WCW24

Aquatera Utilities Inc.'s Wastewater Treatment Plant (WWTP) is a major facility providing wastewater treatment services to the Grande Prairie region, covering the City of Grande Prairie and surrounding communities. The current treatment process includes primary sedimentation, biological treatment with a modified Johannesburg process, and secondary clarification. The plant has equalization basins both upstream and downstream of the treatment plant, where Aquatera makes use of these basins to equalize flow prior to treatment, and downstream of the WWTP prior to discharge to the Wapiti River; this project component is critical as further outlined below. Based on regulatory drivers, the WWTP is to implement disinfection to meet an effluent quality of 100 CFU/100 mL fecal coliforms (monthly average) prior to discharge. The project goal includes the design and implementation of a new disinfection system with a treatment capacity of 65 MLD. The project is unique in that both final effluent from the secondary clarifier, as well as gravity discharge from Aquatera's final effluent lagoon, are to be used as the influent feed into the new UV disinfection facility. This provides Aquatera with flexibility in operation of their plant. Currently, the project is in the detailed design phase, with construction scheduled to begin in Fall 2024 and construction completion by August 2025. Stantec conducted a thorough review of various disinfection technologies and ultimately recommended utilizing open channel UV disinfection due to its lowest net present value and proven reliability with lower operational and maintenance requirements. Following the technology selection, Stantec collaborated with Aquatera to further assess potential locations and configurations at the existing WWTP site. Multiple hydraulic analyses were conducted to ensure the design address the limitations in the plant's pumping and conveyance system; this included maintaining flexibility in terms of diverting flow to and from the final effluent lagoon. Additionally, a life cycle cost analysis was provided to assist Aquatera in selecting an option aligned with their satisfaction. Stantec has recently finalized the preliminary design and is now working with Aquatera through the detailed design stages. This presentation will discuss the advantages and disadvantages of various disinfection options considered, the selection criteria for UV systems, design considerations for tie-in requirements, and the operational strategy for UV disinfection.