Parking lot inflow

FIGURE 8.1 Schematic layout of the Kingston Stormwater Detention pond.

This creek drains an urban catchment with a drainage area of about 4.5 km2. Since the construction of the pond, continued development in the catchment basin has increased the stream flow and hence reduced the effectiveness of the pond. Ongoing sedimentation in the pond has further exasperated the problem. To assess the effectiveness of the pond to trap sediment, a fine sediment transport study was initiated. As part of this study, deposited sediment from the pond and the pond water were collected and tested in a rotating circular flume to ascertain the sediment behavior under different boundary shear stress conditions (Krishnappan and Marsalek16). These experiments had indicated that the pond sediment underwent flocculation when subjected to a flow field, and consequently the settling behavior of the sediment differed significantly from that of the constituent primary particles.

Existing methods for analyzing suspended solids settling in stormwater ponds do not consider flocculation of the sediment, and treat the particles as discrete and noninteracting particles. Such an approach is not satisfactory, and hence there is a definite need for a model that would take into account the flocculation process of the stormwater sediment. To meet this need, Krishnappan and Marsalek15 formulated a flocculation and settling model for the Kingston pond sediment. The formulation of the model was based on their experimental study in the rotating flume for the sediment from the Kingston stormwater pond.

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