Investigation of the Sediment Removal Frequency for Wet-Detention Stormwater Management Ponds

The purpose of this study was to develop methodologies for determining the appropriate sediment removal frequency of wet-detention stormwater management facilities. Using data from a wet pond in the Town of Richmond Hill, a sediment accumulation model was developed using the US EPA’s Stormwater Management Model (Version 5). Two different methodologies were then developed and applied to the facility. The first methodology is a real-time tool that provides the required time for sediment removal for a single cleanout cycle. The second methodology is analysis tool that relates cleanout frequency, annual cost and violations over a 50-year planning period. The results showed that the appropriate sediment removal frequency for the pond was approximately 16 to 17 years, and the annual cost of sediment removal ranged from $2,150 to $2,372, depending on the methodology used. It is recommended that these methodologies be considered for the planning and operation phases of stormwater ponds.