In this project, Flow Science performed hydraulic calculations related to the expansion and upgrading of Plants 1, 2, and 3 at the 91st Avenue Wastewater Treatment Plant.  The work included detailed hydraulic friction headloss determinations and the generation of water surface elevation profiles for the proposed modifications.  Flow Science was also instrumental in proposing innovative designs for the flow mixing needed for proper dechlorination, including the design of weir and diffuser structures. Flow Science aided in identifying the hydraulic bottlenecks within the plant and proposed the implementation of bypasses and overflow structures to prevent plant overflow.  The work also included the redesign of the chlorine contact basins to balance the need for lower headloss and higher T10  detention times.