North & South Plant Tertiary Filter Improvement Project Consulting Services

The City of Naperville, incorporated in 1857, is located in southwestern DuPage County and northwestern Will County and covers an area of approximately 39 square miles. The City is a home rule unit of local government under the 1970 Illinois Constitution. The City has been one of the fastest growing communities in the Chicago Metropolitan area and is the fourth largest city in Illinois. The population is currently approximately 149,000 and is expected to grow to approximately 160,000. The City of Naperville Water Utilities owns and operates Springbrook Water Reclamation Center (SWRC), treating wastewater from Naperville and City of Warrenville, serving a population of 162,563. SWRC uses a conventional activated sludge wastewater treatment process with secondary and tertiary treatment at a rated design capacity of 26.25 million gallons per day (MGD). The SWRC facilities are divided into the North Plant and the South Plant. Screening occurs prior to raw wastewater pumping, after which separate force mains split the flow between the two plants. The existing sand filters provide service for the North Plant flow only, and the flow from the South Plant is currently discharged directly to UV disinfection without filtration. The North Plant was originally constructed in 1974 and has a rated design capacity of 26.25 MGD, with a treatment train includes vortex grit removal, activated sludge aeration basins with vertical turbine aerators/mixers, secondary clarifiers, tertiary filtration, and seasonal disinfection. The disinfection system for the entire facility was replaced with a UV system in early 2024. Construction of the Influent Pump Station is scheduled for completion in summer 2026. The South Plant Grit & RAS project and the South Plant expansion are currently under construction. The South Plant Grit & RAS project is expected to be completed by the end of 2026, and the South Plant expansion is anticipated to be completed in spring 2028. Construction of the North Plant improvements and tertiary filters is planned to begin in 2028. The goal of these improvements is to increase the treatment capacity and achieve an even 50/50 capacity split between the North and South Plants. Based on the facilities improvement evaluation plan completed by Donohue in January 2022, the current North Plant filters have the following issues: The existing North Plant sand filters are operating beyond their design capacity, and they are bypassed during high-flow conditions. The sand filter system consists of 13 units: eight installed in 1974, three installed in 1983, and two installed in 1988. All of the filters have reached the end of their service life. The system is currently experiencing high headloss due to aging equipment and accumulated clogging. The current filter only serves the flow from the North Plant, and the flow from the South Plant does not receive filtration. The proposed filters will be divided into a North Plant Filter and a South Plant Filter. Each will serve flows from the North Plant and South Plant, respectively. The North and South plant filters will use cloth media disc filter technology. Together with other improvements, the system will achieve a design average flow of 26.25 MGD and a design maximum flow of 73.19 MGD, while also providing a 50/50 flow split between the two plants.