How to install a caisson for a well

An autonomous source in the countryside allows you to make life in the house comfortable regardless of the season. So that even at subzero temperatures the water flows into the cottage unhindered, it is advisable to equip the well with a caisson (a special protective chamber in the tip area). It can be built from various materials - reinforced concrete rings, monolithic casting, brick, metal, plastic.

Advantages and disadvantages of the caisson

The protective reservoir is a chamber with dimensions of 1x1 m (minimum) with a depth below freezing. The installation of a caisson for a well carries the following advantages:

• the ability to compactly place pumping equipment, automation, a hydraulic accumulator in one place;
• reliable protection of equipment from vandals, precipitation, frost;
• prevention of freezing of the water supply system;
• the absence of extraneous noise of pumping equipment, which is inevitable when it is installed in the basement of the house;
• the ability to easily preserve the system for the winter with a drain valve installed in the caisson;
• the convenience of laying several pipeline lines for various tasks: watering, filling the pool, water supply to the sauna, cottage.

If there is a caisson, it is easier and faster to dismantle the submersible pump if a winch is installed in the chamber.

Caisson Requirements

The main requirement for the arrangement of a well caisson under water is the absolute tightness of the chamber. Otherwise, the overhead will periodically flood the room, which will not affect the working capacity of the pumping equipment in the best way.

The rest of the caisson is chosen according to the following criteria:

• It is advisable that the depth of the chamber be greater than the level of soil freezing in the region.
• The parameters should allow installing the equipment in the caisson freely, with indentation, so that the master can freely carry out maintenance and repair of equipment.
• The material of manufacture. The most durable is considered a thick-walled polymer with stiffeners. Concrete and brick are in second place in terms of practicality, since they are capable of absorbing water, albeit slowly. This can be avoided by applying the external and internal sealing coat. Metal is the worst option for a caisson. The material oxidizes and rusts over time. Even the use of protective anti-corrosion coatings does not save. Gradually, the composition in some places recedes from the surface of the metal, and the box rusts.

For complete tightness, a top hatch is provided in the caisson chamber. For a convenient descent down - a ladder.

Installation from various materials

To install a protective chamber for the well, first carry out earthwork. Around the casing dig a pit to a depth below freezing. The width and length of the pit corresponds to the parameters of the proposed reservoir, plus 20 cm on each side for backfilling.

The bottom of the pit is carefully compacted and a layer of moistened sand is poured. It is also well compacted. Then produce concrete pouring, which serves as a rigid base for the tank.

Experts assure that it is not necessary to pour concrete mortar under a light polymer structure, but a site is needed. A caisson can be anchored to it, which is especially important for heaving soil or if there is a high groundwater level on the site. Under reinforced concrete or brick tanks, the site is necessary.

Installation of polymer box

Installation of the caisson for the well is carried out in the following sequence:

1. In the bottom of the plastic reservoir, a hole is cut with a hacksaw, equal in diameter to the casing.
2. The caisson is put on the pipe and lowered to the very bottom, on the concrete platform.
3. The tank is anchored with anchor bolts. Under them, it is advisable to lay dense rubber gaskets coated with sealant.
4. It is also worth sealing the junction of the chamber with the casing.
5. On the sides of the caisson, holes are made for the outlet of the pipeline. The gaps between the walls of the chamber, the tube is also well worked out with a sealant.
6. Backfilling of the tank is done simply with soil. But for greater strength, experts recommend using a cement-sand mixture. It is slightly moistened and then tamped in layers.

The hatch of any caisson should be 15-20 cm above the ground. This prevents rainwater from entering the chamber from above.

Installation of a metal well

When equipping a metal caisson for a well, the work is performed as follows:

1. From stainless steel or metal, a box of the necessary parameters is boiled with a hinged hatch.
2. Threaded bushings are welded on the sides at a given height to output the pipeline.
3. A hole is made in the bottom of the chamber along the casing section.
4. The box inside and outside is treated with protective anti-corrosion agents. Two to three layers of coating are applied to the welds.
5. A metal caisson is installed according to the principle of polymer. But here you already have to use special equipment. Since the mass of the box is large enough.
6. The mounted chamber is anchored and then backfilled, with previously drawn piping lines.

When backfilling, it is worth taking care of the insulation of the tank, since the metal has good thermal conductivity. As a protective layer, plates of expanded polystyrene, basalt, expanded clay can be used. The insulation layer is important to close the outside with rolls of roofing material or coat with bitumen mastic.

Reinforced concrete box

This is the most time-consuming version of the protective chamber device due to the mass of the rings. For their installation, it is necessary to hire special equipment. Installation of the caisson is performed as follows:

1. The first ring is lowered onto a previously prepared concrete base.
2. Download the second item. The joints are worked out with bitumen mastic. This also applies to the adhesion zone of the first reinforced concrete ring with a concrete platform.
3. Using a puncher with a special crown, lateral openings are formed for the outlet of the pipes. They are reinforced with stainless steel sleeves.
4. Outside, a caisson of rings is coated with several layers of bitumen mastic for complete tightness of the chamber.
5. It is important to take care of the insulation of the tank. It is wrapped on the outside with mineral or basalt wool, foam shells. A sealing layer is applied on top.
6. Backfilling of the caisson is performed after the pipeline is withdrawn. Each layer of soil is ramped in stages.

The reinforced concrete structure is heavy. Therefore, when one ring is displaced, the deformation cannot be corrected. Have to dismantle the camera and put a new one.

Monolithic caisson device

This version of the camera also has its pros and cons. Of the main advantages distinguish strength, solidity, durability. Of the minuses - high thermal conductivity, the complexity of the process, the risk of depressurization of the chamber with very heaving soils.

Work according to the instructions is performed as follows:

1. On the flooded and completely dried out bottom, the formwork is mounted. It can be installed from wooden boards immediately to the full height or from wooden boards for pouring the caisson in stages.
2. A solution of cement, sand and gravel is prepared in a concrete mixer. The proportions are 1: 3: 6, respectively. The mass should have a consistency of thick sour cream.
3. A metal reinforcing mesh is inserted into the formwork and the walls are filled.
4. 3-5 days are allowed to dry the solution.In this case, the pit must be covered with tarpaulin from direct sunlight, and periodically wet the concrete.
5. After the solution has completely dried, the formwork is removed, and the walls of the caisson on both sides are coated with sealant (bitumen mastic).
6. Using a punch and crowns, technical side holes are made. They are reinforced with sleeves.
7. The gaps after the outlet of the pipeline are closed with mastic.

It is important to take care of high-quality insulation of the monolithic tank. It is made from plate materials resistant to deformation. The best option is extruded polystyrene foam. It is also desirable to insulate the lid of the chamber.

After laying, the insulation is coated with another layer of mastic.

The top of the monolithic caisson is a concrete slab with a hole for the hatch.

Brick caisson device

This option is the most convenient, practical and budgetary, provided that on the private site there are blocks left from the construction of the house or after the dismantling of old structures. You can drive out the walls of the camera with your own hands without the involvement of specialists. The number of required blocks is calculated by the height and width of the walls. First, the estimated height of the caisson is divided by the height of one brick in cm. The number of rows for one side of the tank is obtained. Then the width of the wall is divided by the width of one block and get the amount of material in one row.

It remains to multiply the two resulting numbers between themselves (this is the sum of the blocks on one side of the caisson). The result is multiplied by 4 (number of tank walls).

1. Installation of a brick caisson is performed from the corners according to the usual pattern. The thickness of the masonry seam is about 1 cm.
2. After distillation, the chamber is well dried.
3. Technical gaps are provided even when laying bricks, so as not to work with a puncher later.
4. The finished caisson is coated with bituminous mastic from the outside and from the inside.

The top cover can be made of concrete slab or a strong wooden shield covered with roofing material.

The price of a professional caisson device

If you don’t want to bother with installing the camera with your own hands, you can hire professionals. They do the work in 1-2 days on a turnkey basis. At the same time, the price of installing a caisson per well varies depending on such parameters:

• camera dimensions;
• caisson material;
• the complexity of land work;
• additional services (laying of the pipeline, etc.).

On average in Moscow, the cost of such services is from 50,000 rubles.

To save family funds, you can independently and correctly make your own well for installing downhole equipment.