Repair and maintain
Legakkers are long, narrow strips of land on which, in earlier times, harvested peat was laid to dry for the peat trade. The effects of the weather have caused many legakkers to disappear under water. Unfortunately this erosion process has not stopped. Consequently, the historical landscape structure and recreational functions will be affected. Van Aalsburg B.V has therefore developed a technique to restore and maintain legakkers and reed beds, and with success!
Trial project Loosdrechtse Plassen
Legakkers can still be found in the Nieuwkoop and Loosdrecht lakes, which is where we realised a large trial project. The new legakkers or reed beds are built using fascine mattresses. A fascine mattress is a framework made from willow, which is usually 30 centimetre thick, but in this specific case no less than 3 metres.
Fresh bundles of willow (faggots) were used for the bottom part of the construction, because they are heavier. Dry faggots were used for the upper part. The fascine mattresses were stacked so that they overlapped each other and then tied together to form a continuous and unbroken ‘piece of land’. The construction was built on a pontoon and, after completion, was sunk to the bottom of the lake.
Rocks were then dumped onto it and peat sludge collected by our dredgers in the vicinity was used as a filling. The sludge deposited on top of the construction was first allowed to drain in hopper barges. Corn fabric was placed on the sides of the ‘piece of land’ to prevent the run-off of peat sludge. Finally, the new embankments were planted with reed cuttings and a strip of grass was sown in the middle.
Our technique is new, innovative and patented. The advantages of the technique are:
- Water managers can combine dredging tasks with the realisation of policy objectives, landscape development and recreational objectives
- Sludge released from dredging projects can be used in the area with very limited transport (and therefore hardly any CO2 emissions).
- There is no need for dredging depots.
- Only natural materials (willow, sisal rope, corn fabric) are used in the processing of sludge. Plastics (Geotubes) are not used.
Our technique enables various applications. This could include:
- The creation of new legakkers or islands in shallow lakes.
- The creation of reed beds at the front of quays and retaining walls.
- Embankment protection, an important asset to the natural environment and the landscape.
We only use natural materials for the entire construction. Our new patented technique ensures an efficient reuse of sludge, and provides a natural contribution to the preservation of the legakkers.
Frequently Asked Questions
Legakkers are long, narrow strips of land on which, in earlier times, harvested peat was laid to dry for the peat trade. Many legakkers have disappeared through erosion. This is detrimental to the historic landscape structure and the recreational functions.
The new legakkers or reed beds are built using 3-metre thick fascine mattresses made from willow. The unique method of overlapping the fascines and then tying them together, creates a continuous and unbroken ‘piece of land’, which is then sunk to the bottom of the lake. Rocks are dumped onto the construction, which is then filled with peat sludge.
The plan and the structures are successful. Nature is recovering. Unique plants are now growing on the new islands.
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Flood protection Ooijen-Wanssum
Commissioned by Mooder Maas, we have made the Ooijen-Wanssum area development more water-safe.
Commissioned by Vereniging Natuurmonumenten, Van Aalsburg B.V. realised the sodding of quagmire in the Nieuwkoopse Plassen (PAS project).