Septic tank in clay soils. Septic tank technology in clay soil

many owners country houses Interested in whether it is possible to make a septic tank on clay. the main problem with device treatment plant on this type of soil is that the pre-treated wastewater after passing through the septic tank is discharged into the soil, and the clay does not pass well and filters the water. However, even on clay soil an autonomous cleaning plant can work efficiently and for a long time, provided correct device. In our article, we will consider different types septic tanks that can be made on clay soil, as well as the features of their design and choice.

To make it easier for you to understand which septic tank is needed for clay soils, you need to study the features of this soil. To equip effective system sewers, drains after cleaning in a septic tank are discharged into the ground. The main feature of clay soils is poor absorbency. The earth does not absorb liquid well. This results in wastewater remaining in the treatment plant longer.

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

That is why, equipping a septic tank from concrete rings, plastic or metal containers, it is necessary to organize effective drainage. It 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 cottage or country house is located on a site with clay soil, then the following types of treatment facilities can be used to process wastewater coming from the sewer from the house:

storage tanks. For these purposes, you can use sealed containers made of plastic or eurocubes. However, stainless steel tanks are also suitable for clay soils. It is also possible to make a sealed well from concrete rings if the groundwater level in the area is high. For a small private house, a brick drainage well can be made, provided that the correct technology is used.
Wastewater treatment plant with soil post-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 plant can be made of concrete rings, brick or metal, that is, any material can be used for such soil.
Units with biological treatment- this is the most reliable and effective option for clay soils, suitable for a private house of any size. However, such a septic tank on clay will have the most complex structure, therefore, its choice should be made if there is money and time for its implementation.

Important: sewerage 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 performance of the structure, the required degree of wastewater treatment and GWL.

Storage tanks

If you decide to equip the sewerage 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 there is a high GWL in your area or there is a well near the storage tank, then it is not recommended to use such a design.

Structures with soil aftertreatment

These simple treatment facilities are very similar to storage tanks, but without a bottom. The very design of the well can be made of concrete rings, bricks or a bottomless daughter. A drainage layer is arranged at the bottom of the structure.

To make a drainage filter, it is necessary to use geotextiles, sand and gravel. The thickness of the filtering 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 arranging this septic tank, you need to know the GWL, because the bottom of the filtering layer cannot approach the aquifer closer than 1 m.

Units with biological aftertreatment

These are the most reliable and efficient treatment facilities that can be installed independently of the GWT on the site. These self-contained biological treatment plants treat wastewater so effectively that the water can then be used to irrigate the garden, drain into open water bodies or take it for technical needs.

Usually these are multi-chamber products, where effluents immediately from the sewer are divided into heavy and light fractions. Then the clarified waters go through the process of biological post-treatment with the help of bacteria (anaerobic or aerobic).

Design features

Since any septic tank design can be used on clay soil for the sewerage of a country house, the construction scheme will be standard. but main feature clay soil is that it is a 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 GWL and septic tanks made of light materials. That is why, when installing a septic tank in clay, it is necessary to provide additional clamps in the ground. If the well of the treatment plant will be made of concrete rings, then it is enough just to fill it in the pit without fixing.

The choice of method for fixing the septic tank in the pit depends on the design of the body. 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 cushion at the bottom of the pit.

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

Mounting Features

To perform a more efficient septic tank design, it is recommended to use two chambers and a filtration field. So you can avoid overfilling the tank and get the most purified water at the outlet of the treatment plant. After you decide on the material of the chambers, you can start digging a pit and further work which execute in this order:

When choosing a place for a septic tank, you can observe the minimum recommended gaps from a residential building and sources drinking water(7 m), because the clay does not pass water well. The size of the pit for the treatment plant should be 20 cm larger than the septic tank itself.
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 performed at a considerable depth. It is also worth considering that the septic tanks are interconnected by overflow, so they should be located at a distance of 15-20 cm from each other.
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 each meter of length, the decrease is 2 cm.
Depending on the containers used, the bottom of the pit can be concreted before or after installation. If you use plastic sealed tanks, then the bottom is concreted and reinforced before they are installed. And after installation, these tanks are attached with hummocks to the outlets of the reinforcement. When using concrete rings, the bottom can be concreted after they are installed in the pit.
To make a filter layer at the bottom of the second chamber, sand and crushed stone are used. First, sand is poured and rammed with a layer of 10-15 cm, then they are backfilled with crushed stone 25-30 cm high. If you use the filtration field, then the bottom of the second chamber is also concreted, and the drains are diverted to the filtration fields.
Next, an overflow pipe is installed connecting the two containers. It should exit the first chamber 40-50 cm below the entry point of the sewer pipe. Due to this, heavy components of wastewater will settle at the bottom of the first chamber, and pre-treated and clarified water will enter the second tank.
Mounted ventilation pipes from the cameras.
After that, plastic containers are insulated with foam. For concrete rings, insulation is not required.
The containers are covered with lids with hatches for cleaning.
Now perform backfill pit by hand. Every 15-20 cm, the soil must be rammed. The manhole cover must remain above the ground.

The filtration field is made depending on the GWL on the site:

at low GWL, semi-submerged filter cassettes or filters are used;
at high GWL, surface filtration on sand and gravel pads is used.

Important: dimensions filtration field are directly related to the daily volume of effluents from the house.

One square meter filtration field is able to serve 0.5 cubic meters of wastewater. You can purchase ready-made filter wells based on geotextiles or do the field yourself:

After digging the soil from the field, a pipeline is laid from the last chamber of the septic tank to the filtration field. Laying depth - 70-120 cm from the ground, but not less than 1 m to the groundwater level.
A drainage grid is laid at the bottom of the field. Then a layer of sand and gravel 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.
The drainage pipeline is insulated with foam or a wooden box.

A life modern man 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 managed with an ordinary sewage pit, from which the flowing masses were absorbed into the soil, and when they accumulated exorbitantly, the ditches were cleaned with the help of special machines, or the pit was simply transferred to another place.

The downside 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 bringing it into a state of unsuitability for agricultural use.

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

Today, the cheapest and easiest to install treatment option is septic tank, which is a complex single-section or multi-section design 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 the soil layers, for this you need 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 go around septic systems, they are designed for sand or other types of soil capable of quickly absorbing liquid.

They are not suitable for a clay environment due to poor drainage of this type of soil layer - our specialists always explain this to the owners of clay plots, but they do not always listen and drive themselves into unnecessary waste. A recent case with a septic tank in clay has become a prime example of the irrelevance of such cleaning equipment for clay terrain.

We were approached by people due to a malfunction of the septic tank, when opening the pit, our specialists found a completely deformed container, completely unsuitable for cleaning anything.

Why are septic tanks installed in clay deformed?

By itself, the septic tank is not able to absorb 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 treated water goes into the soil.

Clay does not tend to absorb liquid, and this leads to the accumulation of liquid around the septic tank or complicates the work for drain pipe, and that, in turn, simply cannot accommodate the amount of liquid designed to pass through the soil layer. Thus, pressure is exerted on the body of the cleaning device and it is deformed.

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 a surface outflow of water is also not relevant, since the septic tank does not completely clean the liquid masses and draining such water into a ditch or reservoir threatens the spread of harmful bacteria, which means it promises environmental problems.

What to do if the septic tank is deformed?

Many people who experience a failure of a septic tank installed in clay blame the manufacturers of the septic system or the people who installed it. At the same time, the unfortunate owners again order and install a similar treatment system, and through a short time again get 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. by the most practical solution for non-absorbent soil, a biological treatment plant is considered, which is relevant for any type of soil.

It was this decision that our specialists made, having taken the above-mentioned deformed septic tank out of the ground, and it turned out to be the only correct one.

The thing is that the work of a septic tank is based on absorbable soil and an extensive filtration field, for which clay cannot act as a field of action, since it does not let water through. The sewer 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, either the septic tank itself is deformed if it is made of fragile materials such as polypropylene, or the pipe breaks if the body of the cleaning device is made of concrete mixtures .

Features of the biological treatment plant

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

Since the water obtained after filtering with a biological station is completely safe, it can be drained into a ditch, used for watering plants or for other technical needs, while not a single environmental indicator will be violated. The resulting solid raw material can be safely used to fertilize the soil and plants. The following features of the biological station can also be called important:

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

Principles of installing a septic tank

The septic tank is the simplest form treatment facilities, while 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 the 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 medium for the spread of intestinal bacteria, this distance can be figuratively increased to 80 meters.

The principle of operation of the septic tank is based on the settling of waste, so its capacity should be designed for a three-day rate of liquid waste so that they have time to settle. In clay soil, there is no possibility for repeated ground filtration, and when settling, the liquid drains poorly 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

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

At the same time, there is simply no need for additional ground filtration, because the processing and purification of wastewater is carried out due to the impact of biological organisms (bacteria) on them, for which 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 hermetically sealed and made of durable materials, so for installation it is possible not to move the cleaning station away for long distance from the dwelling, and since the waste after such purification is safe, you should not be afraid of the proximity of the installation to a well or water pipes.

Another advantage of this treatment equipment is that it does not require insulation, since it works from the mains and provides for preheating.

What to choose?

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

Many not entirely conscientious experts offer additional fixing 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 in order to provide at least partial drainage and filtering by the topsoil. At the same time, for the possibility of functioning, the device is insulated with the help of additional materials.

All these methods are good only theoretically, in practice, any of them will soon lead to the destruction of the septic tank and malfunctions 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 plant, 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 extras are often the cause of pollution. environment, especially in places with clay soil. In order not to harm the environment, each owner of private sewer systems is simply obliged to take responsibility for wastewater treatment.

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

The choice of a septic tank for clay soil and its installation is challenging tasks requiring compliance with a number of rules. Incorrect installation of such structures on loam can cause deformation of the septic tank and disrupt its operation.

It is difficult to install a septic tank on clay, because. the characteristics of this soil do not predispose to the rapid disposal and purification of wastewater. Clay does not absorb water well. Effluent stays in the tank. Sandy soil can absorb up to 90 liters of water per day, while loam - only 25 liters. Pure clay has lower water absorption rates. In addition, clay soils are characterized by high density and high weight. When arranging autonomous sewerage these features must be taken into account.

Why are septic tanks installed in clay deformed, and how to avoid this?

Most often, when arranging septic tanks, large-volume plastic containers are used. They are good option for many types of soils, but they are not quite suitable for clay. Having a high density and weight, clay often deforms containers even from dense plastic during seasonal temperature fluctuations. In some cases, deformation of even metal containers is possible. In addition, septic tanks in clay soil are often deformed due to ground movements. This happens especially often if the groundwater is too close to the surface.

When planning the installation of a septic tank in clay soil, it is necessary to take into account the danger of possible deformation of the container. To prevent the occurrence of such a problem, it is desirable to use rigid materials for arranging the structure, including concrete rings, slabs, etc.

Plastic containers can also be used if desired. But to protect them from soil movements, it is imperative to make a special structure made of concrete or strong wooden crate. This will avoid damage to the integrity of the tank due to ground pressure. If the level ground water low, you can use metal fittings or corners to make the crate.

What septic tanks can be used in clay?

When arranging a septic tank on clay soil, it should be borne in mind that it is almost impossible to create high-quality filtration fields, so classical multi-level systems should be abandoned. There are several options for autonomous sewers that can be used effectively.

Storage tanks

The simplest and cheapest option for a septic tank, suitable for arrangement in clay soil, is a storage system. In conditions of clay soil and to save money on pumping water in the future, you can use a complex storage system consisting of several tanks connected to each other. Such cleaning systems can be created on the basis of:

concrete rings;
wells lined with bricks;
large metal barrels;
plastic containers, etc.

Such a septic tank for clay soil is an analogue cesspool and requires systematic pumping of accumulated effluents with a sewage machine.

With soil treatment

Septic tanks, consisting of several storage tanks and an artificially created filtration field, can reduce the cost of pumping wastewater. In this case, some of the already settled effluents will enter the filtration field and go into the soil. The design in this situation will be simple. Several containers are connected in series with each other so that heavily polluted drains remain in the first of them, and the already settled water penetrates into the next container.

It does not have to be only 2 containers. Some homeowners connect 3-4 containers at once. This allows you to ensure that almost clean water enters the last cavities of the septic tank. The difficult moments of arranging such a system are the preparation of the site and the installation of the filtration field system.

Due to the presence of clay in the place where the filtration field will be located, it is required to dig a pit 1 m deeper than the bottom of the pit intended for installing the system. At the bottom of the pit, gravel or gravel is poured, as well as a layer of sand. Perforated pipes are laid inside such a pillow so that purified water from the last tank can be discharged to the filtration field. It should be borne in mind that there must be at least 50 cm of crushed stone and sand on top of the pipes.

In the process of shrinkage, the filtration field can become heavily clogged with clay and cease to perform its function. To delay such an unfavorable outcome, the finished filtration field should be covered with geotextiles. Clay can be poured over this material. This will avoid inflating the clay and clogging the cavities between the rubble with it.

For biological treatment

Closed septic tanks with biological treatment are very popular with owners of sites with clay soils. Such systems are autonomous sewerage stations. They give a high degree purification, so in the future the resulting water can be used for technical needs and for irrigation of the site.

Such autonomous sewers are multi-chamber products, where effluents immediately undergo fractional division and settle. The clarified effluents are additionally treated with special bacteria that process all organic compounds present.

Design features of a septic tank for clay

The physical properties of clay soils change slightly during the period of freezing and thawing. This often becomes the reason for the gradual pushing of the septic tank to the surface. Especially this problem often occurs when installing septic tanks, which were made of lightweight materials, including plastic and metal.

To prevent the appearance this effect fixation of the structure in the pit is required. For additional fixation, metal fittings and concrete mortar. If the surface of the container is equipped with special holes, metal cables can be used to fix it at the bottom of the pit.

In addition, a thick bed of gravel and sand is recommended to prevent tank displacement. It is also possible to make concrete slab, which will serve as the base. When filling it, you can make "ears". With their help, you can later more securely attach the septic tank to the base.

By doing earthworks when arranging an autonomous sewer, all safety measures must be observed, since clay can quickly collapse. It is best to dig a septic tank hole at least 1.5 m wider and longer than required. This will avoid surprises due to the collapse of the clay.

Features of installation on clay soil

When planning the installation of a septic tank on clay soils, it is necessary to observe sanitary requirements location of autonomous treatment facilities. The distance to the house and other capital buildings should be at least 20 m.

In addition, if a septic tank for clay soil has a filtration well and will purify water not only due to the operation of a sewage machine, it must be taken into account that the distance to a well or other source of water must be at least 50 m. This will prevent pollution by drinking water.

It is best to start installation when dry weather sets in for a long time. This will ensure the reduction of groundwater. When digging a pit, all precautions should be observed. The height of the pit must be at least 70 cm more than the height of the selected septic tank. A 10 cm layer of sand is laid at the bottom of the pit. After that, 30 cm of a layer of gravel is poured. On top of this, laying geotextiles is recommended.

After that, a connected reinforcing mesh required for pouring the concrete substrate. If necessary, a wooden or metal crate is formed to protect the septic tank from being squeezed. After the bottom of the pit is prepared, you can proceed to the installation of the septic tank design. Be sure to fix the container with cables or metal rods. After that, you need to install all communication pipes, fill in the cavities around the septic tank and compact the 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 effluents into the ground. The most difficult thing is to mount a septic tank on clay, which has a minimum liquid filtration coefficient.

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

Considering that on clay soils drainage systems(filter fields) in many cases only work in upper layers soil, you have to resort to a shallow septic tank.

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

Insulation of a septic tank with glass wool

In the simplest case, they resort to filling an additional layer of soil above the relief (forming a hillock above the installation site of the septic tank).
It is more efficient to insulate the treatment plant with special heat-insulating materials, the choice of which is quite wide. The most affordable (in terms of cost) method is filling the container with expanded clay. More effective is the use of expanded polystyrene (preferably extruded) or polyurethane foam. In addition, active protection systems against the effects of negative temperatures. To do this, use a heating electrical cable, thermal power which will reliably protect the septic tank from freezing even in harsh climatic conditions.

Removal of treated wastewater

The main problem for those who decide to arrange an autonomous sewage system and mount a septic tank in clay soil is the difficulty of removing treated wastewater. Such a soil has a minimum filtering capacity, which creates whole line sometimes intractable problems.

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

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

The disadvantages of this method include the need for a large capacity device, otherwise pumping will have to be done very often. But if there is no other way out, it is necessary to use this particular technology.

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 effluents even with the minimum drainage capacity of the soil.

The device of a number of serial drainage wells, while 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 the filtering horizons of the soil, which will help to significantly increase the productivity of the structure. Drilled wells must be protected with casing pipes, and install a simple mesh filter at their mouth, which will prevent silting of additional drainage.

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

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

To increase the efficiency of the filtration field, 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 deepened as far as the groundwater level allows.

The filter line is laid in pre-prepared trenches, which are covered with a geotextile sheet. On a bed of crushed granite (it is not recommended to use another one due to the tendency to erode) with a thickness of at least 20 cm are laid drainage pipes. From above, they are also covered with a layer of rubble, which can significantly increase the volume of discharged effluents. The entire resulting system is covered with geotextile, which will ensure the durability of the line.

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

Of course, the installation of septic tanks in clay involves a significant increase in the amount of work performed during installation. But provide efficient work installations of local wastewater treatment even in such conditions is quite possible.

To organize sewage in a private house, so that the septic tank serves for a long time and remains strong and airtight, in addition to many nuances, it is necessary to take into account the type of soil. Currently, different types of septic tanks are used, which are installed underground and above ground. Elevated, however, are already used very rarely, since it comes from them bad smell extending to the area.

Choosing a place to install a septic tank on clay soil

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

Installation Features

When installing a septic tank, take into account:

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

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

It is desirable to insulate the septic tank with foam.

In order for it to be firmly fixed underground, it is necessary to provide good drainage, otherwise the container may go deep into the soil. After the construction of the pit, a drainage is carried out for dispersion. It would also be useful to install a drainage pump.

strengthening the soil and the installation site of the septic tank

In order for septic tanks in clay to be perfectly fixed, it is additionally desirable 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 already placed at a depth of one and a half to two meters.

Installing a clay-based septic tank is more difficult due to the characteristics of this type of soil: its average porosity has a poor ability to pass liquid. So Special attention here should be given 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 site of the septic tank should be calculated in such a way that it was as far as possible from the water intake point. For clay soil, this distance can be from twenty meters. The sump itself is laid 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 sewer system are divided according to the nature of the work into:

accumulative, in the form of sedimentation tanks that are cleaned as sewage flows accumulate;
for deep cleaning, after which water can be used;
for soil filtration when the purified water completely goes into the soil.

In the last two cases, all septic tanks also need to be cleaned periodically, 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 mounted.

They consist of:

one camera;
two cameras;
multiple cameras.

Accumulative septic tanks for clay soil

This kind sewer septic tanks represents pits or special containers that are placed in dug pits. The bottom is treated, drained or a concrete pillow is laid. In excavated pits, runoff is separated into light substances that will float up and heavy solid wastes that settle to the bottom. Such a septic tank is very easy to install, but it is inconvenient to operate it, as an unpleasant odor will come from it.

installation of a Biotank type septic tank for clay soil

Accumulative septic tanks are made of plastic or fiberglass. They are sealed and will not corrode, but require installation to ensure that the device is firmly stable. Sometimes septic tanks are built simply from bricks or reinforced concrete rings.

Some owners of suburban areas dig a hole, install formwork and fill it with concrete. But it will good decision only in case small area and for temporary residence in a private house. In addition, for such a septic tank, you will often have to call a sewage truck for cleaning, and the smell emanating from the pit will obviously 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 fixed.

Septic tank with soil aftertreatment

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 storage form. But it is also more difficult to install it in the ground, since there should be provided additional measures protection.

A concrete pillow is laid 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. A septic tank of this type is easy to install on your own. Wastewater in it, they first fall into one chamber, where they are divided into layers, one of which settles, and the other, on the contrary, emerges. Partially clarified water then enters the next chamber, where decomposition takes place with the help of anaerobic bacteria artificially planted there. In the second chamber, the water is thus purified by sixty percent.

installation of a storage tank for a septic tank on clay soil

Such septic tanks are quite easy to operate and are used frequently. However, they are not suitable for clay soils. Rather, the implementation of the method is possible when laying an artificial sand filter and an additional structure for water drainage. But to do 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 cleaning takes place, as a result of which water can be used for technical needs. The applied method is combined, providing deep cleaning. At the same time, in addition to mechanical settling, chemical and biological methods are used.

Waste masses in it are cleaned as follows. First, as in the previous types of septic tank, they fall into the sump, where a layer of more or less purified water is formed. It passes into the next chamber, where anaerobic bacteria are planted, which perform secondary purification. After that, the water does not come out, but continues to be purified. by chemical means, resulting in the most high level cleaning, achieved ninety-eight percent.

Of course, one hundred percent cleaning cannot be guaranteed by any septic tank used in private country houses. Therefore, you should not drink such water in any case. But it is quite applicable for technical needs. So, it can be used to water the garden, flower beds or just grass near the house, as well as wash cars and more. You can install it either with your own hands or with the help of specialists. It all depends on the complexity of the design.

soil preparation for a septic tank

Such sewerage on clay soils is possible in the same way as on other soil. However, the disadvantage here is the high price of a septic tank. The purchase of this device will be justified only if people live in the house permanently. It usually requires electrical network. 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 GW

If the groundwater level is high on the site, then it is better if professionals install the septic tank. You can also do it yourself, but you need to prepare for difficult work.

Between the walls of the septic tank and the pit, gaps of ten to fifteen centimeters are left.

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

It is necessary to carefully consider the backfill, because if it is done incorrectly, this can cause the container to move. The distance left between the septic tank and the pit is covered with sand.