When Jason Connot first noticed the ventilation system going haywire during heavy rainstorms, the solution was buried nearly a mile beneath the Black Hills of South Dakota. Connot, a mining engineer at the Sanford Underground Research Facility (SURF), had been tracking strange reversals in underground airflow patterns for months before he and his team cracked the case. The answer? Rainwater was essentially functioning as a plunger, pushing vast amounts of air through miles of tunnels like fluid through a syringe.
"We noticed our fan would go haywire at 5 Shaft. Some areas would show reduced or even reversed airflow during large rain events," Connot said. The phenomenon occurred because heavy rainfall overwhelms the facility's water pumping system, forcing engineers to divert extra water down 5 Shaft to the deep pool below—a process similar to an overflow spillway at a dam. What they hadn't anticipated was that this cascade of falling water would displace enormous volumes of air throughout the underground complex.
The breakthrough came from collaboration with an unexpected source: Steve Gabriel, a former Spearfish High School science teacher who led his students in building and deploying airflow monitors throughout the facility. During a test of the shaft deluge system at the 4850L level, these homemade sensors captured the first hard evidence of the correlation. Gabriel later joined SURF as a full-time ventilation technician. Connot then dove into scientific literature and found documentation of similar phenomena in large municipal sewer systems. By adapting those fluid dynamics equations to fit SURF's unique configuration, the team confirmed their hypothesis mathematically.
"When we added our numbers and parameters to the model, everything came out spot on," Connot said. "You would not think the weight of water droplets could move so much air."
The discovery carries implications far beyond academic curiosity. In mining emergencies, engineers sometimes deliberately flood shafts to combat fires—now they know this technique could unexpectedly alter ventilation patterns. Because SURF operates as a dedicated research facility rather than an active mine, Connot's team had the time and mandate to pursue this investigation thoroughly. Bryce Pietzyk, director of underground operations at SURF, praised the methodical approach. "No one had previously taken the time to grasp this issue—but it's absolutely critical," Pietzyk said. "Thanks to this work, we're able to be way ahead of airflow issues, predict what will happen and configure ventilation controls."
The findings have already attracted attention from underground operations worldwide, offering insights that could improve safety protocols for facilities facing similar challenges with nature's most ordinary force: falling rain.