Concrete rings for sewage: building the simplest septic tank

How can concrete rings be used for sewage in a private house? Where is it better to locate an autonomous sewer system and what dimensions should it follow? How to seal the seams between the rings? We will try to answer these and some other questions in the article.

Septic: first acquaintance

For a start it is worth clarifying what exactly we are going to build.

Понятно, что для отвода сточных вод бетонные канализационные кольца с их диаметром от 0,7 до 2 mетров подходят исключительно плохо. Они будут использованы для утилизации стоков там, где нет централизованной канализации. Наша цель - сооружение железобетонного септика.

What it is? Why is a septic tank better than a cesspool?

The fact that it separates the liquid and solid components of the effluent. The settled and purified water is absorbed by the soil; the solid fractions accumulate and require export once every one or two years. For comparison - the cesspool needs discharging at least once a month.

Useful: the so-called cumulative septic tanks - this is just an attempt by marketers to sell a cesspool under a beautiful name. If there is no separation of effluent and their partial utilization, the corresponding construction will not be a septic tank.

How does the simplest septic tank work?

• The effluent flows into the primary sedimentation tank, which has a significant volume, due to which the incoming stream hardly mixes the contents.. Wastewater should be spent in the sump for at least three days. During this time, organics are partially processed by bacteria; light fractions float and eventually form a dense crust on the surface; heavier components settle to the bottom in the form of sludge. In the middle of the tank - settled, relatively clean water, which can be directed to the soil tertiary treatment (in other words, it will be absorbed by the soil).
• For disposal of treated wastewater, a filtering well is most often constructed - a tank with no bottom.. Of course, for its construction, the soil must have a sufficiently high absorbency, and the groundwater level must be low.

Sumpов может быть несколько. Каждая дополнительная емкость повышает качество очистки стоков.

Actually, reinforced concrete rings for sewage are usually used as walls of a settler (settling tanks) and a filter well.

Строительство

First of all, let's decide on the choice of place for a septic tank and the size of containers.

Location

When choosing a place, it is worth adhering to certain minimum distances from other objects on the site.

The size

The minimum size of septic tank (and, therefore, the size of concrete rings for sewage, and their number) limit two requirements:

1. The capacity of the sump should be equal to at least a three-day volume of wastewater. The price of volume reduction is the sharply falling quality of sewage separation and the quick silting of the filter well.

1. The area of ​​the bottom and the water-wetted soil walls of the filtering well must ensure the rate of absorption, at least not less than the rate of flow of wastewater.

What numbers will it pour out?

Sump

With a social water consumption rate of 135 liters (Moscow), it is better to include 200 liters per person per family member in a project. Thus, the minimum volume of the sedimentation tank for a family of 3 people will be 200 x 3 x 3 = 1800 liters, or 1.8 m3.

For a cylinder with a diameter of 1.6 meters, the height corresponding to this volume will be 1.8 / (3.14 x 0.8 ^ 2) = 0.9 m, which corresponds to one ring. In practice, however, it is better to make a sump of at least two: the overflow will be located significantly below the edge.

Useful: concrete wells for sewage (rings with bottom) will be a much more practical solution than a set of rings and bottom. In addition to ease of installation, the well will provide greater tightness.

Filter well

In the case of a filtering well, the surface of the soil walls is important for us.

To provide water access to them regardless of the size of the rings will help a simple maneuver:

1. We dig the pit.
2. We fall asleep with rubble at 30-50 cm.
3. Put a ring on the bedding (or several rings).
4. We carry out backfilling with compacted rubble for concrete.

What are the requirements for the size of the pit? They are determined by the absorbency of the soil in your area. Here are indicative values ​​for some soil types.

При среднесуточном расходе в 600 литров на супесчаных грунтах необходимая площадь дна и стенок ниже перелива составит 600 / 50 = 12 m2; такую поверхность обеспечит, например, котлован кубической формы с размером стенки 1,55 mетра.

Tip: it is better to increase the calculated dimensions of the well at least twice. The instruction is connected not only with silting, but also with the possibility of salvo discharges (for example, during washing).

Costs

We give some prices for concrete products that can be purchased during the construction of a septic tank, and at the same time and storm sewer.

• The cost of concrete rings for sewage ranges from 350 rubles (KS-7-1.0, diameter 70 cm, height - 100 cm) to 4,500 rubles (KS-20-9, diameter 200 cm, height 90 cm).

• Rings with a bottom cost from 2100 rubles (KCD-10-3, meter diameter with a height of 30 cm) to 8,000 (KCD-20-9, 200 cm - diameter, 90 cm - height).
• Concrete trays for storm sewers and drainage without reinforcement are sold at prices from 200 rubles / linear meter. Reinforced concrete sewer trays and fiber-reinforced products (reinforced with fiberglass) are 20-40% more expensive.
• Covers for wells with hatches cost from 1500 rubles.

Useful stuff

Installing concrete rings for sewage is usually done by a crane. However, in the case of a septic tank that does not require the installation of a concrete sewer ring on the rubble, you can do this work with your own hands - the ring on the surface digs in a circle up to its precipitation to the desired depth. Then, using scrap and rollers, the next ring is placed on top, after which the foundation pit continues to deepen.

The seams are sealed with cement and sand sealing solution in a ratio of 1: 3 with the addition of liquid glass.

The overflow that draws water below the surface is made from a common sewer tee. The upper tap is needed for cleaning when clogged.

The hole under the overflow can be done with a conventional punch; However, diamond drilling of holes in concrete will give the best result: the edges will be perfectly smooth, without chipping. In addition, drilling with a diamond bit, as well as cutting reinforced concrete with diamond circles, does not require tool replacement when the armature passes.

Conclusion

We hope that the material proposed to the reader will help him in the independent construction of a local sewage system. As usual, the video in this article contains additional thematic information. Successes!