The Laurel Ridge Levee Extension Project extended the Laurel Ridge Levee to protect an additional approximately 8,500 structures along / within the Amite River floodplain from backwater flooding and high waters. The Laurel Ridge Levee Extension is approximately 4.5 miles long and is constructed to an elevation of 13 to 17 feet. This project maintains the utilization of existing wetlands through seven outfall structures, which minimizes environmental impacts and eliminates the need for pump stations.
A large portion of the protected side of the levee outfalls into the Amite River. Therefore, conveyance was vital to ensure that no adverse impacts were created through
obstruction of the existing drainage system. The levee’s alignment transcends an existing swampland and utilizes existing grades and drainage patterns to passively drain the protected side of the levee through the structures.
The design of this project required delineating existing drainage areas within the protection of the levee. This was necessary to size the structures appropriately and to
determine the appropriate locations to maintain the conveyance of the system. Three alternatives were evaluated during the preliminary phase of the project,
two of which contained pump stations. Through innovative engineering efforts, the selected alignment not only greatly reduced construction cost by eliminating the need for pump stations and providing a shorter route, but also greatly reduced routine operation and maintenance costs incurred on the Parish.
The construction required approximately 450,000 cubic yards of fill (net section). The levee was designed to meet FEMA certification, which will reduce flood stages by several feet and remove thousands of properties from a flood-zone designation, thereby reducing insurance premiums for residents.
Services included alternatives development and assessment, data collection, hydrology and hydraulic modeling and analysis, structure impact analysis, USACE and DNR permitting, preliminary and final design, management of subconsultants, and public meetings and outreach.
*This project was completed by GSA Consulting Engineers prior to joining McKim & Creed in July 2021.