APOLLO BEACH — The federal Occupational Safety and Health Administration fined Tampa Electric $18,108 and gave the company two "serious" citations for its response to a gas leak at the Big Bend Power Station in May, the agency announced late Friday.The May 23 incident involved a release of anhydrous ammonia that sent four workers to the hospital.OSHA also issued two "serious" citations and $25,350 in fines to Tampa Electric contractor Critical Intervention Services, a firm that provides security services at Big Bend.The fines aren’t particularly large, said Jordan Barab, who served as OSHA’s deputy assistant secretary from 2009 to 2017.But they come as Tampa Electric, one of the state’s largest utilities, faces scrutiny over its safety record. OSHA is investigating a June 29 accident at the Big Bend plant that killed five workers and injured a sixth. The agency is expected to issue its findings by the end of December.Barab said the May 23 incident could be a factor in determining how harshly the agency fines Tampa Electric for the June accident."Even when you have safety problems that aren’t directly related, that can be an indicator that you’ve got some systemic safety problems and cultural issues that need to be addressed," he said.Anhydrous ammonia is a hazardous gas that can cause skin burns, respiratory irritation and death by suffocation."Usually when you go to a power plant, there’s a safety video you have to watch about it," said Danny Raines, a Georgia-based safety consultant who spent four decades working in power plants. "If there’s a release, you have to get away from it."The release at Big Bend was blamed on an over-pressurized pipeline, OSHA said.Tampa Electric was cited for having an inadequate emergency response plan and because the employees who were exposed to the gas were not wearing protective masks.Critical Intervention Services was penalized for not having a written hazard communication program and for not training its employees on hazardous chemicals, OSHA said.Tampa Electric said it was reviewing the citations, and planned to meet with OSHA, spokeswoman Sylvia Vega said."Our review of our safety policies and procedures, which is ongoing, includes an evaluation of this equipment," she added.Critical Intervention Services also said it planned to meet with OSHA."In this case, we were the ones who found the leak," CEO K.C. Poulin said. "We’re not part of the team that works with these gasses."The companies have 15 days to contest the findings.Experts say the June accident, which left five dead, could result in far larger penalties, especially if OSHA finds "repeated" or "willful" violations.An August Tampa Bay Times investigation into the deadly accident found that the company had experienced a near-identical incident in 1997 that injured at least three people. The 1997 accident led a committee of workers and managers to draw up new safety guidelines that would have prevented the June incident. But the rules were costly and eventually abandoned, former and current employees told the newspaper.In July, CEO Gordon Gillette promised the company would stop doing the kind of work that led to the accident until investigations into the incident had concluded. But in late August, workers at the plant carried out a similar maneuver anyway. The union complained, and Tampa Electric pledged to further clarify its prohibition.Then in October, two workers trying to fix a boiler cooling system were rushed to the hospital. Their injuries were not life-threatening, a spokeswoman said.The Times has reported that in recent years, more workers have died in Tampa Electric’s power plants than in plants run by any other Florida utility. Tampa Electric has had 10 fatalities since 1997. No other utility has had more than three.Times staff writer Neil Bedi contributed to this report. Contact Kathleen McGrory at [email protected] or (727) 893-8330. Follow @kmcgrory.