The Tennessee Valley Authority has no plans to use the wells it drilled into the Memphis Aquifer earlier in the construction of the Allen Combined Cycle Plant, the $1 billion natural gas-fired power plant it is building in southwest Memphis.

The wells were shut down when high levels of arsenic and lead were discovered at a coal ash pond at the nearby Allen Fossil Plant, the coal-fired facility that the new plant will replace.

The federal agency announced Wednesday, March 7, it intends to continue buying water from Memphis Light, Gas and Water Division and keep the TVA wells on the Allen Combined Cycle Plant site idle beyond the formal opening in a few weeks. The water purchased from MLGW includes 5 million gallons the plant will store in tanks now being built to provide the water needed for peak periods of power generation.

Meanwhile, TVA has confirmed arsenic and the other contaminants found last spring in elevated levels are also in an upper water aquifer, but not in the deeper aquifer that supplies the city’s public water supply, according to the report released Wednesday.

The Tennessee Valley Authority is building tanks at its Allen Combined Cycle Plant to hold 5 million gallons of water it will buy from MLGW. The federal utility plans to keep wells at the new plant idle for now. (TVA)

The Tennessee Department of Environment and Conservation is working with TVA to determine if any additional investigation is needed and on a remediation plan to clean up the ash pond and upper-level aquifer.

And a draft report from the University of Memphis and the U.S. Geological Survey as well as pump tests both entities conducted at the new plant indicated a “hydraulic connection” between the upper, or alluvial, aquifer and the Memphis Aquifer.

“More investigation is necessary to better understand the connection and the impacts of the existing industrial wells in the surrounding area,” reads the TVA statement.

Scott Schoefernacker, program manager for the University of Memphis Center for Applied Earth Sciences and Engineering Research, said the term “hydraulic connection” means points where the two aquifers meet instead of being separated by a clay layer.

“In spots, the clay layer can either be absent … or there could be a fault where it brings the two aquifers into connection,” Schoefernacker said.

There are still a lot of questions about how the connection functions, but some approximate locations have been identified.

“We have some cross-sections in the report that kind of spell out where we think there are two faults nearby in this area – one to the east of the plant and one to the north,” Schoefernacker said. “That’s our general idea. Somehow they are connected. We don’t know the extent or the nature of it. But it’s there.”

But he said it’s far from an automatic assumption that the arsenic would have made it into the lower aquifer.

“It doesn’t surprise me that the arsenic isn’t there,” he said. “I wouldn’t expect it to be there. It would take a lot for it to get there.”

Geologists, engineers and other experts are resuming a mapping effort that stalled several years ago for lack of funding. The new effort to map the breaches or openings in the clay layers is funded with a recent 1 percent hike in MLGW water rates.

The hydraulic connection found along with the arsenic in the upper aquifer will be among the areas mapped because it is also in an MLGW service area.

“The city of Memphis would like to develop more industry out here, and TVA is not going to be the only one that wants to put a production well out here,” Schoefernacker said.

The discovery of the arsenic and lead at high levels changed TVA’s plans for how the new plant would operate.

“The finding of arsenic out there changed the game,” TVA CEO Bill Johnson told the Memphis City Council during a visit to the city in January. “It’s in concentrations never ever seen by a hundredfold in ash. … What matters at the moment is that that doesn’t go anywhere.”

The discovery came as local environmental groups, including the Sierra Club, criticized the drilling of the wells over buying from MLGW and then pushed for the testing that resulted in the findings.

“We stopped a potentially bad thing from happening by making people look more carefully at the situation,” said Scott Banbury, Tennessee conservation programs coordinator for the Sierra Club. “It vindicates what our concerns were here in terms of these particular wells being operated and the threat they could have presented to the future of our drinking water.”

Banbury said he hopes the use of MLGW water will continue on a permanent basis.

“Even absent the operation of the wells, which would really exacerbate the problem, we know that there is contamination leaking out of those ponds,” he said. “And we know now that there could be a direct connection in the area.”