Operated by the Water and Sewer Department, O'Fallon's sewer system includes a vast collection system and full scale, state-of-the-art regional wastewater treatment plant with a capacity of 11.25 million gallons per day, complete with three equalization basins, a Class A bio-solids dewatering and handling facility, 17 wastewater pumping stations, and large capacity interceptor sewers ranging up to 48 inches in diameter. The collection system consists of over 200 miles of interceptor and collector lines with a little over 6,000 manholes.
Originally constructed in 1984, the wastewater treatment plant, utilizes an activated bio-filter process with four unit primary and four unit secondary clarifiers, four high-capacity variable speed submersible bio-tower lift pumps, three bio-filter towers, four aeration basins, an effluent pumping station, sludge digester, and an ultraviolet effluent disinfection process.
The sewer system serves nearly 16,000 customers. The City of O’Fallon provides for the full service operations and maintenance of the wastewater collection, pumping and treatment systems, including customer service and billing, with duly State licensed operating personnel.