Sediment Capture Efficiency of Roadway Grate Inlets: Physical and Computational based modeling

Abstract Submission: Roadway inlets play a significant role in routing stormwater, laden with sediment and pollutants, off roads, but also are at risk of sediment buildup and clogging, impeding their function over time and requiring costly maintenance. Understanding the capture efficiency of grate inlets is imperative to ensure stormwater infrastructure performance. This research employs physical and computational-based modeling to explore the flow and sediment capture efficiency, as well as the bypass of the roadway grate inlet. Fifty-two modeling cases, derived from a combination of five flow rates, two cross-sectional slopes, two longitudinal slopes, and a constant sediment load were tested across three design scenarios, varying the proximity of a roadside curb wall to the inlet. Sediment samples were collected and analyzed below the grate and at the bypass. Results showed that the sediment capture efficiency of the grate inlet is controlled by the slope and flow magnitudes. Longitudinal slope was found to be the most influential factor for grate inlet sediment capture. As the flow increases, coarser sediment particles dominate the sediment load of the captured sediment, resulting in a shift in the particle size distribution of the sediments being routed to the inlet. Additionally, a slight drop in elevation of the grate inlet increased the sediment mass capture by an average of 45 to 64% compared to a roadway flush with the inlet. The results of this research offer guidance for the design and management of stormwater systems, which could aid in optimizing maintenance plans and facilitate design at the city scale.

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