The choice of a septic tank for clay soil and its installation are complex tasks that require adherence to a number of rules. Incorrect installation of such structures on loam can cause deformation of the septic tank and disruption of 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. The effluent is retained in the container. Sandy soil is capable of absorbing up to 90 liters of water per day, while loams - only 25 liters. Pure clay has lower water absorption rates. In addition, clay soils are dense and heavy. When arranging an autonomous sewage system, these features must be taken into account.
Why are septic tanks installed in clay deformed, and how to avoid it?
Most often, when arranging septic tanks, large-volume plastic containers are used. They are a good option for many types of soil, but they are not very suitable for clay. Due to its high density and weight, clay, during seasonal temperature fluctuations, often deforms containers, even from dense plastic. 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, one must take into account the danger of possible deformation of the container. To prevent the appearance of such a problem, it is advisable to use rigid materials for arranging the structure, including concrete rings, slabs, etc.
If desired, you can use plastic containers. But to protect them from soil movements, it is imperative to make a special structure of concrete or a strong wooden crate. This will avoid damage to the integrity of the container due to soil pressure. If the water table is low, you can use metal reinforcement or corners to make the lathing.
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, therefore, classical multi-level systems should be abandoned. There are several options for autonomous sewers that can be effectively used.
Storage tanks
The simplest and cheapest option for a septic tank, suitable for arranging in clay soil, is a storage system. In conditions of clay soil and in order to save money in the future for pumping water, you can use a complex accumulation system, consisting of several containers connected to each other. Such purification systems can be created on the basis of:
- concrete rings;
- wells lined with bricks;
- large metal drums;
- plastic containers, etc.
Such a septic tank for clay soil is an analogue of a cesspool and requires systematic pumping of accumulated wastewater by a sewage machine.
With soil post-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 effluent will enter the filtration field and go into the soil. The construction in this situation will be simple. Several containers are connected in series with each other so that heavily contaminated drains remain in the first of them, and the already settled water penetrates into the next container.
It doesn't have to be only 2 containers. Some owners of personal plots connect 3-4 containers at once. This makes it possible to ensure that water enters the last cavities of the septic tank almost clean. The difficult moments of arranging such a system are site preparation and installation of a 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 the installation of the system. Gravel or crushed stone, as well as a layer of sand, are poured into the bottom of the pit. Perforated pipes are laid inside such a pillow so that the purified water from the last container can be discharged to the filtration field. It should be borne in mind that on top of the pipes there must be at least 50 cm of crushed stone and sand.
During the shrinkage process, the filtration field can become heavily clogged with clay and cease to perform its function. To postpone such an unfavorable outcome, the finished filtration field should be covered with geotextiles. Clay can be poured over this material. This will prevent the clay from swelling and clogging the cavities between the rubble.
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 provide a high degree of purification, therefore, in the future, the resulting water can be used for technical needs and for irrigation of the site.
Such autonomous sewerage systems are multi-chamber products, where the effluent is immediately subjected to fractional division and is defended. Clarified wastewater is additionally purified by special bacteria that recycle all the organic compounds present.
Design features of a septic tank for clay
The physical properties of clay soils change slightly during freezing and thawing. This often causes the septic tank to be gradually pushed to the surface. Especially this problem often arises when installing septic tanks, which were made of lightweight materials, including plastic and metal.
To prevent the appearance of this effect, it is required to fix the structure in the pit. For additional fixation, metal reinforcement and concrete mortar are often used. If the surface of the tank is equipped with special holes, metal cables can be used to fix it to the bottom of the pit.
In addition, to prevent displacement of the container, it is recommended to arrange a thick substrate of gravel and sand. It is also allowed to manufacture a concrete slab, which will serve as a base. When filling it, you can make "ears". With their help, you can further more reliably attach the septic tank to the base.
When performing earthwork when arranging an autonomous sewage system, all safety measures must be observed, since the clay can quickly collapse. It is best to dig a septic tank at least 1.5 m wider and longer than required. This will avoid any surprises due to the collapse of the clay.
Features of mounting on clay soil
When planning the installation of a septic tank on clayey soils, it is necessary to comply with the sanitary requirements for the location of autonomous treatment facilities. The distance to the house and other capital buildings must 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 drains.
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 safety precautions should be observed. The height of the pit should be at least 70 cm higher than the height of the selected septic tank. A 10 cm layer of sand is laid at the bottom of the pit. After that, a 30 cm layer of gravel is poured. Laying geotextiles on top of this is recommended.
After that, a connected reinforcing mesh is laid on the bottom of the pit, which is necessary for pouring a concrete substrate. If necessary, a wooden or metal crate is formed to protect the septic tank from crushing. After the bottom of the pit has been prepared, you can proceed to installing the septic tank structure. It is imperative to fix the container with cables or metal rods. After that, you need to install all the communication pipes, fill up the cavities around the septic tank and tamp the soil.
Many owners of country houses are interested in whether it is possible to make a septic tank on clay. The main problem with the device of a treatment plant on this type of soil is that the pre-treated wastewater after passing the septic tank is discharged into the ground, and the clay does not pass and filter water poorly. However, even on clay soil, an autonomous sewage treatment plant can work efficiently and for a long time, provided it is properly installed. In our article, we will consider different types of septic tanks that can be made on clay soil, as well as the features of their design and selection.
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. In order to equip an efficient sewerage system, the effluent after cleaning in a septic tank is discharged into the ground. The main feature of clay soils is poor absorbency. The earth does not absorb liquid well. This leads to the fact that the waste water remains 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 liters / day. And pure clay absorbs even less water - 20 liters.
That is why, when 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 summer cottage or country house is located on an area with clay soil, then the following types of treatment facilities can be used to process wastewater coming through the sewer from the house:
- Storage tanks... For these purposes, you can use sealed plastic containers or eurocubes. However, stainless steel tanks are also suitable for clay soils. You can also make a sealed well from concrete rings if the groundwater level in the area is high. For a small private house, you can make a brick drainage well, provided that the correct technology is used.
- Wastewater treatment plant with soil post-treatment... This is a fairly effective, budgetary 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.
- Biological treatment units- 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 design, so its choice should be made if there is money and time to complete it.
Important: the sewage system from a country house on clay soil can be diverted to a septic tank of any design. It is important to correctly 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 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 treatment plant. 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 structure.
Constructions with soil purification
These simple wastewater treatment plants are very similar to storage tanks, but without a bottom. The very structure 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, you need to use geotextiles, sand and crushed stone. The thickness of the filtering layer is 30-40 cm. When passing through this filter, the drains are cleaned of coarse fractions and enter the soil.
If there is a well in your area nearby, then such a treatment plant design 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 post-treatment
These are the most reliable and efficient treatment facilities that can be installed independently of the groundwater level at the site. These autonomous biological treatment plants purify wastewater so efficiently that the water can then be used to irrigate the garden, drain into open water bodies or take for technical needs.
Usually, these are multi-chamber products, where wastewater immediately from the sewer is divided into heavy and light fractions. Then the clarified water undergoes a biological post-treatment process using 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. However, the main feature of clay soils is that it is a mobile soil. Therefore, it is worth considering some of the design features of the septic tank.
The fact is that when, after the winter cold, the soil begins to thaw, 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 fixators in the ground. If the well of the treatment plant will be made of concrete rings, then it is enough to simply fill it up in the pit without fixing it.
The choice of the method of 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 excavation.
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 a double drainage, that is, two filtration fields. In this case, the drainage should have 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 made of gravel.
Installation features
For a more efficient design of a septic tank, it is recommended to use two chambers and a filtration field. So you can avoid excessive overfilling of the reservoir and get the most purified water at the exit from the treatment plant. After you decide on the material of the chambers, you can start digging the foundation pit and further work, which is performed in this order:
- 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 plant should be 20 cm larger than the structure of 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 containers of the septic tank are interconnected by an 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, the bottom is concreted and reinforced prior to installation. And after installation, these tanks are attached with hummocks to the outlets of the fittings. When using concrete rings, the bottom can be concreted after they have been installed in the pit.
- To make a filtering layer at the bottom of the second chamber, sand and crushed stone are used. First, sand is poured and tamped with a layer of 10-15 cm, then backfill is made of crushed stone 25-30 cm high.If you use a 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 effluents will settle at the bottom of the first chamber, and pre-purified and clarified water will enter the second tank.
- Ventilation pipes from the chambers are installed.
- After that, the plastic containers are insulated with foam. No insulation is required for concrete rings.
- The containers are covered with lids with hatches for cleaning.
- Now backfill the pit manually. Every 15-20 cm, the soil must be tamped. The manhole cover must remain above the ground.
The filtration field is made depending on the groundwater level at the site:
- with low GWL, semi-buried filter cassettes or filters are used;
- at high ground level, surface filtration on sand and gravel cushions 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 the filtration field is capable of serving 0.5 cubic meters of wastewater. You can purchase ready-made filtering wells based on geotextiles or do it yourself:
- After excavating 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 earth's surface, 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 crushed stone is made. The height of the interlayer 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 plastic or a wooden box.
Which septic tank to choose for clay soil? How realistic is it in this case to organize additional soil wastewater treatment? Can you think of some alternative use for treated wastewater?
In this article we will try to answer all these questions.
In the photo - the construction of a septic tank from reinforced concrete rings in clay soil.
Features of clays and loams
Why, in principle, a septic tank for clay soil should be different from any other?
Remember how a local sewage treatment plant is arranged. In a settling tank (or several settling tanks), wastewater is separated into heavy and light fractions and relatively pure water. Precisely "comparatively": as a rule, it has a specific smell of sewage and must undergo additional soil purification.
To organize the latter, a so-called filter well is being dug - a structure with perforated walls and a drainage bottom. Its performance depends on depth, wall area, water level and ... right. The type of soil.
Note: a square meter of sand can absorb about 90 liters of water per day.
For sandy loam soil, the volume is reduced to 50 liters, for loam - to 25.
Dense clay can absorb 5 liters or less of water per day per square of surface.
It is precisely in the low soil absorption that the problem lies. It is easy to clean the drains, but there is nowhere to dispose of them.
Solutions
Is it really the only way out - digging a cesspool and periodically taking out a sewer truck? It's not that bad. On any type of soil, if you have enough space at your disposal, you can organize a full-fledged sewage treatment plant.
So what should be a septic tank in clay soil?
Several solutions are possible.
Filtration
In the vast majority of cases, the clay layer has a very limited thickness - as a rule, no more than 2-3 meters. If you pass it while digging a well, you may find sandy loam or even sand with excellent absorbency.
In this case, the performance of the well will be higher than that typical for the corresponding type of soil: the water column will create excess pressure.
Before looking for difficult solutions, check with your neighbors how deep the clay layer is. Alternatively, order exploration work. Their price is not so high, while they will pay off handsomely: it is much cheaper to make a septic tank in clay with your own hands than to buy and install a biological treatment station, which may be needed in the most advanced cases.
As for the structure itself, and brick structures. The soil does not impose any restrictions on the material used.
Watering
If black soil has been brought to your site, in which plants are planted, the obvious solution is to use treated wastewater for irrigation. Instead of a filter well, an ordinary sealed container (for example, a plastic tank) is buried in the ground, into which a drainage pump is submerged. With its help, water is supplied to the sprayers placed along the beds.
Let's clarify: for obvious reasons, the solution is only suitable for summer cottages.
In addition, at a low degree with aeration.
Filtration field
If the soil in your area is capable of absorbing at least some amount of water, the obvious solution is to maximize the absorption area. How can this be achieved?
The instruction is simple: we use the filtering field.
- The maximum possible area is covered with rubble.
- Drainage pipes are laid out on it. To avoid silting, the holes in them must be large enough - at least 20 mm; as an option, pipes with a diameter of 110 mm with an interval of 2 meters are opened with tees 110 - 110 - 50. The molding of the pipe is at the rate of 8-10 meters per person permanently living in the house.
- The pipes are filled with rubble at least 10 centimeters.
- Imported black soil is poured on top, on which you can safely plant moisture-loving plants. With a pipe laying depth of 40 cm, they do not freeze even at -30C (of course, subject to constant use of the sewage system).
The solution is convenient because it is undemanding to the degree of wastewater treatment: there are no odors on the surface; however, it is not suitable for dense clay that is completely impervious to water.
An important point: in order to completely get rid of odors, it is recommended to end the drainage pipes with outlets to the surface, equipped with deflector umbrellas.
The recommended height above ground level is 1-1.5 meters.
Ditch discharge
Finally, on soil with zero absorption, it is possible to discharge directly onto the terrain or, more conveniently, into a ditch for water drainage. It is clear that in this case a septic tank in clay should provide extremely high-quality wastewater treatment (at least 95%) and a complete absence of odors.
What is the best septic tank for clay soil in this case? Volatile, using aeration.
The principle of operation of such treatment facilities:
- Air is continuously blown through the tank of the primary clarifier by the compressor. It provides the vital activity of aerobic bacteria, which devour organic matter and decompose it into water and gaseous products with a small residue of odorless sludge. Additional purification is provided by active oxidation of organic compounds.
- The aerated wastewater enters the secondary clarifier, where the sludge precipitates and moves to the first tank by an additional compressor - an airlift.
- From the third chamber, the purified and clarified wastewater is lifted by a drainage pump and discharged into a ditch, which directs them into a reservoir or simply to a large area where water can evaporate.
Conclusion
To organize a sewage system 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 the ground. Aboveground ones, however, are already used very rarely, since they emit an unpleasant odor that spreads to the site.
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 you plan to lay polymer containers.
Installation features
When installing a septic tank, the following are taken into account:
- type of soil;
- groundwater level;
- the location of the house itself;
- fence and other structures;
- vegetable garden.
Based on this, the depth is calculated where the sewer pipe will be carried out. It should be at least seventy-five centimeters. The level of freezing of clay in the cold season is also taken into account, which, by the way, is high. 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 slide is obtained.
It is desirable to insulate the septic tank with polystyrene foam.
In order for it to be firmly anchored underground, it is necessary to provide good drainage, otherwise the container may go deeper into the soil. After the construction of the pit, a diversion is carried out for dispersion. Also, it will be useful to install a drainage pump.
strengthening the soil and the installation site of the septic tank In order for the septic tanks to be perfectly fixed in the clay, it is additionally desirable to attach them with steel ropes. Filter trenches should 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 already 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 peculiarities of this type of soil: its average porosity has a poor ability to pass liquid. Therefore, special attention must be paid here to drainage or filtering 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 property of the 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 by the nature of the work into:
- accumulative, in the form of sedimentation tanks, which are cleaned as sewage accumulates;
- for deep cleaning, after which the water can be used;
- for soil filtration, when the treated water completely goes into the soil.
In the last two cases, all the tanks of the septic tank also need to be periodically cleaned, but this is done much less often 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.
By their form, septic tanks are:
- horizontally installed;
- vertically installed.
They consist of:
- one camera;
- two cameras;
- multiple cameras.
Accumulative septic tanks for clay soil
This type of septic tank is a pits or special containers that are placed in dug holes. The bottom is treated, drained, or a concrete cushion is placed. In excavated pits, wastewater is separated into light substances that will float up and heavy solid waste that settles 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 septic tank of the Biotank type 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 unit is robustly 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 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 often have to call a sewer truck for cleaning, and the smell coming from the pit will clearly not add comfort to your stay outside the city.
This type of septic tank is well suited for clay soil, especially if it is well fixed.
Septic tank with soil post-treatment
For such a septic tank, which provides for additional soil cleaning, the cleaning machine is called less often than for a simple storage tank. This type of septic tank provides for the size of the barrel larger than in the storage form. But it is also more difficult to install it in the ground, since additional protection measures must be provided here.
A concrete pillow is placed on 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. Also, it must be protected from the fact that when burying it simply does not crush the ground. For 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 yourself. Wastewater in it first falls into one chamber, where it is divided into layers, one of which settles, and the other, on the contrary, floats up. The 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 often used. However, alas, 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 this is not only too difficult, but also quite costly. Therefore, on such a soil, usually, a septic tank with soil post-treatment is not used.
Biological deep cleaning
Biological septic tanks 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. In this case, 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 tanks, they enter the sump, where a layer of more or less purified water is formed. It goes to the next chamber, where anaerobic bacteria are added, which produce secondary cleaning. After that, the water does not go outside, but continues to be chemically purified, as a result of which the highest purification level is reached, reaching ninety-eight percent.
Of course, no septic tank used in private country houses can guarantee one hundred percent purification. Therefore, you should never drink such water. But it is quite applicable for technical needs. So, it can be used to water a 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.
preparation of soil for the installation of a septic tank Such a sewage system on clay soils is possible in the same way as on other soil. 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 network to operate. Therefore, for smooth operation, it is necessary to ensure that there are no surges in electricity. An autonomous system is often used for this.
Installation at high ground water level
If the level of occurrence of groundwater is high on the site, then it is better if the septic tank is installed by professionals. You can also do this on your own, but you need to prepare for a difficult job.
Between the walls of the septic tank and the pit, gaps of ten to fifteen centimeters are left.
From below, a sand pillow is laid, at least five to ten centimeters thick, and if the water underground is too close to the surface, then formwork is used.
It is necessary to pay close attention to the filling, since if it is done incorrectly, it can cause the container to move. The left distance between the septic tank and the pit is covered with sand.
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The choice of a septic tank for installation on clay soil is a serious task, because the structure must perform its functions efficiently and be able to purify wastewater from pollution. In addition, some designs allow the use of purified water in a second cycle. The implementation of such a project will be discussed in this article.
Features of clays and loams
A septic tank for clay soil should have some structural differences from conventional devices. To understand how a septic tank works in clay, you need to remember how ordinary sewage treatment plants work: first, the effluent enters the sump, dividing into light and heavy fractions, and then the purified water enters the soil, where the final post-treatment takes place. 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: the depth of the laying, the area of the walls, the level of soil water and the type of soil prevailing in the area.The last indicator has to 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 performed somewhat differently than conventional designs. You also need to know what to do if the septic tank stinks. There are many drugs and remedies to solve this problem.
Options for a septic tank in clay
Despite the fact that the task seems insurmountable, there are still methods for its solution, and for their implementation you will not need to dig an ordinary cesspool, which will then have to be regularly cleaned. 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 correctly considered. Next, there will be described possible solutions that allow you to use a septic tank in clay.Filtration in clay soil
As a rule, a layer of clayey soil is rarely more than 2-3 meters thick. This can be seen when arranging a well: under the upper layers of the earth's surface, one can find sandy loam soils, or even clean sand, which has an excellent indicator of water absorption. 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, it is worth first studying in detail the types of soil located on the site. You can ask the old residents of the area, neighbors who have recently carried out construction work, or order geological exploration. 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 plant, which is well suited only for the most difficult situations.
Structurally, a septic tank on clay soil can be made as you like: you can mount a plastic, brick, reinforced concrete or concrete system. Clay soil does not affect the choice of material at all, so this issue is entirely on the shoulders of the homeowner, and depends on personal preferences and the amount of finance allocated for the construction. Quite often, do-it-yourself concrete rings for sewage are installed, which allows you to reduce costs.
Watering
If there is good fertile black soil on the site, you can use the water purified by a septic tank a second time to ensure watering of the plants. To implement such a project, it will be necessary to make the following design: the filter well must be replaced with a sealed tank to which a drain pump is connected. This pump will supply the cleaned liquid to the irrigation system.Such a septic tank device is well suited for summer cottages, but it is impractical to use it in country houses where people constantly live. Another disadvantage is the low degree of purification, as a result of which the treated wastewater has a characteristic sewer odor. To avoid this problem, you will have to use a septic tank with aeration.
Filtration field
Sometimes even the densest soils show good absorbing qualities. Of course, this does not always manifest itself, but if the analysis of the soil showed that it can absorb at least a small amount of water, then you can take advantage of this and increase the absorption area. Filtration fields are used to implement this idea.
- first, the entire free area allotted for the structure is covered with gravel;
- then drains are laid on it, having holes of at least 2 cm in diameter. The length of the pipeline in this case depends on the number of permanent residents: one person needs about 10 meters of pipe;
- then the pipeline is backfilled with at least a 10-cm layer of rubble;
- a layer of black soil is laid on top, on which moisture-loving plants can be planted.
Ditch discharge
In the case of absolutely non-moisture-absorbing soils, you can dump wastewater directly onto the site or into a special ditch. Naturally, such a system implies maximum wastewater treatment (from 95%) and no odor. To implement the design, it is best to use volatile septic tanks using aeration.Such treatment facilities operate on similar principles:
- the first tank constantly contains air, which supports the vital activity of aerobic bacteria that decompose organic substances that enter the septic tank;
- After passing the aeration stage, the wastewater enters the next compartment, where the sludge goes to the bottom and is transferred to the first tank using a compressor;
- final cleaning is carried out in the third chamber, from which the purified water is pumped out and enters a ditch or a 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.