Congressman wants answers on toxins at TVA coal-fired plant.

U.S. Rep. Steve Cohen is pressing the Tennessee Valley Authority and state regulators for more information about the discovery of excessive levels of arsenic and lead in groundwater under a coal-fired power plant.

Cohen’s office said in a statement Monday that the Memphis Democrat sent a letter to the Tennessee Department of Environment and Conservation asking the agency why it believes toxins found under the TVA’s Allen Fossil Plant in Memphis are not affecting drinking water.

Department officials said last week that the TVA has measured excessive levels of arsenic and lead in shallow wells that monitor pollution from coal ash ponds at the aging Allen plant. Coal ash is the dirty byproduct of burning coal.

One well had arsenic at levels more than 300 times the federal drinking-water standard. The monitoring wells run about 50 feet (15 meters) deep and are about a half-mile (four-fifths of a kilometer) from far deeper wells drilled by the TVA directly into the Memphis Sand aquifer, which provides the city’s drinking water.

The TVA plans to pump 3.5 million gallons (13.2 million liters) of fresh water out of the aquifer per day to cool a natural gas power plant that is replacing the coal plant next year. Cohen and environmental groups have raised concerns about the strategy.

A layer of clay lies between the groundwater and the aquifer. Still, the monitoring wells’ proximity to the deeper wells dug into the aquifer has raised concerns among officials and Memphis residents about the safety of the city’s drinking water.

The environment and conservation department, through spokesman Eric Ward, said it is “confident the contaminants found in TVA wells at the Allen Fossil Plant are not impacting drinking water.” However, the department has asked Memphis Light, Gas & Water — the city’s water utility — to test treated drinking water. Results are expected late this week.

The department has also told the TVA to pinpoint where the contaminants came from.

Spokesman Scott Brooks said the TVA, the nation’s largest public utility, doesn’t know the source of the toxins and is cooperating with state’s instructions. Brooks said Monday that TVA has tested its five aquifer wells at the gas plant “numerous times in the last month and each time the results are negative for arsenic.”

Cohen also wants to know what the TVA and state are doing to make sure the aquifer “remains a viable source of drinking water.”

“We share the congressman’s concerns about the recent monitoring results at the TVA Allen Fossil Plant and are in the process of preparing answers to his questions,” Ward said Monday.