New Orleans Landbridge Shoreline Stabilization and Marsh Creation Project
The goal of the New Orleans Landbridge Shoreline Stabilization and Marsh Creation project is to restore and reinforce marsh habitat along the eastern shore of Lake Pontchartrain and along the northern and western shores of Lake Saint Catherine. Borrow material will be dredged from areas within Lake St. Catherine and Lake Pontchartrain to create 169 acres and nourish 109 acres of brackish marsh. Containment dikes will be constructed around four marsh creation areas to hold sediments during dredging. Bank lines will also be reinforced by creating or extending earthen berms to increase protection from waves. After constructing the marsh areas, vegetative plantings are planned for the marsh areas and shoreline protection berms.
S&ME’s field exploration program included drilling and soil sampling at 8 locations in the marsh creation areas with depths varying from 30 to 50 feet below existing mudline, and at 7 locations in the proposed borrow areas to a depth of 20 feet below existing mudline. Borings were performed by SER under the supervision of an S&ME engineer from a drill rig mounted on an amphibious tracked platform. In addition to the soil borings, S&ME completed CPT soundings at 20 locations in the marsh creation areas using S&ME’s VERTEK CPT cone pushed using GeoProbe direct push equipment and data collection software. S&ME worked to complete laboratory testing for the project and performed thorough QA/QC of the laboratory testing results. S&ME performed an independent low-stress consolidation test at our own expense in conjunction with the QA/QC process.
Laboratory testing for the project included moisture content determination, unit weight determination, Atterberg limits, triaxial testing, gradation, consolidation, organic content, specific gravity, and settling column testing.
Geotechnical analyses for this project included a geological desktop study; slope stability analysis for the earthen containment dikes and rock breakwaters; bearing capacity analyses for the ECDs and rock breakwaters; settlement analyses for the ECDs, rock breakwaters, and the marsh subgrade; and marsh fill analyses.