The City of Sevierville owns, operates and maintains the McCroskey Island Wastewater Treatment Plant (McCroskey Island WWTP) which has design capacity to treat average daily flow of 4 million gallons per day (MGD). The liquids treatment train at the McCroskey Island WWTP currently includes headworks, secondary treatment including an Orbal oxidation ditch with two 80-foot diameter secondary clarifiers, and an effluent facility with chlorine contact basins. The biosolids treatment train currently includes two aerobic digesters, two gravity thickeners and a dewatering belt filter press. The final effluent from the plant is discharged into the French Broad River while the biosolids from the treatment processes is sent to landfill. Although influent flows at the plant have remained below 4 MGD since the plants’ Phase I expansion in the 1990s, the influent biochemical oxygen demand (BOD) and total Kjeldahl nitrogen (TKN) loads have exceeded the plant’s treatment capacity. As a result, the McCroskey Island WWTP is currently under construction for Phase II expansion which will expand the liquids train by adding a Carrousel oxidation ditch, two 120-ft secondary clarifiers, and a new ultraviolet (UV) disinfection system that will replace the existing chlorine disinfection. The solids train at the plant will be upgraded by improving the aeration in the existing aerobic digester and installation of two dewatering screw presses. While the Phase II expansion construction is ongoing, recent influent loads at the plant are already 80 percent of the Phase II design capacity, indicating the necessity for immediate planning towards the next expansion phase (Phase III). This study conducted alternatives evaluation for Phase III expansion for the McCroskey Island WWTP. The purpose of the study was to evaluate suitable liquids and biosolids treatment options and recommend an alternative that will reliably treat the anticipated wastewater strength at projected Phase III flows and loads and reduce reliance on landfills. A total of four treatment alternatives were identified and evaluated which included; - Option 1 (Expand in Kind) - Option 2 (Expand in Kind + Thermal Dryer) - Option 3 (Add Primaries, Anaerobic Digestion and Thermal Dryer) - Option 4 (Add Primaries, Anaerobic Digestion, Post-Aerobic Digestion and Thermal Dryer) For each of the alternatives, capital and annual operations and maintenance (O&M) costs were estimated. Life cycle costs were developed, and non-monetary criteria were also developed with the City to assess each option apart from cost. This presentation will show the results of the Alternative Analysis evaluation and the recommendation of one alternative for Phase III expansion at the McCroskey WWTP.