Hurricane Protection
- Plaquemine's Parish – Five Floodwalls
New Orleans, Louisiana
the challengePlaquemines Parish is the southeastern-most Parish in Louisiana, running southeast of the city of New Orleans. The Plaquemines Parish Hurricane Protection System includes the levee and floodwalls along the Mississippi River, the hurricane levees and floodwalls along the bayous adjacent to the Gulf of Mexico, and the associated pumping stations along both alignments. The purpose of the project was to analyze and provide engineering and design of existing I-Walls, T-Walls, and preparation of alternative design report for the Flood Protection Projects at Point Michel (PFW-1), Childress (PFW-2), Venice (PFW-3), the Duvic Pumping Station (PPS-4), and Grand Liard Pumping Station (PPS-5) in Plaquemine’s Parish, LA. All of these locations are being referred to as part of NOV 15. The Bioengineering Group was contracted by the US Army Corps of Engineers, New Orleans District (USACE) to analyze the surrounding floodwalls at designated pumping stations and the floodwalls at specific Mississippi River locations in Plaquemines Parish.
the interdisciplinary approachThe project provided USACE with 35 percent engineering and design services to enable the selection of the best design solution. The baseline used in the report was created from survey data provided by USACE. A reconnaissance was performed by the Bioengineering Group team to become familiar with the existing structures and levees and identify any potential issues that may affect the analysis and/or design alternatives. The data collected and provided was used for geotechnical, civil, and structural analysis. Floodwalls at the Duvic and Grand Laird Pumping Stations needed to be raised to a protection level of elevation (EL) 15.5 North American Vertical Datum of 1988 (NAVD 88). The Bioengineering Group was required to develop several alternatives for replacing the existing I-Walls and T-Walls at the five locations within the NOV15 area. Three alternatives were evaluated at the pump station locations and two alternatives were evaluated for the Mississippi River Levee floodwall locations. Additionally, a potential third alternative was recommended for the floodwall locations, but analysis and developing costs were not provided.
the results Based on the analysis, design, estimated construction costs and anticipated ROW impacts, alternatives were recommended for PPS-4, 5: modify the existing T-walls and replace the adjacent I-Walls with new T-Walls; PFW-1: remove the existing I-Wall and construct a new earthen levee section to raise the height of the protection to the authorized grade; and PFW-2, 3: an additional alternative needs to be evaluated due to the significant impacts to the adjacent community required from the proposed earthen levee section. The information from the project made it possible for USACE to make a sound decision on a path forward to develop final designs and produce plans and specifications for the preferred alternatives.