Effects of Organic Matter on Settling Characteristics of Fine Grained Coastal Sediments Used in Marsh Creation Projects: Fid-Bau Portal

Effects of Organic Matter on Settling Characteristics of Fine Grained Coastal Sediments Used in Marsh Creation Projects

Ghose-Hajra, Malay / Roberts, Brittany M.

Sediments of coastal Louisiana contains silt clay alluvial deposits mixed with varying percentages of organic matter which are very compressible and erodible in nature. Coastal property development, sea level rise, geologic subsidence, loss of barrier islands, increasing number and intensity of coastal storms, and other factors have resulted in water quality degradation, wetlands loss, reduced storm and surge protection, ground settlement, and other challenges in coastal areas throughout the world including Louisiana. One of the goals towards re-establishing a healthy coastal ecosystem is to rebuild wetlands with river diversion or sediment conveyance projects that optimally manage and allocate sediments and positively affect the water quality. Engineering properties and material characteristics of the dredged material are input parameters in several mathematical models used to predict the long-term behaviour of the dredged material and foundation soil. Proper characterization of the dredged material and their settling properties is of utmost importance in the effective design of a coastal restoration and land reclamation project. This paper presents the results of several laboratory tests performed on coastal sediments containing varying percentages of organic content obtained from southeast Louisiana. The effects of organic matter on the settling characteristics of the dredged sediments used in coastal Louisiana marsh creation projects are discussed in this paper. A lower organic content generated higher settling characteristics for coastal sediments. The zone settling velocity was lower for dredged slurry with higher percentages of organic matter.