Louisville Water Director of Water Quality & Research Dr. Rengao Song reported that no impact has been observed at the B.E. Payne Water Treatment plant three months since the December 19 Ohio River chemical spill. He said that no adjustment to the water treatment strategy was needed due to the riverbank filtration pretreatment at the Payne plant.
Both production operations and water quality have been closely monitoring the water from the riverbank filtration system at the Payne plant for months after a barge accident dumped 467,000 gallons (5.1 million pounds) of a liquid fertilizer called urea ammonium nitrate (UAN) in the river near Cincinnati.
Because the Payne plant uses riverbank filtration, it would take an average of one to two months for the spill to get into the system, which could have been as early as January. Song said he did not anticipate any change in the treatment strategy because riverbank filtration can remove and dilute river contaminants. With riverbank filtration, water is naturally filtered by the earth. A combination of groundwater and water from the Ohio flows through a layer of sand and gravel called an aquifer.
"There are many reasons we didn’t see any impact from the UAN spill," explained Song. "First, riverbank filtration can physically, biologically, and chemically remove and/or transform some contaminants from the Ohio River. Second, the time it takes for some contaminants in the river to enter the riverbank filtration system could take days to months. The spill in the river filters through the riverbank filtration system, and it enters the collector wells. A portion of the spill would enter the system early on and would be diluted by other non-contaminated water already on its way to the collector wells. Therefore, a portion of the spill will reach the wells at a certain given time. This process can last months to years. As a result, the spill is diluted by this blending process to the level of little or no impact."
The water in the collector wells flow into a tunnel and is pumped to the Payne plant for treatment. Riverbank filtration creates a purer, cleaner source of water, meaning significantly less treatment is needed to make drinking water. The production operations and water quality teams were monitoring the water and were ready to adjust the treatment strategy if it was necessary.
Back on December 19, Louisville Water scientists, plant operators, and engineers determined a plan of action to keep the water safe at the Crescent Hill Water Treatment Plant, which sources water to be treated directly from the river. The production operations and water quality departments created a successful multi-step approach to minimize the effects of UAN in the drinking water.
Riverbank filtration pulls up to 70 million gallons of water a day from the aquifer. Louisville Water is the first utility in the world to combine a tunnel with gravity-fed wells as a source for drinking water. In 2011, the Payne Plant was named the "Best Civil Engineering Achievement" by the American Society of Civil Engineers.