External water supply and sanitation systems. What does it consist of and what is an external household sewer network External sewerage device snip

SNiP external sewer networks are used everywhere, both in private homes and in urban areas. This system allows you to use the sewer system with comfort, without problems during operation, provides an ecological cleanliness of the environment and convenience for all people around.

These sewer systems are carried out by specialists; in private areas, you can do the work yourself. In any case, it is necessary to follow all the rules for arranging such a sewage system so that there are no problems or accidents in the future.

Features and types of data sewer systems

External sewerage systems are branches of pipes that direct wastewater away from residential or non-residential premises. to special tanks.

The plumbing must be installed with a slope so that wastewater flows into the tanks by gravity. The second option for the operation of the sewer system by connecting a special pump or installation of pressure networks. Regardless of how the sewage system works, it must be installed with strict adherence to all the rules and state sanitary standards.

Such communications can be divided into several types according to the method of their installation and pipe laying:

In addition to all this, sewer systems can be divided according to other criteria. Sewerage for outdoor use can be located in various places, also its purpose is different. You can consider the following types of sewer systems for outdoor use:

1. Intra-apartment or intra-yard sewer networks, in another way they are called - tracing. It is a laying of plastic water pipes from the start to the end point. They can even take place in an apartment building, the main thing is compliance with all installation rules. The shortest path from the building to the collector is used, the pipes are laid at a distance of at least three meters from the outer walls, always vertically. Such a system provides for connection to the central sewer system, the use of autonomous sewerage impossible.
2. The street sewer network is an extensive system of water pipes. They lie on all streets of the city territory and represent complex piping system and wells. All this ensures the transportation of wastewater to the centralized sewerage system - urban sewers.
3. Collectors are facilities that collect wastewater, and if necessary, transfer it to other collectors. They are usually located on the territory of the sewerage basin and its outskirts. The principle of operation of the entire sewer basin system - transportation contaminated wastewater under pressure or gravity.
4. Wastewater treatment plant is always the end point of wastewater arrival. On these systems, they are completely cleaned almost to the initial state and reset clean water in reservoirs or soil, its use for domestic purposes. Treatment facilities can be autonomous for private sites. Such structures are usually installed in enterprises or in residential buildings if there is no possibility of connecting to a central sewer.

In each individual case, there may be several types laying of water pipes. It depends on many factors, such as groundwater levels, turns and bends in the path. always important observe sewer pipe slope, which varies and depends solely on their diameter. In each case, a large number of different subtleties and additional elements of work can arise. It may be necessary to install a viewing or drainage well, a pump and other nuances.

Components of the external sewage system

The sewer system consists of various parts that allow you to freely transport waste water in the right place for their further cleaning. Sewerage as a whole may consist of the following parts:

In addition to all this, it is possible to use other various elements for full-fledged work sewer system. In order for the sewer to be operated for a long time, it is worth paying attention to material selection for piping and other parts. The rules provide for the use of the following materials:

• polypropylene;
• polyethylene;
• steel;
• polyvinyl chloride;
• cast iron;
• reinforced concrete;
• asbestos cement.

The last two options are usually used only when plumbing is needed. large diameter. In addition, ceramic or glass pipes can be used, but this is rarely practiced.

Rules for installing an external sewerage system

To create such a sewerage system, it is imperative to follow a number of rules, so that later it will be possible operate the building. The requirements of SNiP, which relate to external sewerage and a system of construction of this type, are based mainly on the following factors:

• ground water level;
• soil properties;
• climatic conditions;
• average wastewater volume;
• distance to the nearest treatment plant or pump.

It is important to comply pipe slope, so that the waste can pass through them by gravity. For pipes of each diameter, an optimal slope is provided:

1. Diameter - 50 cm, minimum slope - 3 cm per 1 m of pipe.
2. Diameter - 100 cm, slope - 2 cm per 1 m of pipe.
3. Diameter - 160 cm, slope - 0.8 cm per 1 m of pipe.
4. Diameter - 200 cm, minimum slope - 0.7 per 1 m of pipe.

Features of installation of external sewerage in accordance with all the rules of SNiP

Always carried out first preparatory work. In this case, this is the study of the soil, laying the route of the water supply and a complete calculation of all the details and trifles. The first step is always trenching and its preparation, the supply of additional elements, if necessary.

All pipe joints carefully fixed, treated with sealant and tested before starting the system. Water pipes needs to be insulated so that it does not freeze in a strong drop in temperature. After completing all these works, the sewer is connected to the cleaning system or collector, a test run is performed. Always first, a full design check is carried out and after its approval, the trench is filled and compacted.

Requirements for the components of the water supply

• corrosion resistance, otherwise additional material protection;
• the presence of a base for laying water pipes in accordance with the characteristics of the soil;
• mandatory use of plungers, valves and other additional materials for pressurized sewer networks;
• installation of manholes strictly in places of bends, intersections and slopes of the pipeline;
• working parts of wells must have stairs, fences and manholes;
• the dimensions of the wells are set depending on the size of the pipeline and its diameter;
• rainwater inlets should be installed in all crowded places, just in lowlands, near pedestrian crossings, and so on.

Before you independently engage in the creation of external sewage, you must be well acquainted with all the rules for its implementation. "SNiP 2.04.03-85 Sewerage. External networks and facilities” presents a complete list of all safety rules and features of the installation of this type of communication. Violation of the rules is prosecuted by the legislation of the Russian Federation, negligence in such things can lead to to irreversible consequences.

In order to avoid problems with the sewer system of a country house, when laying its street part, it is necessary to comply with a number of sanitary and building standards. Installation work can be entrusted to professionals or done by hand. If the second option is chosen, then before starting the installation of an external sewage system, you should read the advice of experienced plumbers, otherwise correcting the mistakes made will result in a considerable waste of money and nerves.

The entire sewer system of a private house is divided into internal and external parts. The intra-house component collects wastewater from plumbing fixtures and supplies them to a single riser, which is connected to the outdoor part of the drainage system.

General sewerage scheme of a private house

The main task of external sewage networks is the transportation of wastewater to the place of disposal and the disposal itself (in the case of an autonomous septic tank). They consist of pipelines and treatment facilities.

You can get rid of the collected sewage by:

• connections to a centralized system (if any);
• arrangement of an individual septic tank or cesspool.

In the first case, it is enough to lay pipes and equip a sewer well. And in the second, in addition to installing external sewer networks, you will need to install a local treatment system.

Important! According to sanitary standards, wastewater must be disposed of in such a way that there is no pollution of aquifers and the surrounding area. There are significant fines for non-compliance with these requirements.

Scheme of connecting the cottage to the centralized sewer network

For a private house, one of four methods of individual wastewater treatment is suitable:

1. Cesspool - inexpensive, but not very convenient.
2. Septic storage tank - you will have to constantly invite vacuum cleaners.
3. A two-chamber septic tank with post-treatment - in the first chamber, heavy fractions settle, and in the second, treated water is drained into the ground.
4. Biological treatment plant - special microorganisms are used to decompose sewage.

The first option is the cheapest and the last is the most expensive. But in any case, they will have to lay an external sewage pipeline.

Design and material selection

Regulatory Requirements

Before starting the installation of an external sewage system with your own hands, it is necessary to prepare its project. There are certain requirements for laying pipes and the location of the septic tank.

When developing a project, you will have to consider:

• relief of the local area;
• distance to drinking wells and reservoirs;
• general climatic conditions;
• the number of people living in the cottage (average daily volume of effluents);
• soil characteristics (composition, groundwater level, freezing depth);
• technical conditions for connecting to a centralized system or the need to organize an entrance for sewage equipment for pumping out sewage.

All these requirements are spelled out in the codes of practice “Sewerage. External networks…” (SP 32.13330.2012) and “Single-apartment residential houses…” (SP 55.13330.2011), which replaced the SNiPs of the same name.

When installing an autonomous cleaning system, you will not have to collect a bunch of permits and then pay for utilities. But you will constantly need to monitor the condition of your septic tank and, if necessary, call the sewers.

Important! The entire sewerage system of a private house is built on the principle of gravity sewage. Installation of horizontal sections of sewer pipes outside the cottage should be done with a slope towards the treatment system.

Optimal slope for street sewer pipes

A slight slope of the pipeline ensures the gravity flow of sewage. Do not tilt it too much, as this can lead to blockages of solid fractions at the entrance to the sump. The optimal slope depends largely on the diameter of the pipe:

1. D500 mm - slope 30 mm / running meter.
2. D1000–1100 mm - slope 20 mm / running meter.
3. D1600 mm - slope 8 mm / running meter.

Mistakes made during the design and installation of external sewage networks will lead not only to constantly formed blockages, but also to the poisoning of drinking water sources with fecal waste. Therefore, it is so important to follow SNiPs at all stages of creating sewers.

What pipes are used for the external line

Building regulations for the installation of external sewerage are allowed to use pipes from:

• become;
• cast iron;
• asbestos cement;
• polymers;
• ceramics.

Steel pipes are subject to corrosion, they are rarely used. Cast iron is a classic, but due to its internal roughness, pipelines made from it are prone to silting. Gradually they are replaced by other materials.

Asbestos cement is cheap and not subject to corrosion, but is inferior in terms of durability to high-quality plastic. Ceramic products have the largest resource of strength and reliability, but they are also the most expensive. The best choice in terms of parameters is plastic.

Plastic pipes are easily connected by docking

Plastic pipes for the external sewerage network can be:

1. Polyvinyl chloride (PVC).
2. Polypropylene (PP).
3. Low pressure polyethylene (HDPE).

All of them are suitable for laying a sewer pipeline outside a private house. For their installation, you can use special glue or cold welding technology. But it is much easier to pick up products with a socket at the end, and mount the line by inserting one pipe into another.

Advice! PVC pipes at temperatures below -15 C may crack. They must be carefully insulated.

Installation technology of the house sewer network

In a private house, the laying of external sewage usually begins after the construction of walls and roofing. To do this, a trench is dug to the septic tank, and pipes are laid there.

The boundaries of the depths of soil freezing in Russia

The depth of laying depends on the level of freezing of the ground on the plot. To prevent the sewer pipe from freezing, during installation it must be placed below the freezing point of the soil. It has its own for each locality.

In "cold" areas, instead of digging deep trenches, the sewer line is insulated. For this, moisture-resistant insulation and / or heating cables are used.

Heating cable fastening technology

The laying of the external sewerage network is as follows:

1. A trench is dug from the house to the septic tank, a pillow of sand 10–15 cm thick is compacted at its bottom.
2. The pipeline is laid with a slope from the building.
3. The pipe is insulated and the heating cable is installed.
4. Trench backfilling in progress.

Important! The sewer pipe laid in the trench must not have sagging. Before backfilling, you must make sure of this, otherwise the blockage will be provided.

Often, a footpath or a parking lot for a car is arranged on top of the sewer pipe. In this case, the laying of external sewage is carried out in a "case". If the soil above the pipeline is periodically subjected to mechanical stress, the pipe must be protected. The figure below shows one of the options for such a case.

Sewer pipe in a case

The pipe (7) is wrapped with support rings (6), sealant (3 and 4) and closed with a case (5). At its ends, docking nodes are formed from clamps (1) and cuffs (2). Only such protection can guarantee the durability of the sewer pipeline.

And finally, upon completion of installation work and before filling the pipeline with soil, it must be tested. A test run of water will allow you to check the tightness of the structure and the correct installation.

Video: laying sewer pipes of a country house

The design and installation of external networks of the sewer system of a private house is strictly regulated by building codes. If these rules are grossly violated, both problems with the operation of the sewerage system and negative impacts on nature are possible. Even a beginner is able to cope with installation work. But when preparing a project, it is better to consult with a competent engineer.

Wastewater classification and sewerage systems

SEWERAGE AND SANITARY CLEANING OF SETTLEMENTS

Chapter 10

A necessary form of purification of populated areas from sewage is sewage. Its task is to remove water, liquid waste generated as a result of household activities of the population of cities and towns and the work of industrial enterprises. Together with surface waters (irrigation, atmospheric, ground) that appeared on the surface of urban and rural areas, liquid waste is a contaminated liquid and is called sewage. They contain chemical, biological and organic components. They must be removed, cleaned, disinfected and sent to the nearest water bodies. For this, the sewer system and drains are used.

Wastewater is divided into the following categories:

Household or household - from houses, industrial buildings, formed as a result of human activity. Contain organic mineral, bacterial pollution;

Production - from industrial enterprises, formed as a result of technological processes. Contain organic, mineral, toxic pollution;

Atmospheric - from the territories of the city, roofs of houses, rain and melt water. Contain mineral, chemical pollution.

Wastewater systems depend on the composition of wastewater. The degree of pollution is characterized by the amount of pollution per unit volume. The concentration of pollution depends on the rate of water consumption in the settlement, the nature of production, the place of collection of sedimentary water, and their quantity. The sewerage system of sewage provides reception, transportation, cleaning, disinfection, utilization of useful substances and disposal into the reservoir. There are two types of sewerage: export and floating.

Export sewerage is based on the export of individual volumes of liquid to aeration fields.

Floating sewer consists of a system of underground pipelines and devices that transport wastewater to treatment facilities. This system is most common in large cities. For its device, it is necessary to have an internal water supply with a consumption rate of at least 60 l / day per person.

The floating sewage system consists of internal devices, external networks, pumping stations, treatment facilities and wastewater discharge devices.

Floating sewerage, depending on how the issue of wastewater disposal is resolved, is divided into storm, fecal (household), all-floating, separate (complete, incomplete), semi-separate and combined.

Alloy sewerage carries out the removal of one system of pipelines of storm sewage, which comes after rain from urban areas through rain inlets, and household and fecal water coming from residential buildings and industrial buildings. With separate sewage, two independent sewage disposal systems are used: storm sewer (drainage) and household fecal. Wastewater from industrial enterprises is discharged by a separate system for cleaning them from specific contaminants. Currently, a separate sewerage system is most applicable.

External sewerage consists of underground pipelines, through which water is drained by gravity from houses to pumping stations. The intra-quarter network is connected to the street network. At the junctions, control wells are constructed, located at the red lines of the streets. The canalized territory of the city is divided into separate basins along the border of the watersheds. Street sewage is combined within one pool and sent to the main collector. In the lower sections of the collectors, pumping stations are arranged to raise wastewater and ensure their further gravity-flowing fusion (pressure collector). Collectors of large diameter are called channels.

Sewer networks are designed on the basis of the master plan. According to absolute horizontal lines, the boundaries of the sewage basins along the watersheds and the directions for laying the main collectors with a natural slope are found on the terrain. Then they design connections to them and intra-quarter networks.

Sewerage schemes are selected depending on the terrain conditions: perpendicular, crossed, parallel, zone (zone), radial.

The sewerage route is selected using a feasibility study of possible options. When laying several pressure pipelines in parallel, the distances between the outer surface of the pipes to structures and utilities should be taken in accordance with SNiP 2.04.03-85 based on the conditions for protecting adjacent pipelines and performing work.

The smallest laying depth is taken in accordance with SNiP 2.04.03-85 for sewer pipes with a diameter of up to 500 mm, 0.3 m less than the greatest depth of penetration into the soil of zero temperature, but not less than 0.7 m to the top of the pipe, counting from the layout marks, for pipes of large diameter - less than 0.5 m.

The diameters of the sewer pipes of the system depend on the amount of wastewater, which is determined by the degree of improvement, i.e., the rate of water consumption, the presence of hot water supply. So, the rate of wastewater consumption per 1 person. with centralized hot water supply and the presence of a bath - 400 l / day, and with gas heating installations - 300 l / day. .

For sewer networks, cast-iron, asbestos-cement, plastic, concrete, reinforced concrete and ceramic pipes are used, depending on the presence of pressure and the composition of wastewater.

For pressure collectors, cast-iron, reinforced concrete, steel and asbestos-cement pipes are used; for non-pressure and gravity collectors - cast iron, asbestos-cement, plastic, concrete, reinforced concrete and ceramic pipes. Collectors are laid from round reinforced concrete pipes and prefabricated elements.

BUILDING REGULATIONS

OUTDOOR NETWORKS AND FACILITIES
WATER SUPPLY AND SEWERAGE

SNiP 3.05.04-85*

USSR STATE CONSTRUCTION COMMITTEE

Moscow 1990

DEVELOPED VNII VODGEO Gosstroy of the USSR (candidate of technical sciences IN AND. Gotovtsev- theme leader VC. Andriadi), with the participation of the Soyuzvodokanalproekt of the Gosstroy of the USSR ( P.G. Vasiliev and A.S. Ignatovich), Donetsk Promstroyniiproekt Gosstroy USSR ( S.A. Svetnitsky), NIIOSP im. Gresevanova Gosstroy of the USSR (candidate of technical sciences V. G.Galician and DI. Fedorovich), Giprorechtrans of the Ministry of River Fleet of the RSFSR ( M.N.Domanevsky), Research Institute of Communal Water Supply and Water Purification of the AKH them. K.D. Pamfilov of the Ministry of Housing and Communal Services of the RSFSR (Doctor of Technical Sciences ON THE. Lukinykh, cand. tech. Sciences V.P. Krishtul), Institute of the Tula Promstroyproekt of the Ministry of Tyazhstroy of the USSR.

INTRODUCED VNII VODGEO Gosstroy USSR.

PREPARED FOR APPROVAL by the Glavtekhnormirovaniye Gosstroy USSR N.A. Shishov).

SNiP 3.05.04-85* is a reissue of SNiP 3.05.04-85 with amendment No. 1, approved by Decree of the USSR Gosstroy of May 25, 1990 No. 51.

The change was developed by VNII VODGEO Gosstroy of the USSR and TsNIIEP of engineering equipment of the State Committee for Architecture.

Sections, paragraphs, tables in which changes have been made are marked with an asterisk.

Agreed with the Main Sanitary and Epidemiological Directorate of the Ministry of Health of the USSR by letter dated November 10, 1984 No. 121212/1600-14.

When using a regulatory document, one should take into account the approved changes in building codes and regulations and state standards published in the Bulletin of Construction Equipment magazine of the USSR Gosstroy and the information index "State Standards of the USSR" of the State Standard.

* These rules apply to the construction of new, expansion and reconstruction of existing external networks 1 and water supply and sewerage facilities in settlements of the national economy.

_________

1 External networks - in the following text "pipelines".

1. GENERAL PROVISIONS

1.1. When building new, expanding and reconstructing existing pipelines and water supply and sewerage facilities, in addition to the requirements of projects (working projects) 1 and these rules, the requirements of SNiP 3.01.01-85 *, SNiP 3.01.03-84, SNiP III-4-80 * and other norms and rules, standards and departmental regulations approved in accordance with SNiP 1.01.01-83.

1 Projects (working projects) - in the following text "projects".

1.2. Completed pipelines and water supply and sewerage facilities should be put into operation in accordance with the requirements of SNiP 3.01.04-87.

2. EARTHWORKS

2.1. Earthworks and foundation works during the construction of pipelines and water supply and sewerage facilities must be carried out in accordance with the requirements of SNiP 3.02.01-87.

3. PIPING INSTALLATION

GENERAL PROVISIONS

3.1. When moving pipes and assembled sections with anti-corrosion coatings, soft tongs, flexible towels and other means should be used to prevent damage to these coatings.

3.2. When laying pipes intended for domestic and drinking water supply, surface or waste water should not be allowed to enter them. Before installation, pipes and fittings, fittings and finished units must be inspected and cleaned from inside and outside from dirt, snow, ice, oils and foreign objects.

3.3. The installation of pipelines should be carried out in accordance with the project for the production of works and technological maps after checking the compliance with the project of the dimensions of the trench, fixing the walls, bottom marks and, in case of above-ground laying, supporting structures. The results of the check should be reflected in the work log.

3.4. Flare-type pipes of non-pressure pipelines should, as a rule, be laid with a flare up the slope.

3.5. The straightness of sections of free-flow pipelines between adjacent wells, provided for by the project, should be controlled by viewing “into the light” using a mirror before and after backfilling the trench. When viewing a pipeline of circular cross section, the circle visible in the mirror must have the correct shape.

The permissible horizontal deviation from the circle shape should be no more than 1/4 of the pipeline diameter, but not more than 50 mm in each direction. Deviations from the correct form of the circle vertically are not allowed.

3.6. The maximum deviations from the design position of the axes of pressure pipelines should not exceed ± 100 mm in plan, the marks of the trays of non-pressure pipelines are ± 5 mm, and the marks of the top of pressure pipelines are ± 30 mm, unless other standards are justified by the project.

3.7. Laying pressure pipelines along a gentle curve without the use of fittings is allowed for socket pipes with butt joints on rubber seals with an angle of rotation in each joint of no more than 2 ° for pipes with a nominal diameter of up to 600 mm and no more than 1 ° for pipes with a nominal diameter over 600 mm.

3.8. When installing water supply and sewerage pipelines in mountainous conditions, in addition to the requirements of these rules, the requirements of Sec. 9SNiP III-42-80.

3.9. When laying pipelines on a straight section of the route, the connected ends of adjacent pipes must be centered so that the width of the socket gap is the same around the entire circumference.

3.10. The ends of pipes, as well as openings in the flanges of shut-off and other fittings, during breaks in laying, should be closed with plugs or wooden plugs.

3.11. Rubber seals for the installation of pipelines at low outdoor temperatures are not allowed to be used in a frozen state.

3.12. Sealing and “locking” materials, as well as sealants according to the project, should be used to seal (seal) the butt joints of pipelines.

3.13. Flange connections of fittings and fittings should be mounted in compliance with the following requirements:

flange connections must be installed perpendicular to the axis of the pipe;

the planes of the connected flanges must be even, the nuts of the bolts must be located on one side of the connection; bolts should be tightened evenly crosswise;

elimination of distortions of flanges by installing beveled gaskets or tightening bolts is not allowed;

welding of joints adjacent to the flange connection should be carried out only after uniform tightening of all bolts on the flanges.

3.14. When using soil for the construction of a stop, the supporting wall of the pit must be with an undisturbed soil structure.

3.15. The gap between the pipeline and the prefabricated part of the concrete or brick stops must be tightly filled with concrete mixture or cement mortar.

3.16. Protection of steel and reinforced concrete pipelines from corrosion should be carried out in accordance with the design and requirements of SNiP 3.04.03-85 and SNiP 2.03.11-85.

3.17. On the pipelines under construction, they are subject to acceptance with the preparation of certificates of examination of hidden works in the form given in SNiP 3.01.01-85 anti-corrosion protection of pipelines, sealing of places where pipelines pass through the walls of wells and chambers, backfilling of pipelines with a seal, etc.

STEEL PIPING

3.18. Welding methods, as well as types, structural elements and dimensions of welded joints of steel pipelines must comply with the requirements of GOST 16037-80.

3.19. Before assembling and welding pipes, they should be cleaned of dirt, check the geometric dimensions of the groove, clean the edges and the inner and outer surfaces of the pipes adjacent to them to a width of at least 10 mm to a metallic sheen.

3.20. Upon completion of welding work, the outer insulation of pipes in the places of welded joints must be restored in accordance with the project.

3.21. When assembling pipe joints without a backing ring, the offset of the edges should not exceed 20% of the wall thickness, but not more than 3 mm. For butt joints assembled and welded on the remaining cylindrical ring, the offset of the edges from the inside of the pipe should not exceed 1 mm.

3.22. Assembly of pipes with a diameter of more than 100 mm, made with a longitudinal or spiral weld, should be carried out with a displacement of the seams of adjacent pipes by at least 100 mm. When assembling the joint of pipes in which the factory longitudinal or spiral seam is welded on both sides, the displacement of these seams can be omitted.

3.23. Transverse welded joints should be located at a distance of not less than:

0.2 m from the edge of the pipeline support structure;

0.3 m from the outer and inner surfaces of the chamber or the surface of the enclosing structure through which the pipeline passes, as well as from the edge of the case.

3.24. The connection of the ends of the joined pipes and sections of pipelines with a gap between them exceeding the permissible value should be carried out by inserting a "coil" with a length of at least 200 mm.

3.25. The distance between the circumferential weld of the pipeline and the seam of the branch pipes welded to the pipeline must be at least 100 mm.

3.26. Assembly of pipes for welding must be carried out using centralizers; it is allowed to straighten smooth dents at the ends of pipes with a depth of up to 3.5% of the pipe diameter and adjust the edges using jacks, roller bearings and other means. Sections of pipes with dents greater than 3.5% of the pipe diameter or with tears should be cut out. The ends of pipes with nicks or chamfers with a depth of more than 5 mm should be cut off.

When applying the root seam, the tacks must be completely digested. The electrodes or welding wire used for tacks must be of the same grade as for welding the main seam.

3.27. Welders are allowed to weld joints of steel pipelines if they have documents for the right to carry out welding work in accordance with the Rules for the certification of welders approved by the USSR Gosgortekhnadzor.

3.28. Before being allowed to work on welding joints of pipelines, each welder must weld a tolerance joint under production conditions x (at the construction site) in the following cases:

if he first started welding pipelines or had a break in work for more than 6 months;

if pipes are welded from new steel grades, using new grades of welding materials (electrodes, welding wire, fluxes) or using new types of welding equipment.

On pipes with a diameter of 529 mm or more, it is allowed to weld half of the tolerance joint. The tolerance joint is subjected to:

external inspection, in which the weld must meet the requirements of this section and GOST 16037-80;

radiographic control in accordance with the requirements of GOST 7512-82;

mechanical tensile and bending tests in accordance with GOST 6996-66.

In case of unsatisfactory results of checking the tolerance joint, welding and re-inspection of two other tolerance joints are carried out. In the event that unsatisfactory results are obtained during repeated control at least at one of the joints, the welder is recognized as having failed the tests and may be admitted to welding the pipeline only after additional training and repeated tests.

3.29. Each welder must have a brand assigned to him. The welder is obliged to knock out or build up a brand at a distance of 30 - 50 mm from the joint from the side accessible for inspection.

3.30. Welding and tacking of butt joints of pipes is allowed to be carried out at an outdoor temperature of up to minus 50 ° C. At the same time, welding work without heating the welded joints is allowed to perform:

at outdoor air temperature up to min s 20 ° C - when using carbon steel pipes with a carbon content of not more than 0.24% (regardless of the pipe wall thickness), as well as low-alloy steel pipes with a wall thickness of not more than 10 mm;

at an outside air temperature of up to minus 10 °C - when using pipes made of carbon steel with a carbon content of more than 0.24%, as well as pipes made of low-alloy steel with a wall thickness of more than 10 mm. When the outside air temperature is below the above limits, welding work should be carried out with heating in special cabins, in which the air temperature should be maintained not lower than the above, or the ends of the pipes to be welded should be heated in the open air for a length of at least 200 mm to a temperature not lower than 200 °C.

After welding is completed, it is necessary to ensure a gradual decrease in the temperature of the joints and the adjacent zones of the pipes by covering them after welding with an asbestos towel or in another way.

3.31. In multi-layer welding, each layer of the seam must be cleaned of slag and metal spatter before applying the next seam. Sections of the weld metal with pores, cavities and cracks should be cut down to the base metal, and the weld craters should be welded.

3.32. In manual arc welding, individual layers of the seam must be superimposed so that their closing sections in adjacent layers do not coincide with one another.

3.33. When performing welding work outdoors during precipitation, the welding points must be protected from moisture and wind.

3.34. When quality control of welded joints of steel pipelines should be performed:

operational control during assembly and welding of the pipeline in accordance with the requirements SNiP 3.01.01-85 *;

checking the continuity of welded joints with the detection of internal defects by one of the non-destructive (physical) control methods - radiographic (X-ray or gammagraphic) according to GOST 7512-82 or ultrasonic according to GOST 14782-86.

The use of the ultrasonic method is allowed only in combination with the radiographic method, which must be used to check at least 10% of the total number of joints to be controlled.

3.35. During the operational quality control of welded joints of steel pipelines, it is necessary to check the compliance with the standards of structural elements and dimensions of welded joints, the welding method, the quality of welding consumables, edge preparation, the size of the gaps, the number of tacks, as well as the serviceability of the welding equipment.

3.36. All welded joints are subject to external inspection. On pipelines with a diameter of 1020 mm and more, its welded joints, welded without a backing ring, are subjected to external inspection and measurement of dimensions outside and inside the pipe, in other cases - only outside. Before inspection, the weld and adjacent surfaces of pipes to a width of at least 20 mm (on both sides of the weld) must be cleaned of slag, splashes of molten metal, scale and other contaminants.

The quality of the welded seam according to the results of the external examination is considered satisfactory, if it is not found:

cracks in the seam and adjacent area;

deviations from the allowable dimensions and shape of the seam;

undercuts, sinkings between the rollers, sagging, burns, unwelded craters and pores emerging on the surface, lack of penetration or sagging at the root of the seam (when examining the joint from inside the pipe);

pipe edge displacements exceeding the allowable dimensions.

Joints that do not meet the listed requirements are subject to correction or removal and re-control of their quality.

3.38. Welded joints for control by physical methods are selected in the presence of a representative of the customer, who writes down in the log of the production of works information about the joints selected for control (location, welder's brand, etc.).

3.39. 100% of welded joints of pipelines laid at crossings under and over railway and tram tracks, through water barriers, under highways, in urban sewers for communications when combined with other engineering communications should be subjected to physical control methods. The length of controlled sections of pipelines at sections of crossings should be taken at least as follows:

for railways - the distance between the axes of the extreme tracks and 40 m from them in each direction;

for highways - the width of the embankment along the sole or excavation along the top and 25 m from them in each direction;

for water barriers - within the boundaries of the underwater crossing, determined by Sec. 6SNiP 2.05.06-85;

for other engineering communications - the width of the crossed structure, including its drainage devices, plus at least 4 m on each side of the extreme boundaries of the crossed structure.

3.40. Welded seams should be rejected if cracks, unwelded craters, burns, fistulas, as well as lack of penetration at the root of the seam made on the backing ring are found during physical inspection.

When checking welds by radiographic method, the following are considered acceptable defects:

pores and inclusions, the dimensions of which do not exceed the maximum allowable according to GOST 23055-78 for the 7th class of welded joints;

lack of fusion, concavity and excess penetration at the root of the weld, made by electric arc welding without a backing ring, the height (depth) of which does not exceed 10% of the nominal wall thickness, and the total length is 1/3 of the inner perimeter of the joint.

3.41. If unacceptable defects in welds are detected by physical methods of control, these defects should be eliminated and the quality control of the doubled number of welds compared to that specified in Art. If unacceptable defects are detected during the re-inspection, all joints made by this welder should be checked.

3.42. Weld sections with unacceptable defects are subject to correction by local sampling and subsequent welding (as a rule, without overwelding the entire welded joint), if the total length of the samples after removing the defective sections does not exceed the total length specified in GOST 23055-78 for the 7th class.

Correction of defects in the joints should be done by arc welding.

Undercuts should be corrected by surfacing thread rollers with a height of not more than 2 - 3 mm. Cracks less than 50 mm long are drilled at the ends, cut out, carefully cleaned and welded in several layers.

3.43. The results of checking the quality of welded joints of steel pipelines by physical control methods should be documented in an act (protocol).

CAST IRON PIPING

3.44. Installation of cast-iron pipes manufactured in accordance with GOST 9583-75 should be carried out with sealing of socket joints with hemp resin or bituminized strand and device asbestos-cement lock, or only sealant, and pipes manufactured in accordance with TU 14-3-12 47-83, rubber cuffs supplied complete with pipes without a lock device.

Compound asbestos-cement mixtures for the device of the lock, as well as sealant is determined by the project.

3.45. The gap between the stop surface of the socket and the end of the pipe to be connected (regardless of the material of the joint seal) should be taken, mm, for pipes with a diameter of up to 300 mm - 5, over 300 mm - 8-10.

3.46. The dimensions of the elements for sealing the butt joint of cast-iron pressure pipes must correspond to values ​​given in.

Table 1

3.53. Sealing of butt joints of folded non-pressure reinforced concrete and concrete pipes with smooth ends should be carried out in accordance with the project.

3.54. The connection of reinforced concrete and concrete pipes with pipeline fittings and metal pipes should be carried out using steel inserts or reinforced concrete fittings made according to the project.

PIPING FROM CERAMIC PIPES

3.55. The gap between the ends of the laid ceramic pipes (regardless of the material for sealing the joints) should be taken, mm: for pipes with a diameter of up to 300 mm - 5 - 7, for large diameters - 8 - 10.

3.56. Butt joints of pipelines made of ceramic pipes should be sealed with hemp or sisal bituminized strand followed by the installation of a lock from a cement mortar grade B7, 5, asphalt (bituminous) mastic and polysulfide (thiokol) sealants, if other materials are not provided by the project. The use of asphalt mastic is allowed at a temperature of the transported waste liquid of not more than 40 ° C and in the absence of bitumen solvents in it.

The main dimensions of the elements of the butt joint of ceramic pipes must correspond to the values ​​\u200b\u200bgiven in.

Table 3

3.57. The sealing of pipes in the walls of wells and chambers must ensure the tightness of the joints and the water tightness of wells in wet soils.

PIPING FROM PLASTIC PIPES*

3.58. The connection of pipes made of high-pressure polyethylene (LDPE) and low-pressure polyethylene (HDPE) between themselves and with fittings should be carried out with a heated tool using the method of flash butt welding or socket welding. Welding between pipes and fittings made of polyethylene of various types (HDPE and LDPE) is not allowed.

3.5 9. For welding, installations (devices) should be used that ensure the maintenance of the parameters of technological modes in accordance with OST 6-19-505-79 and other regulatory and technical documentation approved in accordance with the established procedure.

3.60. Welders are allowed to weld pipelines from LDPE and HDPE if they have documents for the right to perform welding of plastics.

3.61. Welding of pipes made of LDPE and HDPE is allowed to be carried out at an outside air temperature of at least minus 10 ° C. At a lower outside air temperature, welding should be carried out in insulated rooms.

When performing welding work, the welding site must be protected from the effects of precipitation and dust.

3.62. Pipe connection made of PVC(PVC) between each other and with shaped parts should be carried out by gluing in-line (with the use of glue grade GI PK-127 in accordance with TU 6-05-251-95-79) and using rubber cuffs supplied as a set with pipes.

3.63. Glued joints within 15 minutes should not be subjected to mechanical stress. Pipelines with adhesive joints should not be subjected to hydraulic tests within 24 hours.

3.64. Bonding work should be carried out at an outdoor temperature of 5 to 35 °C. The place of work must be protected from the effects of precipitation and dust.

4. PIPELINE CROSSINGS THROUGH NATURAL AND ARTIFICIAL OBSTACLES

4.1. Construction of crossings of pressure pipelines for water supply and sewerage through water barriers (rivers, lakes, reservoirs, canals), underwater pipelines to water intakes and sewer outlets within the channel of reservoirs, as well as underground crossings through ravines, roads (roads and railways, including metro lines and tram tracks) and urban passages should be carried out by specialized organizations in accordance with the requirements SNiP 3.02.01-87,SNiP III-42-80(section 8) and this section.

4.2. Methods for laying pipeline crossings through natural and artificial barriers are determined by the project.

4.3. The laying of underground pipelines under the roads should be carried out with constant mine surveying and geodetic control of the construction organization for compliance with the planned and high-altitude positions of the cases and pipelines provided for by the project.

4.4. Deviations of the axis of protective cases of transitions from the design position for gravity free-flow pipelines should not exceed:

vertically - 0.6% of the length of the case, provided that the design slope is ensured;

horizontally - 1% of the length of the case.

For pressure pipelines, these deviations should not exceed 1 and 1.5% of the case length, respectively.

5. WATER SUPPLY AND SEWERAGE FACILITIES

SURFACE WATER INTAKE FACILITIES

5.1. The construction of structures for the intake of surface water from rivers, lakes, reservoirs and canals should be carried out, as a rule, by specialized construction and installation organizations in accordance with the project.

5.2. Prior to the beginning of the construction of the foundation for the channel water intakes, their center axes and marks of temporary benchmarks should be checked.

WATER WELLS

5.3. In the process of drilling wells, all types of work and key indicators (driving, diameter of the drilling tool, fastening and extraction of pipes from the well, grouting, water level measurements and other operations) should be reflected in the drilling log. At the same time, the name of the rocks passed, color, density (strength), fracturing, granulometric composition of rocks, water content, the presence and size of a "plug" during the sinking of quicksand, the water level that appeared and became established in all aquifers encountered, the absorption of flushing fluid. Measurement of the water level in wells during drilling should be carried out before the start of each shift. In flowing wells, water levels should be measured by extending pipes or measuring water pressure.

5.4. In the process of drilling, depending on the actual geological section, it is allowed, within the limits of the aquifer established by the project, by the drilling organization to adjust the depth of the well, the diameters and the depth of landing of technical columns without changing the operating diameter of the well and without increasing the cost of work. Changes to the design of the well should not worsen its sanitary condition and productivity.

5.5. Samples should be taken one at a time from each layer of rock, and in a homogeneous layer - after 10 m.

By agreement with the design organization, rock samples may not be taken from all wells.

5.6. Isolation of the exploited aquifer in the well from unused aquifers should be carried out with the drilling method:

rotational - by annular and annulus grouting of casing strings to the levels provided by the project:

percussion - crushing and driving the casing string into a layer of natural dense clay to a depth of at least 1 m or carrying out under-shoe cementation by creating a cavity with an expander or an eccentric bit.

5.7. To ensure the project granulometric According to the composition of the well filter bedding material, clayey-sandy fractions should be removed by washing, and the washed material should be disinfected before backfilling.

5.8. The exposure of the filter during its backfilling should be carried out by raising the casing string each time by 0.5 - 0.6 m after backfilling the well by 0.8 - 1 m in height. The upper boundary of the backfill must be at least 5 m higher than the working part of the filter.

5.9. After completion of drilling and installation of a filter, water wells must be tested by pumping performed continuously during the time provided for by the project.

Before starting pumping, the well must be cleaned of cuttings and pumped, as a rule, by an airlift. In fissured rock and gravel and pebble in aquifers, pumping should start from the maximum design drawdown, and in sandy rocks, from the minimum design drawdown. The value of the minimum actual decrease in the water level should be within 0.4 - 0.6 of the maximum actual.

In the event of a forced stoppage of works on pumping water, if the total time stop exceeds 10% of the total design time for one drop in water level, pumping out water for this drop should be repeated. In the case of pumping out from wells equipped with a packed filter, the amount of shrinkage of the packing material should be measured during pumping once a day.

5.10. The flow rate (productivity) of wells should be determined by measuring capacity with the time of its filling at least 45 s. It is allowed to determine the flow rate using weirs and water meters.

The water level in the well should be measured with an accuracy of 0.1% of the depth of the measured water level.

The flow rate and water levels in the well should be measured at least every 2 hours during the entire pumping time specified by the project.

Control measurements of the depth of the well should be made at the beginning and at the end of pumping in the presence of a representative of the customer.

5.11. During the pumping process, the drilling organization must measure the water temperature and take water samples in accordance with GOST 18963-73 and GOST 4979-49 with their delivery to the laboratory to check the water quality in accordance with GOST 2874-82.

The quality of cementation of all casing strings, as well as the location of the working part of the filter, should be checked by geophysical methods. mouth self-flowing wells at the end of drilling must be equipped with a valve and a fitting for a pressure gauge.

5.12. Upon completion of drilling a water well and testing it by pumping water, the top of the production pipe must be welded with a metal cover and have a threaded hole for a plug bolt to measure the water level. The design and drilling numbers of the well, the name of the drilling organization and the year of drilling should be marked on the pipe.

In order to operate the well, in accordance with the project, it must be equipped with instruments for measuring water levels and flow rates.

5.13. Upon completion of drilling and testing by pumping out a water well, the drilling organization must transfer it to the customer in accordance with the requirements SNiP 3.01.04-87, as well as samples of breeds passed and documentation (passport), including:

geological and lithological section with well design corrected according to geophysical survey data;

certificates for laying a well, installing a filter, cementing casing strings;

a summary log with the results of its interpretation, signed by the organization that performed the geophysical work;

a logbook of observations of water pumping from a water well;

data on the results of chemical, bacteriological analyzes and organoleptic water indicators according to GOST 2874-82 and the conclusion of the sanitary and epidemiological service.

Documentation before delivery to the customer must be agreed with the design organization.

CAPACITY FACILITIES

5.14. When installing concrete and reinforced concrete monolithic and prefabricated capacitive structures, in addition to the requirements of the project, the requirements of SNiP 3.03.01-87 and these rules should also be met.

5.15. Backfilling of soil into the sinuses and backfilling of capacitive structures must be carried out, as a rule, by a mechanized method after laying communications to capacitive structures, conducting a hydraulic test of structures, eliminating identified defects, performing waterproofing of walls and ceilings.

5.16. After the completion of all types of work and the concrete gaining design strength, a hydraulic test of capacitive structures is carried out in accordance with the requirements.

5.17. Mounting drainage distribution systems of filtering structures are allowed to be carried out after a hydraulic test of the structure's capacity for tightness.

5.18. Round holes in pipelines for the distribution of water and air, as well as for the collection of water, should be drilled in accordance with the class indicated in the project.

Deviations from the design width of slotted holes in polyethylene pipes should not exceed 0.1 mm, and from the design length of the slot in the light ± 3 mm.

5.19. Deviations in the distances between the axes of the couplings of the caps in the distribution and discharge systems of filters should not exceed ± 4 mm, and in the marks of the top of the caps (along the cylindrical ledges) - ± 2 mm from the design position.

5.20. Weir edge marks in water distribution and collection devices (gutters, trays, etc.) must comply with the project and must be aligned with the water level.

When installing overflows with triangular cutouts, the deviations of the marks of the bottom of the cutouts from the design ones should not exceed ± 3 mm.

5.21. On the inner and outer surfaces of the gutters and channels for collecting and distributing water, as well as for collecting precipitation, there should be no shells and growths. Trays of gutters and channels must have a slope specified by the project in the direction of water (or sediment) movement. The presence of sites with a reverse slope is not allowed.

5.22. It is allowed to lay the filter load in facilities for water purification by filtration after a hydraulic test of the tanks of these facilities, flushing and cleaning of the pipelines connected to them, individual testing of the operation of each of the distribution and collection systems, measuring and locking devices.

5.23. Materials of the filter load placed in water purification facilities, including biofilters, according to granulometric composition must comply with the project or the requirements of SNiP 2.04.02-84 and SNiP 2.04.03-85.

5.24. The deviation of the layer thickness of each fraction of the filter load from the design value and the thickness of the entire load should not exceed ± 20 mm.

5.25. After completion of work on laying the loading of the filtering facility for drinking water supply, the facility should be washed and disinfected, the procedure for which is presented in the recommended one.

5.26. Installation of combustible structural elements of wooden sprinklers, water trapping gratings, air guides shields and baffles of fan cooling towers and splash pools should be carried out after completion of welding work.

6. ADDITIONAL REQUIREMENTS FOR THE CONSTRUCTION OF PIPELINES AND WATER SUPPLY AND SEWERAGE FACILITIES IN SPECIAL NATURAL AND CLIMATIC CONDITIONS

6.1. During the construction of pipelines and water supply and sewerage facilities in special natural and climatic conditions, the requirements of the project and this section should be observed.

6.2. Temporary water supply pipelines, as a rule, must be laid on the surface of the earth in compliance with the requirements for laying permanent water supply pipelines.

6.3. The construction of pipelines and structures on permafrost soils should be carried out, as a rule, at negative outdoor temperatures with the preservation of frozen foundation soils. In the case of the construction of pipelines and structures at positive outdoor temperatures, it is necessary to keep the foundation soils in a frozen state and prevent violations of their temperature and humidity mode set by the project.

Preparation of the base for pipelines and structures of ice-saturated soils should be carried out by thawing them to the design depth and compaction, as well as by replacing ice-saturated soils with thawed compacted soils in accordance with the design.

The movement of vehicles and construction machines in the summer should be carried out on roads and access roads built in accordance with the project.

6.4. The construction of pipelines and structures in seismic areas should be carried out using the same methods and methods as in normal construction conditions, but with the implementation of the measures provided for by the project to ensure their seismic resistance. Joints of steel pipelines and fittings should be welded only by electric arc methods and the quality of welding should be checked by their physical control methods in the amount of 100%.

During the construction of reinforced concrete capacitive structures, pipelines, wells and chambers, cement mortars with plasticizing additives should be used in accordance with the project.

6.5. All work to ensure the seismic resistance of pipelines and structures performed during the construction process should be reflected in the work log and in the certificates of survey of hidden works.

6.6. When backfilling the sinuses of capacitive structures under construction in undermined territories, the safety of expansion joints should be ensured.

The gaps of the expansion joints over their entire height (from the bottom of the foundations to the top above the foundation parts of structures) must be cleared of soil, construction waste, concrete sagging, mortar and formwork waste.

Inspection certificates for concealed works should document all major special works, including: installation of expansion joints, arrangement of sliding joints in foundation structures and expansion joints; device for passing pipes through the walls of wells, chambers, capacitive structures.

6.7. Pipelines in swamps should be laid in a trench after the water has been drained from it or in a trench flooded with water, provided that the necessary measures against their floating are taken in accordance with the project.

The pipeline strings should be dragged along the trench or moved afloat with plugged ends.

Laying of pipelines on fully compacted dams must be carried out as in normal soil conditions.

6.8. During the construction of pipelines on settled soils, pits for butt joints should be made by compacting the soil.

7. TESTING OF PIPING AND STRUCTURES

PRESSURE PIPING

7.1. If there is no indication in the project about the method of testing, pressure pipelines are subject to strength and tightness testing, as a rule, by hydraulic method. Depending on the climatic conditions in the construction area and in the absence of water, a pneumatic test method can be used for pipelines with an internal design pressure P p , not more than:

underground cast iron asbestos-cement and concrete glands - 0.5 MPa (5 kgf / cm 2);

underground steel - 1.6 MPa (16 kgf / cm 2);

elevated steel - 0.3 MPa (3 kgf / cm 2).

7.2. Testing of pressure pipelines of all classes should be carried out by a construction and installation organization, as a rule, in two stages:

the first- a preliminary test for strength and tightness, performed after backfilling the sinuses with soil tamping to half the vertical diameter and powdering of pipes in accordance with the requirements of SNiP 3.02.01-87 with butt joints left open for inspection; this test can be performed without the participation of representatives of the customer and the operating organization with the drawing up of an act approved by the chief engineer of the construction organization;

second-the acceptance (final) test for strength and tightness should be carried out after the pipeline is completely backfilled with the participation of representatives of the customer and the operating organization with the preparation of an act on the test results in the form of mandatory or.

Both stages of the test must be carried out before the installation of hydrants, plungers, safety valves, instead of which flange plugs should be installed during the test. Preliminary testing of pipelines accessible for inspection in working order or subject to immediate backfilling during the construction process (work in winter, in cramped conditions), with appropriate justification in the projects, may not be carried out.

7.3. Pipelines of underwater crossings are subject to preliminary testing twice: on a slipway or site after welding of pipes, but before applying anti-corrosion insulation to welded joints, and again - after laying the pipeline in a trench in the design position, but before backfilling with soil.

The results of preliminary and acceptance tests must be drawn up in an act in the form of a mandatory one.

7.4. Pipelines laid at crossings over railways and highways of categories I and II are subject to preliminary testing after laying the working pipeline in a case (casing) until the annular space of the case cavity is filled and before filling the working and receiving pits of the transition.

7.5. The values ​​of the internal design pressure РР and test pressure Р and for carrying out preliminary and acceptance tests of the pressure pipeline for strength must be determined by the project in accordance with the requirements of SNiP 2.04.02-84 and indicated in the working documentation.

The value of the test pressure for tightness Р g for both preliminary and acceptance tests of the pressure pipeline must be equal to the value of the internal design pressure Р р plus the value Р, taken in accordance with the upper limit of pressure measurement, accuracy class and pressure gauge scale division. In this case, the value of Р g should not exceed the value of the acceptance test pressure of the pipeline for strength Р and.

7.6* Pipelines made of steel, cast iron, reinforced concrete and asbestos-cement pipes, regardless of the test method, should be tested with a length of less than 1 km - in one go; with a greater length - in sections of no more than 1 km. The length of the test sections of these pipelines with the hydraulic method of both tests is allowed to be taken over 1 km, provided that the value of the allowable flow rate of pumped water should be determined as for a section 1 km long.

Pipelines made of HDPE, HDPE and PVC pipes, regardless of the test method, should be tested with a length of no more than 0.5 km at a time, with a longer length - in sections of no more than 0.5 km. With appropriate justification, the project allows testing of these pipelines at one time with a length of up to 1 km, provided that the value of the allowable flow rate of pumped water should be determined as for a section with a length of 0.5 km.

Properly executed design and installation of external sewage networks determines the duration and quality of their operation. The main provisions and rules for the construction and repair of an external sewer network are determined by SNiP 2.04.03-85. The document regulates the full cycle of work on the installation of an engineering system from the installation of a pipeline to the construction of treatment facilities. SNiP sewerage external networks and structures will help you choose the best material and build an effective wastewater and rainwater disposal system.

What is outdoor sewage

External sewerage includes branched pipelines and system elements necessary for transporting wastewater from residential buildings and other facilities to treatment facilities. The design of the engineering network is carried out simultaneously with the preparation of water supply plans. Systems are interconnected by the need to maintain a balance of water consumption and disposal. Installation and maintenance of urban outdoor sewerage is assigned to public utilities. The maintenance of autonomous sewerage in private houses is carried out by the owners themselves.

There are two ways to transport wastewater:

• non-pressure or gravity;
• pressure, requiring the installation of pumping equipment.

Sewer types

To ensure the safety of the functioning of external sewerage, SNiP offers several ways:

• duplication of communications - providing the possibility in case of an accident to switch the flow to a parallel pipeline or channel;
• reliable power supply, availability of an alternative (backup) source;
• margin when designing network bandwidth

Attention. When installing sewer facilities, a certain sanitary zone must be observed up to the construction sites of residential and public buildings.

Block diagrams

According to SNiP, external sewage is divided into several systems according to the laying method:

• Combined - according to this installation scheme, all drains - domestic, storm, melted - are sent to one sewer or tank.
• Separate - the system is arranged so that household wastewater and melted (rain) water are transported through various pipelines and enter various treatment facilities or storage tanks.
• Semi-separate wastewater and storm sewers are sent through different lines into one tank.

Alloy scheme

Attention. It is forbidden to discharge wastewater untreated to established standards into water bodies.

Sewer system classification

External engineering communications are arranged in various places and have their own purpose.

Yard network - used to service one building. It consists of the following elements: pipes of small diameter (150 mm), outlets of the building, intake and manholes. This concept is used for a system connected to a central sewer, it is not used for a stand-alone system.

Yard network

Intra-quarter - the network is arranged inside the quarter, it consists of the same elements as the yard.

The street network is designed to transport wastewater collected from all quarters. Such a pipeline is called a collector, its function is to collect wastewater and divert it to a pumping station or treatment plant.

Attention. Ground laying of a sewer pipeline in settlements is not allowed.

Schemes of drainage networks

Depending on the features of the terrain, one of the external drainage schemes is selected:

• perpendicular - used for rain sewer collectors for the speedy transportation of water to the general stream;
• zone - a rare option applied to objects with a significant difference in height, a pump is installed in the lower manifold;
• cross - the main collector is installed along a river or other body of water to intercept sewage;
• radial - wastewater is sent to various treatment facilities.

Components of the external sewer system

The engineering network consists of several main parts:

1. Pipeline - a line of pipes of various lengths and diameters, laid with a slope.
2. Wells - structures differ in purpose, they are - drainage, viewing, differential and rotary. The wells are equipped with brackets for the descent of repairmen and hatches with covers.
   
   Pipeline and well
3. Outlets to water receivers - elements that ensure the free exit of wastewater from the pipeline to the reservoir.
4. Collectors - underground tunnels in the form of pipes of large diameter (from 2000 mm), through which sewage is transported to the end point of the network.
   
   Collector
5. Local treatment facilities - installations used for the treatment and discharge of wastewater into water bodies. These include septic tanks, biological treatment plants and other equipment. The number of houses served depends on the size and performance of the structure.
6. Pumping stations - are installed at separate facilities that need a dosed supply of wastewater.

The choice of a method for discharging household and rainwater depends on a whole list of factors that are taken into account at the design stage:

• properties and nature of the soil;
• climatic features, such as the depth of freezing;
• volume of transported effluents;
• groundwater level;
• distance from the point of release from the building to the treatment plant.

Attention. The smallest allowable slope of the pipeline depends on the minimum speed of the sewer flow.

The choice of material for the pipeline

The materials used for the installation of lines and channels must be resistant to aggressive environments and the effects of abrasive particles contained in the liquid. To prevent gas corrosion of the upper part of the collector, ventilation is installed to prevent gas stagnation.

SNiP external sewerage provides for the use of pipe networks from the following materials for installation:

• polyethylene;
• polyvinyl chloride;
• polypropylene;
• steel;
• asbestos cement;
• cast iron;
• reinforced concrete.

Polymer pipes

Cast iron pipes

Reinforced concrete pipes

In rare cases, ceramic and glass pipes are used when installing the network, such materials are allowed by the rules.

Polymer products are the best choice for the installation of external engineering networks. They have all the qualities that ensure reliable and long-term operation of the system:

• resistance to mechanical stress;
• frost resistance;
• high throughput due to smooth surface;
• resistance to corrosion;
• durability.

Rules for the installation of sewerage networks

Pipe diameter

The throughput of a non-pressure network depends on the size of the pipes. Building codes determine the minimum diameter of pipes of a gravity-flow engineering system:

• street network - 200 mm;
• autonomous sewage - 110-150 mm;
• intra-quarter - 150 mm;

The size of the rain and common alloy street system is 250 mm, the intra-quarter system is 200 mm.

Speed

The SNiP contains tables that determine the speed of wastewater movement depending on the size of the pipeline or tray. These indicators help to avoid silting of sewer networks. The flow contains suspended particles, which, if the speed is insufficient, settle on the surface of the line.

Basic calculation data:

• diameter 150-250 mm - 0.7 m / s;
• 600-800 mm - 1 m / s;
• more than 1500 mm - 1.5 m / s.

The lowest speed of movement of clarified wastewater through the trays and pipes is 0.4 m/s. The maximum value of the speed of transportation of wastewater:

• for metal and plastic pipes - 8 m / s;
• for concrete and reinforced concrete - 4 m / s.

For rainwater drainage, the indicators are:

• metal and plastic pipes - 10 m / s;
• concrete and reinforced concrete - 7 m / s.

Pipeline slope

One of the basic rules when laying a pipeline is compliance with the slope norm. For systems where the fluid moves under the influence of gravitational forces, this parameter is of decisive importance. The negative consequences of installation errors in the direction of decreasing or increasing the slope lead to malfunctioning of the network, blockages and breakdowns.

Attention. The normative indicator is calculated per 1 linear meter of pipe.

For autonomous sewer pipes that are smaller than central networks, the following standards apply:

In special conditions associated with the terrain, a decrease in slope is allowed:

• pipes 150 mm up to 0.008;
• pipes 200 mm to 0.007.

Storm water inlets are connected to a common system with a slope of 0.02.

Network depth

The minimum depth of the sewer pipeline depends on the heat engineering calculation. Also take into account the practice of exploitation of engineering networks in the area. Pipes are laid 0.3-0.5 m below the freezing point of the soil. The maximum depth depends on several factors:

• pipe material;
• type of soil;
• pipeline diameter;
• laying method.

Requirements for wells

Wells are an integral element of the sewer network, therefore, the rules and regulations for their installation are described in SNiP.

Manholes

For the revision of the pipeline, special elements are installed - manholes. Their installation is carried out in two cases:

• at the junction of pipes;
• at the site of the change in the direction of the pipeline.

SNiP determines the diameters of wells depending on the size of the pipes:

• line up to 600 mm - well 1000 mm;
• pipeline from 700 mm and more - pipe size + 400 mm in length and 500 mm in width.

manhole

On straight sections of the gravity network, observation structures are located every 35 m, for highways of medium diameter (500-600 mm) - 75 m, for large pipes (1500-2000 mm) - 200 m. The working part of the structure is equipped with a hinged ladder for descent.

Rain sewer

Storm sewers are used to quickly drain rain and melt water. It is open, closed and mixed. An open network consists of trays and channels, a closed network consists of storm water inlets and an underground pipeline, a mixed network is a combination of pipes and trays. To reduce the length of the system, discharge is carried out into the nearest reservoir or ravine.

When installing rainwater drainage, it is necessary to provide for the installation of facilities for the treatment of the most polluted drains generated during heavy rains. For this, sand traps, sedimentation tanks and filters are installed. It is also recommended to design the possibility of using purified rainwater for irrigation and industrial needs.

Wastewater treatment devices