Stormwater Capture Efficiency of Roadway Grate Inlet under Different Conditions

Abstract Submission: Urbanization, while driving economic development and the expansion of cities, also results in urban flooding, water pollution, and in some regions water shortages. The design of stormwater infrastructure plays a critical role for managing runoff volumes from roadways, addressing potential flooding issues, and mitigating damage to properties, transportation systems, and utility infrastructure. Additionally, the effectiveness of drainage inlets along roads is essential for efficiently directing runoff water away from road surfaces and into stormwater infrastructure. Although grate inlets are a common drainage facility, the systematic study of their hydraulic characteristics focusing on smaller water quality events has only recently received attention. This study explored the flow capture efficiency of roadway grate inlet, focusing on these smaller events which is important for the effective functioning of Stormwater Control Measures (SCMs) that have been previously overlooked. To achieve this, a physical model flume experiment was conducted to evaluate the capture efficiency of different construction geometries under various longitudinal and cross-sectional slopes. The experiment involved using a grate inlet, both with and without a drop in invert elevation, and varying the distance from the curb wall (ie., 2.5 inch and 6 inch) to assess its effectiveness. The grate inlet placement and slope combination (L1%C2%) are integral to achieve the maximum effective capture efficiency ranging between 60%-90% of runoff from highways at lower flows. The physical experiment is verified via computational model.
The research findings will be used to enhance roadway designs and optimize the construction of grate inlets, contributing to the scientific understanding of the hydrologic performance of the entire watershed.

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