Design Guidelines and Mitigation Strategies for Reducing Sedimentation of Multi-Barrel Culverts, TPF-5(445), December 2024

(2024) Design Guidelines and Mitigation Strategies for Reducing Sedimentation of Multi-Barrel Culverts, TPF-5(445), December 2024. Transportation, Department of

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Abstract

The accumulation of sediments at culverts is a chronic operational issue, frequently occurring at multi-barrel culverts located in erosion-prone watersheds. Sediment deposits can develop rapidly, impairing the culvert’s capacity to convey design flows and potentially leading to damage to both transportation infrastructure (e.g., road and culvert overtopping) and upstream areas (e.g., flooding). Current culvert design protocols focus primarily on flood flow conveyance, with less attention given to assessing the potential for sedimentation due to the limited understanding of the complex erosion and transport processes leading to culvert sedimentation. Consequently, costly culvert cleaning is often required to maintain operational functionality. The overarching goal of this experimental study, funded by the Iowa, Mississippi, Missouri, New Mexico, and Utah Departments of Transportation (DOT), is to develop mitigation solutions for reducing or eliminating sediment accumulation at three-barrel culverts. The study builds on the experience garnered through pioneering research initiated by the Iowa DOT to substantially advance the understanding of complex flow and sediment transport through culverts located in various hydrological and geomorphological conditions. The proposed mitigation solutions are based on the Self-Cleaning-Culvert (SCC) concept, which relies on the stream’s hydraulic power to pass sediment carried by the stream through culverts. The laboratory study entails 180 stand-alone tests conducted in two flume arrangements: Iowa-Mississippi-Missouri (IMM) and New Mexico-Utah (NMU). The tested SCC designs demonstrated satisfactory sediment conveyance efficiency for the IMM culverts, with more than half of the designs increasing sediment conveyance capacity by 50 to 72%. However, the addition of the SCC at the NMU culvert entrance displayed reduced conveyance (less than 25%) due to changes in geometry that further hampered the structure’s capability to handle the much heavier sediment load carried by typical NMU flash floods compared to the extreme precipitation events occurring in the IMM landscape.