Autonomous (local) sewerage for summer cottages

Recommendation points

• How to equip local sewerage
• Fundamental principles of the local sewerage device
• Septic tank equipment and laying of external household sewage
• Fecal sewerage – sewage treatment plant or cesspool
• The device of the simplest fecal sewerage
• Laying of an external line and methods of protecting external sewage pipes from freezing
• Conclusion. Some helpful tips

How to equip local sewerage

“Civilization is where the sewer is!” – the truth that does not require confirmation. If in cities with civilized wastewater disposal everything is more or less in order, then with individual construction it is far from always possible to connect your house to central wastewater collection systems.

In this case, the problem of waste disposal becomes very acute. There are several ways to solve it. The simplest of them is the equipment of an outdoor toilet and a portable washbasin in the kitchen. But this approach cannot be considered seriously when living in your own home all year round. Then it makes sense to equip the household with a local sewage system..

Fundamental principles of the local sewerage device

With regard to local sewerage, you can use the well-known expression: “Divide and conquer!” Indeed, unlike a city apartment, where all wastewater, both household and fecal, is merged into one sewer riser, in a country house it makes sense to separate them and send them to different septic tanks. The fact is that household drains (sink in the kitchen, bathroom, shower, washing machine – machine) are not considered contagious. Therefore, they can be dumped into the ground without any cleaning. Considering that the volume of domestic sewage effluents per day can reach significant values ​​(about 1000 liters), the decision to separate discharges in a private house can be considered the only correct one. In addition, microbes work in any design of a fecal septic tank, and washing powders, soap, shampoo and household chemicals act on the biological environment of the septic tank in the most destructive way..

However, when choosing a place for a septic tank for domestic water on the site, one should be guided by the SanPiN standards, which state that it is prohibited to wash cars, wash and rinse clothes by watering animals and other activities that contribute to water pollution, at a distance of less than twenty meters from wells. That is, the distance from the septic tank to any well (including yours) must be greater than this value.

To drain faecal water, a separate line should be laid, to which only toilets will be connected (if the house is on several levels and each has a toilet). When determining the installation site of treatment facilities (or a cesspool, or a finished tank), it should be borne in mind that the minimum distance from the base of your house to the septic tank should be at least 9 m, to the water intake sources (yours or neighbors) at least 30 m, regardless of the type septic tank.

Septic tank equipment and laying of external household sewage

A septic tank for discharging domestic wastewater of a country (rural) house is a pit, the depth of which should be greater than the level of soil freezing in your area, but not deeper than the level of the water intake horizon. On average, 1.5 m depth will be sufficient.

Two concrete rings with a diameter of 90 cm are lowered into the pit and set one on top of the other.If the soils in your area are sandy, then the open area of ​​the septic tank bottom will be enough to disperse water, if the soils are loamy or clayey, then several rows of holes with a diameter must be drilled in the lower ring in advance not less than 32 mm. In this case, before backfilling the septic tank, it is necessary to overlay the first ring up to about half of its height with additional scattering elements (large broken bricks, porcelain insulators, large rubble, etc.). A thick construction film or geomembrane should be laid on the top of the elements to prevent excessive drainage of rainwater.

Photo 1 shows a general view of such a septic tank after backfilling. To exclude freezing, after laying the line, it should be additionally collapsed and a cover made of frost-resistant material should be picked up (sidewalls from cable coils are well suited).

The work on laying the external highway begins with digging a trench. Photo 2 shows that the trench has a shallow depth and a slope towards the septic tank. The slope for the trench is taken at least 1 degree. In this case, the depth of the trench at the basement of the house was 0.5 m, and at the inlet to the septic tank 0.7 m. The length of this trench is about 8 m. Such values ​​are due to the high level of groundwater in this area. The lower their level is, the deeper the pipe can be laid, the quieter you can winter. In this case, you will have to take measures for additional insulation. Photo 3 shows that a pipe for external sewer wiring with a diameter of 110 mm is laid on foam panels 50 mm thick.

After the pipe is laid, it is necessary to mark with chalk the place of its entry into the ring and punch a hole of a larger diameter using a hammer or a hammer drill with a hammer function. The assembly of the line begins from the well of the septic tank, where the end of the pipe is released by about 30-40 cm. The assembly is carried out “by water”, that is, the end of the pipe without a neck should be in the well. General view of the assembled line is shown in photo 4.

Of course, the best option in order to pass the pipe through the foundation of the house is to take care of this in advance and lay at least a piece of asbestos-cement pipe of a larger diameter at a certain depth, but most often, when building a house, the passage holes are left much higher. In this case, the technological hole is made at a height of 1 m from the zero mark. There is nothing wrong with laying sewer pipes outside the building. To protect it from frost, it will be enough to make a box at least from the same foam. In photo 5, you can see that the pipe of the lounger approaches the foundation and a 90-degree elbow is installed at its end. At this point, the lounger turns into a riser.

Now it remains to bring the external pipeline into the house through the left technological hole. This process is clearly visible from the outside (photo 6) and from the inside (photo 7) sides of the house..

After the pipe of the external line is brought into the house, one more knee must be connected to it in turn at 90 degrees, revision, crosspiece, vacuum valve. The assembly process can be seen in photos 8 – 10. The vacuum valve is needed in order to compensate for the air pressure difference when draining the water so that the siphons do not empty. Otherwise, a vertical ventilation riser would have to be installed through all floors of the house with an outlet above the roof. Since all the rest of the sewage system runs inside the house, then, starting with the cross, pipes and fittings for internal wiring are used (they are gray). For a domestic sewage device, 50 mm pipes are sufficient. In our example, there are two lines – a drain from the kitchen and a drain from the bathroom. The wiring is visible in photo 11.

After all the internal highways have been laid, you need to spill each of them with plenty of water. For this you can use a bucket and a large funnel, for example. The flow of water must be given the maximum, simulating a drain from a bath or a full kitchen sink. And only after making sure that all connections are airtight, you can proceed to the final seal. The technological hole is blown out with polyurethane foam, and the pipe of the bed in the trench is covered from above with styrene panels with a thickness of at least 50 mm in the form of a house, after which backfilling is performed. The start of water into the septic tank is shown in photo 12, the appearance of the technological hole blown out with foam is in photo 13, and the installation of insulation is in photo 14. In order not to spend a lot of foam on sealing a large hole, you can lay strips of foam or styrofoam.

As the experience of operating such septic tanks shows, with a significant fluctuation in the water level in them, depending on the volume of discharge, the condition of the soil (the ability to adsorb depends on the degree of its moisture content) and the season, it never overflows, it practically does not silt (cleaning is required once at two years old) and does not cause trouble for the owners or neighbors.

Fecal sewerage – sewage treatment plant or cesspool

The device of fecal sewerage is much more difficult both technically and in relation to compliance with all building and sanitary standards. Before deciding which system to give preference to, you need to carefully calculate the location of the possible location of local treatment facilities (VOC) on the site. The thing is that not all regions of Russia have sanitary standards that determine the minimum distance from the location of the VOCs themselves and from the point of discharge of treated water into the filtration trench. Such structures are still considered to be something from the realm of fantasy and there are no standards for them..

If your region does not have its own standards, then you will have to be guided by the norms of SanPiN 2.2.1 / 2.1.1.1200-03 “Sanitary and Epidemiological Rules and Regulations”. Section “Sanitary protection zones and sanitary classification of enterprises, structures and other facilities”, adopted in 2003. According to the requirements of this document, closed-type VOCs must be at a distance from residential buildings at least 50 m. Now estimate the size of your site. So it turns out that it is far from always possible to install VOCs that discharge treated wastewater into a filtration trench. In addition, the high water table puts an end to this venture..

There are two options left – a cesspool or the use of a standard large-volume tank for collecting fecal waste. The device of a sealed cesspool is an expensive business and does not always justify the investment, since it is very difficult to achieve one hundred percent tightness of such a structure. A good way out of this situation would be the installation as a collecting tank of a spent barrels from fuel and lubricants or other similar containers. The main thing is that its volume would be equal to or exceed 3 cubic meters. Since such is the volume that an ordinary fecal machine can pump out at a time. It is necessary to position the container in such a way as to provide a quick and convenient access to the vacuum truck.

As an illustrative example, consider the installation of such a tank with a volume of 5 cubic meters on a site with a high groundwater level.

The device of the simplest fecal sewerage

In order to arrange the simplest fecal sewage system, the following materials and equipment will be required:

• a sealed container with a hatch, suitable in volume, depending on the number of residents (minimum capacity – 3 cubic meters);
• sewer pipe for outdoor work (in accordance with the desired distance from the house, but not less than 10 m / linear);
• asbestos-cement pipe with an internal diameter of at least 150 mm (according to the number of sewer pipes);
• insulation made of expanded polyethylene with a diameter of 108 mm and a thickness of 9 mm (according to the number of sewer pipes);
• couplings for asbestos-cement pipes (based on considerations that the length of such a pipe is 4 m);
• bituminous mastic for metal for a container (if the container is steel);
• sewer revision, pipes for internal wiring around the house with a diameter of 110 mm, fittings for them (in accordance with the project of in-house wiring);
• a toilet with a cistern with two drain modes – normal and economical;
• vacuum valve.

The main equipment for the fecal sewage system is an excavator, or strong hands and a shovel. Moreover, if the groundwater is high, then the second will not work – water arrives in the hole faster than the excavator works.

In the case considered as an example, it was decided to use a thick-walled steel tank from under fuels and lubricants as a septic tank (of course, having undergone appropriate processing from fuel residues so that the tank does not fly up into the air) with a volume of 5 cubic meters. Calculation for a family of two working people with infrequent visits of guests. Such a load on the fecal sewerage system is equivalent to 40 liters of wastewater per day. Accordingly, the volume of the container will be sufficient for 4 months. With the cost of the services of a vacuum truck about 1000 rubles for pumping out one machine, operating costs will be about 3000 rubles per year. Expenses in a city apartment will be approximately the same amount, based on the calculation that the same family pays 300 rubles for water disposal. per month.

So, the container must be carefully treated with bitumen mastic from the outside. For this, any car anticorrosive materials designed for processing the underside of cars are ideal. Photo 15 shows such a container after processing..

In advance, it is necessary to prepare a pit with an excavator so that the barrel ideally plunges into it completely, and there is a margin around the edges so that there are no problems during its installation when the work of a crane is needed. The pit is shown in photo 16..

In the area where the work was carried out, groundwater arrived so quickly that the pit was completely filled in literally four to five hours. The photo shows the moment before the installation of the barrel, when almost all the water was downloaded by the drain pump. When installing the container, there should be no water, otherwise it will float. Another geological feature of this area is a limestone slab, which lies at a depth of about 2 m from the surface. Thus, there were serious restrictions on the level of penetration, which affected the level of the tie-in into the tank. Ideally, the depth of the pit should be such that the level of the inset of the sewer plank bed is as high as possible to the upper edge of the tank. This will significantly reduce the risk of highway freezing in winter. Indeed, in this case, the water in it will not stagnate.

The next step is to install the container in place with a crane. Photo 17 shows the working moment of transferring the container, and photo 18 – the container is already installed.

To prevent the container from floating, it must be anchored. An ideal option for this is to install foundation blocks next to the barrel on both sides, through the loops of which to throw steel annealed wire rod with a diameter of 8-10 mm and pull the container with it. In this case, there were no blocks, but there were two fragments of the road slab, which were laid on top of the container and thus loaded it by 8 tons. Empty container weight – about 1.5 tons. In total, it turns out to be 9.5 tons, which is twice its displacement. This is a guarantee that it will not be displaced by the soil in winter. Photo 19 shows the moment of laying one of the slab fragments. After these works are completed, you can start laying the external highway.

Laying of an external line and methods of protecting external sewage pipes from freezing

The laying of the external sewage system begins after the container is installed. But if you have an excavator at your disposal, then it makes sense to dig a trench along with the pit in advance. Let the slope not be strictly executed, but the amount of manual work will be significantly reduced. When choosing a direction to the house and moving away from it, you need to calculate the trench so that there are no turns on it. The highway must be straight! Otherwise there is a risk of clogging at the bend. But if it is not possible to connect the exit point from the house with the entry point of the pipe into the tank in a straight line, then you will have to arrange a sewer well with a hatch like those installed in the city.

In the example under consideration, the distance of the container from the point of exit from the house was 21 meters. This is due to the need to remove it from the neighbor’s well by 30 m, as well as from its own water well. The trench was dug by an excavator in advance, and then worked manually to the required slope. To determine the slope of the trench, you need to proceed from a standard value of at least 1 degree. That is, on 21 m of the trench, you will need to set a slope relative to the point of release from the house of at least 20 cm, but it is better to make the slope more. In this project, it is set unevenly. At the outlet from the house, the first 4 meters of the pipe run with a slope of 15 degrees, and the rest of the line – 5 degrees. This is due to the aforementioned soil characteristics.

In order to protect the sewer pipes from freezing, the “sandwich” technology is used. Foamed polyethylene insulation is put on the plastic pipe, and then the entire assembly is placed in an asbestos-cement pipe. This process is shown in photos 20 – 22..

Pipe assembly starts from the container. A hole is made in it at the design point, where the first asbestos-cement pipe is inserted (photo 23). She is given a slope in accordance with the planned value. The slope of 5 degrees corresponds to the position of the air bubble in the water level, as shown in photo 24. The easiest way is to set the pipes, set the slope and calculate the point of entry into the tank using a laser level. But a device for internal work is not suitable for these purposes, and not every company can afford a real tool. In this project, all work is done using a simple water level.

Then, two plastic pipes are inserted into the first asbestos-cement pipe, with insulation on them, pre-connected to each other. The next two pipes are inserted in the indicated way into a free asbestos-cement pipe and joined to the previous one, not forgetting to connect the asbestos pipes together through a coupling. This continues until the entire line is assembled (photo 25).

The insulated “sandwich” is brought into the basement of the house through its technological opening and goes into the riser equipped with a revision, as shown in photo 26. Then the fan pipe is wrapped under the floor slab and goes to the pipe for internal wiring. The transition begins with a tee in which the vacuum valve is installed, the purpose of which was mentioned earlier. The pipe under the ceiling runs at a slope and is additionally fastened with a homemade welded clamp on two anchor bolts (photo 27). After that, the pipe is fed to the place of the projected installation of the toilet bowl, except for which no other plumbing equipment (if there are no other toilet bowls) can not be connected to it!

The further procedure for work is the same as in a regular high-rise building – installing a toilet, connecting it to a water supply and a sewer outlet. The toilet is needed with two flushing modes – normal and economical. The toilet system (installed or conventional) does not matter, but it must be from a very good manufacturer, whose shut-off valves would exclude the slightest leak for many years. After all, the speed of filling the container depends on this, which means the costs.

Conclusion. Some helpful tips

Local sewerage installation is a very time-consuming and capital-intensive business. It, like any other, has its own subtleties that simplify the work. Here are some tips to help you increase productivity and avoid blunders:

1. Sewer pipes, especially of large diameter, are difficult to plant on rubber gaskets, without which the joint will lose its tightness. To make this operation easy, you need to coat the gasket with either silicone or a grease that does not corrode rubber (for example, grease for CV joints) before connecting the pipes;
2. Asbestos-cement pipes are connected with plastic couplings. To avoid problems with their installation, the couplings must be kept in boiling water or very hot water. Then they become elastic and pipes can be easily inserted into them;
3. The use of bacterial preparations for closed-type septic tanks promotes the disappearance of odors, and deep processing of organic matter with sedimentation of sludge to the bottom. Due to this, in some areas, you can pump out clarified water yourself;
4. Together with the fecal sewerage device, build an ordinary outdoor toilet on the site, which would be intended for guests in the warm season – this will save the resource of the tank and insure against malfunctions;
5. According to the law of communicating vessels, the liquid in them is established at the same level. If the container is practically full, then water will stagnate in the line. Avoid filling to this level during the cold season. The line will not freeze if there is no liquid in it;
6. Never throw toilet paper down the toilet! Cellulose is not processed by bacteria intended for septic tanks!