Dredged Materials in Dike Construction

The use of dredged materials in dike construction is a new promising method to use it in a sustainable way. According to the German waste management law (KrW-/AbfG) there is an urgent need to recycle the material and to use it in a sustainable way. Several million m3 of dredged materials accrue every year in the coastal areas of the North and Baltic Sea. A part of the dredged material is deposited directly on spoil fields on land.

Dredged Materials in Dike Construction – Dike Core

Sandy dredged material, usually sea sand, is widely used in sea dike construction as core material. The investigations in the project DredgDikes include also cross-sections with a pure sand core of sea sand or sandy dredged material. However,the pure sand is not in the focus of investigations.

Dredged Materials in Dike Construction – Surface Layer

Due to the decreasing regional incidence of marl, which is commonly used as dike construction material in the Baltic Sea Region, the replacement by fine-grained dredged sediments is aspired for ecologic and economic reasons.  On the coast of Mecklenburg – West Pomerania the dredged material is mostly unpolluted and can therefore be used in dike constructions without hesitation. In the project DredgDikes the following questions on the use of dredged materials will be clarified:

  • Overall stability
  • Cracking
  • Erosion stability
  • Turf development

Projects relevant to Dredged Materials in Dike Construction

In following projects fine-grained dredged material (silt) has already been used as dike construction material:

Spoil Field „Drigge“ Island Rügen

By order of the Water and Shipping Authority (WSA) Stralsund, a test dike of 100 m length has been built on the spoil field Drigge (Rügen) in the fall of 2008 in cooperation with the Chair of Environmental Geotechnics and Landscape Construction of the University of Rostock. Since then the soil mechanical parameters of the four test dike sections have been under investigation. In addition to the WSA and the University of Rostock the company Baugrund Stralsund and the Federal Waterways Engineering and Research Institute (BAW) are involved in the project.

Norddeich CT 4, Bremerhaven

As part of the expansion of a container terminal in Bremerhaven a dike of 900 m length has been built to protect the terminal area. The original planned sand core was replaced by dredged material from Bremerhaven and covered with clay. The dredged material origins from the spoil field west of the Lune. In the end of 2005 approximately 35.000 m3 of dewatered dredged material were used in the first section of the northern dike (approx. 300 m) (Source: HTG Fachbericht: Verwertung von feinkörnigem Baggergut im Bereich der deutschen Küste; 2006).

Further Projects:

  • Drewer Hauptdeich, Hamburg
  • Maadedeich, Landkreis Friesland
  • Rodewischhafen, Hamburg

On the page Links you will find more information to various projects.