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Title: West Shore Lake Pontchartrain Hurricane and Storm Damage Risk Reduction Study: Final Integrated Feasbility Report and Environmental Impact Statement
Authors: United States. Army. Corps of Engineers. Mississippi Valley Division.
Keywords: Pontchartrain, Lake (La.)
Flood control
Environmental management
Publisher: United States. Army. Corps of Engineers. New Orleans District.
Abstract: The West Shore Lake Pontchartrain (WSLP) Hurricane and Storm Damage Risk Reduction project proposed by the U.S. Army Corps of Engineers, Mississippi Valley Division, New Orleans District, will provide risk reduction measures to address tropical/hurricane storm surge events in St. Charles, St. John the Baptist and St. James Parishes in southeast Louisiana. Impacts from the National Economic Development (NED) plan are described in this Final Environmental Impact Statement. WSLP communities are at increasing risk to storm surge flooding due to wetland loss and relative sea level rise. The project purpose is to reduce the risk of flood damages caused by hurricane and tropical storm surges. An overview of the entire risk reduction system is shown on Figure 5-1. The Recommended Plan is Alternative C, which includes an 18.27-mile levee around Montz, Laplace, Reserve and Garyville, reducing risk to over 7,000 structures. The construction of the levee system in St. Charles and St. John the Baptist Parishes would be based on a 1% probability storm level of risk reduction (commonly known as a ‘100-year storm’) and a 2020 intermediate sea level rise condition and would include future lifts to maintain that protection. The recommended plan also includes the construction of localized storm surge risk reduction measures in St. James Parish which includes berms and flapgates on existing drainage and roadway features in the communities of Gramercy, Lutcher and Grand Point which are located outside of the proposed levee system. The Recommended Plan also includes raising 14 residential structures; flood proofing 4 non-residential structures to +3.0 feet above the ground elevation; and constructing 5 smaller berms for 5 light industrial/warehouse facilities. All localized storm surge risk reduction measures will provide a level of risk reduction above a 1% probability storm level of risk reduction storm stage in 2020. Future lifts for the berms, to compensate for any relative sea level rise, are not included as part of this plan. The sponsor is responsible for the operation, maintenance, repair, rehabilitation and replacement (OMRR&R) of the berms at the elevation for which the berms were designed and constructed. That OMRR&R may require lifts to address subsidence or settlement. In the future, the effectiveness of the localized storm surge risk reduction measures would depend on the actual rate of relative sea level rise. There is a potential for direct, indirect and cumulative impacts to wetlands, wildlife, fisheries, and water quality due to the implementation of the recommended plan. Habitat impacts that require compensation include 1,090 Average Annual Habitat Units (AAHUs) of swamp habitat and 99 AAHUs of bottomland hardwood (BLH) habitat. To compensate for these impacts, the mitigation plan includes restoration of 3,002 acres of swamp, 156 acres of BLH and the purchase of 72 AAHUs of swamp mitigation bank credits (details can be found in Appendix A, Annex K). Mitigation would be constructed in St. Charles, St. James, Ascension, and Livingston Parishes.
Description: Integrated Feasibility Report and Environmental Impact Statement
Rights: Approved for Public Release; Distribution is Unlimited
Size: 147 pages / 2.432 Mb
Types of Materials: PDF/A
Appears in Collections:Environmental Documents

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