Improving Hydraulic Performance of Sediment Retention Ponds

This study addresses the effect of different inlet and outlet configurations and the influence of baffles on the hydraulic performance of a model pond. The physical model is a trapezoidal pond with top dimensions of 4.1 × 1.6 m × 0.3 m deep and side and end slopes of 2:1.Three perforated T-bars were fixed to an outlet riser to simulate a floating decant dewatering system. Solid and partial-width baffles were also investigated for their influence on the hydraulic efficiency of the system. Compared with the conventional point inlet and outlet system, the results herein showed that distributing the inflow over the entire width of the pond could successfully improve the hydraulic efficiency, albeit with short circuiting along the sloping side walls. Monitoring the dye aided recognition of preferential flow paths which were subsequently removed by modifying the inlet. On the other hand, the outlet span was adjusted to boost the residence times. Hydraulic efficiencies of about 0.50 compared with 0.18 for the conventional system, illustrated the effectiveness of these configurations. Furthermore, both types of the tested baffles significantly lifted the hydraulic performance giving the highest hydraulic indices of all the tested cases.