St. Clair Wastewater Treatment Plant Rehabilitation

The St. Clair Sewer Authority Wastewater Treatment Plant (WWTP) serves four municipalities and has a design flow of 750,000 gallons per day. The WWTP was originally constructed in 1966 for primary treatment only and upgraded to secondary treatment in 1976. Since 1976, no major improvements had been made. The authority needed to provide a cost-effective solution to improve the WWTP in order to meet their permit requirements and keep user rates affordable.

The project included an Asset Management Plan for evaluating the existing facility, recommending improvements, designing improvements, securing all permits, providing contract and construction administration, and securing funding for the project.

This project involved the construction of a new headworks building equipped with an automated bar screen, a grit removal system, an emergency bypass and enhanced operational controls. The project also included the transformation of anaerobic sludge digesters into aerobic digesters and the construction of a new sludge handling facility, which housed a sludge rotary press. The existing chlorine disinfection system was replaced with a new ultraviolet light disinfection system, a Stamford baffle system was installed in secondary clarifiers and the old controls were upgraded to a new Supervisory Control and Data Acquisition (SCADA) system with remote access capabilities.

These upgrades resulted in all permit limit requirements being met, and the plant is now capable of handling increased flows during wet weather events. Additionally, the implementation of the SCADA system has significantly enhanced the operators’ ability to improve WWTP performance. The project also resulted in a reduction of sludge disposal costs by approximately $50,000 per year and a notable decrease in maintenance costs, further underlining the success and efficiency of the improvements made to the St. Clair Sewer Authority WWTP.