In this July 21, 2017, photo, a hog waste pond is seen adjacent to hog houses at Everette Murphrey Farm in Farmville, N.C. (AP Photo/Gerry Broome)

Hurricane Florence’s potential for destruction also includes increased risks for the environment and public health as torrential rains could overwhelm the pits where toxic waste from power plants is stored. Animal-manure lagoons are also at risk of flooding.

Duke Energy was ordered two years ago to clean up coal-ash ponds in North Carolina that posed risks to the environment and public health. The company won’t be done in time for the storm, leaving the sites vulnerable to spills that can unleash the waste. The state is also a major producer of poultry and hogs, and man-made lagoons that hold manure also could be at risk of overflowing into fields and nearby waterways.

Florence continues to grow in size and strength, now poised to become the strongest hurricane in almost 30 years to hit the Carolinas as more than 1 million people began fleeing the U.S. coastline.

Duke came under pressure to address coal-ash storage after about 39,000 tons spilled in 2014 from a pond near Eden, North Carolina. In 2016, the state gave the company until Aug. 1, 2019, to dig up and close some coal-ash pits and almost a decade more to deal with others. Duke has begun work at several high-risk sites.

Coal-Ash Sites

“The coal-ash sites are very vulnerable to this hurricane and any other,” said Frank Holleman, senior attorney at the Southern Environmental Law Center.

Duke owns 31 coal ash basins in North Carolina. They contained about 111 million tons of coal ash as of August 2017, according to state estimates.

Duke is moving staff and equipment toward North Carolina’s coast to monitor the disposal sites for coal ash, a byproduct of burning coal to generate electricity. It contains metals including arsenic, chromium, and mercury that pose risks to public health and the environment if spilled into drinking water supplies. After the storm hits, staff are prepared to inspect the sites by foot, boat, and drone.

Five sites slated for closing that are closest to the coast have lower water levels and “can hold significant rainfall,” Erin Culbert, a spokeswoman, said in an email.

Still, many coal-ash storage ponds are near rivers that are vulnerable to overflowing during big storms.

“The risk is probably not that rain is going to fall into the pits,” Holleman said “The risk is that land and water will compromise the dams.”

Manure Lagoons

From the livestock industry, one environmental impact from the storm could be from the lagoons, or lined earthen pits, that hold treated manure. They are commonly used to manage swine waste.

The waste is held in lagoons because it’s generally considered a safe way to store the manure before it’s used to aid crops.

“There’s just certain times of year when you just don’t want to put waste on fields,” said Mike Yoder, an associate director and coordinator for emergency-response programs at North Carolina State University Extension.

The waste can be a significant problem when there’s storm surge and heavy rain, as a lot of North Carolina’s hog production is close to the coast, according to Will Sawyer, an Atlanta-based economist at CoBank. Farmers will be using the next several days to prepare for the storm, he said.

There’s the potential that spillover from open lagoons or wash away from barns or fields could get into water used for drinking or recreation, according to the Waterkeeper Alliance, an environmental group.

Wet Waste

More than 10 billion pounds of wet animal waste is produced annually in the state, according to a June 2016 report by the group, which has monitored the impact of past storms. North Carolina is the top U.S. turkey producer, ranks third for chicken and is home to more hogs than any state other than Iowa, government data show.

“This increasingly severe, potentially unprecedented storm is hurdling to the epicenter of animal agriculture in North Carolina,” said Will Hendrick, a staff attorney and manager for a water campaign in the state for the Waterkeeper Alliance. “Because waste is managed using archaic practices, it presents a significant threat to water quality, primarily through run off and/or breach or inundation of hog lagoons.”

Still, the hog industry disputes the idea that there’s much environmental risk from the waste lagoons, said Andy Curliss, Chief Executive Officer of the North Carolina Pork Council. He said there was no impact during 2016’s Hurricane Matthew, which struck the state. During that storm, only 14 lagoons out of several thousand flooded, Curliss said. This year, farmers have been using manure as fertilizer through the year and the lagoons can handle as much as 25 inches (64 centimeters) of rain.

“If we get more than 25 inches of rain, then we’ll start to be concerned,” he said.

Bloomberg’s Justina Vasquez and Megan Durisin contributed to this report.