Horizontal Dewatering drainage makes it possible to lower ground water levels in such a short time that the groundwork for sewer’s, building excavations, cables and pipes can be done in the dry, without any risks in a short space of time.
It is achieved by special designed trenching machine systems to drain the ground water from the soil. Pumping out the ground water lowers the water table and modifies the subsurface flow pattern. The system can be installed accurately by means of laser depth control.
For certain soil profiles, Horizontal Dewatering drainage is the best drainage system.
This is especially the case for terrains with a porous surface layer and an impermeable underground. Thanks to the application of Horizontal Dewatering drainage in terrains that are prone to setting, the setting will take place more quickly.
Because of this, the great amounts of sand that are normally needed as a preparatory load will not have to be used and the period needed for setting will be drastically reduced.
This means there is no free water and the larger pores are filled with oxygen. The soil will feel moist and the conditions are ideal for plant growth. If the larger pores are also filled with water and the soil can’t take up any more water we talk about Saturation.
Normally this will happen for a short time until the water in the larger pores has drained by gravity to a fluctuating water table.
Above the water table we will have a capillary fringe after water has freely drained away. Salt stored in the soil will mix with the water and rise with the water table and pull into the capillary fringe.
If the process of adding water continues the roots will end up in this capillary fringe or worse in the water table.
Lowering of the groundwater level
Horizontal Dewatering makes it possible to lower groundwater levels in such a short time that the groundwork for sewer’s, building excavations, cables and pipes can be done “in the dry”, without any risks.
Principle of Horizontal Dewatering
The principle of Horizontal Dewatering is simple. A trench is dug by means of a specially constructed dewatering trenching machine. During the digging a flexible synthetic filter pipe is inserted in this trench directly behind the digging chain, through a steel case. The beginning of the flexible pipe is not perforated and is dug in from the surface level.
When it has reached the desired depth the non perforated pipe becomes a horizontal perforated pipe that is connected to a vacuum pump. The groundwater is sucked through the perforations because of the under pressure. Then it is pumped up through the blind pipe by the vacuum pump.
In this way it can be controlled and drained off.
The maximum digging depth of our Horizontal Dewatering machine is 5 m. If necessary, the width of the trench can be 40 cm. Depending on the characteristics of the soil and the requirements that have to be met, the filter pipe can be covered in advance with, nylon sleeves or polypropylene fibers. The trench can also be partly or completely filled with porous materials such as coarse sand, gravel, granules of clay etc. The drain length can be 80 – 100 meters.
Advantages as opposed to Vertical Well-drainage
- The cost are lower because less manpower is necessary for the installation.
- By bending the filter pipe towards the edge of the work area, e.g. when a pipeline is constructed, a work area is created that is completely free from obstacles.
- With Horizontal dewatering the complete system in nearly underground, so excavators and other equipment can move without restrictions over the area.
- In layered soil profiles the result is much better because disturbing layers are broken through all the length of the line.
- The Horizontal Dewatering system can be used over and over again. The filters remain in the ground. It is sufficient to connect a vacuum pump to the intact blind pipe to re-use the system. In this way the groundwater level can again be lowered.
- Because there are no overground obstacles like Vertical Well-drainage, the building terrain is easily accessible and the building activities are not hampered by the drainage installation.
- The Horizontal Dewatering system can be installed very quickly.
- The amount of water that has to be pumped up is much lower than with Vertical Well-drainage.
Originally horizontal dewatering was used for the construction of pipelines.
The advantages of the system appeared to be so clear that it is now also used for scores of other activities:
- industrial estates
- building excavations
- sewage treatment plants, etc.
Before starting the building activities the building terrain is provided with a system of filter pipes. Where necessary the desired lowering of the groundwater level can be reached quickly by means of a few vacuum pumps.
The greatest advantage is that in this way the planning of the ground and construction work is completely independent from the Horizontal Drainage.
Moreover, the installed system can be used again later when there are reparations, extensions etc.