Development & source maintenance
Constructing a new drinking water source does not end with the installation of a filter. The next, necessary step is the optimisation of the soil around the filter. Only after this phase is the system ready for use. This process is referred to as the development of the source.
Removing drilling fluid
In the construction of an HDDW, the removal of the drilling fluid is an important step in the development of the source. Upon its removal, the mantle pipe *) takes along the drilling fluid present in the system. This is done with special duct pullers and other materials. This results in a clean drill hole that closes around the filter pipe and its screen correctly as well.
After removing the drilling fluid, the screen is optimised. There are several ways of doing this, including:
- High capacity extraction
The filter system extracts water from the ground at high capacity. Due to the high pressure, the water transports all the superfluous soil particles and the last remnants of drilling fluid to the filter pipe. The pumps in the system suck the water with the particles through the filter crevices, which results in a clean, optimum screen.
- Mechanical vibration
When this method is used, the filter system pumps highly pressurised water through the filter pipe into the screen.The surrounding sand bed expands as a result. Sand particles rub against each other and the unwanted soil particles and remaining drilling fluid sink into the filter pipe through the perforation. The pumps in the system suck up the particles, which results in a clean and optimum sand bed.
This completes the development of the source, making the new source ready for use.
he development of a source in a natural screen requires much more of an effort and is also riskier because the exact soil structure is unknown. This is another reason why the development of an artificial screen is important.
*) Watch the full HDDW video and see how the mantle pipe is removed.
The techniques applied to develop the source can also be applied to maintain it. By sending water through the filter at high pressure, the (artificial or natural) screen is shaken loose. This releases floating particles. By extracting water at the same time, the released floating particles are sucked in and removed. As a result, the filter and the screen are completely clean again.
Reduction in maintenance costs
The HDDW is characterised by its high capacity per source. Only a limited number of sources are required to achieve the same capacity as the vertical method achieves. This saves maintenance costs. The horizontal position in one water quality prevents contamination of the filters. This limits the maintenance costs as well.