Coastal, River, & Wetland Restoration
- Jefferson Parish Sector Gate South – Engineering Alternatives Report
Jefferson, Orleans, & Plaquemine's Parish, Louisiana
the challengeThe Bioengineering Group was contracted by the US Army Corps of Engineers, Hurricane Protection Office (USACE-HPO) to perform all professional services required for the preparation of a Detailed Alternative Study Report. The location of the work is on the west bank of the Mississippi River in the Parishes of Jefferson, Orleans, and Plaquemines. The area impacts components of three subprojects: Westwego to Harvey, West of Algiers Canal, and East of Algiers Canal. Designs for all three alternatives shall terminate at the same point – south of the confluence of the Algiers and Harvey Canals on the Gulf Intracoastal Waterway (GIWW). The project includes preparing designs for all alternatives, development of data for environmental assessments, surveying and mapping, rights-of-way, identification of utilities and facilities proposed for relocation, geotechnical designs, probable construction methodologies and duration, detailed cost estimates, identification of operations and maintenance requirements and costs, submittal of design documents for review, resolution of review comments and coordination with all applicable local, state and federal authorities.
the interdisciplinary approachThree alternatives were analyzed. The first, a Parallel Protection system, which includes construction of a system of levees and floodwalls along the existing project alignments. The second, a GIWW Gate, which involves construction of a sector gate structure and pump station adjacent to the existing GIWW, south of the confluence of Algiers and Harvey Canals. The third, a floodwall-sluice gate system traversing an environmentally sensitive 404(c) area to tie from the Westwego to Harvey levee system, tying into the existing East of Algiers Canal levee system. This is a system of parallel protection to provide a retention basin on the protected side of the new structure. At Algiers Gate it will include all requisite tie-ins to the existing levee/floodwall alignments and the levees along the Harvey Canal. It will also extend from the proposed Algiers Gate location to the southern project limit on the flood side of the new structures. This system will provide parallel protection through a retention basin on the protected side of the Algiers Gate.
the resultsThis project provides 100-year protection to the Westwego to Harvey, West of Algiers Canal, and East of Algiers Canal project area Sector Gates and Pump Stations. It includes the design and development of conceptual construction sequencing of: (1) one sector gate closure structure; (2) re-aligned GIWW channel; (3) two pump stations, one of which will be located near the existing GIWW channel and the second adjacent to Algiers Lock with the pump station assumed to utilize 1250 cfs horizontal pumps; (4) temporary cofferdams/ dewatering systems, as required (developed through innovative construction procedures that would reduce time, cost and disruption to navigation); (5) flow separator; and (6) a flow control structure adjacent to the sector gate that will maintain velocities through the gate opening during non-hurricane rainfall events that will meet safety requirements and thus avoid the need for pump station operation.