Building Project - Excavation and Stabilisation

There used to be a cornfield at the site where the Underwater Park is now. A few metres further on begins a 40,000m² large lake area that was built by us. With part of the debris, we built a u-shaped dam. In-between the excavation for the Underwater Park was made. The biggest problem is the ground water that begins at a depth of one metre - we dug four metres beyond that depth.

 
On the outside you can see the heaped up walls, after a depth of 1m the ground water begins seeping into the excavation from all sides. This makes the sany floor soft like pudding, nearly liquid. After building a ring-shaped trench the surfaces are passable - except for one spot:
 
In an old bomb crater the ground structure was destroyed to the point the even the broad tracks of the excavator weren't sufficient. The excavator sank deep into the quicksand and threatened to sink completely. It took us hours and all our machinery to rescue it.


Precondition for this sort of work is the lowering of the ground water level. We placed filtration tubes 3m apart through which the ground water was drained. The water is transported to three pumping stations over a 4km system of pipes. We built a ring-shaped drainage system to evacuate the water directly from under the ground of the excavation as backup.

The pumps' capacity was 1,000m³ per day.
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The partially filled lake: The lateral chain of filters primarily drains invading water. The ring-drainage stabilises the water level under the layer of scree.

One of three pumping stations. More than 4km of pipe transported the ground water through 105 filter-tubes. The stations managed 1,000m of water per day.
The ring-drainage transported water that rose from the bottom to a central extraction point. This safety reserve saved the project several times...
The sand-pudding was covered with fleece and 2,000 tons of scree and debris. This stabilised the ground so that our truck could pass over it.