Mixing in a Retention Pond: Small-and Full-Scaled Study Comparisons

A retention pond, crucial for managing stormwater runoff, temporarily regulates flooding by storing water and gradually releasing it through its outlet. Featuring an inlet-outlet system promoting natural mixing, it lacks documented procedures for optimizing inflow and outflow orientations to enhance this mixing. Addressing this gap, this study examines the impact of various inflow-outflow configurations on natural mixing within a small-scaled circular tank acting as a retention pond. Different combinations of inflows and outflows yield different Total Suspended Solids (TSS) outcomes. Results indicate that the setup with the lowest inflow and highest outflow levels achieves the most effective natural mixing, as evidenced by the TSS testing. The study was extended to a full-scaled experimental setup by adopting the position of the inlet and outlet of I1-O2. A tracer study was conducted for a full-scale pond. Hydraulic efficiency obtained was good with λ = 0.83, and no bypass was experienced in the system with short-circuiting value S = 0.32.