photo by: Josie Heimsoth/Journal-World

The Baldwin City solar field is pictured Thursday, December 19, 2024.

In the debate about solar projects in Douglas County, there’s been much talk about things like floodwater management and the use of prime agricultural land. But below the surface — literally — there’s been another debate about zinc.

Solar panels have to be supported by piers that are partially below the ground, and these piers are coated in zinc to resist corrosion and extend their lifespan. The question from some landowners and planning leaders in Douglas County is whether that zinc coating threatens to leach into groundwater, and the Douglas County Commission will soon weigh in on a new rule that would require groundwater testing for any solar projects proposed in the future.

Specifically, the proposed change to Douglas County’s zoning and land use regulations would require wells to be dug upstream and downstream of future solar projects, and samples would be taken to see if zinc contamination existed downstream. In December, the Lawrence-Douglas County Planning Commission voted to forward it to the County Commission with a recommendation that it be approved.

Planning Commissioner Charlie Thomas said at a meeting on the topic in November that he wouldn’t feel comfortable if such tests weren’t required for solar projects.

“I would fall on the side of any time we introduce one element into such a compacted area, I would want to test and make sure we are not hurting residents of Douglas County,” Thomas said.

According to the Harvard University School of Public Health, zinc can be toxic in large amounts, resulting in symptoms such as nausea, abdominal cramps and diarrhea, but this occurs almost exclusively from taking excessive zinc supplements, not from any dietary source. Currently, according to the Environmental Protection Agency, there is no maximum contaminant level for zinc in public supplies of drinking water in the U.S. There is a secondary or recommended limit of 5 milligrams of zinc per liter in drinking water, but this is primarily related to zinc’s metallic taste.

Not everyone in the planning process has agreed that zinc pollution from solar arrays is even a problem.

Planner Mary Miller told planning commissioners in November that in her research, she did not flag zinc contamination as a potential problem from solar arrays, and because of this, she advised the Planning Commission to deny the amendment.

“In order for me to recommend testing, I have to be able to say there’s a reason to test,” Miller said at the meeting.

Miller said that she contacted experts at the Kansas Geological Survey about the possibility of zinc leaching into groundwater, and they told her zinc would not pose a risk to water resources. KGS said that if some corrosion occurred, it would be in low amounts and would not travel far.

“The metals precipitate. In other words, they will combine with some other species in the soil solution and actually form other compounds,” Don Whittemore, senior scientific fellow at KGS, told the Journal-World. “… That slows down the movement of the metals and will decrease the amount of metals that could be dissolved in solution because they will be in the solid phase in the soil.”

The final decision on the zinc testing requirements will rest with the County Commission, which has not yet scheduled a vote on them.

But whatever happens, one thing that is certain is that it won’t apply to the Kansas Sky Energy Center solar project, which is slated to put about 8 million square feet of solar panels on fields in the Kansas River valley north of North Lawrence. Miller told the Journal-World via email that changes to the regulations would not apply retroactively to previously approved projects.

Concerns about groundwater contamination from solar farms have been around for a while in Douglas County. As the Journal-World reported, in 2023, Dan Fuller, who owns a winery in southeastern Douglas County, voiced concerns about potential groundwater contamination from solar farms and asked county commissioners to initiate a code amendment to require annual testing near solar energy developments for not just zinc, but also other metals such as lead and cadmium.

At the Planning Commission meeting in November, Fuller said he wanted to urge local leaders to think seriously about regulating zinc because he wants to protect the residents in the areas where these solar arrays are located.

“(Zinc contamination) may not ever happen,” Fuller said. ” … But who wants to take a chance?”

How the rule would work

The proposed text amendment to the zoning regulations specifies that continuous testing for zinc contamination would be conducted on galvanized solar panel piers installed within 4 feet of the groundwater surface.

Groundwater zinc concentrations would be tested using monitoring wells upstream and downstream of the site. Upstream monitoring wells would be located in the expected flow direction, as determined by a qualified hydrologist. Downstream monitoring wells would be installed between the piers and nearby water wells, within 0.25 miles of the solar facility and in the anticipated flow path. The reason for the wells both upstream and downstream is to check whether any contamination is coming from the solar array or from some other source farther upstream.

The groundwater samples would be taken before the installation of the solar panels to establish a baseline and every 12 months thereafter. If zinc levels were to exceed 5 milligrams per liter, testing and reporting would increase to every six months, and water would also be tested at area property owners’ wells within 0.25 miles of the monitoring wells, with the property owner’s consent.

The operator of the solar facility would be responsible for mitigation measures, as they would be required to be included in future conditional use permits for solar projects.