Design and construction of an autonomous water supply and sanitation system is a time-consuming, physical and financial effort. At the stage of arrangement of the mine, the selection and installation of the casing is of great importance. A well without a casing is characterized by a short service life, low quality of produced water, there is no strengthening of the walls of the structure, which threatens to collapse.
Purpose and scope of casing for the well
First of all, you need to decide what a casing pipe is and for what purposes it is used. This is a special column equipped with a reinforced casing, the main task of which is to strengthen the internal structure of the hydraulic structure. As a rule, more than one functional element is installed in a deep well shaft. They are interconnected, and the seams are treated with sealant to obtain a single casing.
The wall thickness of the casing rings should be determined by the type and characteristics of the structure, as well as the material used to make the walls of the string.
Products made of concrete and metal are characterized by a large wall thickness, diameter and length, in comparison with plastic parts. To create a tight connection of the elements, the end of one pipe always has a coupling. The other end is equipped with a ring that protects the thread from damage.
Casing pipes of the source are necessary for the following tasks:
- Protect the water pump or pump system installed in the shaft against possible contamination and mechanical damage.
- Ensure the integrity of the water intake over the entire life cycle. Products are characterized by increased strength, resistance to deformation and damage.
- Protect the well from high soil pressure.
- To prevent the leakage of sewage or groundwater into the well, which threatens water contamination and infection by pathogens.
It is necessary to give preference to the threaded connection method, otherwise it is almost impossible to achieve reliable sealing of the casing.
Types of pipes and selection criteria
Casing pipes are divided into several types, depending on the material of manufacture:
- plastic (PVC, NPVH);
- metal;
- asbestos-cement.
Each material has a specific life, and also affects the quality of well water. To determine the choice of material, you need to study in more detail the features of each.
Steel is used to strengthen the casing quite often, especially in artesian wells, characterized by great depth. Steel products are durable and reliable, with proper installation and maintenance can last several decades. A casing pipe for a well from a sewer steel pipe is a common occurrence.
Negatively affect the design of the movement of soil strata. Also, the material is subject to corrosion, due to which the quality of well water deteriorates. To avoid such a problem, it is necessary to give preference to stainless steel, but the cost of arranging the well will increase significantly.
Long life and excellent characteristics are characteristic of asbestos-cement products. However, there is a fairly extensive list of disadvantages:
- Insufficient strength at great depths, where the pressure of the soil layers reaches critical levels.
- Asbestos, although it is bound to cement, may, over time, begin to decompose into components that adversely affect the quality and taste of the water.
- Due to the large wall thickness of the casing rings, the diameter of the well needs to be drilled more, which negatively affects the cost of the work.
Asbestos-cement products are best used for casing wells with a depth of not more than 15 meters.
Increasingly, casing of the well with plastic pipes is encountered. This is due to the fact that products made of low-pressure polyethylene or polyvinyl chloride have excellent qualities used in different communications.
- In comparison with previous analogues, the cost of products is much lower.
- The material is not afraid of corrosion, plaque does not form on its surface.
- Products do not decompose, do not adversely affect water quality.
- Due to its high strength and reliability, a long service life is ensured.
- The use of modern methods of connecting parts ensures the tightness of the channel.
- Due to its low weight, the casing is easier to install.
The use of plastic pipes is limited by depth. As a rule, they are used for wells up to 50 meters. The diameter depends on the volume of water consumed and the depth.
Mounting Features
Installation of casing parts is carried out by drilling soil with a drill. The diameter of the drill should be less than the diameter of the casing. Then it is taken out of the ground and the pollution removed. The casing is lowered when the well depth reaches 2 meters. Further, drilling should be carried out together with the casing until the moment when the aquifer is overtaken.
The classic version of the casing is as follows:
- The filter for rough cleaning of well water is a wire or a stainless mesh.
- A bottom filter made from gravel. Protects water from pollution, which can penetrate the source from a greater depth.
- Sealed head that prevents contaminants from entering the well shaft from the outside. Its fastening is accompanied by the formation of negative pressure, which leads to increased water flow. To increase the negative pressure indicators, the head is cemented.
From a freshly drilled source it is not recommended to consume water for food purposes. Having installed pumping equipment, pump out fluid from the mine for the maximum possible expansion.
When choosing a suitable casing for a well, they are guided by a simple but proven combination of quality and price. Due to these parameters, it is determined how long the construction will work.
Wells with great depth are recommended to be designed with metal products equipped with external and internal threads. If the depth of the well’s shaft is less than 50 meters, they prefer a budget analogue - plastic pipes. Asbestos-cement products are installed at a well depth of not more than 15 meters, otherwise the material may not withstand the pressure exerted by the soil layers.
