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https://hdl.handle.net/11681/36054| Title: | Final Individual Environmental Report Supplemental, Improved Protection on the Inner Harbor Navigation Canal, Orleans and St. Bernard Parishes, IERS #11.c - Tier 2 Borgne - INHC |
| Authors: | United States. Army. Corps of Engineers. New Orleans District. |
| Keywords: | Pontchartrain, Lake (La.) Flood control Hurricanes Environmental management Inner Harbor Navigation Canal (La.) |
| Publisher: | United States. Army. Corps of Engineers. New Orleans District. |
| Abstract: | The U.S. Army Corps of Engineers, Mississippi Valley Division, New Orleans District, has prepared this Individual Environmental Report Supplemental #11.c Tier 2 Borgne (IERS #11.c) to evaluate the potential impacts associated with proposed project revisions to the original IER #11 Tier 2 Borgne. On October 21, 2008, the District Commander signed the Decision Record for IER #11 Tier 2 Borgne. On December 10, 2009, the District Commander signed the Decision Record for IERS #11a Tier 2 Borgne. On November 29, 2010, the District Commander signed the Decision Record for IERS #11.b Tier 2 Borgne. IER #11 Tier 2 Borgne, IERS #11.a Tier 2 Borgne, and IERS #11.b Tier 2 Borgne documents are hereby incorporated by reference into this supplemental document. Copies of the documents and other supporting information are available upon request or at www.nolaenvironmental.gov. This supplemental document has been prepared to address proposed changes in the Government’s approved plan. The project approved in IER 11 Tier 2 Borgne consisted of constructing two miles of a new floodwall/gated system, to an elevation of approximately 24 to 26 feet (ft) North American Vertical Datum, from the Michoud floodwall north of the Gulf Intracoastal Waterway and extending to the new floodwall on the west side of the MRGO. The floodwall/gated system would cross the GIWW, Bayou Bienvenue, the Mississippi River-Gulf Outlet, and the Golden Triangle Marsh. As described in IER 11 Tier 2 Borgne, to construct the floodwall, a 350 ft wide channel was dredged through the marsh. The floodwall was constructed within this dredged channel, and the remaining excavated area was developed into a 250 ft access channel on the flood side of the structural wall for use during construction and after construction for maintenance purposes and a 96 ft plunge pool on the protected side of the structural wall to absorb impact from overtopping. Near the end of construction, shoreline protection was to be provided on both banks along the entire length of the access channel. IER 11 Tier 2 Borgne stated that the shoreline protection would consist of riprap, concrete slope paving, geotextiles, or other means. The protection would extend approximately 30 ft into the channel bottom and 5 feet onto the channel bank. Additionally, the scour pad on the protected side of this channel would provide shoreline protection as well. During a survey of the construction access channel for the Borgne barrier, it was observed that in some areas the bankline has eroded past the right-of-way (ROW) disclosed in IER #11 Tier 2 Borgne. In order to inhibit further erosion and to account for current erosion, CEMVN is accelerating the design and construction of the shoreline protection measures generally described in IER #11 Tier 2 Borgne. |
| Description: | Individual Environmental Report Supplemental |
| Rights: | Approved for Public Release; Distribution is Unlimited |
| URI: | https://hdl.handle.net/11681/36054 |
| Size: | 56 pages / 4.88 MB |
| Types of Materials: | PDF/A |
| Appears in Collections: | Environmental Documents |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| IERS 11.c Tier 2 Borgne Final Document.pdf | 4.88 MB | Adobe PDF |  View/Open |