The Riverkeeper alliance reported that water samples taken on February 4, just downstream of the huge Duke Energy coal ash spill in Eden, NC, were highly toxic. These results were apparently inconsistent with results reported by a Duke University geochemist that the water was safe in the water samples measured by Duke University students. However, the samples measured by Duke University were taken from further downstream. The results may be compatible. (Please note: I have a PhD in geochemistry so this is my expert opinion.) The dissolved toxins may have adsorbed onto sediments on the river bed as the contaminant plume moved downstream. Adsorption onto riverbed sediments makes the water easier to treat for drinking, but makes the clean up of the river a slower process. Organisms living in the river bottom may bioaccumulate toxins. Fish in the river should be considered unsafe to eat given that there was already an advisory to limit fish consumption because of highly toxic PCB contamination.
The high dissolved iron levels are a clue to what could be limiting arsenic levels in the water. Iron dissolves under low oxygen conditions. Arsenic and selenium, two of the toxins of greatest concern in coal ash dissolve under oxidized conditions. Under low oxygen conditions they are relatively insoluble and immobile. The high levels of dissolved iron are unusual for river water because it it generally thoroughly oxygenated. They indicate that the stagnant conditions in the waste impoundment were anoxic so iron in the wet coal ash dissolved. As the river flows and oxygenates the water, the iron will oxidize and precipitate out of solution, removing arsenic and selenium with it, in a manner similar to the process in an engineered water purification system. However, over longer time periods, biological activity could release some of these toxins back to the environment.
On Tuesday, February 4, Waterkeeper Alliance took water samples from a stretch of the Dan River downstream of the spill located between Eden, North Carolina and Danville, Virginia. [See the map of samples here.]
Coal ash is a waste product from coal combustion and presents a serious threat to aquatic ecosystems and drinking water because it contains heavy metals and other toxic compounds. Laboratory results of Waterkeeper’s samples, also show that, compared to the levels found in a “background” water sample taken upstream of the spill, arsenic levels immediately downstream of the spill are nearly 30 times higher, chromium levels are more than 27 times higher, and lead levels are more than 13 times higher because of Duke Energy’s coal ash waste.
Waterkeeper’s testing found an arsenic concentration in the polluted water immediately below the discharge of .349 mg/L. Arsenic is a toxic metal commonly found in coal ash and is lethal in high concentrations. The .349 mg/L concentration found in Waterkeeper’s sample is greater than EPA’s water quality criterion for protection of fish and wildlife from acute risks of injury or death. It is more than twice as high as EPA’s chronic exposure criterion for fish and wildlife, and is almost 35 times greater than the maximum contaminant level (MCL) standard that EPA considers acceptable in drinking water.
Waterkeeper Alliance also found a lead concentration in the polluted water of 0.129 mg/L. Lead is another metal commonly found in toxic coal ash. Lead poisoning can cause developmental delays and permanent damage in exposed infants and children, as well as kidney damage and high blood pressure in adults. In very high doses, lead poisoning can cause death. According to the Occupational Safety and Health Administration, lead poisoning in the blood causes damage to many systems in the human body, and that damage can arise after periods of exposure as short as days if the level of exposure is acute. The 0.129 mg/L concentration found immediately downstream of Duke Energy’s coal ash spill is more than double the EPA’s water quality criterion for protection of fish and wildlife from acute risks of injury or death. It is about 50 times greater than EPA’s chronic exposure criterion for fish and wildlife, and more than 1,000 times greater than EPA’s recommended action level to prevent contamination of drinking water.
before the spill according to the local newspaper, the Register Bee, that told the story of a local fisherman who stopped eating the fish.
Like other streams and rivers in Virginia, the Dan River had fish-consumption advisories before Sunday’s coal ash spill from Duke Energy’s old Dan River Steam Station in Eden, N.C. That incident resulted in nearly 85,000 tons of coal ash flowing into the bottom.
Boyd stopped consuming the Dan’s aquatic life due to pollutants — such as mercury and PCBs (polychlorinated biphenyls that were used as coolants in electrical systems) — that led the state to impose an advisory against eating catfish more than 32 inches long. It also says to avoid eating more than two fish meals of any other species per month out of the Dan River — and that was before Sunday’s coal ash spill.
“It kind of pisses you off,” Boyd said of the river’s pollution. “What can you do about it? Nothing.”
Duke University (not associated with Duke Power) geochemist Avner Vengosh reported that water samples taken one mile downstream, and twenty miles downstream near Danville's water intake, showed
safe levels of toxic elements. Danville's water supply appears to have dodged a bullet.
“We do not see elevated levels of arsenic, it’s very low,” Vengosh said. “We do not see selenium. What we found in other ponds, we do not see it in this spill.”
His group tested water at the spill site, at a location one-mile downstream, and in Danville’s treated water about 20 miles downstream.
In all cases the water was safe, he said.
Vengosh stressed that coal ash ponds are a very serious environmental threat, especially in other locations across the state.
Still, the spill may have a long term environmental impact on the Dan River. Coal ash sediment could accumulate at the bottom of the river and affect the food chain. Shellfish, insects and other animals born on the bottom of the river could accumulate unsafe metals that would eventually be concentrated in the fish that eat them.
But Danville’s drinking water will not be affected, he said.
“In this case we were lucky,” Vengosh said.
There are dozens of dangerous coal ash impoundments across the southeast. We might not be so lucky next time. Remedial action needs to be taken to keep the coal ash from endangering human lives and our water.
