As a subconsultant to URS Corporation, CIA evaluated the scum system for Dry Creek Wastewater Treatment Plant, one of three plants servicing Metro Nashville/Davidson County. The scum system consists of eight 16-inch-diameter rotating weir troughs feeding a common scum sump. The scum sump was frequently overloaded with floatables and inorganics. This caused an agglomerated mass at the sump that required physical removal with hand tools and a vacuum truck. To combat mass formation and eliminate the need for manual removal, CIA designed a retrofit chopper pump that will transfer scum to the scum screen. The design also called for a mix-flush system to be added to the sump to agitate the contents of the sump during pump operation.