Ecodesign structures on the foreshores of the OosterscheldtIn May 2009, the Dutch Department of Public Works awarded Van Oord
Nederland a D&C contract for 'Foreshore Protection in the Oosterscheldt and
Westerscheldt'. To prevent progressive erosion of the flood defences in the two
estuaries, Public Works has deemed it necessary to protect the foreshores at
five different locations. The relevant locations in the Oosterscheldt have
special ecological value. Van Oord and Public Works have therefore joined forces
with delta technology institute Deltares and consulting marine researchers
GiMaRIS to design and construct an underwater ecological landscape on a scale
unparalleled in the world.
Tendering phase
Van Oord had already recognised the ecological value of the
Oosterscheldt locations during the tendering phase. It proposed optimising the
design according to 'Building with Nature' principles, leading to a sustainable
solution that combines dike protection with the creation of a new nature
conservation area. After discussing the project with various stakeholders,
Public Works recognised that the ecological value of the chosen locations could
not be ignored and that it was possible to arrive at a win-win solution.
Stakeholders
After the contract was awarded, Van Oord and Public Works investigated
the options for nature conservation within the project context. Public Works
called in Deltares and GiMaRIS to advise, and the two organisations ran a
workshop for a large group of stakeholders. The four partners used the
information that emerged from the workshop to produce a design that enriches
the unadorned technical foreshore plan, which had been approved and was already
under construction.
Special engineering process
The engineering process was highly innovative not only because of the
exceptional aim that had been identified, but also because of the way the
various parties interacted. Ecological specialists at Deltares and GiMaRIS
optimised the ecological aspect of the engineering design, while Van Oord kept
a close eye on the technical feasibility. Public Works looked at what could be
accomplished within the relevant contract and budgetary restrictions. Input
from all four partners therefore made it possible to optimise every aspect of
the design, from biology to costs and technical execution.
Building blocks
The partners' unique approach to enriching the foreshore involved
creating as many different habitats as possible. The engineering design called
for a variety of different materials, gradients and shapes to create
differences in height, hiding places, and variations in the exposure to and
shelter from the current. To ensure flexibility, the engineers came up with a
modular system of building blocks consisting of round, criss-crossed and
atoll-shaped piles of stones and linear elements, all in varying sizes.
Combining these building blocks made it possible to achieve more variety at a
larger scale. In the final landscape plan, the combined building blocks gave
rise to delineated spaces and areas that will gradually fill with silt
deposits. In future, adding extra alternative materials to these spaces will
turn them into valuable new habitats.
Execution
After Public Works had finalised the budget in January 2010,
construction of 43 building blocks at two locations could begin. Because Van
Oord had examined the feasibility of the plan closely in the engineering phase,
it was possible to construct the building blocks within just a few weeks, as
soon as the technical designs had been completed for both locations.
Monitoring
The building blocks already proved to be effective this past summer. Not
only did vegetation grow on the quarry stone within just a few months, but rare
species such as lumpfish, cuttlefish and seahorses have even been spotted, a
unique occurrence so soon after reinforcement work of this kind. To encourage
both professional and recreational divers to monitor the areas closely, a
diving route has been marked out through the landscape. Van Oord supplied
the high-visibility route markers.
Filling in the space
The partners are now considering how to give nature
another boost in the underwater landscape by filling in the open spaces of the
design with various natural materials. Van Oord, Deltares and GiMaRIS are
conducting the necessary research. Their work is being funded by the Coastline
Management Project. In week 50, a covering of natural materials will be
deposited in one of the smaller spaces. The materials will create a greater
variety of habitats for various organisms.
Please click here to see the ecodesign video
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