of equipment, Collins explained. But the explosion in Lakeland destroyed the breaker, the transformer and the control house (the brain of the system) around 12:30 a.m. July 11. He said the damage was extreme.
"When the control house is gone, then the whole thing is gone," Collins said.
The initial recovery stage
The power was back on for residents by about 4-5 a.m., Collins said. The existence of Substations 84 (at Old Brownsville Road) and 85 (at U.S. 64) made that possible. One was built in 2001 and the other in 2008, despite community opposition, he pointed out. "If we hadn't built those two stations, you would be in the dark right this minute."
In response to the July 11 substation damage, just that switching of its normal load to Substations 84 and 85 was a challenge. The ability to transfer power from another substation is limited by how voltage drops over distance, among other factors. There's really no way to get power from MLGW's 61 other substations in Shelby County, Collins said.
MLGW is having to do a lot of work behind the scenes to support customers in Lakeland and Arlington during the repair period. Normally, there are areas south of substation 85 that would draw power from that substation, he said, but those are temporarily getting power from other substations so MLGW can make the maximum amount of power available to affected areas in Lakeland/Arlington.
The city board also heard concerns from property owners. Lakeland resident Tim Joyce lives on Evergreen Creek Road, with his back fence facing MLGW Substation 68's property. He described his location as "Ground Zero" of the substation's explosion. He said his backyard is about 15 feet from the back door to his fence, and from there it's less than 100 feet to the substation.
Joyce, a former Tennessee state representative, said the pop and grinding sound of voltage discharging woke him and his wife. They called 911 immediately.
At the time, they feared the worst. Joyce said, "We knew the house was going up."
But it didn't, and then the Bartlett Police arrived first, and other neighbors began coming outside to see the flames and brilliant lights. Joyce estimated that the worst of the substation destruction happened within about 10 minutes.
Neighbors began speculating on what happened, whether the fire threatened their homes, and if the thick black cloud billowing out from the explosion was dangerous in any way.
Neighbors' concerns about their exposure to volatile/hazardous materials during the incident spiked even higher when they spotted MLGW workers on site, wearing protective coverings that resembled hazardous materials (hazmat) suits.
Collins, however, said the Tyvek suits were not designed for handling hazardous materials; they were just to protect the workers' clothing from caustic materials.
The chemicals involved
The breaker that failed had about two pounds of a sulphur compound, found in the surrounding area of about 20-30 feet, Collins said. When the compound gets wet, it can turn into sulphuric acid. Workers sprayed a caustic material on the sulphur compound to neutralize it. The Tyvek suits protected them from the caustic spray and any oil from the transformer.
Juanita Boothe, MLGW environmental engineer 3, said some workers did use a type of breathing apparatus for part of the cleanup, but it was only because they were so close to the sulphur.
The insulating oil that was in the transformer is mineral oil, and onlookers could see the footprint of where the oil sprayed during the explosion because it left a black stain. That stain is visible in the substation up to about 40 west of where that transformer was, Collins said.
Mineral oil, as it's normally encountered, is a familiar and not particularly alarming substance, but it can be a point of concern when it combusts, according to a 2012 paper from CIGRE, the international council on large electric systems. The toxic substances are associated with the soot rather than being released in combustion gases, according to the paper, titled "Impact of a Fire in Electrical Equipment Containing Insulating Oil Contaminated with Polychlorinated Biphenyls (PCBs)."
Toxicity of a transformer's mineral oil in a fire depends on the presence and concentration of PCBs, which lead to the creation of multiple substances, including two chemical compound families (dioxins and furans) that are known to be highly toxic, the paper stated. Only 8 percent of the PCBs remain in the soot, and the fire destroys the rest. Any dioxins and furans are at much lower concentrations.
MLGW is currently reviewing a Bartlett Express request for information on whether the mineral oil used in Substation 68's exploded transformer contained PCBs.
The CIGRE paper noted that even without PCBs, a mineral oil fire will generate toxic products such as soot, carbon monoxide, and the greatest risk for exposure in this type of fire — polycyclic aromatic hydrocarbons (PAH).
The CIGRE paper states, "The greatest toxic risk of soot and smoke is closely linked to their physical characteristics: a substantial number of very small particles with large adsorption surfaces. Once inhaled, they penetrate deeply into the lungs, which makes them all the more difficult to get rid of."
However, the paper concluded that, under the tested circumstances upon which the paper was based, such fires can be handled with traditional firefighting procedures.
In high-level discussions with Lakeland's city board and the citizens at the July 14 meeting, Collins acknowledged that it was a "volatile situation," with the big explosion of the transformer's oil. But he commented, "I've got 40 people working out there today, and they're not wearing any protective clothing. They've got on a hard hat and safety glasses, which they would have on any site."
Mayor Wyatt Bunker asked how likely it is that an accident like this would happen again. He got a vivid response from Neil Strongosky, MLGW's supervisor of substations and transmission engineering, who explained just how unlikely it is to recur.
"You've all heard of a 100-year flood," Strongosky said. "This is like a 500-year flood on an electric system."
Strongosky has been with MLGW for 24 years and has only seen catastrophic failure of a transformer three times in that period, and each was less destructive than what happened at Substation 68. He also said that this is the only time for MLGW that a failure has destroyed the control house, and that level of damage is very unlikely to happen again.
Commissioner Sherri Gallick asked if MLGW has protocol in place for notifying city officials in the case of catastrophic failures like that of Substation 68. Bunker said Arlington Mayor Tim Wissman emailed with similar concerns and a desire to improve communications.
Lakeland's City Manager Jim Atkinson and a Lakeland Public Works representative showed up at the July 11 substation fire, but not because of MLGW notifications. Currently, Lakeland officials only receive notifications if a public building is affected or something obstructs a public road (such as when a tree falls during a storm).
Bunker said he knows that the visible presence of city vehicles is reassuring to residents. He also pointed out that Shelby County handles emergency management for the city and is an extension of the city in that role, so he wants Lakeland to check on those response times.
He said that city administrators and MLGW need to develop a clear communications plan with specific personnel tasked with the notifications of city officials and the general public.
In addition to being without clear and immediate communication from MLGW or city leaders with direct responsibility for emergency public communications, some nearby residents worried because — as far as they could tell — firefighters concentrated only on the large substation fire and not the adjoining neighborhood's homes.
In his prepared remarks for the meeting, Joyce wrote, "For the record, no one from the Fire Department or Shelby County Sheriff's office came into this part of the neighborhood to support us, and I called 911 myself and gave them my address."
Joyce noted that he definitely wants his home and yard to be reviewed for reassurance it's safe and no damage has occurred. The fire alone singed a varied of his plants and trees.
In response, Bunker asked to attend a neighborhood association meeting along with first responders to discuss response times, how many responded, and first responders' strategy on where to concentrate their resources (such as when they focus on the main fire and when they perform safety checks of nearby residences at risk). He asked Atkinson to set up that meeting.
Collins also said MLGW is happy to work with the city to improve communications.
MLGW has not yet issued any press releases in response to Lakeland residents' concerns about short- and long-term health hazards and whether homes are located a safe distance from substations. Some citizens have also worried about possible impact on property values and potentially lerry buyers for homes located nearest to substations.
Low power during repairs
An article on Lakeland's city website explained that there are two substations near the southern portion of Lakeland that are currently providing power to the Lakeland and Arlington area, but the distribution network is at maximum capacity, causing low voltage problems and other issues. There have also been short-term outages mostly due to switching out equipment within the network as they work to increase capacity.
Normally, Substation 85 would also serve areas south of it, but other substations have been taking over that load so Substations 84 and 85 can direct more power to Lakeland and Arlington.
Lakeland citizen Bill Rose spoke up at the July 14 meeting about the damaging effects of low voltage to home appliances and equipment.
Collins, who worked at an appliance store for eight years while he was in college, nodded and said he understands Rose's concerns.
"Low voltage can damage equipment — there's no question about it," Collins said. "Which is why we're working really hard, all day and all night, trying to shift loads so we can correct that low voltage situation."
Collins cited an example of a low voltage situation, such as a 480-volt piece of equipment only getting 450 volts. That can cause the equipment to run poorly and be damaged.
"So we are working feverishly to correct that by installing four voltage regulators in this area. And also the crews are doing numerous switching operations, trying to move load around to other substations so we can accommodate the load here in Lakeland and Arlington."
He expects to see the low voltage issues improve daily as the company continues with repairs.
Recovery of Substation 68
The company expects to restore one of the Lakeland substation’s transformers within four weeks, in time for the start of the 2016-17 school year. That will restore full function for the substation, at least as far as how it affects customers.
Full restoration of the substation is likely to take about six months.
Commissioner Michele Dial asked Collins about power problems if the repairs are not completed before school begins on Aug. 8 in Lakeland and Arlington, when power demands will spike as those five schools fill with students. Collins agreed it would be a problem if repairs lag, but he was confident of the repair timeline.
"We fully intend to have half of Sub 68 back into service within four weeks, which is about the time that the schools open," he said. "We're going to try to beat that if we can, but four weeks is a reasonable estimate. And once we get half that station back up and running, then things are going to be like normal."
Written by Carolyn Bahm, Express editor. Contact her at (901) 433-9138 or via email to firstname.lastname@example.org.