NEW ORLEANS -- The U.S. Army Corps of Engineers has released a draft environmental assessment for the proposed Neptune Pass Rock Closure for a public review ending Aug 31, 2024.
The draft environmental assessment (EA), “Mississippi River, Baton Rouge to the Gulf of Mexico, Louisiana, Neptune Pass Rock Closure, Plaquemines Parish, Louisiana EA# 589 and draft Finding of No Significant Impact (FONSI)”, evaluates the potential impacts associated with constructing flow control structures in both Neptune Pass and Quarantine Bay.
The EA and FONIS evaluated alternatives to eliminate a navigational hazard in the Mississippi River at Neptune Pass, a natural crevasse which existed prior to 1985 but has increased in size and flow during recent annual high river events.
Additional design and modeling, as well as feedback from a September 2022 draft environmental assessment, informed a redesign of the recommended plan for the Neptune Pass flow control feature with the addition of flow control features in Quarantine Bay. The recommended plan of the current environmental assessment consists of two features that will work together to provide a sustainable solution to remove the navigation hazard – the inlet structure and the outlet structures.
The proposed inlet structure would consist of a stone sill, with a 100-foot-wide notch, that would reduce the outlet of the Mississippi River and the inlet of Neptune Pass to 7,200 square feet. While the outlet structures would consist of approximately 20 V-shaped Sediment Retention Enhancement Devices (SREDs), at the outlet of Neptune Pass in Quarantine Bay to help reduce the velocity of water coming through the stone sill. The SREDS are built with earthen material, as well as placement of geotextile fabric and stone riprap.
While unavoidable impacts would occur due to project actions within Neptune Pass and Quarantine Bay, the proposed action would not constitute a major federal action significantly affecting the human environment. Based on the draft assessment, a determination has been made that the proposed action would have no significant impact on the environment.
All comments received by the end of the public comment period will be considered in finalizing the Environmental Assessment. Comments received and Mississippi Valley Division, New Orleans District responses will be included in the final environmental assessment.
Comments should be mailed to the attention of:
U.S. Army Corps of Engineers, Regional Planning and Environment Division, South
New Orleans Environmental Branch, CEMVN PDS-R
7400 Leake Avenue, New Orleans, Louisiana 70118
Comments and questions may also be provided by email to: mvnenvironmental@usace.army.mil
An electronic copy of the report and its appendices are located on the CEMVN District web page at:
https://www.mvn.usace.army.mil/Missions/Environmental/NEPA-Compliance-Documents/Civil-Works-Projects/2024-Civil-Works/
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