Gaillard Island Bio-degradable Geotube Test Project, Mobile Bay, Alabama

PURPOSE This Coastal and Hydraulics Engineering Technical Note CHETN describes the use of a natural bio-degradable fabric for dredged material containment in a shallow water test at a demonstration project at the Gaillard Island dredged material placement area in Mobile Bay, AL. The primary purpose of the project was to test the physical limits and constructability of natural bio-degradable materials in the form of geotextile tubes geotubes, turbidity curtains, and cross dikes. Bio-degradable materials were selected for the project to avoid the use of petroleum-based synthetics and issues associated with the long-term degradation of synthetics in the environment. Bio-degradable structures have been shown to be more hospitable to re-vegetation by deep-rooted plants and may provide a feasible construction alternative in regions that do not allow either synthetic or hard structures on dunes and coastal shorelines. Geotubes, anti-scour aprons, spur dikes, and turbidity curtains incorporated into the project were constructed with bio-degradable products. The performance of these materials was evaluated as part of the overall project. Information and data contained in project reports, including material selection, construction, and monitoring, are summarized herein.