Coatings for water wells in Sardinia

One of the steps to be performed in the construction of the well is the lining. This, with a smaller diameter than the hole, is lowered inside it to allow suitable protection. The lining piping can be in PVC, polypropylene or metal. The PVC material has been tested longer than the younger polypropylene. The PVC guarantees a seal and a higher mechanical resistance to traction, as it is less flexible. Due to its non-polarity characteristics, polypropylene is much more resistant to high temperatures, over 120 degrees centigrade, to chemical agents such as salts, acids, etc. Compared to techno polymers it has low mechanical resistance to traction and compression. Therefore, according to the inherent needs of the hole, the type of coating must be adapted.
At the level of discovery of the aquifer concerned, drainage pipes or more simply called micro-slits are positioned, not to be confused with windowed pipes. The former are micro-perforated with special machines, the latter slotted in an artisanal way on site. The micro-perforated holes permeate the water inside the well, leaving the finest particles on the outside, ensuring better water quality. These pipes are particularly suitable in the presence of sandy materials with fine grain sizes. In these cases, to cope with extreme situations, there are filter tubes equipped with special sleeves or fixed metal nets around the tube with low inlet ports. It is important to clarify that these products are certified for the food use of water, are environmentally friendly and comply with ministerial health regulations (Article no. 174 of 06 April 2004).
A separate chapter deserves the metal coating, whose use is intended for extreme conditions. In the presence of landslide materials such as sands and unstable materials, the only solution is the metal coating. This type of coating guarantees the crossing of landslides by subjecting the coating to strong traction and compression. By doing so, the total piping of the well can reach the desired height.