Owners of summer cottages and country houses try to provide themselves with the most comfortable living conditions. For these purposes, all the necessary engineering networks, including sewerage, are installed in houses.
Considering that in most cases it is not possible to connect the wastewater system of a country house to a centralized sewerage network, the site organizes its own wastewater disposal system in the form of a factory-made septic tank or one built by hand.
Regardless of what type of septic tank is intended to be used, before its manufacture it is necessary to make a competent calculation of its useful volume necessary for the disposal of wastewater from a particular house. To do this, you need to know how to calculate the volume of a septic tank.
What is the basis for calculating the volume of a septic tank?
This article will provide detailed instructions that will help you calculate the minimum acceptable useful value. As an example, we will present the calculation of the volume of a septic tank made of concrete rings for a small family.
What you need to know to calculate the volume of a septic tank
The most common option for a septic tank is a two- or three-chamber treatment system. It consists of two or three reinforced concrete or plastic containers located next to each other, connected in series with each other using sewer pipes.
As wastewater enters the septic tank, it is cleared of mechanical impurities in the first container and slowly flows into the second container, in which the remaining part of the impurities precipitates and biological treatment of wastewater occurs.
Bacteria in the water process organic substances that contain wastewater. After this, purified water is formed, which is supplied for further purification to a third container, and from there, clean water enters the soil or is used for watering plants. In the case of a two-chamber system, water from the second tank is supplied to the filtration fields for soil purification.
According to water treatment technology, for the proper functioning of the treatment system, it must contain at one time the amount of water that will be consumed in the house within three days.
Technology for calculating the minimum required volume of a septic tank
The basic basis for calculating the volume of a septic tank is the total volume of wastewater produced by all people living in the house in one day. According to statistical data, it is conventionally accepted to consider the average daily water consumption at the rate of 200 liters. for one person.
Accordingly, to calculate it is necessary to multiply 200 liters by the number of people living in the house. You can determine the approximate value of the required volume of a home treatment plant using the table below.
Volume calculation table for a two or three-chamber wastewater treatment system.
However, the data given in the table is indicative only. The actual value may vary within small limits, both up and down, and depend on many factors.
For example, the presence of a bath or sauna in the house, as well as household appliances that consume large amounts of water, such as a washing machine or dishwasher, can cause a significant increase in water consumption, and accordingly, an increase in the volume of household wastewater.
Advice! If the water supply is connected to a centralized water supply system, installing a water consumption meter (in other words, a water meter) will not only help you maintain more economical water consumption, but will also help reduce the load on the treatment system.
An example of calculating the volume of a septic tank
As an example, we suggest considering the calculation of the volume for a family of 4 people who permanently live in a country house.
- Based on simple calculations, it can be calculated that the total daily volume of wastewater is 0.8 m³. (0.2 m³ X 4 people = 0.8 m³)
- Taking into account the need to settle wastewater for three days, we obtain the value of the minimum total volume of the septic tank equal to 2.4 m³. (0.8 m³ X 3 days = 2.4 m³)
- If a two-chamber treatment facility is planned to be made from standard concrete rings KS 15-9, we take for calculation its internal diameter 1 m, useful height 0.7 m, we obtain a useful volume = 1.64 m³. Accordingly, two chambers will give a total volume of 3.28 m³.
- From here we see that the value of the total volume of the septic tank is greater than the minimum allowable, and still provides some reserve that allows you to increase the daily volume of wastewater without overloading the treatment system.
Note! When calculating the useful volume of a concrete ring, one should take into account not the full height of the ring, but the useful height that the wastewater reaches before it overflows into the next chamber, that is, the height from the base of the ring to the lower edge of the overflow pipe.
Conclusion
As you can see from the article, in order to properly organize a home-made treatment plant on your site, you need to carry out very simple calculations and follow the rules and recommendations for arranging septic tanks. The price of concrete rings allows even families with a relatively low level of income to install such a treatment system on their summer cottage ().
In the video presented in this article you will find additional information on this topic.
If everything is clear with sewerage in the city, then what about its arrangement in the private sector or on a summer cottage? Fortunately, there is a solution. You can build a septic tank. Moreover, it can be made from various materials. And concrete rings are considered one of the most popular technologies for creating this structure.
Design and principle of operation
A septic tank is a structure designed to clean sewage that is formed as a result of the use of a bathtub, dishwasher and, of course, toilet. It is a structure made of several tanks connected by pipes at a certain height so that water entering the septic tank can flow from one chamber to another. Typically this structure has two or three chambers - their number often depends on the volume of drainage. In this case, as a rule, one of the sections of the septic tank is a filtration well, where an additional cleaning process takes place and the liquid is discharged into the environment.
The principle of operation of a three-chamber septic tank is as follows: wastewater, flowing through the drainage sewer pipe, enters the first chamber, where the primary stage of purification occurs - large inclusions, according to the laws of gravity, begin to settle to the bottom of the tank. Further, as the chamber is filled, partially purified water passes through a pipe located at a certain level (but located lower than the inlet pipe) into the next chamber - the secondary settling tank. There it settles further, and some of the lighter particles also have time to settle to the bottom.
On a note! Additionally, anaerobic bacteria can work to purify the water in the second purification chamber, which process pollutants. For them, this is their favorite “delicacy.”
The third chamber is a filtration well, which, unlike the previous two, has a bottom that is not sealed, but through, but covered with sand and crushed stone. The liquid begins to seep and go into the ground, further purifying itself in this layer. Such a septic tank, one might say, does not need, since the water goes into the soil layers on its own. But still, every few years it is necessary to remove sediment deposited at the bottom from it. Vacuum trucks are called for this purpose.
A septic tank consisting of two compartments works on the same principle, only the water after the first chamber immediately enters the drainage well and goes into the ground. By the way, soil purification can also be carried out on filtration fields or using biofilters, and not only in filter wells.
What are the benefits of septic tanks made from concrete rings?
One of the most common and inexpensive ways to build a septic tank with your own hands is to make it from concrete rings. Such rings come in different sizes, and can also have additional parameters - a certain thickness, the presence of holes in the walls, etc. In addition to these products, round bottoms and covers are also produced, in which a hole is provided for installing a hatch.
Table. Types of concrete rings.
| View | Characteristic |
|---|---|
| Such rings are also called additional rings. They are used only in situations where standard parameter rings are not suitable. Such designs are made to order. |
| Ideal for use when installing wells and other various communications. For example, they make excellent drainage wells, water canals, gas pipelines and others. |
| A neck can be formed from such rings during the construction of a septic tank. They are used for the manufacture of the upper part of any types of communications and wells. |
| Prefabricated, closed with a bottom, with ceilings, with a lock, etc. |
A septic tank made of concrete rings is a time-tested design. But during installation you will have to work hard. Most likely, to install the rings in the pit prepared for the septic tank, you will have to call in special equipment - a truck crane. It is very difficult to move such structures on your own - they have considerable weight. There are, of course, options for installing and digging reinforced concrete rings into the ground without the use of machinery, but the problem is that the ring itself is, nevertheless, quite fragile. If such an element is dropped even from a small height, it can easily break.
The disadvantage of using concrete rings as the basis for a septic tank is the need for a large space. In a small area, it is unlikely that such a design will be implemented in compliance with all rules and regulations. Also, when building a septic tank from concrete rings, great attention should be paid to sealing seams and joints. "How does it happen? , you can look in our article.” The advantages of a septic tank made of reinforced concrete rings are as follows:
- these structures are not afraid of exposure to aggressive chemicals that enter the drain. And the waste water itself is far from having the most harmless composition;
- such a septic tank will not be afraid of temperature changes;
- the structure will cope perfectly with the unexpected influx of large volumes of water.
On a note! When choosing rings for a septic tank, it is best to choose those that have fittings inside. Such rings are much stronger than ordinary concrete ones and will last as long as possible.
We calculate the sizes
Calculating the dimensions of the future structure is an important point in the design of a structure. The parameters of the space occupied, as well as the amount of materials needed, will directly depend on this. The first step is to calculate the volume of the septic tank, which depends on the volume of wastewater, which, in turn, depends on water consumption. On average, a person uses about 200 liters of water during the day. This means that a family of three will spend 600 liters per day. However, according to the standards, the septic tank must be three times larger in volume. This means that it must contain at least 1800 m 3 of liquid.
Now we need to calculate the internal volume of one concrete ring. It is easier to figure it out using the formula for the volume of a cylinder. This V = 3.14*D 3 *H/4, where H is the height of the structure, D is its internal diameter, and V is the volume required for further calculations. Let's say the ring has a diameter of 1 m. Then its volume will be equal to 0.79 m 3. In this case, the height of the ring does not need to be measured - this is a standard value and is equal to 1 m. Although sometimes there are rings with a height of 0.9 m on sale. Additional rings can have very small dimensions.
Attention! When making calculations, it is important to remember that the last, upper ring should never be filled entirely with liquid, but only 1/3. Thus, the working volume of the upper ring is 0.79/3 = 0.26.
Based on the calculations described above, you can deduce the number of rings that need to be purchased. Thus, one section of the septic tank will need 3 rings. To build a structure of three chambers, 9 reinforced concrete rings will be required.
The rings that are sold in stores usually have standard sizes and can be of different diameters - 70, 100, 120, 150, 200 cm. If the sewer system will be built for a house where many people live, then it is better to use structures with a diameter of at least 100 cm For small families, you can purchase 70 cm rings. The larger the ring, the heavier it is, and therefore, to install a septic tank from products 100 cm or more in diameter, you will definitely have to call a truck crane, since the weight of these rings varies between 700-900 kg.
Advice! When making calculations, it is worth remembering that the upper ring should protrude above the ground by about 20-30 cm.
In order for a suburban area to be suitable for full-fledged living, it is necessary not only to provide all the appropriate communications (light and water) to it. It is also necessary to install a septic tank, which will ensure normal drainage.
Types of septic tanks on the site
There are several types of such structures that are used on the site:
The last type is considered the most popular and easiest to construct.
Choosing a location for a septic tank on the site
It is worth noting: in order to perform a high-quality installation of a septic tank that will be used for a long time, you need to choose the right place for it.
Firstly, the drainage pit should be located as far as possible from the residential building and any outbuildings. This will protect buildings from flooding. Secondly, there should be no plantings in an area of several meters around the septic tank. This especially applies to the vegetable garden.
Advice. It is better to install a septic tank closer to the entrance to the yard, so that it can be cleaned normally using special equipment.
Work plan for installing a septic tank in a suburban area
It is worth considering that the installation of a septic tank is carried out in stages. First, you need to choose the right place for it. Secondly, make a drawing of the future structure.
Important. This stage is the most critical, since based on its data it is possible to correctly calculate the required amount of materials for installing drain wells.
- dig a pit;
- install concrete rings;
- lay and connect all necessary pipes;
- seal the joints of the material;
- installation of floors;
- backfilling the septic tank.
This is a unique septic tank installation scheme that allows all work to be completed correctly and efficiently. In this case, special equipment and improvised tools are used.
Note. You can easily install a septic tank with your own hands; you do not need to have special knowledge in this area. It will be enough just to know the operating principle of such a design.
Digging a pit
Once the location for the hole has been chosen, you can begin digging the pit. It is worth considering that the size and diameter of such a structure depends on the daily water consumption for each family member. To make it possible to live unhindered on a suburban area, it is enough to make a hole up to 3 m deep. In this case, its width (or diameter) will be:
- 70 cm;
- 80 cm;
- 90 cm and so on.
This parameter is based on the diameter of the selected concrete rings.
If the pit is dug manually, then for the work you will need:
- hand drill or simple drilling rig;
- shovel;
- bucket.
Initially, along the perimeter of the future septic tank, using a shovel and other garden tools, all vegetation is removed from the soil surface, a hole of 20-30 cm is dug. Then a drill is installed and they begin to work with it to a depth of 50 cm. Then a hole of the required depth and diameter is dug with a shovel. Excess soil is lifted to the surface using a bucket. It is also necessary to use a ladder for easier descent and ascent.
If the septic tank is dug using equipment, then a minimum amount of available tools will be required: a shovel. A specialized machine will use a bucket to make the necessary recess.
Important. You need to dig carefully. Especially if a person does not know at what level the groundwater is. They should be as far away from the septic tank as possible so that contaminated wastewater does not clog them.
Installation of concrete rings
Since such products have a large mass, they need to be installed only using a special tripod, which is constructed independently, or
Advice. It is better to perform installation using special equipment. This will greatly facilitate the work and reduce wasted time and effort.
The first ring is installed on a special substrate. It is made from sand, crushed stone and gravel. This is a kind of natural filter that can trap harmful substances in the pit. It is necessary to ensure that the ring is in a flat plane after installation. For this reason, further installation will be simple and quick.
The second ring is mounted on the first, and so on. This results in a smooth structure that requires additional finishing.
Laying pipes
Initially, pipes are laid from the house. They are laid at a depth below the freezing level of the soil. Otherwise, you need to insulate them using special materials or apply lining technology. It has been used for a long time and is a “pipe-in-pipe” design, that is, the drain pipe is insulated with mineral wool and inserted into a pipe with a large diameter. Because of this, the entire structure will not only be insulated, but also protected from moisture and soil pressure.
The pipes are brought almost to the center of the septic tank. In some cases they can be placed at the bottom. Just keep in mind that quite often, due to the influx of a large amount of wastewater, the pipes become clogged and it will not be possible to clean them yourself.
Sealing the structure
Firstly, the rings installed in the septic tank must be fastened together. To do this, use a concrete solution prepared using sand, concrete and water and with the addition of special substances to give the product moisture resistance and strength. It is applied to the joints and crevices of the material.
Secondly, the outer diameter of the septic tank must be lined with roofing felt or other material to protect it from flooding with rain or melt water.
Sewer pit filling
The final stage will be filling around the septic tank to a depth of 50 cm. Gravel or crushed stone of small fractions is used for this. They are filled along the outer diameter of the structure and covered with a layer of purified sand on top. Can be filled with concrete mortar.
Once all the work is completed, you can use the septic tank.
When installing an autonomous sewer system, overflow septic tanks made of concrete rings are most often used. Such structures are durable, highly durable, and their maintenance does not take too much time.
Septic tank installation
Overflow septic tanks consist of 2-3 concrete wells. The first (or first two) of them is to prevent sewage waste from entering the soil have a concrete bottom and serve for sedimentation of solid particles. Wastewater, entering them, gradually settles, and partially purified water flows by gravity through an inclined pipe into the second, and then, after settling, into the third well.The last, third container (drainage well) has no bottom and serves for final filtration of clarified waters. The fine suspension in it is cleaned using a mechanical filter: layer of gravel, crushed stone or expanded clay. In such a drainage well, fully filtered water seeps into the soil. The accumulated sediment from the first tank is periodically pumped out using the fecal pumps of a sewer truck.
Overflow 2-chamber septic tank
On a summer cottage, with minimal use of plumbing, a device consisting of 2 chambers is sufficient. For private residential buildings, with active use of a shower or bathtub and a connected washing machine, it is better to install a larger 3-chamber septic tank.
3-chamber septic tank
In areas with clay soil or close proximity to groundwater, the absorption process slows down. In this case, you should additionally use pumps to pump out liquid or increase the cleaning area using drainage field(an area with a layer of gravel or crushed stone on which pipes with partially clarified waters are discharged).
Construction of a drainage field for filtration
Calculation of septic tank sizes
In accordance with SNIP, each family member requires 200 liters of water per day. However, cleaning the overflow septic tank occurs gradually - a minimum period of 14 days. It should also be taken into account that the topmost ring should only be filled 2/3 full.That is, for a family of 3 people the minimum total volume of all three chambers should be equal to:
200 × 14 × 3 = 8400 liters (8.4 cubic meters)
Each septic tank chamber, as a rule, consists of 2-3 rings. Thus, to build a 3-chamber septic tank you will need 6-9 concrete rings. Ring volume, having a diameter of 1 m, is equal to 0.7 cubic meters. The one and a half meter ring has a volume of 1.5 cubic meters. Thus, for a family of 3 people, you can use a 3-chamber septic tank, two chambers of which will have a diameter of 1 m, and the third - 1.5 m:
2 × (0.7 + 0.7 + 0.7) + (1.5 + 1.5 + 1.5) = 8.7 cu. m
3-chamber septic tank for a family of 6-8 people
Sanitary norms and rules
According to SNIP, overflow septic tanks are installed at a distance of 5 m from residential buildings (including, of course, neighbors). The distance from wells, reservoirs and drinking wells should be even greater - 30-50 m. The distance from the roadway is also regulated - they can be installed at least 5 m from the nearest roads.
Rules for installing a drainage septic tank
Please note that if you violate sanitary standards and rules, you may be subject to criminal liability. Art. 250 of the Criminal Code states that for polluting groundwater, as well as water supply sources, a violator can be fined (the fine is 80 thousand rubles) or sentenced to correctional work for up to 1 year.
Installation procedure
1. To avoid melt water from entering the settling tanks, it is advisable to locate the septic tank on a small hill.2. Since the overflow septic tank requires periodic pumping, it should be installed near the roadway so that a sewage disposal truck can drive up to it.
The septic tank should be installed near access roads
3. In order for wastewater from the sewer to flow into the septic tank by gravity, sewer pipes are installed on a slight slope(about 1-2 cm per meter of pipeline). A slope is also required for the pipes connecting each of the concrete wells. In this case, the pipe leading to the sump or drainage well must be 20 cm lower than the previous one.
Overflow pipes are made at a slope
Important! When supplying sewer pipes, bends and turns are extremely undesirable, since solid waste will very quickly clog the pipeline.
4. To accommodate each of the septic tanks, pits are prepared for them. Moreover, their depth should be 40 cm above the groundwater level in the area. For ease of installation and waterproofing work, the pits are made slightly wider than the diameter of the concrete ring. For the lower part of the first two settling tanks, rings with a solid bottom are installed. The third well is made without a bottom.
5. To prevent concrete rings from being squeezed out during soil heaving, they are mounted on a cushion of crushed stone or gravel. At the same time, the thickness of its layer is from 50 cm. During operation, such a pillow will silt, so it must be changed every 5 years.
6. Cement mortar is used to connect the rings to each other. To increase waterproofing properties, you can add liquid glass to it.
Important! To prevent sewage from seeping into the soil, concrete rings require additional waterproofing on both sides of the tanks. The inside of each container is coated with mastic or liquid glass. After impregnation with mastic, their outer sides can be wrapped in several layers of roofing material.
External waterproofing of septic tank
7. Since the concrete rings are quite massive, they are installed using a crane. The installation of subsequent rings is carried out only after connecting them with cement mortar and waterproofing the previous ones.
8. The fully assembled well is covered with a slab made of reinforced concrete, with a hole for an additional ring. An additional ring is mounted on it, which will serve as the neck of the tank. The inspection hatches are installed last. They can be made of polymer or metal.
Installation of additional ring
9. Finally, each pits filled with soil and compacted.
The septic tank is ready for use
One of the most affordable options for installing an autonomous sewer system for a private home is a septic tank made of concrete rings. It has a simple structure and principle of operation, it is easy to calculate and build, and, if desired, it is easy to increase the standard productivity.
First of all, it is worth noting that many people confuse a classic cesspool and a septic tank made of concrete rings. These are slightly different things, both in terms of design and in terms of operating principle. The first option consists of a maximum of one well, and the waste water entering the reservoir simply accumulates there and is not cleaned in any way. Accordingly, the pit requires constant pumping using specialized equipment.
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A septic tank made of reinforced concrete rings is equipped with at least two tanks. For better wastewater treatment, three rings are sometimes installed, each of which has its own structure and functional purpose. The first two tanks are made airtight. The third is equipped with a drainage bottom, through which purified water can go into the ground. All septic tank wells made of reinforced concrete rings are connected to each other in series by an overflow pipe.
The principle of operation of a septic tank made of concrete rings
The above-described structure works according to a very simple and understandable principle. Wastewater flows from the house through a sewer pipe into the first well. In it they settle, separating into liquid and solid particles that precipitate. They will need to be removed periodically, however, this procedure is required very rarely if the septic tank from the rings is correctly designed and built.
When the settled liquid in the first well reaches the level of the overflow pipe, then it gradually passes into the next tank. If there are three such containers in total, then the second one is made airtight, like the first.
The function of the second well is to create an environment most favorable for the rapid decomposition of substances. To do this, it must be equipped with a ventilation duct for supplying oxygen and removing methane. As a result of this process, the wastewater is purified, partially turning into a gaseous state and evaporating, and partially into biologically inactive sludge, settling at the bottom.
70% purified water enters the third container in a similar way - through an overflow pipe. From this well it can either be periodically pumped out or used for agricultural purposes as fertilizer. When a drainage bottom is installed in this container made of concrete rings, the water simply goes into the ground without harming the environment.
As a result, it turns out that the work of a septic tank made of rings is aimed not only at accumulating sewage waste (like a cesspool), but also at partially cleaning it and discharging it into the ground. If all the important nuances were taken into account during the arrangement, then the septic tank will not require cleaning, pumping, or any other maintenance for many years, due to which this option for organizing a sewer system for a private home is very popular.
Stages of arranging a septic tank made of concrete rings
It is quite simple to build a classic and effective septic tank from concrete rings. All work on its arrangement can be divided into the following 5 stages:
- Calculation of septic tank volume.
- Determining the location of the septic tank.
- Preparing the pit.
- Construction of wells.
- Covering works and backfilling.
It is worth noting that this is the sequence of construction of the simplest septic tank, the design of which will not include a forced aerator (a device that saturates decomposing sewage with oxygen). A few words will be said about this modernization after describing the above actions.
Calculation of the volume of a septic tank made of concrete rings: algorithm and example
This stage relates more to design than to construction, but in no case should it be neglected. If you make a septic tank from reinforced concrete rings too small, then it will not cope with the processing of all the wastewater that will be produced during the operation of the plumbing. If you do the opposite and build a treatment plant with an excessively large volume, then this will take a lot of time, money and space on the site, which in total is not advisable.
The algorithm for calculating a septic tank with the configuration described above is based on the generally accepted rate of water consumption per person permanently residing in the house. This same rate is multiplied by the total number of people using the sewer system, and then tripled. The latter must be taken into account because, according to construction criteria, the septic tank must contain at one time all the waste generated during the operation of the water supply and sewerage system for three days.
You can clearly understand the described algorithm using the following simple example. Let’s say 4 family members permanently live in a house and use communications. According to the norm, one person spends an average of about 200 liters of water per day, which corresponds to a volume of 0.2 m3. Accordingly, four family members use 800 liters of water (or 0.8 m3) during the same period. According to the described algorithm, this figure must be multiplied by 3 (the norm for three days). As a result, it turns out that the volume of a septic tank for a family of four should have a volume of at least 2.4 ×.
How many rings will be needed to provide such a calculated volume? There are two ways to count. Firstly, if the rings are standard, then their volume, as a rule, is approximately 0.6 m 3 each. That is, for four people (norm 2.4m3) you need a septic tank of four standard rings. Secondly, you can calculate using a simple formula from school geometry. If you measure the diameter of the ring and its height, then its volume will be:
V =π × r 2 × h
(n - 3.14, r - half the ring diameter, h - ring height)
Having the volume of one purchased ring, by analogy with the example described above, the required number per family is calculated.
It should also be clarified that the resulting figure is not the volume of the entire septic tank assembly. Such a container is needed only to receive sewage, that is, in the example described above, the volume of the first well must be at least 2.4 m 3.
Determining the location of the septic tank: basic rules
The second, no less important stage, also related to design and not to construction work, is determining the location of the sewer septic tank. In this matter, not everything is as simple as in the first one, so it is better to trust the professionals. However, this cannot be an obstacle to independently navigating the basic rules for choosing a location for a septic tank. These include the following points:
- Distance from home. Even if the sewerage system is completely sealed, it must still be located at a distance of at least 5 meters from the residential building.
- Removal from water supply. This refers to a well or borehole. A distance of at least 50 meters must be maintained from them and the septic tank.
- Distance from bodies of water. Several other nuances are taken into account in this matter, but the figure ranges from 10 to 30 meters.
- Removal from fruit trees. If the septic tank is located in or near the garden, then the distance to the nearest fruit tree should be at least 3 meters.
- Moving away from the road. The septic tank must be at least 4 meters away from the public roadway.
- Landscape. If the site is relatively uneven, then the septic tank is designed where the ground level is lowest (taking into account all the above criteria).
- Neighbours. It often happens that on a neighboring site the septic tank is located in close proximity (behind the fence) to the place where you plan to build it. As a result, such a neighborhood threatens to oversaturate the soil with treated wastewater and, as a rule, reduce the efficiency of one of the devices. Therefore, before building a septic tank, you should definitely ask whether your neighbors have the same device too close.
There are other nuances that are taken into account by specialists when designing this engineering system. These include the location of water pipelines, the height of groundwater, other buildings (garages, outbuildings, gazebos), underground cellars, and so on.
Pit preparation
This stage is the most labor-intensive, as it is associated with excavation work. As a rule, no matter how many wells there are at the septic tank, a common pit is dug for them. Its width is made such that after installing the rings, the seams between them can be treated with cement-sand mortar.
As for the depth, in addition to the calculated height of all rings, the need to arrange a sand cushion is taken into account. In addition, if the lower rings are not sealed (without a monolithic bottom), then the height of the poured concrete base should also be added to the depth of the pit. The soil removed during excavation work is not transported far, as it will be needed for backfilling the septic tank.
Arrangement of concrete rings
According to the designed number of wells, rings are installed in the previously prepared pit. The distance between them must be at least one meter. Concrete products are laid on top of each other using mortar. The seams are coated on both sides. When making, additional treatment of reinforced concrete with sealing compounds is performed.
At a certain height, the wells are connected by overflow pipes. It is recommended to use curved plastic pipes so that they work on the principle of a hydraulic seal (preventing the overflow of treated wastewater into primary wells).
Covering and backfilling
At the final stage, the installed wells are covered with special concrete covers with holes made for metal (plastic) hatches. In the first and second wells, ventilation must be installed from the same plastic sewer pipes.
The space behind the wells is filled with previously dug soil and compacted methodically. Later (in six months to a year), the soil filled around the septic tank will certainly shrink, so the filling is repeated as necessary.
Increasing the efficiency of a septic tank made of concrete rings
To increase the efficiency of a classic septic tank, you can go in two ways at once. The first, simpler one is the periodic addition of special dietary supplements to the second well. They will contribute to a more accelerated proliferation of bacteria, due to which the decomposition of wastewater into water and inactive solid sludge occurs.
The second way is to install an aerator in the same second well. It consists of a pressure compressor and a regular plastic pipe, which is immersed 2/3 of the depth of the lower ring. As a result of the operation of the aerator, the wastewater will be additionally saturated with oxygen contained in the atmospheric air, which will help create a more favorable environment for the development of active bacteria. The result will be accelerated processing of wastewater and improved quality of treatment.
Septic tank made of concrete rings: advantages and disadvantages
The above-described ring sewage system has only one significant drawback, which plays a role only if you compare it with a full-fledged biological treatment station. It lies in work efficiency. If the station produces 98% purified water at the outlet, which can even be used to wash a car, then a conventional septic tank purifies wastewater by only 70%.
The advantages of such a sewage system are much greater than the disadvantages:
- not expensive;
- does not require frequent cleaning and pumping;
- does not depend on electricity (no aerator);
- does not emit unpleasant odors;
- takes up little space;
- has a simple and understandable device;
- made from available materials.
If you are interested in a similar option for arranging an autonomous sewage system for a private home, call us or contact a consultant through the feedback form. Our specialists will provide you with more information on septic tanks of this type (made of concrete rings), and will also help you with its calculation and arrangement on the site.
