Bayou Segnette Waterway Dredged Material Placement Study Preliminary Assessment: Summary of Findings and Recommendations

Abstract : The Bayou Segnette Waterway (BSWW) has a history of shallowness due to shoaling and consequently requires periodic dredging to maintain its navigability. However, traditional dredged material placement sites along the BSWW are either at or near capacity. Therefore, this study set out to identify viable options for future maintenance dredging and recommend innovative methods of transport and placement of material dredged from the BSWW. The approach of this study was to characterize existing conditions of the waterway and nearby landscapes, as well as to inventory dredge history information (past and future volumetric estimates of the channel and placement area capacities). The landscape analyses performed as part of this study consist of land change, habitat, and elevation assessments. The majority of the landscape surrounding the BSWW is highly stable, but does contain viable shallow-water areas for beneficial use applications. The BSWW area consists of comparatively healthy attached and floating fresh marsh. Floating landscapes provide opportunities for applying relatively novel dredged material placement applications, especially in areas where placement capacities are limited. Additionally, the BSWW area consists of elevations that are lower than those ideal for fresh and intermediate marshes. Adding sediment to floating and attached marshes within the BSWW project area could potentially provide elevation and nutrient benefits to those areas. The BSWW area has adequate placement capacity for the volume of material to be dredged, assuming thin-layer placement on floating marsh is a viable placement option, and estimated capacities at identified wetland sites are reasonable.