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Roseville Public Works, Environment and Transportation Commission Agenda Item DATE: May 28, 2024 ITEM: 5.a. ITEM DESCRIPTION: Trout Brook Interceptor Flood Analysis Background Capitol Region Watershed District (CRWD) originally developed a hydrologic and hydraulic model of the Trout Brook Interceptor (FBI) watershed as part of the Trout Brook Storm Sewer Interceptor Hydraulic Evaluation project in 2005. The model was subsequently revised and calibrated in 2012. Since 2012, CRWD has completed several model maintenance and revision projects including a major model update in 2018 to incorporate Atlas 14 precipitation data, update model hydrologic and hydraulic source data, and recalibrate the model. Prior to this study, TBI watershed modeling efforts were focused on evaluating watershed routing to, and storm water conveyance within, the TBI. For this reason, models developed through 2018 contain a high degree of detail and resolution along the TBI alignment, but a lower degree of resolution throughout the TBI watershed (i.e., large subwatershed divides to major storage features, simplified hydraulic routing assumptions, etc.). In addition to increasing the resolution of the existing XPSWMM model, major tasks associated with the Trout Brook Storm Sewer Interceptor Detailed XPSWMM and P8 Modeling Project are summarized below: • Increase the resolution of the existing XPSWMM model to the scale of intersections and individual storm sewer inlets. • Develop water quality P8 models spanning the TBI watershed, capturing all public and regional BM Ps. • Calibrate the XPSWMM and P8 models to monitoring data collected by CRWD. • Summarize model results and develop a flood prioritization area study to evaluate, score, and rank flood areas throughout the watershed. • Develop flood mitigation and water quality improvement feasibility studies for selected, high priority flood areas. The major goal of CRWD and its partners (Saint Paul, Roseville, Maplewood, Falcon Heights, Ramsey County, and MnDOT) is to develop highly detailed models and watershed planning tools which can serve as the foundation for future flood mitigation and water quality improvement efforts. This report provides detailed documentation of the major project tasks described above, and summarizes results based on the goals and objectives of the CRWD and its partners. Recommendation Receive the Trout Brook Interceptor Flood Analysis Presentation from Capitol Region Watershed District staff. Attachments None Page 37 of 115