Hurricane Protection
- Non-Federal Levee Hurricane Protection System
Oakville to St. Jude in Plaquemine's Parish, Louisiana
the challengeThe project was located to the west of Hwy 23 in Plaquemines Parish, Louisiana, stretching from Oakville to St. Jude. The purpose of the project was to provide a concept level evaluation of alternative alignments that could be used to support the analysis for, and preparation of, a Supplemental Environmental Impact Statement (SEIS) and a Project Description Document (PDD). Preliminary Engineering and Design (PED) was accomplished for the alternative alignments and documented in an Engineering Alternatives Report (EAR), which described all the alternatives considered for a particular construction route that could assist in identifying the selected alternative. One of the guiding assumptions was to minimize impact to wetland areas by the alignments.
the interdisciplinary approachThe US Army Corps of Engineers, New Orleans District Hurricane Protection Office (USACE-HPO) contracted the Bioengineering Group to evaluate alternative levee alignments that would raise the existing levees to the federal system's design elevation level as part of the New Orleans to Venice Hurricane Protection Project as authorized by Public Law 190-234. The role of BioGroup was to ensure coordination between the engineering and environmental branches of the USACE-HPO. This was made possible through weekly meetings with project representatives from each branch to decide on the most important attributes of the project. Investigation of existing utilities and facilities was conducted to determine possible relocation requirements. Preliminary cost estimates for major work items and proposed levee alignment routes were developed to assist in the selection of the geotechnical designs. Three geotechnical solutions for the levees were evaluated for seven typical sections in order to select the most appropriate geotechnical alternative for the total 72 cross-sections. Concept ideas with plan layout and typical wall sections were created for the report. Structural quantities were developed based on the concept layouts and used as the basis for developing cost per one-foot of wall. Recommended pump station capacities were derived from the hydraulic analysis of both 2-year and 25-year storm events for each respective drainage area. Pump station construction costs were estimated from historical construction cost data.
the resultsSolicited information and volunteered commentary obtained by the The Bioengineering Group from the meetings with the representatives from USACE-HPO were used as guidance by the project team to accurately address all aspects of the various alternatives. Each individual set of levee alignment alternatives were laid out to: (1) be in compliance with the proposed typical levee cross-section, (2) utilize T-walls when ROW footprints increases prohibited earthen levee usage, (3) minimize impact to existing residential structures, commercial structures, or stormwater drainage canals, (4) minimize encroachment of construction activities to the marsh area outside the existing levee system and to wetland areas within the existing levee system, and (5) conserve accessibility to future flood side residential area or commercial communities by providing roadway ramps or swing gates.