by James A. Bacon
After months of controversy, Dominion Virginia Power will start draining today more than 200 million gallons of water from its coal ash ponds at the Bremo Power Station. “We’re treating to levels that will be fully protective of the river,” Jason Williams, the environmental manager in charge of the project, told a media gaggle invited yesterday to view the water treatment facilities.
Treating the water to meet quality standards protective of aquatic life will cost about $35 million at Bremo and take a year or more, depending on how smoothly the process goes and how much rainwater is added to the coal ash ponds during the period. If Dominion consistently meets those standards, Department of Environmental Quality (DEQ) officials say that the odds of event negatively impacting human health or aquatic life in any given year are less than three in one thousand.
While the eight-step water-treatment system is basically the same design that the company submitted with its permit application to the Department of Environmental Quality, Dominion agreed to stricter protocols for treating, monitoring and testing the water quality in a settlement with the James River Association.
Coal ash is the residue from coal combustion, and it contains heavy metals that are toxic in high enough concentrations. Historically, electric utilities have stored the ash in ponds where it mixed with water to create a sludge. To prevent leaks and spillage from the ponds, the Environmental Protection Agency (EPA) is requiring power companies to remove the water and then find a safe place to store the ash. The James River Association has signed off on Dominion’s plan to de-water the coal ash at Bremo. Meanwhile, Dominion is applying for a separate permit to cover the disposal of the de-watered ash, which will create its own set of issues and potentially generate a fresh controversy.
For now, though, everyone is on board with the de-watering plan. Williams outlined the eight-step process, which he calls “state of the art.”
- Aeration. Water from the coal ash pond is piped into a tank where the addition of air facilitates the water-cleaning process.
- pH adjustment. Acidity is reduced, which encourages particles in the water to separate and settle.
- Clarification. Chemicals are added to the water to help the particles clump together so they will settle out of the water.
- Settling tanks. Solids from the clarification process are separated from the water, collected, and disposed of in a landfill.
- Filtering. The water is passed through filters to remove even more particles.
- Enhanced treatment. The water is tested. If certain constituents such as heavy metals remain close to trigger levels agreed to by the James River Association, the water is run through an extra piece of equipment to remove them.
- pH adjustment. If needed, the pH level of the water is adjusted back to levels that are safe for the river.
- Holding tanks. The water is pumped to one of four 950,000-gallon holding tanks where it is tested again before being released into the water. Dominion expects the water in these tanks to meet standards, but if it doesn’t, it will be routed through the treatment process again.
Normally, Dominion hopes, the process will clean the water to state standards in only seven steps — the “enhanced treatment” step is held in reserve as a backup. If internal monitoring shows that certain constituents exceed agreed-upon “trigger” levels, the water is run through this extra step, which uses activated alumina and limestone to remove undesirable constituents by absorption.
Dominion is limited to discharging 1,500 gallons per minute into the James River. That compares to a river flow of 5.5 million gallons per minute in normal conditions. But the standards are set to keep aquatic life in the river safe outside a “mixing zone” in low-flow conditions statistically expected to occur once every ten years.
Dominion and the James River Association have expressed optimism that the treatment process could provide a model for the de-watering of coal ash at the Chesterfield Power Station. With minor modifications, the treatment process is the same at Dominion’s Possum Point Power Station. However, the Potomac Riverkeeper Association is appealing the permit on the grounds that DEQ is using an inappropriate standard.
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