Drain pit device: popular design schemes + parsing depth rules
Building a local sewage treatment plant capable of returning clean water to sewage is much more expensive than installing a simple storage tank.
As a result, the lonely owners of country houses, as well as all those who appear in the garden only on weekends, prefer to have a drain hole. We will try to find out what design schemes can be oriented when choosing a rake.
Drain pit - part of the autonomous sewer
To collect household and household waste a storage tank is needed, which must be regularly emptied with the help of special equipment. Usually it is a large container or structure buried in the ground.
The sizes and shapes of the cesspools may differ, but some components must be present in all structures:
- tank, the volume of which corresponds to the needs of home owners;
- a drain inlet through which sewage flows into the reservoir;
- technical hatch required for monitoring and maintenance;
- ventilation pipe leading to a safe height of harmful gases.
Often, the ventilation device is neglected, leaving a hole or a gap to allow air to penetrate inside, or even tightly plugging the hole. This is wrong: the unpleasant smell of gases at a certain concentration is also dangerous.
Everyone who feels the discomfort of walking in the morning chill, has long been equipped with a full sewer network. It includes connections to the toilet, sinks, bathtub or shower, and the pipeline connecting the points inside the house, with a reservoir buried nearby.
The minimum "summer" set, which allows you to regularly wash and keep the house clean is a toilet + shower + sink in the kitchen. Accordingly, the sewage system inside the building connects sanitary devices. The outer part of the system is a pipe from the wall of the house to the storage tank.A straight and relatively short pipe (but according to the norms of SNiP not shorter than 5 m) is the ideal scheme for moving wastewater.
Sometimes it is necessary to equip complex communications connecting several sleeves (suppose, to drain drains from a house, bath, garage or summer kitchen). But in this case, instead of the usual drain hole, a septic tank is installed, which, in addition to collecting and accumulating, also purifies water, and then removes it for purification into the ground (well, ditch).
Types of cesspools by material production
For arranging the drain holes, both pre-fabricated workpieces and the material at hand are used, for example, automobile tires or red brick left over from the construction of a house. Consider the design features of different models and find out which of the storage tanks will last longer.
Brickwork with waterproofing
With the advent of ready-made concrete rings, the installation process of which reduced the construction of the pit several times, the brick became less and less used.It makes sense to use it in extreme cases when there is no possibility to purchase another, more modern material. Sometimes it remains in large quantities after the construction of the house, and if time permits, you can build a brick grab.
Brickwork is performed in the traditional way, but first the bottom is prepared. A concrete slab is placed on the sand-gravel pad, which is fixed in the ground with the help of reinforcement. The finished slab can be replaced by pouring cement mortar. Slabs of concrete can be useful in the construction of the upper part - the ceiling, which is attached to the technical hatch.
Thus, the device of a brick pit includes the following elements:
- concrete bottom;
- brickwork around the perimeter;
- floor slabs;
- hatch with cover;
- plastic ventilation pipe.
When arranging a reservoir consisting of relatively small elements, it is important to correctly seal, so that the drains do not fall into the adjacent ground. It consists of two stages - waterproofing the inner and outer sides. Bitumen-based coating mastics, as well as modern penetrating Penetron-type materials, have proven themselves well.
Car Tire Well
The most unreliable solution, the service life of which does not exceed 10 years, is a rake of tires. Automobile rubber is not intended for use as parts for sewage, therefore, over time, it does not withstand the effects of aggressive chemicals and collapses. In addition, difficulties arise with the sealing of the joints between the tires to ensure the sealing of the well.
The bottom of the pit is equipped in the traditional way for all drives: they lay a concrete slab or make a cement screed.In the upper part, the flooring is usually built of durable boards and a hole is left with a lid for maintenance - pumping out sewage. The tire drive can not be large in volume, so be prepared for the frequent call of vacuum trucks.
It should be understood that after a certain period (in some cases, from 3 to 5 years), it will be necessary to analyze the rubber construction and build a new well, because the construction of tires cannot be repaired.
For this reason, experienced builders recommend installing more durable structures designed for 50 years - for example, drives made of concrete billets.
Monolithic concrete tank
The device of volume capacity from concrete essentially differs from a construction of designs from separate ready elements (bricks, blocks, tires). It is not in the assembly, but in the creation of formwork, followed by concrete pouring. The result of construction work should be a durable, reliable, sealed concrete tank with a service life of at least 50 years.
The order of the drainage of monolithic concrete:
- preparation of a ditch, alignment of a bottom;
- reinforcement and concrete foundation;
- construction of formwork;
- installation of reinforcement for walls;
- phased concrete pouring;
- installation of floor slabs;
- waterproofing facilities;
- device ventilation and hatch;
Often, when building a simple septic tank, a more complex scheme of two chambers is used. Simply put, a concrete partition with a hole for overflow is installed approximately in the center of the structure. The two-chamber construction partially brightens the drains, and the use of an additional filter well allows part of the sewage to be sent directly to the ground.
A feature of the monolithic concrete pit is a long period of construction and compliance with the standards for the preparation of cement mortar.
Rack of concrete rings
The construction of prefabricated ready-made concrete blocks is preferred for several reasons:
- construction takes less time;
- cost refers to the category of democratic;
- subject to the rules of construction, the facility has been serving for more than 40 years;
- a well of heavy rings, fastened with a lock joint, is much stronger than a construction made of tires or bricks.
Concrete rings, as well as other parts for construction (bottom, floor slabs, dobora), can be purchased at the nearest enterprise producing concrete goods. We will have to rent equipment (truck, crane) and hire a brigade of workers, but the installation will take place quickly, in contrast to the creation of a monolithic tank.
In addition to concrete blanks, backfilling is required for the foundation (sand and gravel), waterproofing for sealing joints and external sealing of the finished structure. To add strength and stability to the structure, dry cement is added to the primer.
In spite of the presence of schemes of bottom-less cesspits, single-chamber tanks are recommended to be made airtight, since insufficiently purified water pollutes the soil and the fertile soil layer.
Plastic container factory production
If you want to install a drain hole in one day, pay attention to the finished models of modified plastic, presented on the market of autonomous sewage by well-known companies. They differ in shape and size, but all have sufficient strength not to collapse under the pressure of the ground or from the movement of groundwater.
The installation of a plastic container is carried out according to a simple scheme: digging a foundation pit, strengthening the bottom (in case of unreliable soils or high groundwater), install the tank, connect it to the pipe and make filling.The process of pumping sewage waste occurs in the usual way - with the help of vacuum trucks.
Overview of popular schemes
Despite the material of manufacture, sewers can have a different design. The difference concerns, to a greater extent, the number of cameras - from one to three. Consider the schemes that are most suitable for providing private homes with autonomous sewage.
Separate storage capacity
Rake from one sealed chamber - the easiest option. It does not pollute the environment, therefore, safe and environmentally friendly. Such a pit occupies a minimum of space, and since it is under the ground, it does not interfere with growing flowers or sowing beds nearby. Restrictions relate to planting trees, which by their roots can depressurize sewer construction.
Single-chamber drive is relevant for those who rarely use the sewer system, that is, rarely visit the country.There is another option - if a lonely person lives in the house, and the sewer system consists of a minimum of active points of use (toilet, shower, sink).
When arranging the tank, it must be remembered that it is not filled to the very top, but to the level of the pipe inlet, therefore it is involved only on 2/3 of the volume. A simple drive requires regular pumping, and for this you should prepare a convenient access road for vacuum trucks and it is better to conclude an agreement for permanent maintenance.
Drain pit without bottom
Option of a single drive - a pit with a filter bottom. The main purpose of the filter is to pass part of the effluent directly into the ground in order to reduce the load on the structure and reduce the number of calls for specialists to pump waste. The design of the lower part of the tank (it may be a structure made of concrete billets, a brick well or a plastic container) differs from the deaf bottom of the sealed chamber.
In soils with a weak capacity, for example, in plastic sandy loams, it is advisable to arrange additional perforation of the walls. For this, small holes are formed in approximately 10 to 15 cm. They are located along the entire height of the soil filter in a checkerboard pattern. Such methods increase the filtration area, as a result, the recycling process is accelerated.
Two important filtering device conditions:
- sandy or sandy soil (loose, with a high degree of permeability);
- low level of occurrence of water horizons.
Dense clay soils, hard sandy loam, loam of any consistency, just will not absorb water, thus, the perforation device is useless.
This scheme is more suitable for the construction of filter wells, which are the second or third compartment and are installed after the drive. The quality of tertiary treatment in the ground partially clarified water is much higher than the unstable sewage from the first storage tank. Pumping waste from a pit without a bottom is carried out a little less than from a conventional pit. If the filter is clogged - the pumping mode is the same.
Two-chamber septic tank of concrete rings
A sophisticated version of the drain hole - double tank. It may have a different design:
- concrete tank, divided into 2 parts by a partition;
- 2 wells connected by an overflow pipe.
Despite some differences in the design, the goals of the construction of two-chamber models are the same - to divide the waste according to the degree of pollution. In the first section (which is a full-fledged accumulator), the waste is processed by anaerobes, as a result of which a solid precipitate and a turbid liquid are formed. In the second - the wastewater is further clarified, the sediment is much less.
If the second tank is equipped with a compressor, the cleaning will be more efficient, since the processing will also be carried out with aerobic microorganisms. Two-chamber models, in fact, are no longer just drives, but septic tanks that can partially clean sewage drains.
How to determine the depth of the rake
The dimensions of the drain hole, including the depth, depend on the volume of wastewater. First, we calculate the total amount of waste per day, multiply by 10-14 days (depending on the frequency of pumping), we find the desired working volume. A worker means only up to the level of a pipe tie-in.
If you need a working volume of 4 m³, then add another 1/3 and get the volume of the tank - 6 m³. Knowing the volume, we calculate how many concrete rings are needed or what is the length / width / height of the monolithic structure.
At the device of a ditch we add 0,3 m on alignment of the basis and the device of a sand-gravel pillow. We calculate the depth of the drain hole so that during the installation part of the neck (approximately 0.2 m) could be seen above the ground. A small ledge - insurance against spring flood. At risk of seasonal flooding, the neck can be raised by 0.5 m.
Slightly different calculation of the depth of the pit without the bottom. The excavation pit with a perforation is deeper than a sealed analog due to the installation of a meter sand-gravel filter.In order not to be mistaken with the calculations, we simply add the thickness of the filtering pad to the height of the structure.
When calculating do not forget about the location of water horizons - from the base of the sump to the upper aquifer should be at least 1 m.
Conclusions and useful video on the topic
The rules for the construction of storage tanks and septic tanks are very similar, so we recommend viewing the following interesting thematic material.
Construction of a brick pit with overflow in high groundwater conditions:
Useful information on the device of a two-chamber construction:
Details on the construction of septic tanks:
Acquainted with the construction features and characteristics of cesspools, you can independently equip the sewer system in the suburban area. If you have difficulty in drawing up a chart or calculating the depth, we recommend that you contact experienced engineers.