This paper focuses on water treatment plant design, specifically how innovative process andhydraulic design translates into real world conditions at operating facilities. Datapresented here compares original design values with field measurements and operationaldata. Treatment performance of the new facility is quantified and compared to theoriginal plant.The new 150-million-gallon-per-day (mgd) Scott Candler Water Treatment Plant(SCWTP), located in the Atlanta metropolitan area, is one of the largest and mostsophisticated facilities in the southeastern United States. The new plant replaced theoriginal 128-mgd conventional surface water treatment plant, first built in 1942 andexpanded eight times afterward.During planning and preliminary design, DeKalb County staff recognized the need foradditional treatment barriers and reduced disinfection byproduct (DBP) concentrations.To accomplish these goals, a combination of advanced treatment techniques and proventechnology were selected including high-rate sedimentation, ozonation, and deep-bedbiological filtration. The new facility was designed to achieve current and futureregulatory requirements, and to meet high standards for reliability and risk-basedredundancies.Since full scale production began in July 2007, the SCWTP has been meeting orexceeding treatment and process goals set during design phase. Settled water turbiditieshave been reduced. TOC removal within the treatment process has increased. DBPlevels in the distribution system have been reduced.In addition to notable process design for the new plant, the hydraulic design includesseveral unique features. The intermediate ozone facility includes six contactors, three oneither side of a central gallery, with each side having a tapered inlet channel to aid inflow distribution. The contactors are also equipped with an innovative design feature toturn inlet flow downward toward the ozone diffusers located at the bottom of the firstcell. Includes figures.
