Sav Morn News: Hyundai wells offer evidence of "robust" Floridan Aquifer at site

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Hyundai's groundwater well test shows a "robust" Floridan aquifer

The test showed "very good indications that these wells are going to have minimal impact to adjacent wells," said Thomas and Hutton Engineer Trent Thomas.

Jillian Magtoto

Savannah Morning News

• Recent tests show the aquifer recovers quickly, but concerns remain about the impact on nearby private and agricultural wells.
• A $1 million fund has been established to mitigate potential issues for well owners within a five-mile radius of the new wells.
• The plant will eventually switch to using surface water from the Savannah River, reducing its reliance on groundwater wells.

 

On Oct. 22, representatives of engineering firm Thomas & Hutton and the Savannah Economic Development Authority (SEDA) presented a groundwater update to the Georgia House of Representatives' Resource Management Water Subcommittee, regarding the well system permitted to withdraw more than 6 million gallons per day for the Hyundai Motor Group Metaplant America (HMGMA) and HL-GA plants on the 2,500-acre complex in Bryan County.

In the update, Thomas & Hutton Vice President of Infrastructure Trent Thompson presented the results of a 24-hour test of groundwater wells pulling from the Floridan Aquifer. According to the firm, the tests went well.

 

"I think we... forget how lucky we are to be in an area that has the Floridan Aquifer," said Thompson, "which is a vast and pristine source of water."

Hyundai's water use and discharge process has undergone a series of trials and tribulations, including sparsely attended public meetings, a smattering of violations, and a stream of largely dissastisfied public comments. Still, the four-county water plan chugs along as Hyundai's plants turn on the tap, laying pipes, building out a $129 million water treatment plant, and putting the finishing touches on its first of four groundwater wells, expected to come online later this month. Even after the wells go offline, Thomas & Hutton's tests demonstrate the Floridan aquifer will remain a viable source.

"When wells stop operating, it'll rebound right back," said Thompson.

The Floridan, a 100,000-square-mile underground tub

Underneath 100,00 square miles spanning the entirety of Florida and sections of Mississippi, Alabama, Georgia and South Carolina lies a mostly rain-fed basin producing 2 million Olympic-sized swimming pools, or 1.2 trillion gallons of water each year, according to the Argonne National Laboratory.

Water wells to the aquifer were first drilled in the 1880s by the city of Savannah, and increased as the industrial supply for pulp and paper mills dominated and drove demand. Now, the acquifer is the primary drinking water source for over 10 million people and supports the irrigation of more than 2 million acres.

But its use has led to a cone of depression, a vacuum in areas that draws water from the surrounding aquifer, including an influx of saltwater that can lead to contamination of drinking water, reduced soil fertility, and damage to coastal ecosystems. Savannah's withdrawal has put Chatham and south Effingham counties in the "red zone" and surrounding counties in "yellow" zones.

 

While strain on the aquifer in these zones have been drained by paper and pulp companies, most notably International Paper's mill in Savannah, the city's aquifer water level has risen by about 2 feet since the mill ceased its operations last month, as reported by The Current with data from the U.S. Geological Service (USGS). That would, it seems, leave more room for other users such as HMGMA and HL-GA to withdraw from it for cooling, sanitation, vehicle washes, metal finishing processes and more.

"With International Paper going and changing its business there, there could be even further improvements to that," said Thompson. "That's kind of a wait-and-see."

See, here is water

So far, "Hyundai is supplied by yellow zone wells in Bryan County," said Thompson. "What we are nearing completion on is the groundwater wells... in the green zone," co-owned by Bryan and Bulloch counties.

Two of four wells will go online later this year, Thompson said. The next will be completed sometime early next year, all about a mile and a half to three miles from each other. And before they come online, Hyundai's contracted engineering firm Thomas & Hutton presented a 24-hour drawdown test of four wells, drawing 2,700 gallons per minute, which is 50% greater than the well's designed capacity at 1,800 gallons a minute, said Thompson.

 

The goal: to determine the capacity of each well and its ability to produce water.

Recovery times spanned from 45 minutes to 8 hours, which have given "us an idea of how robust and prolific" the aquifer is, Thompson stated.

The results are "nothing surprising," said University of Georgia Department of Geology Head and Professor of Hydrogeology and Remote Sensing Adam Milewski. The Floridan is a carbonate aquifer, made of porous sands and gravel that allow water to move through.

 

"When we think about aquifer efficiency, we think of it in both directions," said Milewski. "It's how much water we can pull out quickly and easily, and then how much it responds and how fast it recovers."

Thomas & Hutton's study "tells us that's a good aquifer," he added.

As for whether groundwater will effect the megasite's neighbors, Milewski sees the value of having more data."What we are ultimately doing is thinking about a three dimensional picture of what's beneath our feet, and we do it by poking a few holes in the ground and correlating those together."

Along with the need for more data points to complete a fuller picture, said Milewski, "what would also be helpful is to say, what about the folks that live in a neighboring county? Did they look at some of those cones of depression or monitor those?"

A five-mile radius of impacts

The Georgia Environmental Protection Division (EPD) developed a model that ran the four wells together at full permit capacity for 10 years and 24 hours a day to overestimate what the impacts might be.

"They're designed to operate one at a time and cycle throughout the day, really, not to run more than about 10 [to] 12 hours a day," said Thompson.

From the model, the EPD determined a 5-mile zone of impact.

Within the radius, Thomas & Hutton looked at impacts to agricultural and private wells, Thompson said. "If there's an issue there, we want this joint well mitigation fund to cover those impacts... This is very conservative."

 

In 2024, HMGMA, Bulloch and Bryan counties' development authorities, and the JDA chipped in $250,000 each to a $1 million fund for impacted wells within a 5-mile radius of the planned wells.

But one Bulloch County peanut farmer, Ray Davis, told Savannah Morning News last year that the energy required to pump deeper water could cost him more than $100,000 per well.

Nearly 30 other wells in this 5-mile radius could face a "a potential drawdown impact,” the EPD stated in a written response to public comments to its groundwater withdrawal permit issuances on Oct. 7, 2024. Since plans for the wells were made public in 2022, nearby farmers and residents have voiced their concerns about changes in drawdown.

Still, Savannah's economic authorities and developers are hoping Thomas & Hutton's well test quashes these concerns.

"We've had to deal with a lot of bad information, a lot of sensationalism from folks who have called us a lot of names... that we're taking all the water away, how folks aren't able to irrigate their farms," said SEDA President and CEO Trip Tollison at a recent SEDA board meeting, where Thompson also presented the groundwater update. "This presentation and the work that is going on here hopefully should kill all of those concerns and make it all go away."

 

About five miles away, tests confirmed a 10-foot drawdown.

"Ten foot drawdown is a pretty good number," said Thompson at the Oct. 14 SEDA meeting.

Whether five miles is sufficient, however, Milewski was unable to provide comment.

Future water without wells

Water is already flowing through Hyunda's plants.

"Water is being treated on site," said Thompson. "Then it goes to Bryan County's wastewater treatment facility, which is in its startup and commissioning phase." Finally, it connects the Savannah's Water Reclamation Facility, then discharged into Savannah River. Once the North Bryan Water Reclamation Facility (WRF) gets its "bugs and biologicals growing so that we can reach full treatment" in 2026, water will be discharged into the Ogeechee River.

 

The EPD has already permitted HL-GA and Hyundai Motor Group Metaplant America plants on Sept. 30 to discharge a combined 0.85 million gallons per day of pretreated wastewater to the North Bryan Water Reclamation Facility, far from its expected well withdrawals of about 6 million gallons per day.

"It is not standard practice to issue pretreatment permits with flow limits lower than the eventual expected output, but it was a necessity in this situation," wrote EPD Spokesperson Sara Lips in an email. "EPD will consider flow expansions to the two pretreatment permits when the North Bryan WRF commences its discharge to the river."

 

In the future, Hyundai Motor Group plans on using surface water, instead of groundwater wells, in a roughly $500 million project to intake more water from the Savannah River, expand the Savannah Industrial and Domestic Water Plant, develop an Effingham County treatment plant, and more to all be completed by 2032, funded by the Appropriations Act signed by Governor Brian Kemp in March.

Once that surface water system feeds HMGMA and HL-GA plants, "we won't terminate use of the wells, but the day-to-day usage will go down," said Thompson. "They may only come online in the event of a fire or something like that."

Jillian Magtoto covers climate change and the environment in coastal Georgia. You can reach her at jmag...@gannett.com.