APOLLO BEACH, Fla. - It's been more than two-months since a tragic accident at TECO's Big Bend plant killed five people and left one person with severe burns.

It happened while they were doing routine maintenance but something went wrong and were burned with molten slag.

Now Representative Kathy Castor is trying to appeal to the Occupational Safety and Health Administration, demanding clearer rules to keep workers safe.

"Many slag related injuries and deaths have occurred in at least six states since 2009," she wrote in a letter to OSHA, describing the effort as "dangerous technology."

Heather McCort, whose father, Michael, was one of those killed, is still reeling from her father's death.

He was a senior plant operator who worked for TECO for over 35 years.

“I was devastated. It’s been hard," she said. "It hasn't been easy. It's something I want no other families to go through."

She believes changes are needed at the company.

“That’s the reason that these procedures are put into place to prevent people from dying," she said. "Obviously, they didn't follow their own procedures. Something like this, to this magnitude could have been prevented. I think.”

A number of changes have been made at the company, TECO spokesperson Cherie Jacobs said.

“We immediately made the commitment to stop this type of work on Slag tanks while the unit is online until we have more information,” she said. “We're also doing a complete evaluation of all of our safety procedures across the company with special attention being paid to high risk procedures like the slag tank.”

Jacobs also addressed the recent Tampa Bay Times investigation that claims this has happened before.

“We're currently looking into that incident 20 years ago at our Gannon plant and it's a big part of our investigation,” she said.

TECO has a policy where workers can refuse any work they deem unsafe, a rule that has been in place for years, Jacobs said.

The Tampa Bay Times also found other incidents at TECO plants:

June 26, 1997: Four employees were injured at the Port Sutton plant in an accident involving hot slag that spewed from a tank, causing first-degree and second-degree burns to two workers. A plug controlling the slag fell out, releasing the dangerous coal by-product. "It came out sort of like hot, molten lava," then- TECO spokesman Mitch Lubitz said.

April 1999: A generator at the Port Sutton plant exploded, killing three mechanics. The blast created a fireball that blew off wall paneling and injured 50. One worker who died suffered burns to over 90 percent of his body. TECO was fined $25,200 for safety violations.

April 2, 2002: Conveyor belts caught fire at the Port Sutton plant. Seven employees weretreated for mild smoke inhalation but none were hospitalized. The fire was the second in two weeks to reduce the plant's generating capacity.

July 14, 2014: Bryan Hagan, 31, of Mulberry fell 40 feet to his death from a catwalk at the Port Sutton plant.