MGE Substation

A transmission explosion and fire at a Madison Gas & Electric substation caused a major downtown power outage July 19. 

Update: After asking for further information on an American Transmission Company transformer failure in July, Mayor Satya Rhodes-Conway called the company's response "wholly inadequate" and said she is still waiting for the full report. 

ATC responded Friday afternoon to the mayor's letter demanding more details on the failure that caused a fire and widespread power outages downtown and on Madison's east side. 

Mike Rowe, chairman, president and CEO of ATC, repeated in a letter to the mayor that the cause of the incident was shared publicly, outlining what ATC has done to avoid similar problems in the future. 

"We are taking what steps we reasonably can to avoid a similar failure elsewhere on the ATC system, taking what we now know and applying it," Rowe said in the letter.

Rowe said ATC has canvassed its fleet of transformers for any similarities they might have with the Blount Street transformer and completed a review of test results.

"While we follow industry practices, we commit to revising internal procedures as to transformer diagnostics and responding to anomalies to continuously improve maintenance practices," Rowe said. "We are working on a corrective action plan to attempt to avoid a reoccurrence." 

The mayor was not convinced.

"They did not turn over the investigative report, and they did not even address the questions I raised in my letter. It makes you wonder what they are not telling us," Rhodes-Conway said. "It is nice of them to offer me a meeting, but it is the public that deserves answers." 

Months after a transformer fire erupted in downtown Madison, Mayor Satya Rhodes-Conway said she has not received a full investigative report about the cause of the failure.

Rhodes-Conway said in a letter sent Thursday to Mike Rowe, chairman, president and CEO of American Transmission Co., that the company has not released sufficient answers about the July 19 incident.

“The public deserves to see the full investigative report without further delay,” Rhodes-Conway said.

Rhodes-Conway posed questions to ATC asking about any indicators of the failure, the timeline for taking the transformer out of service, if any employees have been held responsible and if any new procedures have been put in place since the incident.

ATC released a statement Wednesday, sharing the summary of a report conducted jointly with the nonprofit Electric Power Research Institute. The investigation identified that a voltage regulator component failed, generating combustible gases that caught fire.

“Our investigation wrapped up last week, and we shared our findings of the cause publicly this week,” spokeswoman Anne Spaltholz said. “We also offered this week to answer any questions the city might have.”

Mary Bottari, chief of staff to Rhodes-Conway, said the mayor is waiting on answers to the questions she included in the letter, the full report or both. 

ATC conducted inspections on July 15, 16 and 17 in response to changes in gas samples that an annual test showed in June. ATC made plans to take the transformer out of service for a “detailed internal inspection” on July 22 — three days after the failure occurred.

The fire caused major traffic delays and power outages across the isthmus, disrupting government operations and the lives of Madison residents on a day with an excessive heat warning.

Environmental cleanup is ongoing as tests show that high concentrations of chemicals found in firefighting foam, known as PFAS, were found in water samples taken near the utility’s Blount Street substation, in the storm water system and in outlets that spill storm water into Lake Monona.

Spaltholz said ATC follows industry standards and conducts inspections monthly at a substation like Blount Street, which has a power transformer, and tests insulating fluid in the transformers annually.

“I think certainly what we are doing internally is taking a look at what steps can be reasonably done to avoid any kind of failure like this,” Spaltholz said. “What occurred was extremely rare.”

Rhodes-Conway said she met with Greg Levesque, ATC’s director of environmental and local relations on Aug. 5 to discuss the cause of the explosion. She said she received “few answers” and was told Levesque would make available a “privately contracted, investigative report” within a week.

Spaltholz said she was unaware if ATC promised the city a full report.

Rhodes-Conway said in the letter that Levesque would not release the report to her. She also said he indicated Thursday morning the press release online was “sufficient.”

When asked if Levesque refused to release the report to the mayor, Spaltholz reiterated that ATC shared the cause of the fire as determined by the investigation in the press release.

“We did indicate to the city that we would entertain any questions they had, that offer still stands and that we’re looking forward to meeting should they like to,” Spaltholz said.

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