MIAMI — Dozens of personnel from the Environmental Protection Agency worked to secure some of the nation’s most contaminated toxic waste sites as Hurricane Irma bore down on Florida. The agency said its employees evacuated people, secured equipment and safeguarded hazardous materials in anticipation of storm surges and heavy rains.

The Associated Press surveyed six of the 54 Superfund sites in Florida before Irma’s arrival, all around Miami in low-lying, flood-prone areas. There was no apparent work going on at the sites this past week. The EPA said that if there was no activity, a site should be considered secured but would be closely monitored. The sites were in various stages of federally directed, long-term cleanup efforts.

At the Miami-Dade Emergency Operations Center on Saturday, Republican Sen. Marco Rubio said the EPA workers he’s spoken with seem “generally positive” about the prospects for toxic sites remaining secure in the coming hurricane. But “they can’t guarantee it 100 percent,” he said.

“EPA feels they got a handle on it.” he said. “They think that the risk is real but certainly not as severe as some other places. Not to minimize it – it’s something to think about.”

“If any site in the path of the storm is found to pose an immediate threat to nearby populations, EPA will immediately alert and work with state and local officials and inform the public – and then take any appropriate steps to address the threat,” EPA spokeswoman Liz Bowman said Friday. “So far, no sites have risen to this level that we are aware of.”

A risk analysis by the EPA concluded in 2012 that flooding at such sites in South Florida could pose a risk to public health by spreading contaminated soil and groundwater. Flooding could disturb dangerous pollutants and wash them onto nearby property or contaminate groundwater, including personal wells, said Elizabeth “Betsy” Southerland, who retired last month as director of science and technology in EPA’s Office of Water after 30 years at the agency.

A recent analysis for the Government Accountability Office by two researchers at American University found that a storm surge in South Florida of just 1 to 4 feet could inundate the half-dozen sites visited by the AP in recent days. Irma was predicted to push in a wall of water up to 12 feet high.