Which septic tank is suitable for clay soil? We are building a septic tank from reinforced concrete rings: design diagram and features of the work. Septic tank from rings on clay soil.

Installation of local sewage treatment systems (septic tanks) is often complicated by mining and geological conditions (soil composition) and high groundwater levels.

These reasons create problems with the discharge of treated wastewater into the ground. The most difficult thing is to install a septic tank on clay, which has a minimum coefficient of filtration of liquids.

The main problem at this stage is related to the fact that almost all clays (90%) belong to soils prone to frost heaving. It is because of this reason that the installation can be squeezed onto the surface, so it is necessary to resort to additional fastening of the local treatment plant during the installation process. Most often, a so-called bandage of steel strips or cables is used for this, which encircles the septic tank and is attached to the concrete base in the pit.

Considering that on clay soils, drainage systems (filtration fields) in many cases work only in the upper layers of the soil, it is necessary to resort to shallow installation of a septic tank.

In this case, it is necessary to provide measures for insulating the structure:

Insulating a septic tank with glass wool

• In the very simple case resort to pouring an additional layer of soil above the topography (forming a mound above the installation site of the septic tank).
• It is more effective to insulate the treatment plant with special heat-insulating materials, the choice of which is quite wide. The most affordable (cost) method is filling the container with expanded clay. The use of polystyrene foam (preferably extruded) or polyurethane foam is considered more effective. In addition, active protection systems against exposure are increasingly being used. negative temperatures. To do this, use a heating electric cable, the thermal power of which will reliably protect the septic tank from freezing even in harsh climatic conditions.

Discharge of treated wastewater

The main problem for those who decide to install an autonomous sewage system and install a septic tank in clay soil is the difficulty of draining treated wastewater. Such soil has minimal filtering capacity, which creates a number of sometimes intractable problems.

There are several main ways to remove treated wastewater from a septic tank in such conditions.

It is used if the soil on the site does not accept water at all. In this case, the entire volume of treated wastewater enters a sealed container or well, from which it is then pumped out using sewage disposal equipment or drainage pumps.

The disadvantages of this method include the need to construct a large-volume container, otherwise pumping will have to be performed very often. But if there is no other way out, this technology has to be used.

Increasing the drainage area

There are several varieties of this technology, but they all boil down to the need to increase the filtration area in order to ensure the removal of the required volume of treated wastewater even with minimal drainage capacity of the soil.

• Construction of a number of sequential drainage wells, in which case it is necessary to use rings of the largest possible diameter.

In practice, systems of two or three overflow drainage wells are used, which can fully meet the needs of a family of 3-4 people.

To increase the filtering capacity of wells, they resort to drilling additional drainage wells. This method allows, in some cases, to reach filtering soil horizons, which will help to significantly increase the productivity of the structure. Drilled wells must be protected with casing pipes, and a simple mesh filter must be installed at their mouth, which will prevent siltation of additional drainage.

• Install a septic tank in clay with your own hands It is also possible with the construction of filtration fields of a large area. This method is used at high GWL (groundwater level).

The most productive is a drainage system using corrugated plastic pipes and geotextiles. Pipes of this type are characterized by increased strength; they are able to provide effective removal of treated wastewater. And geotextiles prevent siltation of the system.

To increase the efficiency of the filtration field, laying two-level drainage is often used. In this case, a number of lines (drains) are laid close to the surface, and the main part is buried as deep as the groundwater level allows.

The filter line is laid in pre-prepared trenches, which are covered with geotextile fabric. Drainage pipes are laid on a bedding made of granite crushed stone (it is not recommended to use anything else due to the tendency to erosion) with a thickness of at least 20 cm. They are also covered with a layer of crushed stone on top, which can significantly increase the volume of discharged wastewater. The entire resulting system is covered with geotextiles, which will ensure the durability of the line.

To ensure filtration of wastewater in clay soil conditions, it is necessary to lay out filtration fields of significant area.

Of course, installing septic tanks in clay involves a significant increase in the volume of work performed during installation. But it is quite possible to ensure effective operation of local wastewater treatment plants even in such conditions.

Today you can install any septic tank for your dacha with your own hands, for which you have not only the time, but also the funds. Before purchasing, it is better to calculate the approximate volume of wastewater and determine the type of soil on which such a container will be installed. One of the obstacles may be such difficult soil as clay, on which it is difficult to carry out installation. Therefore, you should choose a septic tank carefully. Today, several types of waste storage containers are used. These are aboveground and underground. Above-ground containers are used extremely rarely, which is not only due to their unhygienic nature, but also due to the rather unpleasant odor that they spread around. The most optimal is an underground septic tank installed in the soil.

To arrange the bottom of a hole that is dug in the ground, two options are used:

• gravel backfill in the form of a drainage layer;
• concrete pad, which is considered a more preferable option, especially for polymer containers.

Let's find out what types of septic tanks for a summer cottage you can install with your own hands, and how realistic it is to do this in clay.

Features of installing a septic tank in clay

To install a sewer septic tank in a country house, the following points must be taken into account:

The degree of sewage treatment in a septic tank is at least 60%.

• soil type;
• ground water level;
• the location of buildings, fences, residential buildings, vegetable gardens, etc. next to the planned septic tank;
• the depth of the sewer pipe that will go from the residential building to the septic tank.

Such a pipe can be laid at a depth of 75 cm, taking into account the level of freezing in winter time. For clay soil where the groundwater level can be quite high. You can only install a septic tank with your own hands, the ground filtration of which will take place above the water level. Otherwise, the suction will be poor, that is, the installation of the septic tank will be incorrect.

The pipe is laid shallow; it is simply sprinkled with a small amount of earth on top so that a low hill is formed.

To install a septic tank in clay with your own hands, you will first have to provide excellent drainage so that the container does not go into the soil. To do this, not only a pit is built for the container, but also an outlet for dispersion; it is recommended to install and drainage pump.

Installation of a septic tank sanitary standards, allowed at a distance of at least 5 meters from the house.

The pit for the barrel must be made deep, but the level of freezing must be taken into account so that the barrel does not simply get crushed. It is better to secure septic tanks in clay additionally using steel channels. It is required to install two-stage filter trenches. The right one should have a cushion of sand and gravel 30 cm thick. It is in this trench that the filtering perforated pipe is laid, the depth of which should be from half a meter to one. The pipe should be placed in another trench of the system to a depth greater than in the first - from one and a half meters to two.

Not every septic tank can be used for clay. Let's consider the most preferable options.

Types of septic tanks for country houses

You can build various types of septic tanks at your dacha with your own hands. All types of containers for the sewer system can be divided according to different criteria. Based on the principle of operation, septic tanks built by yourself can be classified into:

If there is a well with drinking water on the site, then the septic tank should be located at least 30 meters from it.

• storage tanks;
• septic tanks for deep biological treatment;
• septic tanks with a system for soil filtration.

It is customary to divide sewage tanks according to materials of manufacture:

• brick;
• monolithic and prefabricated septic tanks made of reinforced concrete;
• metal in the form of barrels;
• plastic modern PVC containers.

Based on their shape and installation, septic tanks can be divided into vertical and horizontal. There is a division by type of chamber (surface and underground). According to the principle of operation, septic tanks can be divided into:

• two-chamber septic tanks that process wastewater daily;
• storage septic tanks;
• septic tanks with soil treatment;
• with biological deep cleaning.

Cumulative septic tanks and with soil post-treatment

Concrete blocks with a bottom are sold specifically for sewerage. This greatly simplifies the installation of a septic tank.

Storage septic tanks are cesspools and storage tanks, which are pits or special barrels. Such containers are installed in special dug holes; a special drainage or concrete pad is installed for the bottom of such holes. In prepared pits, the wastewater is divided into two parts: light substances and fatty residues float to the top, hard and heavy substances sink to the bottom. Among the advantages, it is necessary to note the simplicity of execution, but such a septic tank is inconvenient for operation, since it must be cleaned frequently, and the smell from which it originates is quite unpleasant;

Septic tanks with soil post-treatment differ in that it is necessary to call a sewage disposal truck for cleaning less often than for a regular one. The volume of such barrels is larger, but their strength is much higher. The device requires more force than a conventional storage device, and when installed in the ground, some protective equipment must be provided.

A concrete pad is used for the bottom, on which the barrel is placed; chains are attached to it to hold the barrel in place, since in winter such a septic tank is simply pushed out. And when digging into the ground, it is necessary to ensure that the walls of the septic tank are not crushed by the soil. For such options, you can use batteries for septic tanks, which can significantly reduce the frequency of waste treatment. The principle of operation of such a septic tank, which you can easily install with your own hands, is quite simple: wastewater through a pipe first flows into one chamber, where it is located, like in a sump. Here they are divided into separate factions. After this, the initially purified water enters another chamber, where it is further purified under the influence of anaerobic bacteria. 60% purification occurs here.

The advantage of such septic tanks is their ability to process wastewater. They are characterized by simple maintenance; sewer equipment is not used for cleaning. The disadvantage is this: this type of septic tank cannot be installed on clay soil, there is no way to provide the necessary conditions for the bottom of the pit, and cleaning at the last stage in this case is simply impossible.

Biological deep cleaning

From the house to the septic tank, the pipe should be laid at an angle.

Such septic tanks are considered the most modern and reliable; they allow you to completely purify wastewater, after which the water can even be discharged into fish ponds. The deep cleaning method is used here, that is, a combined method is used. This is not only mechanical settling of wastewater, but also chemical and biological methods of purifying water entering septic tanks. The operating principle of a biological septic tank is as follows: the first chamber accumulates wastewater and separates it into heavy and light fractions. This is followed by cleansing using aerobic and anaerobic bacteria. Before water is discharged, it is cleaned with special chemicals.

Biological septic tanks, which are easy to install with your own hands, are characterized by high,

almost one hundred percent level of purification. Such devices can be installed even on very heavy soils, including clay. Installation is simple, the station is ready for use in about two days. The downside is the high price. If you are going to install a septic tank in a country house where you plan to live only in the summer, then there is simply no point in such an expensive installation.

Other options for septic tanks

Now let's consider the type of storage containers depending on what material is used for this. Plastic and fiberglass septic tanks are produced industrially from very durable materials. The advantages of such barrels are that they are sealed, that is, they do not allow leaks and are resistant to corrosion. Among the disadvantages, it should be noted that plastic barrels have a small mass. When installing such a septic tank, it is necessary to use a special concrete pad for the bottom, to which the barrel will be attached with chains or steel ropes. There is a high probability that the walls of the barrel will simply be crushed under the weight of the soil. For such containers, there is often little concrete bottom; the walls must be protected in the same way.

There are septic tanks that are constructed from ordinary bricks, for which one-brick masonry is used. But such septic tanks are used only for small areas where significant volumes of wastewater are not planned. Although septic tanks are easy to build using only your own hands, it is simply impossible to create a complete seal here. It is necessary to ensure ventilation of the pit and its frequent cleaning.

Reinforced concrete septic tanks can be monolithic or prefabricated. In the first case, a hole is made into which formwork is installed and filled with concrete. In the second case, reinforced concrete rings for wells are used. There is an option in which the septic tank is constructed from a metal tank, which must be pre-treated with anti-corrosion compounds.

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When installing a homemade or purchased septic tank great importance given to the quality parameters of the soil. The nature of the soil, freezing depth (DF), and groundwater level (GWL) play a role. Considering that in the middle zone the most common type of soil is clay, many owners of a suburban area are faced with the problem of arranging an autonomous sewage system. The catch is that clay and loam differ poorly throughput– liquid passes very slowly through layers of such soil. In turn, this entails additional costs when arranging a drainage area - a filtration field.

If installing a settling tank in clay is not particularly difficult, then the drainage of the septic tank should be given increased attention. In situations where the thickness of clay and loam exceeds 3 meters, you should be prepared to carry out full-scale excavation work. In particular, it will be necessary to replace part of the soil with crushed stone and sand - materials that have good throughput. It is also necessary to provide for a slight slope of the pit under the aeration field (2-3 degrees), which would be sufficient to discharge treated wastewater into roadside trenches or onto an unoccupied (unowned) site.

In the situation we are considering, it is worth considering increasing the absorbing area of ​​the filtration field. This means that the network of drainage pipes should be branched out as much as possible (don’t forget about the insulation of the septic tank), using a large area. It is good if the use of treatment plants is seasonal, but in the case of constant use of the installation, the septic tank structure must undergo some changes. In particular, it is necessary to take into account the terrain and rely on the construction of a treatment plant as far as possible from the house. The ideal option is when there is a natural pond on the outskirts of the site. In this case, the slope of the drainage area can be made in its direction, and then the reservoir will play the role of a collector without harming the environment.

Considering the heaving nature of clay and loamy soil, it is necessary to correctly approach the installation of a septic tank, i.e. strive to ensure that most of the settling tanks are below the depth of soil freezing. It is not necessary to follow the path of deepening the pit for containers - it is enough to make an artificial embankment above the treatment plant.

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Features of clay soils

To make it easier for you to understand what kind of septic tank is needed for clay soils, you need to study the characteristics of this soil. To arrange effective system sewerage, wastewater after treatment in a septic tank is discharged into the ground. The main feature of clay soils is poor absorption capacity. The earth does not absorb liquid well. This results in wastewater remaining in the treatment plant longer.

It is important to know: sandy soil absorbs 90 liters of water per day, the absorption capacity of clay soils is 25 l/day. And pure clay absorbs even less water - 20 liters.

That is why, when installing a septic tank made of concrete rings, plastic or metal containers, it is necessary to organize effective drainage. This can be a drainage well made of concrete rings without a bottom with a filter layer or a filtration field.

What septic tanks can be used in clay?

If your dacha or country house is located on an area with clay soil, then you can use the following types treatment facilities:

• Storage tanks. For these purposes, you can use sealed plastic containers or Eurocubes. However, stainless steel metal tanks are also suitable for clay soils. You can also make a sealed well from concrete rings if the groundwater level on the site is high. For a small private house, you can make a brick drainage well, provided you use the right technology.
• Wastewater treatment plants with soil treatment. This is a fairly effective, budget and simple option for a small country house, built on clay soil. The well of such a treatment facility can be made of concrete rings, brick or metal, that is, any material can be used for such soil.
• Biological treatment units are the most reliable and effective option for clay soils, suitable for a private home of any size. However, such a septic tank on clay will have the most complex design, so its choice should be made if you have the money and time to complete it.

Important: sewage from a country house on clay soil can be diverted to a septic tank of any design. It is important to properly design and install a treatment plant on such soil. In this case, the choice should be made taking into account the productivity of the structure, the required degree of wastewater treatment and groundwater treatment.

Storage containers

If you decide to equip the sewer system of a private house using a storage tank, then you need to make a sealed structure. For these purposes, you can use plastic containers, Eurocubes, steel barrels or welded cubes, structures made of concrete rings or bricks.

It is quite easy to carry out such a cleaning installation. It is enough to dig a pit, concrete the bottom and install containers or concrete rings. However, if your area has a high groundwater level or there is a well near the storage tank, then using such a design is not recommended.

Structures with soil post-treatment

These are simple wastewater treatment plants They are very reminiscent of storage tanks, but without a bottom. The structure of the well itself can be made of concrete rings, bricks or bottomless water. A drainage layer is installed at the bottom of the structure.

To make a drainage filter, you need to use geotextiles, sand and crushed stone. The thickness of the filter layer is 30-40 cm. When passing through this filter, the wastewater is cleared of large fractions and enters the soil.

If there is a well nearby on your site, then this design of the treatment plant is also not suitable. When installing this septic tank, you need to know the groundwater level, because the bottom of the filter layer cannot approach the aquifer closer than 1 m.

Units with biological purification

These are the most reliable and efficient treatment facilities that can be installed regardless of the water supply system on the site. These autonomous biological treatment stations purify wastewater so effectively that the water can then be used to water the garden, drained into open reservoirs, or taken for technical needs.

Usually these are multi-chamber products, where the wastewater directly from the sewer system is divided into heavy and light fractions. Then the clarified water undergoes a process of biological purification using bacteria (anaerobic or aerobic).

Design features

Since any septic tank design can be used on clay soil to sewer a country house, the construction scheme will be standard. However, the main feature of clay soils is that it is mobile soil. Therefore, it is worth considering some design features of the septic tank.

The thing is that when the soil begins to thaw after the winter cold, the characteristics of such soils change somewhat and they can push the septic tank to the surface. This is especially true for soils with high groundwater levels and septic tanks made of light materials. That is why, when installing a septic tank in clay, it is necessary to provide additional fasteners in the soil. If the well of the treatment plant is made of concrete rings, then it is enough to simply fill it in the pit without fixing it.

The choice of method for fixing the septic tank in the pit depends on the design of the housing. If there are no protrusions on the surface of the tank, then steel cables are more suitable. If there are loops or protrusions on the body, then reinforcement outlets can be tied to them, which will be laid in a concrete pad at the bottom of the pit.

Also, the filtration system for a septic tank on clay soil has some features. When installing a septic tank in clay, it is better to arrange double drainage, that is, two filtration fields. In this case, the drainage should take the form of a two-stage trench, in the upper part of which pipes will be laid, and in the lower part there will be a drainage layer 300 mm high of gravel.

Installation features

To make a more efficient septic tank design, it is recommended to use two chambers and a filtration field. This way you can avoid excessive overfilling of the tank and at the exit from the treatment plant you will receive the most purified water possible. After you have decided on the material of the chambers, you can begin digging a pit and further work, which is carried out in this order:

1. When choosing a place for a septic tank, you can observe the minimum recommended gaps from a residential building and sources of drinking water (7 m), since clay does not allow water to pass through well. The size of the pit for the treatment facility should be 20 cm larger than the septic tank structure itself.
2. When digging a pit, you need to know at what depth the clay layer ends. If it is more than three meters, then the work will be complicated by the fact that the drainage layer will have to be carried out at a considerable depth. It is also worth considering that the septic tank containers are connected to each other by an overflow, so they should be located at a distance of 15-20 cm from each other.
3. Together with the pit, they dig a trench for laying a sewer pipe from the house to the treatment plant. At the same time, the slope of the bottom of the trench from the house to the septic tank is observed, taking into account that for every meter of length the decrease is 2 cm.
4. Depending on the containers used, the bottom of the pit can be concreted before or after installation. If you use plastic sealed tanks, the bottom is concreted and reinforced before they are installed. And after installation, these tanks are attached with hummocks to the valve outlets. When using concrete rings, the bottom can be concreted after they are installed in the pit.
5. To make a filter layer at the bottom of the second chamber, sand and crushed stone are used. First, sand is poured and compacted in a layer of 10-15 cm, then backfill is made of crushed stone 25-30 cm high. If you use a filtration field, the bottom of the second chamber is also concreted, and the wastewater is discharged to the filtration fields.
6. Next, install an overflow pipe connecting the two containers. It should exit the first chamber 40-50 cm below the entry point of the sewer pipe. Thanks to this, heavy components of the wastewater will settle at the bottom of the first chamber, and pre-purified and clarified water will flow into the second tank.
7. Ventilation pipes from the chambers are installed.
8. After this, the plastic containers are insulated with foam. Concrete rings do not require insulation.
9. The containers are covered with lids with hatches for cleaning.
10. Now backfill the pit manually. The soil must be compacted every 15-20 cm. The manhole cover must remain above the surface of the ground.

The filtration field is made depending on the groundwater level in the area:

• at low groundwater levels, semi-buried filter cassettes or filters are used;
• at high groundwater levels, surface filtration on sand and gravel beds is used.

Important: the size of the filtration field is directly related to the daily volume of wastewater from the house.

One square meter of filtration field is capable of serving 0.5 cubic meters of wastewater. You can purchase ready-made filter wells based on geotextiles or make the field yourself:

1. After digging up soil from the field, a pipeline is laid from the last chamber of the septic tank to the filtration field. The laying depth is 70-120 cm from the ground surface, but not less than 1 m to the groundwater level.
2. A drainage mesh is laid at the bottom of the field. Then a layer of sand and crushed stone is made. The height of the layer should be such that it rises above the inlet pipe by no more than 50 mm. All pipes with holes are laid with a slope of 1 cm per meter of length.
3. The drainage pipeline is insulated using foam plastic or a wooden box.

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Types for installation in clay

Storage containers

Most often, they are used as plastic containers, in particular Eurocubes of various sizes. But barrels and homemade welded cubes made of stainless steel can be installed. The storage container can be made of brick or concrete. Such septic tanks are often found in villages and towns. They are easy to set up: just dig a pit the right size, after which its bottom and walls are laid out with bricks. Or they install concrete rings with a diameter of 1 m and concrete the bottom of the pit.

For biological treatment

They are the most reliable and modern. These products are autonomous biological wastewater treatment stations capable of producing water that can be used for watering a garden or discharged into a pond with fish. The operating principle of such septic tanks is to separate fractions into heavy and light. This is facilitated by the design of the station.

The main work of wastewater treatment is performed by aerobic or anaerobic bacteria. The life activity of the former is possible only under the condition of constant air pumping. The latter live in silt or soil and do not need additional stimulation. These stations can be installed on heavy soils, including clayey ones.

With soil purification

These are the simplest wastewater storage tanks to set up. They are arranged in a similar way to storage tanks, but without concreting the bottom. That is, you can use all the same materials: brick, concrete, plastic or iron, but you need to install a drainage layer at the bottom. It is made of sand and crushed stone. Here, large fractions are filtered, after which the wastewater penetrates the clay and receives better purification.

Such septic tanks are good because the sewer truck needs to be called less often than in the case of storage tanks. However, in clayey soil the process of filtration and wastewater removal will be hardly noticeable. Therefore, you will have to pump out sewage with the same regularity as if you have a container with a concrete bottom. Such a septic tank can be built quite quickly with your own hands.

Installation technology

1. You need to decide what will be used for the storage tank device. In order to speed up cleaning and make it more effective, it is recommended to build a two-chamber structure with a filtration field. This will allow you to avoid overfilling the main tank and obtain the most purified wastewater at the output.
2. 2nd step - determining the location of sewage receivers. Here you need to focus not only on the convenience of their placement on the site, but also on sanitary and hygienic standards. Since clay does not allow water to pass through well, the risk of runoff entering a well or well is small. Therefore, it is possible to install a septic tank with your own hands at the minimum distances from water intake points and residential premises - 7 m.
3. When the location of the containers has been determined, proceed to earthworks. It would be a good idea to ask your neighbors in advance about the depth at which the clay/soil boundary lies. If it is located below 3 m from the soil surface, the work will be complicated by the need for a device drainage system at quite a great depth. When digging pits, take into account that one container should be separated from another at a distance of no more than 2 m.
4. After installing concrete rings, plastic cubes or laying bricks along the walls of the pits, they begin to install a drainage layer directly in the containers themselves. To do this, backfill with sand and crushed stone. For the first, a layer of 10-15 cm is enough. For the second - 25-30 cm. If plastic barrels are used as tanks, then during installation it is recommended to strengthen them with chains or otherwise. This is necessary because during floods and when the soil freezes, the container can be squeezed out of the hole.
5. Both containers must be connected with a pipe so that it flows 40-50 cm below the sewer pipe, which runs from the house to the main wastewater tank. This device allows wastewater to flow into the 2nd chamber and promotes the separation of fractions. Heavier ones settle in the first container.
6. Further, if free-standing containers were used as containers, they must be insulated. This can be done using polystyrene foam. Such a septic tank, insulated with your own hands, will not freeze in the most severe frosts.

Filter field

In clay conditions, if the groundwater level (GWL) is below 1.5 m, semi-buried filters or filter cassettes are installed. At high groundwater levels, it is rational to arrange surface filtration using gravel-sand pads.

The dimensions of the post-treatment field depend on the daily water consumption in the house. If the volume of wastewater does not exceed 0.5 m³, according to established standards, a filter area of ​​1 m² will be sufficient. If the daily volume of wastewater is more than 1 m³, a field measuring 1.5-2 m² will be required. There are ready-made designs of filter wells available for sale. The price of these products is low, and installation is simple. The role of the main filter in them is played by geotextiles. But if there is no desire or opportunity to buy a ready-made structure, you can make the post-treatment field yourself.

After the soil is removed, a pipe is laid connecting the second container with the filtration field. As a rule, the laying depth is 0.7-1.2 m from the ground surface, but not lower than 1 m from the groundwater level. The bottom of the pit is leveled and a drainage mesh is installed on it. After which sand and crushed stone are poured. The height of the pillow should be such that its top rises above the inlet pipe by at least 5 cm. We should not forget that the pipes are installed taking into account the required slope. It must be at least 1* per 1 m. Pipes must be insulated using a wooden box and polystyrene foam.

Drainage device

Since such soil is not capable of good fluid permeability, a drainage system will be required to remove rain and flood water from the tanks for receiving sewage. To do this, not wall drainage, but ring drainage is performed. To install the pipeline you will need drains. You can use purchased perforated pipes or make them yourself from sewer plastic pipes with a diameter of 110 mm. Perforation is carried out with a drill 1.5-2 mm thick at a distance of 2-2.5 cm from each other. The holes should be staggered.

A trench is formed around the septic tank so that its bottom is 20-30 cm below the freezing point of the soil. Next, the bottom is leveled with a slope that should be at least 1 cm per 1 m towards the storage well. After this, they fill it with 5-7 cm of sand and 10-15 cm of gravel. Then geotextiles are laid on the bottom of the trench. A pipeline is installed inside the ditch and the pipes are wrapped with previously laid material. Then they begin backfilling.

Device Feature

Clay is a highly heaving soil. This property is especially evident if it is wet rather than dry. During seasonal freezing and thawing, such soil can easily push a plastic or other container placed in it out of the hole. Therefore, during the installation of containers for sewage drainage, provision should be made for their fastening in the pit.

This can be done using metal rods, which can be angles or small diameter pipes. The purpose of the rods is to fix the location of the container and prevent it from moving during soil heaving. For this purpose, you can also use steel chains, one end of which is firmly fixed in the soil.

For deeper wastewater treatment, two-stage trenches can be made for the filtration field. In the upper part of such a ditch there are pipes through which wastewater is discharged, and in the lower part there is a sand and gravel cushion up to 30 cm thick. Using such trenches, you can build a full-fledged filter system and remove wastewater outside the site.

The depth of the pits should be such that the liquid in the pipes does not freeze in winter, that is, below the freezing point of the soil. Each pipe will need to be perforated in the same way as a drainage pipe, but the holes should be larger, since the liquid will include small fractions. To prevent clogging of the holes with soil, each pipeline element is wrapped with geotextile.

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Features of clays and loams

A septic tank for clay soil should have some design differences from conventional devices. To understand how a septic tank works in clay, you need to remember how conventional treatment plants work: first, the wastewater enters the sump, being divided into light and heavy fractions, and then the purified water enters the soil, where final purification occurs. To organize soil cleaning, filter wells are used, the design of which includes perforated walls and a drainage bottom. But the performance of such a system depends on several factors: laying depth, wall area, soil water level and the type of soil prevailing in the area.

The last indicator must be considered in more detail, since the efficiency of the entire structure depends on it. For example, one square meter of sandy soil can absorb about 90 liters of liquid per day.

In sandy loam soils this volume is reduced to 50 liters; loamy soils can process no more than 25 liters. In the case of dense clay soil, the situation is even worse: the soil can absorb less than 5 liters of water per day. That is why a septic tank on clay is constructed somewhat differently than conventional structures.

Options for installing a septic tank in clay

Despite the fact that the problem seems insoluble, there are still methods for solving it, and their implementation does not require digging an ordinary cesspool, which will then have to be cleaned regularly. Regardless of the type of prevailing soil on the site, a high-quality local treatment plant can be created if all the factors affecting its performance are properly taken into account. Next will be described possible solutions allowing the use of a septic tank in clay.

Filtration in clay soil

As a rule, the layer of clay soil rarely has a thickness of more than 2-3 meters. This can be noticed when constructing a well: under the upper layers of the earth’s surface you will find sandy loam soils, or even clean sand, which has an excellent water absorption rate. In this case, the well will work much better than it could work in homogeneous soil: the water column will create high pressure.

When choosing a suitable solution, you should first study in detail the types of soil located on the site. You can find out from the old residents of the area, neighbors who have recently carried out construction work, or order a geological survey. The latter option will have maximum accuracy, and there is a point in studying the geology of the site: making a septic tank in clay is much easier and cheaper than purchasing a ready-made biological treatment station, which is only good for the most difficult situations.

Structurally, a septic tank on clay soil can be made in any way: you can install a plastic, brick, reinforced concrete or concrete system. Clay soil does not affect the choice of material at all, so this issue rests entirely on the shoulders of the homeowner, and depends on personal preferences and the amount of finance allocated for construction.

Watering

If there is good fertile black soil on the site, you can reuse water purified by a septic tank to water the plants. To implement such a project, you will need to make the following design: the filter well must be replaced with a sealed tank to which a drainage pump is connected. This pump will supply purified liquid to the irrigation system.

This septic tank design is well suited for summer cottages, but it is not practical to use it in country houses where people permanently live. Another disadvantage is the low degree of purification, as a result of which the treated wastewater has a characteristic sewer smell. To avoid this problem, you will have to use a septic tank with aeration.

Filtration field

Sometimes even the densest soils demonstrate good absorption qualities. Of course, this does not always manifest itself, but if a soil analysis has shown that it can absorb at least a small amount of water, then you can take advantage of this and increase the absorption area. To implement this idea, filtration fields are used.

The structure is prepared as follows:

• first, the entire free area allocated for the structure is filled with crushed stone;
• then drains with holes of at least 2 cm in diameter are laid on it. The length of the pipeline in this case depends on the number of permanent residents: one person requires about 10 meters of pipe;
• then the pipeline is covered with at least a 10-centimeter layer of crushed stone;
• A layer of black soil is laid on top, on which moisture-loving plants can be planted.

This solution is quite convenient: in this case, little depends on the degree of wastewater treatment, because the smell will not be able to escape. In addition, if the depth of the pipes is more than 40 cm, then the sewer can be used even in winter, since the pipeline will not freeze. The disadvantage of the design is the impossibility of using it on soils that are completely impermeable to water.

Dumping into a ditch

In the case of soils that do not absorb moisture at all, you can dispose of wastewater directly onto the site or into a special ditch. Naturally, such a system implies maximum wastewater purification (from 95%) and absence of odor. To implement the design, it is best to use energy-dependent septic tanks using aeration.

Similar treatment plants operate on similar principles:

• the first tank constantly contains air, which supports the vital activity of aerobic bacteria that decompose organic substances entering the septic tank;
• Having passed the aeration stage, wastewater enters the next compartment, where the sludge sinks to the bottom and is transferred to the first container using a compressor;
• final purification is carried out in the third chamber, from which the purified water is pumped out and ends up in a ditch or large area from which it can evaporate.

Conclusion

As you can see from this article, a septic tank in clay soil is not a big problem. The main thing is to correctly understand the characteristics of the site and choose the most suitable design that best suits the specific situation.

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Owners of country houses and summer cottages are faced with the problem of arrangement, which significantly improves the quality of life and comfort of the inhabitants. The simplest and in a reliable way is the construction of a cesspool where all sewage will go.

There are several types of structures. For summer cottages where the amount of waste per day is small, a cesspool without a bottom is perfect. A sealed tank can solve the problem in a country house. Its disadvantage is that you need to periodically call the vacuum cleaners or clean the pit yourself. The third type of design is a storage septic tank. This is a cesspool where artificially grown microorganisms process and decompose sewage.

When choosing the type of cesspool that could handle waste from your home, you need to consider the following parameters:

• groundwater level;
• volume of waste per day;
• number of residents of the house;
• Availability household appliances that consume water (washing machines and dishwashers);
• location of the house and other outbuildings;
• soil type.

Clay soil is one of the main problems of summer residents and owners of country houses. Urban crops do not grow well on such soil; water often stagnates on the site, especially in spring. The installation of sewer tanks on clay soil is also accompanied by some difficulties.

A cesspool in clay soil can often silt up and slowly leak liquid. The most optimal solution for such areas is to install a hermetic tank. You just have to dig a pit and install the container in the hole. But if sewerage is needed in a dacha, where the owners rarely visit, then a sealed cesspool in clay does not justify itself.

Sanitary standards

To avoid troubles during the operation of the drain, when constructing a cesspool in clay soil, it is necessary to comply with sanitary and hygienic requirements.

• The distance from the pit to the well or well should not be less than 20 meters.
• The distance from a residential building is at least 5 meters.
• When setting up a pit on clay soil, it is necessary to take into account the reserve, since liquids settle slowly and the container may overflow.

Important! Failure to comply with sanitary and hygienic standards during the construction of cesspools can cause a number of troubles: misunderstandings with representatives of the law, an unpleasant odor in the area, the spread of infections.

Installation Features

If you install a classic sewer system on an area with clay soil, the efficiency of such a cesspool will decrease. Liquids seep through clay very slowly, so you need to take care of additional outlets. There are two ways to do them well.

Method No. 1

First you need to carry out the necessary earthworks and dig a pit. Now we drill holes at the bottom of the pit where plastic pipes with a large number of holes will be located. To prevent the pipe from clogging, install a plug on it. Thanks to this design, the absorption surface will increase, all the water will drain away faster, and solid impurities will remain at the bottom of the pit.

Method No. 2

This option will help solve the question of how to make a cesspool in loamy soils and on clay soil. It involves the installation of an overflow system, which will help prevent sewer overflow. To do this, you need to dig an additional pit next to the cesspool. To connect them, you should use an inclined trench so that the slope is towards the freshly dug pit.

Note! Various materials can be used to make the walls of a cesspool on clay soil, but they are best suited.

Most often, a cesspool is installed on clay soil using the second method. Two holding tanks can handle large amounts of wastewater faster and more efficiently. When the level of liquid waste in the main tank reaches the place where the connecting pipe is installed, the water will overflow. Solid sewage will remain in the cesspool, so there will be no need to clean the additional pit.

The life of a modern person is filled with a variety of items that provide comfort and convenience. These include water supplied to the house, bathroom fixtures, and a toilet.

But such comfort systems, if they are not part of common system, the presence of which is possible in urban apartment buildings, need an individual wastewater and waste treatment system. Previously people they made do with an ordinary sewer pit, from which the flowing masses were absorbed into the soil, and if they accumulated excessively, they cleaned the ditches using special machines, or the pit was simply moved to another place.

The disadvantage of this method of getting rid of sewage was the saturation of the soil and even water wells with pathologically dangerous microorganisms, which, as a result, became the cause of many diseases in humans and animals. As well as contamination of the land and rendering it unsuitable for agricultural use.

In order to protect the earth and people from dangerous microorganisms, wastewater treatment systems were invented; our company has been installing such systems for many years.

The cheapest and easiest to install treatment option today is a septic tank, which is a complex single-section or multi-section structure that provides partial purification of wastewater and its absorption into the soil or partial drainage. At the same time, the septic tank provides for ground filtration, in which the liquid passes through layers of soil; this requires good drainage properties of the soil and a considerable field of drainage action.

Installing a septic tank on clay soil

Many people, in order to save money, use septic tanks and install them in clay, but such a solution is simply a waste of money and labor. Whatever myths circulate around septic systems, they are intended for sand or other types of soil that can quickly absorb liquid.

They are not suitable for clayey environments due to poor drainage of this type of soil layer - our experts always explain this to the owners of clayey areas, but they do not always listen and drive themselves into unnecessary waste. The recent case of a septic tank in clay became a striking example of the irrelevance of such treatment equipment for clayey areas.

People contacted us due to a malfunction of the septic tank; when opening the pit, our specialists discovered a completely deformed container, completely unsuitable for cleaning anything.

Why do septic tanks installed in clay become deformed?

The septic tank itself is not capable of absorbing large amounts of water, since it is designed for low-volume flow; in addition, it requires good drainage, that is, so that part of the purified water goes into the soil.

It is not typical for clay to absorb liquid, and this leads to the accumulation of liquid around the septic tank or complicates the work of the drain pipe, which, in turn, simply cannot accommodate the amount of liquid designed to pass through the soil layer. This puts pressure on the body of the cleaning device and causes it to deform.

Due to the impassability of the soil, the water simply crushes the septic device. An additional destructive factor is such a feature of clay as frost swelling, in which winter period the clay soil itself begins to put pressure on the septic tank and either pushes it out or deforms it if it is securely fixed.

Making surface drainage of water is also not relevant, since a septic tank does not completely cleanse liquid masses and discharging such water into a ditch or reservoir threatens the spread of harmful bacteria, and therefore promises environmental problems.

What to do if the septic tank is deformed?

Many people who have experienced the failure of a septic tank installed in clay blame the manufacturers of the septic system or the people who carried out the installation. At the same time, unfortunate owners again order and install a similar cleaning system, and after a short time they again receive the same result.

The only solution to this problem, as practice shows, is to replace the wastewater treatment system with an option that is suitable specifically for clay. The most practical solution for non-absorbent soil is considered to be a biological treatment station, which is relevant for any type of soil.

This is exactly the decision our specialists made when they pulled out the above-mentioned deformed septic tank from the ground, and it turned out to be the only correct one.

The thing is that the operation of a septic tank is based on absorbed soil and an extensive filtration field, for which clay cannot act as a field of action because it does not allow water to pass through. The waste pipe of the equipment is not able to do the work for the soil, that is, to pass such a large amount of water, in this case the septic tank itself is deformed if it is made of fragile materials such as polypropylene, or the pipe ruptures if the body of the cleaning device is made of concrete mixtures .

Features of the biological treatment station

The main advantage of the biological station is that it is suitable for any type of soil. It differs from a septic tank in its high level of purification, which is about 98%. In fact, any impurity, thanks to special microorganisms on the influence of which the operation of the device is based, is converted by this installation into two types of useful raw materials: clean process water and compost.

Since the water obtained after filtration using a biological station is completely safe, it can be drained into a ditch, used for watering plants or for other technical needs, without any environmental indicators being violated. The resulting solid raw material can be safely used to fertilize the soil and plants. The following features of a biological station can also be called important:

• Compact, since such a cleaning device does not take up much space;
• Tightness and strong structure, in which the entry of sewage into the soil or water bodies is completely eliminated;
• Duration of operation, which can reach more than 50 years;
• Possibility to use the raw materials obtained after purification for technical purposes.

Principles of installing a septic tank

A septic tank is the simplest form of treatment facilities, and its installation requires compliance with certain rules. Due to the fact that such a cleaning system is not particularly safe, since it is not characterized by complete purification of liquids, such a device should be located no closer than twenty meters from a residential building.

An additional condition for installation is the location of a well or well with drinking water; the distance between it and the septic installation should be no more than 50 meters.

For clay soils, which have low drainage rates, but are considered an excellent environment for the spread of coliform bacteria, this distance can be figuratively increased to 80 meters.

The principle of operation of a septic tank is based on settling waste, so its capacity must be designed for a three-day norm of liquid waste so that it has time to settle. In clay soil there is no possibility for repeated ground filtration, and when settling, the liquid does not drain well due to the strength of the clay, which makes the relevance of a septic tank in clay a common myth.

Principles for installing a biological treatment plant

A biological treatment plant is smaller in size because it does not involve a long-term settling process. Unlike a septic tank, in which waste liquids must stand idle for three days, this device allows you to clean the raw materials in a time not exceeding several hours.

At the same time, there is simply no need for additional ground filtration, because wastewater is processed and purified through the action of biological organisms (bacteria), for which the waste becomes a food product. As a result of such biological processing, the water obtained as a result of processing can be discharged into any reservoir, ditch, ravine, or used for watering plants, since it does not contain hazardous substances at all.

The body of the biological station is always sealed and made of durable materials, so for installation you don’t have to move the treatment station to a great distance from the living room, and since the waste after such purification is safe, you don’t have to be afraid of the installation’s proximity to a well or water pipes.

Another advantage of this cleaning equipment is that it does not require insulation, since it operates from the network and provides preheating.

What should you choose?

Some owners of clay plots still prefer to use a cheaper septic tank instead biological system cleaning and looking for options for its correct installation.

Many not entirely conscientious experts suggest additional securing of the septic tank in order to prevent it from being pushed out during frost. It is often recommended to install a septic device near the surface to ensure at least partial drainage and filtration by the top layer of soil. At the same time, in order to be able to function, the device is insulated with the help of additional materials.

All these methods are good only in theory; in practice, any of them will soon lead to the destruction of the septic tank and problems in the autonomous sewer system.

If the site is endowed with clay soil, the only way to provide high-quality wastewater treatment is a biological treatment station, without which it is simply impossible to make an autonomous sewer system located on clay soils safe.

It just so happens that our comfort and additional amenities often become the cause of pollution. environment, this especially applies to places with clay soil. In order not to harm the environment, every owner of private sewer systems is simply obliged to take responsibility for wastewater treatment.

Saving in the form of a septic tank would in this case be a wrong decision, threatening unforeseen consequences; therefore, preference should still be given to a biological treatment plant.

To organize sewerage in a private house, so that the septic tank lasts a long time and remains durable and airtight, in addition to many nuances, it is necessary to take into account the type of soil. Currently using different types septic tanks that are installed underground and above ground. Aboveground ones, however, are already used very rarely, since they give off an unpleasant odor that spreads to the area.

Choosing a place to install a septic tank on clay soil

When digging a hole underground, you can use a gravel pad or a concrete pad. The latter option is more preferable, especially if you plan to lay polymer containers.

Installation Features

When installing a septic tank, the following are taken into account:

• soil type;
• groundwater level;
• the location of the house itself;
• fence and other buildings;
• vegetable garden

Based on this, the depth where they will be carried out is calculated. sewer pipe. It must be at least seventy-five centimeters. The level of freezing of clay in the cold season, which, by the way, can be high, is also taken into account. The septic tank must be installed in such a way that filtration occurs above the groundwater level, otherwise suction will be insufficient. After laying, the pipe is covered with earth until a small hill is obtained.

It is advisable to insulate the septic tank with polystyrene foam.

In order for it to be firmly anchored underground, it is necessary to ensure good drainage, otherwise the container may go deeper into the soil. After the pit is constructed, a diversion is carried out for dispersion. It would also be a good idea to install a drainage pump.

In order for septic tanks in clay to be perfectly fixed, it is additionally advisable to attach them with steel ropes. Filtration trenches must be two-stage. The right pillow is made of gravel and sand thirty centimeters thick. At a depth of fifty centimeters to a meter, a perforated pipe is laid for filtration. In the second trench, the pipe is placed at a depth of one and a half to two meters.

It is more difficult to install a septic tank on a clay base due to the characteristics of this type of soil: its average porosity has poor ability to pass liquid. Therefore, special attention should be paid here to the drainage or filter floor. This will entail additional material costs. If the thickness of the clay exceeds three meters, then it is necessary to replace part of the soil with crushed stone and sand, since these materials have excellent throughput.

The installation location of the septic tank should be designed in such a way that it is as far away from the water intake point as possible. For clay soil, this distance can be from twenty meters. The settling tank itself is placed below the freezing depth of the soil due to the heaving properties of clay.

Thus, despite the difficult nature of this type of soil, it is possible to install a septic tank, but the behavior of clay soil should be taken into account.

Types of septic tanks

Not all types of septic tanks are suitable for clay soil.

Tanks for the sewer system are divided according to the nature of their work into:

• storage, in the form of settling tanks that are cleaned as sewage accumulates;
• for deep cleaning, after which the water can be used;
• for soil filtration, when purified water completely goes into the soil.

In the last two cases, all septic tank containers also need to be periodically cleaned, but this is done much less frequently than in the first case.

Devices can be:

• monolithic;
• prefabricated.

According to the material produced, they are divided into septic tanks from:

• reinforced concrete;
• bricks;
• metal;
• plastic.

According to their form, septic tanks are:

• horizontally installed;
• vertically installed.

They consist of:

• one camera;
• two cameras;
• several cameras.

Storage septic tanks for clay soil

This type of sewer septic tanks consists of pits or special containers that are placed in dug holes. The bottom is treated, drained or a concrete pad is laid. In dug pits, wastewater is separated into light substances, which will float, and heavy solid waste, which will settle to the bottom. Such a septic tank is very easy to install, but it is inconvenient to operate, since it will emit an unpleasant odor.

Storage septic tanks are made of plastic or fiberglass. They are sealed and do not corrode, but require installation to ensure the device remains firmly in place. Sometimes septic tanks are simply built from brick or reinforced concrete rings.

Some owners of suburban areas dig a hole, install formwork and fill it with concrete. But this will be a good solution only in the case of a small plot and for temporary residence in a private house. In addition, for such a septic tank you will have to call a sewer truck quite often for cleaning, and the smell emanating from the pit will clearly not add to the comfort of staying outside the city.

This type of septic tank is well suited for clay soil, especially if it is well secured.

Septic tank with soil treatment

For such a septic tank, which provides for soil post-treatment, a cleaning machine is called less often than for a simple storage tank. This type of septic tank provides for a barrel size larger than in a storage form. But installing it in the ground is more difficult, since additional protection measures must be provided here.

A concrete cushion is placed at the bottom, the septic tank itself is placed and secured with chains. This is done so that it stays firmly in one place and cannot be pushed out, which can happen in the cold season. It also needs to be protected from being simply crushed with earth when buried. To do this, it is filled with water when instilled. Sometimes special batteries are used, which can significantly reduce the frequency of cleaning. This type of septic tank is easy to install yourself. The wastewater in it first enters one chamber, where it is divided into layers, one of which settles, and the other, on the contrary, floats up. Partially clarified water then enters the next chamber, where decomposition occurs with the help of anaerobic bacteria artificially planted there. In the second chamber, the water is thus purified by sixty percent.

Such septic tanks are quite easy to operate and are used frequently. However, unfortunately, they are not suitable for clay soils. More precisely, the implementation of the method is possible by laying an artificial sand filter and an additional structure for water drainage. But doing this is not only too difficult, but also quite expensive. Therefore, on such soil, usually, a septic tank with soil post-treatment is not used.

Biological deep cleaning

Septic tanks with biological treatment are reliable and durable. With their help, high-quality purification occurs, as a result of which the water can be used for technical needs. The method used is a combined one, providing deep cleaning. In addition to mechanical settling, chemical and biological methods are used.

The wastewater in it is treated as follows. First, as in previous types of septic tanks, they end up in a sump tank, where a layer of more or less purified water is formed. It moves into the next chamber, where anaerobic bacteria are added, which perform secondary purification. After this, the water does not come out, but continues to be purified chemically, as a result of which the most high level purification achieved by ninety-eight percent.

Of course, not a single septic tank used in private country houses can guarantee one hundred percent cleaning. Therefore, you should never drink such water. But it is quite applicable for technical needs. So, you can use it to water your garden, flower beds, or just the grass near your house, as well as wash cars, etc. You can install it either with your own hands or with the help of specialists. It all depends on the complexity of the design.

Such sewerage on clay soils is possible in the same way as on other soils. However, the disadvantage here is the high price of the septic tank. The purchase of this device will be justified only if people live in the house permanently. It usually requires an electrical outlet to operate. Therefore, for uninterrupted operation, it is necessary to ensure that there are no surges in electricity. Often an autonomous system is used for this.

Installation at high groundwater level

If the level of groundwater in the area is high, then it is better if the septic tank is installed by professionals. You can also do this yourself, but you need to prepare for difficult work.

Gaps of ten to fifteen centimeters are left between the walls of the septic tank and the pit.

A sand cushion with a thickness of at least five to ten centimeters is laid below, and if the water underground is too close to the surface, then formwork is used.

It is necessary to pay careful attention to backfilling, since if it is done incorrectly, this may cause the container to move. The remaining distance between the septic tank and the pit is covered with sand.