The arrangement of a private house is, first of all, the installation of communications: electricity, water, sewage. Without them, life in a cottage would not be comfortable enough. When installing the collector, it is important to correctly calculate at what depth to dig the sewer pipe in a private house (the outer part of the communication). The operability of the system as a whole at any time of the year depends on the correctness of the selected parameter.
Why sewerage depth matters
The importance of observing the correct depth of the pipeline is justified by several factors:
- A correctly laid line does not succumb to the negative effects of subzero temperatures. In pipes mounted below the level of soil freezing, ice does not form, so the collector functions normally, without plugs, freezing.
- Optimally selected depth provides easy access to the highway in case of repair work, if the collector gives a leak.
- It is also worth considering static / dynamic pipe loads. If the collector is laid under a site with high loads (parking for cars, traffic in the yard), you need to place it a little deeper. This will protect the tubes from subsequent deformation.
The septic tank is buried so that only its upper hatch protrudes above the surface of the earth. If there is a need to deepen the camera more, the outlet will have to be artificially extended upward.
Requirements for the depth of the sewage in a private house
When calculating the depth of the sewer pipe in a private house, you need to be guided by SNiP. The documents state that "The ultimate pipe laying depth is based on the operational experience of using networks in a particular region." The wizard can independently determine the desired parameter, based on the technical data of already installed highways.
In addition, SNiP 2.01.01.82 offers the attention of specialists a special map table. It contains recommended values for the depth of the collector, depending on the region of the country. In the northern parts of Russia, the desired level of pipe laying in the soil is from 1.4 m. In the southern regions of the country, a value of 0.8 m can be adhered to.
It is important to pay attention to the height of the pipe outlet from the house. SNiP regulates the indicator of 30 cm or more from the average for the region level of laying the sewer line. If the calculated optimal collector depth is 80 cm, then the output is mounted at a height of 1.1 m.
In addition, SNiP establishes approximate norms for the occurrence of the collector depending on the cross-section of the pipes (for southern regions). With a trunk diameter of 500 mm or more, it is laid to a depth of 50 cm or more. If the tube has a cross section up to 500 mm, the collector can be deepened at a small elevation of 30-50 cm. If dynamic pressure is exerted on the pipeline, the line is already laid at a minimum elevation of 90 cm.
If the collector is laid too deep, you may encounter a number of such problems:
- Labor costs: digging trenches / foundation pits, attracting special equipment, etc. This is reflected in the cost.
- The risk of fatigue cracking on pipes. They arise under the pressure of heaving soil and groundwater.
- Complex system maintenance: flushing, possible repair.
In some cases, SNiP still recommends putting the sewer system deeper. With a high level of groundwater or the presence of rock in the pipe section, they are mounted at a level of 3-4 m from the ground.On dry non-porous soils, you can lay the highway at a maximum elevation of 5-8 meters.
When installing the collector, it is advisable to avoid steep corners and turns. If it is impossible to refuse them, I install revision hatches in the “difficult” places of the pipeline.
Factors affecting the level of pipe laying
When compiling project documentation for the sewer system, a number of factors that affect the final depth indicator must be taken into account:
- features of the site relief: the presence of sharp changes in height from the house to the end point of the sink receiver;
- soil type: swampy, heaving, rocky, clay, sandy;
- climatic indicators in the region: taken from the table of sanitary norms and rules;
- type of sewer system: pressure, non-pressure;
- pipeline installation method: with or without trays.
It should be borne in mind that wastewater moving through pipes has an average temperature of 14-16 degrees. They can warm the collector from the inside. But the longer the line, the greater the likelihood that dirty water will cool to minus temperature already in the middle of the pipeline. Therefore, betting on relatively warm drains is risky. The chance that this will really work is extremely small.
Calculation of the depth of the drainage
To carry out accurate calculations and determine the final mark on which you can bury the pipeline, it is necessary to take into account several parameters:
- recommended in the region depth of the sewage;
- the height of the septic tank, including from concrete rings or even car tires;
- the length of the line from the exit from the house to the receiver;
- collector slope.
As an example, we take the middle lane of Russia, for which the recommended laying depth of the collector varies between 80-120 cm. At the same time, we have a septic tank height of 1.5 m. The total length of the highway is 15 meters. Here we take into account that the recommended slope for pressureless sewage is 0.8-1 cm per linear meter (for pipes with a cross section of 220 mm). From the exit point from the house to the septic tank, the collector will deepen by 15 cm. This means that a trench is dug at a depth of 80 cm from the exit from the cottage and the end point of the channel is already made at around 95 cm.
If, due to the characteristics of the relief, it is impossible to comply with the recommended depth in one of the sections of the collector length, this part of the pipes should be properly insulated. When laying the pipe, it is necessary to securely fix it so that over time they do not move under static or dynamic load.
The ditch under the sewer line is always dug 15-20 cm deeper. This place will be taken in the future by a sand pillow-base under the highway.
Options for reducing the depth of the reservoir
If the relief of the site does not allow to deepen the pipes to the desired distance from the ground, they are mounted at an acceptable level. In this case, resort to several options for ensuring reliable operation of the system:
- High-quality pipe insulation. To do this, you can use a heating electric cable (it is wound on the outside of the tube), expanded clay sprinkling of the trunk or fiberglass heaters. They are put on tubes by the type of casing.
- Using a special fecal-drainage pump, which will drive sewage through pipes from the house under pressure. As a result of the increased speed of sewage media, plugs in the system will not form.
- Artificial increase in the layer of soil over the stacked tubes. Have to make a kind of mound over the system. It can be decorated for elegant landscape design solutions (mounds, high lawns). However, complex powerful plants with a large root system cannot be planted on them. Only flowers or lawn grass.
- The use of pipes with thick walls. More often it is cast iron or steel. But they are expensive and require a lot of labor when installing a collector.If plastic elements are taken, it is advisable to lay them in a special protective corrugation.
Each master must carefully weigh the capabilities of the site in order to properly lay the sewer line at an acceptable minimum depth. Only in this case will the system function smoothly. The same goes for the storm drainage system of the closed type.
