The key scientific and geological findings that support the cause of the problem (installing the solar array) and its potential effects (contamination and structural failure) are centered around the unique nature of karst geology, the mechanism of frost heave, and documented evidence of pile movement in cold climates.
Findings on Karst Vulnerability and Rapid Contamination
The geological structure of the region provides the foundation for the high-risk scenario:
High Vulnerability Classification: Groundwater in karst regions is classified as highly vulnerable to contamination by the Minnesota DNR and leading geologists.
Rapid Contaminant Movement:
Karst landscapes allow surface contaminants to move rapidly into wells and springs. Pollutants can travel from the surface into aquifers in **hours—sometimes even minutes**—without natural soil filtration. The Minnesota DNR has confirmed that contamination in karst can move from the surface to the aquifer in hours or days.
Destabilization from Construction:
Large-scale construction in karst regions is known to elevate sinkhole risk and destabilize subsurface systems. Specifically, the karst region is confirmed by the Minnesota DNR and multiple scientists and hydrologists as unable to withstand the hundreds of thousands of fractures to the bedrock that would result from driving the solar piles.
Irreversibility of Harm:
Once aquifers in karst are contaminated, remediation is considered **extraordinarily difficult, often infeasible.
Findings on Frost Heave Mechanics and Pile Movement
The cold climate acts as the mechanism that guarantees the pathways for contamination will open and widen over time:
Mechanism of Frost Heave:
Frost heave (or frost jacking) occurs when moist soil freezes, forming ice lenses that expand, gripping the pile, and lifting it upward. This repeated freeze–thaw cycle ensures that misalignment is cumulative.
Documented Movement in Cold Climates:
Field evidence from Ontario solar farms confirms that 7% to 17% of piles moved 20–36 mm (0.8–1.4 in) within two to three winters.
Extreme Movement Data:
Between 1% and 9% of piles exceeded 36 mm (approximately 1.5 in) of movement in documented cold-climate solar farms.
Structural Consequences:
This movement, even 1–2 inches, creates racking stress, structural fatigue, and ultimately necessitates costly remediation and maintenance to reset thousands of piles.
Mitigation Limitations:
Research consensus confirms that frost heave cannot be stopped entirely in cold-climate soils. Mitigation measures, such as bond-breaker sleeves or insulation, can only reduce, but not prevent, movement.
Findings on Contamination Pathways
The combination of fragile geology and physical pile movement creates a definitive risk pathway:
Creation of Conduits:
The movement caused by frost heave widens the gaps along the steel piles. These gaps form long-term conduits that allow surface water and pollutants to bypass soil filtration and reach the critical aquifer.
Compounding Risk:
The equation for risk is summarized as: frost heave + karst = more pathways, faster movement, higher contamination risk.
Types of Contaminants Affected:
This accelerated pathway allows common farm chemicals, such as nitrates, pesticides, and herbicides, to travel faster through the karst features into wells.
Toxic Release Risk:
Catastrophic storm damage (e.g., tornado or hail) could shatter panels, potentially releasing hazardous substances or deadly toxins into surface runoff and soils directly connected to the karst features.