Septic tank of concrete rings: device, diagrams + step-by-step installation process
Concrete rings are a good material for the manufacture of sewage in a private household. A septic tank made of concrete rings allows you to organize wastewater treatment up to 70%, but the percentage of treatment in it is lower than in high-tech biological stations (98%).
If the territory does not belong to nature conservation zones, then you can save money on sewage systems, since the cost of such a septic tank is twice as cheap as buying a cleaning station.
How to place a septic tank on the site
Before starting work, it is necessary to determine the type of soil on the site. The choice of a filtration system depends on its characteristics, since the construction of a septic tank of concrete rings involves several tanks. According to sanitary standards, water should be subjected to a three-day and more upholding before it is discharged into the ground.
The type of soil can be determined by digging a hole, interviewing neighbors owning a well or a well, requesting information from the organization conducting the construction or drilling near the site.
Slightly higher filtration coefficient in loams, slightly higher in sandy loams. However, their filtration properties are still not enough for the installation of an after-treatment groundwater treatment system on the above clay soils.
In addition, almost all clay soils are characterized by heaving - the ability to increase in size during the freezing process and decrease during thawing. These ground movements can easily push concrete containers out, completely destroy them, or simply squeeze them until cracks appear.
Sand, gravel, pebble and rubble sediments have good absorbing properties.They freely pass water into their thickness, do not interfere with its movement into the underlying layers. True, coarse sediments, such as gravel and pebbles, occur mainly in the floodplains of rivers, and rubble at the foot of the mountain formations.
On river and mountain slopes, filtering structures do not suit, because part of the draining fluid will not be able to undergo an after-treatment cycle sufficient for disposal into the ground. Therefore, the normal conditions for the installation of filtration fields, absorption wells and the installation of infiltrators are considered to be sandy soils of all sizes and density of addition, except for silty.
In addition to geological conditions, it is necessary to observe the norms of its location from residential buildings and water sources.
If sanitary standards are neglected, biological water pollution may occur. Dangerous pathogens of infectious diseases develop in sewage. These include E. coli, which causes severe poisoning. It easily gets to the source of drinking water through groundwater.
How to calculate the required capacity
To organize a septic tank of concrete rings, it is necessary to calculate the volume based on daily water consumption. According to the norms, per one resident person accounts for 200 cubic liters of water per day.
The first tank for settling drains should have a volume of not three times the size of consumption (200 liters) per person. The second tank with a bottom for settling should have a volume equal to 1/3 of the size of the first. The number of rings can be determined by dividing the volume of the container by the volume of the ring. Their size is small, medium and large.
For a family of two
The volume of the first tank = (200 * 2) * 3 = 1 200 cubic liters.
The volume of the second and third tanks = 1 200/3 = 400 cubic liters.
The number of rings for two containers = (1200 + 400) / 700 = 4
The number of rings for three containers = (1200 + 400 + 400) / 700 = 5
Bottom line: 2 rings for the sump, 2 for the sedimentation tank and one for the drainage well.
For a family of three
The volume of the first tank = (200 * 3) * 3 = 1,800 cubic liters.
The volume of the second and third tanks = 1 800/3 = 600 cubic liters.
The number of rings for two containers = (1 800 + 600) / 700 = 4
The number of rings for three containers = (1 800 + 1200) / 700 = 6
Bottom line: 2 rings for the sump, 2 for the sedimentation tank and two for the drainage well.
Septic schemes of concrete rings suggest the presence of one, two or three chambers, where sewage sedimentation and their biological processing take place.
In essence, a single-chamber septic tank is an ordinary accumulator, from which drains are pumped out by sewers.
The first and second tanks must have a bottom. This is followed by the third compartment, where also ground cleaning is carried out. The next stage of purification is the withdrawal of excess flow into the soil through the bottom of the filtering well.
All cameras are arranged with a monolithic bottom, cleaning is done by settling. The pooled liquid is discharged into the infiltrator or filtration field for subsequent disposal into the ground.
Depending on the absorptive capacity of the soil, you can choose several filtering options for the device of a septic tank of concrete rings:
- Septic system with a filter field.
- Septic system with drainage well.
- Septic system with a filter cassette (infiltration).
The most common filtering option is a drainage well. It is used with good absorption properties of the soil.
Between the level of the conditional bottom of the absorption well and the highest level of groundwater in the autumn / spring rainy period there is no meter required by the standards, a filtration field is established. For its construction on the site should be enough space.
This is the optimal solution for areas where the groundwater level does not exceed 2.5 meters. It should be remembered that between the bottom edge of the drainage pipes of the filtration field and the roof of a water-saturated reservoir there should also be a thickness of the soil not less than a meter thick.
This design is not widely used in the CIS countries.
You need to decide on the filtration system before installing a septic tank made of concrete rings, since this will allow you to prepare in advance the foundation pit of the required size and depth. If you install filtration systems after installation, you can damage pipes and tanks. Therefore, the space that borders the wall of the second deposition tank will have to be manually digged in, without the use of special equipment.
Installation of a septic tank with two sedimentation tanks
Before starting work, it is necessary to check the level of groundwater. This can be done if the house has a cellar or basement, without a concrete bottom. It is necessary to measure the height from the ceiling to the surface layer of soil. This is the depth at which to dig.
To find out how deep the groundwater lies, you can dig a small, but deep hole in diameter. Groundwater begins when a clearly damp earth appears. This is a sure sign, no need to dig further.
After it became known approximate GWL, you can start excavation work. It is necessary to outline the place where the septic tank will be located. For this you need to outline the pit. To do this, take a building thread or any strong thread, measure 80 cm. Tie two pegs to both ends.
Insert one end in the middle of the place where you plan to place the first settling tank. Draw a circle. This is the approximate diameter of the desired pit. Next, you need to retreat the meter, and draw the boundaries for the second tank. Next you need to outline the boundaries of the filtration facilities.
Consumables and tools
Before you begin, you need to collect all the necessary materials and tools. For work you will need:
- perforator and large drill for concrete;
- nozzle mixer to the puncher;
- sovok and bayonet shovels;
- capacity for mixing the solution;
- strong nylon rope;
Materials for mounting a septic tank of concrete rings:
- bitumen or liquid glass;
- metal brackets;
- Mineral wool or polystyrene foam;
After the equipment has been selected and prepared for all phases of work, you can begin digging the pit.
How to dig pits for septic tank
If you think that it is difficult to excavate in such volumes manually, so you can use the services of organizations possessing special equipment.
At the bottom of the pit it is necessary to pour sand, where the lower rings of the tanks will be installed. The thickness of the sand cushion is 20-25 cm. The foundation must be leveled. Next, the sand needs to be shed with water to cause shrinkage. After pressing the sand base, it is possible to break the assembly of the rings.
Installation of sedimentation tanks
To install concrete rings pre-delivered to the site for a septic tank, you need to build a base. To do this, a wooden formwork is arranged around the perimeter of the pit floor. The height of the formwork walls should be 30-40 cm. After the formwork has been constructed, it is necessary to lay the reinforcing mesh and dilute the cement mortar. To do this, you need to take 1 part of cement to three parts of the mixing and tilling mixture (mixture of sand and gravel).
You can mix the solution using a construction mixer. As a plasticizer in the solution, you can add two spoons of liquid soap. This will make the concrete more resistant to pressure and moisture. After pouring the base, you need to wait 10 - 14 days until the solution hardens and acquires the necessary strength. Formwork can not be removed. If leased equipment is used, it is better to purchase ready-made concrete slabs as a base.
After the base is ready, rings can be mounted. The weight of concrete structures is impressive, so you need to use a crane. Installation of tanks occurs in stages.
On the concrete base, immerse the first ring. Following it falls and set the second.The ring needs to be moved smoothly, avoiding its blows or slipping. Scraping is done after installation.
In the next stage, until the cover is lowered, it is necessary to cover the seams between the rings. After installing the floor in the tank will become dark and there is a risk of leaving the raw joints. For this, cement mortar is used. For ease of movement inside the tank mounted running brackets. They are necessary for maintenance of a septic tank, in case of blockages or depressurization.
The adjacent sedimentation tank is installed in the same manner. In both tanks it is necessary to make holes for sewer pipes and install them. The inlet for sewage should be located higher than the overflow pipe between the tanks.
Next, you need to install overlaps with holes that are sufficient so that a person can descend through them.
This installation of a septic tank of concrete rings ends, and follows the installation of the ventilation system.
Installation of the ventilation system
Ventilation is necessary for admission to the air system, which ensures the normal functioning of microorganisms. They carry out the processing of domestic waste and free from the organic component. To ensure constant circulation of air flow, two ventilation pipes are needed.
The first pipe is mounted in the section of the sewer pipe, which is as close as possible to the walls of the residential building. The best solution would be to install from the inside of the wall, but you can also mount outside (+)
In this case, you will have to lay an electrical cable to warm the pipe, because in the collision of warm and cold air, condensate forms in it, which blocks the access of oxygen. It must be fixed with fasteners or clamps. Vertical length of the riser, must be at least the height of the wall of the house.
Ventilation also eliminates the unpleasant smell that periodically appears from containers and can spread throughout the house.Often this happens with a long absence of residents and the drying of the liquid in the siphon.
The second pipe is mounted in the overlap of the deposition tank. To do this, using a perforator in the ceiling punches a hole that coincides in diameter with the ventilation pipe. The air duct should rise 70-100 cm above the earth's surface. The position of this pipe will be fixed by the weight of the soil and does not need additional fastening.
Installation of aeration field
From the second concrete tank, a pipe goes to the distribution well. For the well, you can use a plastic barrel in which to cut holes suitable for aeration pipes.
You can purchase ready-made distribution well.
To do this, you need to purchase pipes based on the size of the field. For a family of four, an area of 20 square meters (10 × 2) is enough. To do this, you will need three pipes 10 m long. In addition, you will need three corner pipes where the ventilation pipes will be installed.
The field is pre-filled with sand and gravel to improve the absorption capacity of the soil.
Perforated pipes that are connected to a distribution well are laid on the prepared drainage. At the ends of the aeration pipes are mounted corner pipes, in which a background riser is installed, one for each pipe. After that, the pipes are covered with geotextiles and filled with a mixture of gravel and sand, then leveled. As silting occurs, the aeration field must be moved or cleaned, changing drainage.
Installation of the filtering well
The filtering well has several advantages over the aeration field. It occupies less useful area on the plot. But the quality of the treated water will be higher at the aeration field, because before entering the groundwater, the drains will be filtered by the soil, and its layer under the aeration field is much larger than the well with drainage. The area of the well can not handle the amount of waste that takes aeration area.
It is necessary to install a well according to the same principles as sedimentation tanks, excluding concreting the bottom of the tank. In addition to a sand cushion, crushed stone, gravel, or another filter composition should be placed at the bottom of the well. The standard capacity of the soil filter in the absorption well is estimated at 1 m or more.
To increase its capacity, it is possible to supplement the filtration well with side drainage. For his device, the lower concrete ring of the septic tank must be perforated.
This process is best done on the surface, until the ring is lowered into the pit. You also need to make a hole for the overflow of water from the sedimentation tank, it should be located slightly lower than the previous overflow.
The walls and joints of the filter well must be fastened with brackets, but there is no need to seal them. By connecting the play, you can bury the structure. Sprinkle the first ring from the outside with rubble, to the point of connection with the second segment.The rest of the volume can be filled with soil from the infield.
The process of preparing to launch
If the temperature in winter falls below 30 degrees, it is necessary to prepare insulation for the inner hatch cover. Since the tank itself is located below the freezing level, it does not need additional insulation.
To insulate the lid, you need to take a foam and cut a circle suitable for the diameter of the inner small concrete ring.
Next you need to cut the cover itself. For this, ordinary plywood of sufficient strength will be suitable. It can be screwed to the door handle, so that it was convenient to open. Similarly, it is worthwhile to insulate the inner lids of the second deposition tank and the drainage well.
Before using a septic tank, the first sedimentation tank must be filled with water at 1–4 of its volume.Into the filled container pour a biological product that will help the septic tank to reach full capacity faster. After these actions it is necessary to close the hatches.
Conclusions and useful video on the topic
The video shows step by step the process of installing a two-chamber septic tank:
How does the septic system function:
If the construction of a septic system of concrete rings is made in compliance with the rules, it will serve for 20 years. We must not forget about the rules of operation and timely maintenance. The pipes are made of plastic, so they are easy to damage. It is strictly forbidden to install equipment or a car in the place where the tanks are located.