ROCHELLE — City officials heard a preliminary report on the source of radium that has been appearing in the water supply over the last two years.

Dr. David Malone, Professor of Geology at Illinois State University, presented his findings to Rochelle City Council during Monday’s meeting. Malone’s scope of work is just one of three segments being researched by his team and graduate students in a two-year study.

According to Malone’s findings, the source of radium has been pinpointed to a sandstone layer deep underground, directly above the Galesville aquifer — one of the aquifers the city draws its water from. It is only when the water is extracted at larger amounts does it creates a sag in the sandstone layer, called a cone of depression. This allows the sandstone layer, rich in radium, to mix in with the water in the aquifer that eventually is pumped to the surface.

Malone referred to the sandstone layer as the “Franconia Sandstone,” containing Glauconite, which is a mineral with higher than average uranium concentrations. He explained radium is a naturally occurring element in rocks and as a dissolved solid in water that originates from uranium as it decays, eventually decaying to lead.

“We can safely say, by water moving through this Franconia formation, we are liberating radium and bringing radium into our wells,” Malone explained to council members. “By pumping these wells, we are drawing more water down and it’s reacting with this glauconite-rich layer and liberating uranium and radium and that’s the problem.”

Hypotheses

Malone explained he was first contacted by Adam Lanning, superintendent of water/water reclamation, to discuss the occurrence of radium in the groundwater.

“Adam raised a question I didn’t have a good answer to,” he said. “We know that radium is naturally occurring … we developed the idea for the project. My part was to determine the source of the radium, where it came from and where it sits. We have the ongoing part of the project now and we are trying to develop a groundwater model for this area. Adam is providing some of the pump data so we can figure out the groundwater flow. Once that is done, another student will figure out how it gets from where we think it is in the rock into the water, and how the water gets in the wells.”

Malone indicated the uranium has nothing to do with the nuclear power plants, predating any in the area. He said Northern Illinois is not alone with radium issues, as it occurs in parts of the Atlantic coast, the high plains and the Pacific northwest.

Lanning said ISU anticipates finalizing the study and presenting it to city council. 

“The city hopes to gain an understanding of the radium issue for future planning and development,” said Lanning. “We don’t know if this study will help us avoid the radium; it might not be possible but understanding where it comes from and how it gets in