MEMPHIS, Tenn. (AP) — The public water supply in Memphis, Tennessee, is not affected by high levels of arsenic and other toxins found in monitoring wells at a coal-fired power plant, according to results of an investigation by the Tennessee Valley Authority released Wednesday.
However, the report also shows a connection between the shallow aquifer where toxins were found and the deeper Memphis Sand Aquifer that provides the city’s drinking water.
TVA began investigating last year after toxins ended up in wells that monitor pollution from coal ash ponds at its Allen Fossil Plant in Memphis. The shallow monitoring wells are near far deeper wells drilled directly into the Memphis Sand Aquifer. The TVA had planned to use the deeper wells to cool a nearby natural gas plant that will replace the coal plant later this year, but it has decided it will not use the cooling wells at this time.
Discovery of the toxins raised concerns from Memphis residents and environmental groups that the contaminants could seep from the shallow Alluvial aquifer where the monitoring wells are located into the deeper Sand Aquifer that supplies the city’s slightly-sweet drinking water. A layer of clay about 30 to 70 feet thick separates the two aquifers.
The Tennessee Department of Environment and Conservation stated at the time that news of the toxins’ existence was released that the department was confident the contaminants “are not impacting drinking water.”
Still, the department asked Memphis Light, Gas & Water — the city’s water utility — to test treated drinking water, and it came up clean. The department also told the TVA, which has a history of difficulties handling coal ash, to investigate.
The remedial investigation showed that arsenic, lead and fluoride have been contained in the shallow upper aquifer, which holds the wells at the Allen coal plant. The toxins have not migrated into the Memphis Sand Aquifer, the TVA said.
“The public water supply from the deeper Memphis Aquifer is not impacted,” a news release discussing the report said.
The U.S. Geological Survey and the University of Memphis completed pump tests at the new natural gas plant, across the street from the old coal plant. That testing shows there is a “hydraulic connection” between the shallow and deep aquifers.
TVA says more investigation is needed to understand the connection and it is not operating the cooling wells at the natural gas plant. TVA is planning to buy water from Memphis Light, Gas & Water for daily operations, it said.
Amanda Garcia, staff attorney with the Southern Environmental Law Center, said discovery of the connection between the aquifers “confirms our biggest fear.”
“Although TVA is working on a contingency plan to supply cooling water from Memphis Light, Gas & Water, we still have major concerns that the pressure from pumping millions of gallons of water each day from a nearby station could pose similar contamination risks,” she wrote in an email.
Garcia said TVA should involve the public in deciding how to provide water for the gas plant, including using recycled water.