November 29, 2025

Carbon Hill is a small village in Grundy County, Illinois, home to 372 residents as of the 2020 census. Like many small communities, its wastewater system had been asked to do more than it was originally built for. The village’s recirculating sand filter (RSF) had been fielding BOD loadings far beyond its design intent, and the filter media was paying the price, clogging faster than it could recover.