Polluted flood waters swamped coal ash ponds at power plants. Rising waters engulfed private septic systems in back yards. The unwholesome mix inundated hog waste lagoons on farms. And the torrent overwhelmed municipal waste water treatment plants in towns large and small.
In some cases these waste-handling facilities took on so much water they experienced structural damage and partially collapsed, disgorging their contents into the flood.
121 million gallons
The state’s pig farmers and the hog industry trade group frequently express frustration that their industry attracts a disproportionate amount of negative publicity, while pollution from other sources — septic tanks, poultry farms, sewer systems and industrial waste — sometimes go unmentioned.
The comparative effects of sewage spills on the environment and on public health will likely never be known in any precise way, because the volumes of spills, overflows, breaches and discharges are estimated and sometimes unknown.
What is known is that some 121 million gallons of untreated and partially treated sewage washed out at more than 200 waste water treatment systems.
Some backed up and bubbled out of manhole covers, and some was deliberately released to prevent backups and overflows. The bilge was disgorged in nearly 600 separate incidents, flowing into streets, fields and waterways, according to the most recent data from the N.C. Department of Environmental Quality provided by Jim Gregson, deputy director of the N.C. Division of Water Resources, last week in a phone interview. The biggest of the spills released 17 million gallons in Troy over multiple days when an overflow-basin wall breached during flooding.
The total volume is equivalent to 200 Olympic size swimming pools of sewage. And it is about 28 percent more feces, urine, dishwater and other household waste expelled into the environment than the agency had previously estimated and reported to the state legislature in mid-November.
The waste water plants were disabled by flooding, mechanical problems, electrical failures and malfunctioning emergency backup generators, Gregson said. Two weeks after Florence, eight waste water plants were down and nine were partially operational.
Several small systems are still not fully recovered, Gregson said. For example, the town of Spring Lake, with a population of 15,000, has a damaged chlorination system and is using chlorine tablets “with very little success,” resulting in inconsistencies during disinfection of treated water that is discharged into the Lower Little River.
The agency so far hasn’t issued any violation notices or civil fines against waste water treatment plants that malfunctioned during or as a result of Hurricane Florence, Gregson said. Nor has the agency fined any hog farms for hurricane-related spills.
How does it compare to hog waste?
There is no comparable information for failures at hog lagoons, of which there are 3,300 in the state. Farmers self-reported six breached lagoons, including one that failed and released 2.7 million gallons of swine waste. In addition, 33 lagoons were covered over by flood waters, so that hog lagoon contents mixed with the flood and some likely flowed out.
The Department of Environmental Quality is still gathering information on hog lagoon spills and breaches, Gregson said. But Gregson said it’s impossible to estimate how much waste flows out of lagoons that are overtopped by flooding.
Even if we knew the precise amount, Gregson noted, hog waste and human waste are not equivalent. Hog waste in a hog lagoon is partially decomposed and has lower concentrations of bacteria and pathogens. Gregson said hog lagoon liquids can contain up to 20 times as much nitrogen as human waste in sewage. Nitrogen is the chemical element that serves as energy food for algae, which can turn a waterway into a greenish soup that becomes toxic to aquatic life.
One consequence of elevated pollution levels after major flooding is fish kills. But the fish die-offs are not caused exclusively by agricultural waste or human waste, but by all organic material that washes downstream and sucks up oxygen as it decomposes.
There were at least a half-dozen fish kills documented after Hurricane Florence by the Department of Environmental Quality, including a big one in the Waccamaw River that claimed at least eight species, including eels, carp, catfish and largemouth bass. “Total losses are incalculable but certainly exceed 100,000 fish,” a DEQ summary report states.
What does it mean for our health?
If people are exposed to flood waters and swallow a gulp, or three, they could get ill from ingesting pathogens and developing gastrointestinal illness. The number of people who got sick is not known; many can put up with a stomach ailment for a few days or even weeks without seeking medical help. The illness could range from an upset stomach to diarrhea and vomiting in serious cases.
“Everything in our waste water comes from what’s in our body,” Gregson said of human waste. “If people are sick, there are viruses, there are bacterial infections.”
Water contamination from all sources was high enough to cause a spike in pathogens that wormed their way into private drinking wells, through cracks or other entry points. According to data compiled and provided by the Department of Health and Human Services, testing showed that 13.1 percent of private wells had E. coli and total coliform bacteria, and 31 percent of the wells had total coliform, as of Dec. 7.
Those contamination levels were significantly higher than the 2 percent of private wells that tested positive for the same pathogens before Hurricane Florence.
The bacteria measured aren’t necessarily dangerous but they are indicators of pathogens that cause illnesses. The most common offenders are salmonella and campylobacter, both common causes of food poisoning, as well as norovirus, adenovirus and enteroviruses, which can cause illnesses severe enough to require hospitalization, said Rachel Noble, a professor in UNC’s Department of Environmental Sciences and Engineering and the Department of Marine Sciences.
When people do get sick, it’s usually from sloshing around in a stew of flood waters, or from drinking contaminated water from the tap. During Florence, a total of 72 public water systems issued boil-water notices as a precaution, without waiting to confirm contamination. Twenty systems were temporarily unable to produce drinking water during the hurricane.
Flood-borne pathogens don’t live forever, but they have a lifespan ranging from a few hours to a few days to a few weeks, Noble said.
After a major storm, pathogens are carried downstream and eventually wash out to sea or settle in sediments, Gregson said. This leads to another unwelcome impact: contamination of shellfish. These marine creatures are filter-feeders that accumulate bacteria and viruses, sometimes at concentrations that are unhealthy for humans.
As a precaution, after major storms state officials temporarily close waters to the harvesting of oysters, clams and mussels until testing shows that the bacteria levels have subsided and the shellfish are safe for human consumption.
Florence forced the closure of harvesting waters from Sept. 13 until the last shellfish growing area was reopened Oct. 27, one of the longest shellfish harvest closures in the state’s history.
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