Performing a horizontal directional drilling and maintaining the dam’s water level, requires a lot of knowledge and expertise. The HDDW technique combines both proceedings and provides a perfect tool to keep the dikes stable.
The construction of a HDDW requires the following steps:
1. The drilling pilot
A rig (this is a drill) pushes the drill head accurately through the ground. A hollow pipe behind the drill head fills the hole with drilling fluid to prevent it from collapsing.
2. Emptying the borehole
Upon emptying the borehole a rig pulls a reamer through the borehole. Depending on the desired diameter, this process takes place one or more times. The diameter of the reamer will increase during this process. The use of drilling fluid prevents the drill passage from collapsing.
3. Construction of the filter
When the borehole is large enough, the casing is set in place. In this temporary casing, the filter tube is placed. If necessary, the artificial gravel pack will be installed. The casing will be removed, the required pumps installed and the system is ready.
4. Development of the source
In order to be able to take a HDDW in use is the development of the source is necessary. This means that the drilling liquid is removed and the soil composition optimized.
After developing and applying the pumps, measurement- and control techniques, the HDDW is ready to use.