Application of Long Distance Conveyance (LDC) of Dredged Sediments to Louisiana Coastal Restoration

Restoration of Louisiana's marshes and other coastal habitats will, in many cases, require dredged sediments to provide suitable substrate. Potential restoration sites are often at great distances from the sediment source. It will require special efforts, commonly referred to as long distance conveyance (LDC), to pump sediment to the sites. For the purposes of this report, LDC projects are defined as those Louisiana coastal restoration projects that involve hydraulic transport of slurry (mixture of sediment and water) through pipeline distances of 16 km (10 miles) or greater. Pumping slurry through a long pipeline is a mature technology for bulk transport that has been used efficiently in specific applications like coal and iron ore transport. At the workshop entitled "Long-Distance Pipeline Transport of Dredged Material to Restore Coastal Wetlands of Louisiana," the consensus of panelists and the audience (that consisted of national and international experts in the field of long-distance transport of dredged sediment and other materials by pipeline) was that there were no fundamental technological challenges to the delivery of sediment via LDC (Hales et al. 2003). The engineering challenges will be to optimize LDC design, operation, and maintenance to achieve respective strategic restoration goals in the most efficient, cost-effective, and environmentally acceptable manner possible. Technical literature was reviewed and interviews with personnel involved in LDC-related projects conducted to summarize state-of-practice LDC dredging project information. Dredging and transport methodologies in relation to LDC state-of- practice are presented, and potential environmental impacts of long distance pipeline transport across wetlands are discussed. Scientific and engineering uncertainties related to LDC optimization of dredged sediment for coastal restoration are identified.