TAMPA, Fla. – A Florida utility has been fined $500,000 and placed on three years’ probation for a 2017 explosion at a coal-fired power plant that killed five workers.

The U.S. Justice Department said in a news release Friday that Tampa Electric Co. also must adhere to a new safety compliance plan. The fine is the maximum allowed for willful Occupational Safety and Health Administration workplace rules violations such as this.

The explosion at TECO's Big Bend plant near Tampa happened when an effort was made using high-pressure water to clear a slag byproduct that accumulates in tanks under the coal-fired furnaces. The workers died and several more were injured when they were sprayed with molten slag that came loose.

The sentencing came after TECO reached a plea agreement with federal prosecutors in which the utility admitted it did not conduct any briefings for employees about the work, including the potential hazards and necessary safety precautions, prosecutors said.

“The department takes this conduct very seriously, and accordingly pursued the maximum remedy available under the law,” said Todd Kim, assistant attorney general for the Justice Department's Environment and Natural Resources Division.

The agreement also notes that the company previously reached confidential civil settlements with the families of the victims and others injured by the explosion.