Beneficial on-site reuse of dredged harbor mud: A geotechnical challenge in alternative sediment management

Sediment accumulation in waterways, estuaries and harbors results in expenditures of more than 1 billion Euros annually in Europe alone. These costs are mainly due to dredging for maintenance of navigable water depth and subsequent relocation, transport, treatment and/or disposal of the dredged material. Of special concern is the treatment of sediments dredged from harbors. A pilot study to use dredged harbor mud as backfill material was conducted in the East Harbor of Bremerhaven, Germany between 2005 and 2007. During this project, a total of about 180,000 m3 of harbor mud was relocated by pumping behind a newly installed sheet piling, creating 14 acres of new harbor area. The subsequent occurrence of strong surface deformation of the backfill, indicating a partial collapse of the mud layer, highlights the need to better understand the geotechnical properties of harbor mud. The purpose of this work is to gain a better understanding of the usability of harbor mud as backfill material and therefore help improve the planning reliability in using dredged harbor sediments in future land reclamation projects.