The Central Johnston County Regional Wastewater Facilities (Permits NC0030716 and WQCS00060) collect and treat wastewater from the towns of Smithfield, Selma, Four Oaks, Wilson’s Mills, Pine Level, and Clayton. County facilities also extend to and serve the East Clayton Industrial Park, the Cleveland community, NC 42 area east of the Neuse River, and the McGee’s Crossroads area.

The County operates and maintains a system of sewer line interceptors that extend through Smithfield to Selma. Wastewater from Pine Level is pumped into this interceptor. Wastewater from Four Oaks is transferred to the treatment facility through a series of force mains and interceptors involving three (3) pumping stations or can be directly pumped to Benson. Each town is responsible for operating its own collection system. Wastewater from the others areas identified above is pumped to the County’s treatment facility or the Town of Clayton wastewater treatment facility.

The treatment plant (NPDES Permit # NC0030716) is located south of Smithfield. The plant is a tertiary facility permitted to treat and discharge 9.5 million gallons per day to the Neuse River. The plant treatment works consist of primary screening, activated sludge with biological nutrient removal, secondary clarification, denitrification filtration, and ultraviolet light disinfection. Additionally, the plant stabilizes and dewaters biological sludge for disposal in the County’s lined landfill facility.

The County also treats process water (NPDES Permit # NC0084735) from the County’s Timothy G. Broome Water Treatment Plant in Wilson’s Mills. This facility consists of surge decanting tanks, solids thickener, and fine solids polishing basins with the effluent dechlorinated prior to discharge to the Neuse River. These processes are located on the water plant site.