Golden Triangle Marsh Creation

The Golden Triangle Marsh Creation Project (PO-163) was a key project identified by MSMM staff when providing water resources planning for the MRGO Ecosystem Restoration Plan at the USACE New Orleans District. MSMM staff developed the conceptual project as a means to provide natural ecosystem restoration in front of the IHNC Surge Barrier, under the Multiple Lines of Defense strategy for hurricane risk reduction. While the MRGO plan failed to move forward because of the lack of a willing non-Federal sponsor, the Golden Triangle element was brought back as a stand-alone element when the New Orleans District was competing for RESTORE Act funding. Based on having prior knowledge of the project, MSMM was chosen to provide engineering design services for this project.

The Golden Triangle marshes chosen for restoration are a highly fragmented intermediate to brackish marsh system that has crisscrossing pipeline corridors and multiple internal and lateral bayous. Upon receiving the job, MRGO staff started the process of field investigations by completing the following: side scan-sonar data identifying hard bottom substrate within Lake Borgne to provide available borrow sites, followed by soil borings at the restoration site and borrow pit location, as well as survey data and bathymetry data.

Once field investigations were completed, MRGO started the process of identifying potential design acreage amounts, identifying bayous to be left open for traversing the site, and identifying areas of interest for recreational activities like fishing and hunting. Meeting with multiple user groups was key as all had a distinct interests/needs for the site, and the overall restoration goal of the project needed to be maintained. The restoration goal of the project was to restore and nourish approximately 4,000 acres of marsh.  Design features consisted of perimeter dikes, vinyl sheet closure pile structures, and internal weirs.

Through a collaborative design process with the engineering branch staff at MVN, the NGO community advocating for restoration of this site, the recreational user groups and the oil and gas companies that rely on this site, MSMM was able to identify the site configuration above as best meeting the design goals of the project. To date the project has not been constructed by USACE, but is being constructed under the RESTORE ACT program, for the Coastal Protection and Restoration Authority of Louisiana.