Underwater placement in bulk of fill material

Once unloaded the THSDs or barges require less draft, which may favour the operational conditions in the sand placement area. 

Fill may also be placed under water through the discharge pipeline of a CSD which may be provided with a diffuser to control the soil mixture flow, see section 6.5.2. 

The TSHDs/barges must have access to the reclamation area. The site should not be fully enclosed by bunds. The water depth should also be sufficient to prevent grounding of the vessels after dumping. 

In order to create a more continuous process of sand delivery into the reclamation, a CSD is sometimes used to re-handle fill that has been dumped by trailing suction hopper dredgers or barges in specially created underwater pits near the fill area, see also section 4.5.3. 

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