Urban Flooding and the Trash Amendments
The California Statewide Trash Amendments require that Phase I MS4 Permittees initiate retrofit programs to eliminate Trash in discharges from MS4s through the implementation of Trash Control BMPs. In addition, development projects are also required to incorporate LID BMPs that provide the full retention of the 85th-percentile storm runoff. The presentation will assess how green infrastructure impacts compliance with the 100-year level of flood protection. Per Title 44 of the Code of Federal Regulations (CFR), the design of storm conveyance infrastructure must provide a 100-year, or 1-percent Annual Exceedance Probability (1% AEP), level of flood protection to all habitable structures. Limited literature data is available to quantify the impacts of implementing LID BMPs and Trash Control BMPs on the Base Flood Elevation (BFE). Based on the findings of a literature review, two separate case studies were developed to assess the hydraulic impacts of green infrastructure. The implementation of infiltration chambers in an interior drainage pond located in the City of Oxnard resulted in a slight increase of the pond volume (1.3%) due to the loss in hydrostatic pressures on the outlet flap gate. Typical MS4 maintenance of catch basins are performed once to twice every year, when catch basins are 25% to 50% full. A 2D hydraulic model for the western part of the City of Simi Valley showed that a blockage factor of 25% would result in an additional 33 parcels in a designated flood zone. The audience will learn proposed updates to the drainage and Trash Control BMP design guidelines to meet compliance with the local drainage criteria. A 3D flooding animation will be shared with the audience to highlight the impacts of Trash Control BMPs on local flooding.
Remi Candaele has more than 11 years of experience in storm water management. His domains of expertise include hydraulic and water quality modeling, statistical analyses, stream rehabilitation, hydromodification, sediment transport, and comprehensive watershed strategic plans. He is recognized for his technical expertise, responsiveness, leadership, and strategic initiatives. Mr. Candaele has prepared numerous publications and conference proceedings covering his wide range technical knowledge.