But they also perform many other functions. Usually, there are several types of such devices in the system, interconnected in a single network. And in order for the system to work smoothly and efficiently, certain rules must be followed when installing all its parts.

One of the nuances is a certain distance at which you need to install a certain type of sewer well. Knowing this data, you can independently make or control the work of a hired company.

Types of sewer wells

The first step is to understand the types of these devices and what functions they perform. So, the main structures are:

1. Viewing - are responsible for monitoring sections of the system and for cleaning it in the event of blockages.
2. Swivel - control over the areas where the drains change the direction of movement, facilitate access to turns and bends, in which blockages often form.
3. - compensate for the slope of the pipeline, too large or small slope leads to the accumulation of solid particles in it.
4. Nodal - access to the connecting pipes.

As for the distance between all types, it is regulated in.

Video: Sanitary standards for the construction of wells and septic tanks

Distance between manholes

Distance between drop wells

If the site on which the sewer will be installed has a complex terrain, then this type of wells is used. In an area with a large slope, the slope of the pipeline will also be large. And this threatens that the liquid component of the effluent will pass through the pipes faster, and the solid particles will settle on the surface and form a blockage. Drop wells compensate for the flow rate.

The SNiP does not indicate specific distances between these structures, but several other requirements are imposed:

• the height of one drop should not exceed 3 m;
• with a drop up to 0.5 m deep, the drop well can be replaced with a viewing well with overflow;
• structures are installed at the bends of the branch pipes.

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Who rules the ball in the underworld: factors affecting the distance between sewer wells

Surely you at least once in your life wondered why so many sewer manholes come across on your way. Looking ahead, I will say that this is not someone's whim, but a necessity dictated by the technical requirements for laying the sewage system. To clarify these points, I have summarized all the current regulations and will gladly share my knowledge with you. So, let's hit the road.

Everyday educational program

For those who do not like to read for a long time, I inform you that, according to clause 4.14. SNiP 2.04.03-85 on all sewer networks, without exception, wells are provided. The permissible distance between two underground devices depends on the diameter and ranges from 35 to 300 meters.

Those who really want to find out the features of the location of sewer wells should arm themselves with a couple of minutes of patience and read the article to the end.

So, what is hidden under the hatch? Directly below it is a special hydraulic room, called ... yes, yes, a well. Depending on the type, they are designed for a specific type of maintenance work:

1. manhole serves to directly control difficult areas waste system. In the event of clogging, which is inevitable when sewage is removed, both social and industrial, through such wells, repair teams gain access to problem areas;

1. Rotary wells duplicate the functions of observation points, located at points of direct change in the direction of movement of sewage. Turn or bend sewer pipe increases the likelihood of clogging; this type of underground structures allows to quickly eliminate the problem;
2. Where the landscape creates too much slope, or at the intersection with other engineering and technical underground structures, drop wells are installed;

It would seem that the greater the slope, the faster the drains will leave the pipe. But in fact, an excessive slope, like its complete absence, harms the sewer system - the solid fractions of wastewater, not keeping up with the more liquid ones, accumulate, clogging the pipe lumen.

In the photo - a sewer differential well with the cover removed.

1. Nodal wells unite several pipelines and allow them to be controlled.

Regulatory documentation

Let you not be surprised by the fact that SNiP 2.04.03-85 of the USSR Civil Code for construction, approved back in 1986, still regulates the construction of sewer networks.

In our time, and more specifically, in 2012, the Ministry of Regional Development published the Code of Rules SP 32.13330.2012. In fact, this is a revised edition of SNiP 2.04.03-85, which introduces some additions to the text.

Along with this, there is also SNiP 3.05.04-85, which pays more attention to the laying technology and the materials used.

Well dimensions

cross section

We return to the wells. The cross section of reinforced concrete rings, from which in most cases they are constructed, depends on two factors:

1. Sections of the sewer pipe over which it is erected;
2. Depth.

For the first parameter:

If the depth of the well exceeds 3.0 m, then the smallest diameter of the rings must be at least 1.5 m.

The typical height of the well (its working part, measured from the tray to the cover) is 1.8 m. It is quite expected that this value is affected by the terrain - either upward or downward. For example, if the depth is >1.2 m, then the cross section should not be less than 1 m.

Depth

Regarding the depth of occurrence, it should only be said that this value depends not only on climatic conditions.

The loads on the soil should also be taken into account, for example, when the pipe is located under carriageway. The cost of a mistake is very high - from the likelihood of a pipe freezing in winter to damage or depressurization of the sewer by vehicles passing over it.

In some cases, sewer pipes can be laid in a reinforced concrete tray, as well as additionally insulated.

Distances according to SNiP

Lookouts

Let's move on to the most interesting - knowing which type of wells we are talking about, we will find out the largest and smallest distances between sewer wells according to SNiP. Let's start with the manholes.

In practice, the distance is determined based on the cross section of the sewer pipe connecting two wells:

Diameter (Ø) of the pipe, m	Min. allowable distance, m
0,15	35
0,20 – 0,45	50
0,50 – 0,60	75
0,70 – 0,90	100
1,00 – 1,40	150
1,50 – 2,00	200
Over 2.00	250 — 300

Rotary and nodal

There are no specific values ​​regarding distances in the regulatory documentation for this type of wells. Why?

To answer the question, you should remember for what purposes they are built:

1. Nodal - in all places of connection of sewer pipes;
2. Rotary - in all places where the pipe changes direction. Moreover, they must be taken into account by the project at each point of change in the slope of the landscape or the section of the pipe.

The pipe turning radius also plays a role:

1. If the pipe Ø exceeds 1.2 m, then the minimum turning radius is 5 Ø.
2. If the pipe is less than 1.2 m, then the turning radius is equal to its Ø.

Captain Evidence suggests: for pipes of large Ø at the beginning and at the end of the turn, manholes are built without fail.

Now you know that there are no specific figures indicating the distance between the nodal and rotary wells in SNiP - everything is determined individually when designing the sewer network of a particular object (house, quarter, district).

Variable

About drop wells should be told in more detail. Such structures are installed in places where there is a large difference in height between the incoming and outgoing pipes.

The very slope of the pipes of the external sewer network primarily depends on:

• landscape;
• Underground structures and structures encountered on the path of sewage flow;
• Depth of inlet pipe.

At the same time, the design of overflow wells will also be different. For example, to reduce the flow rate, the design of the well will be multi-stage. There are often designs where, instead of pipes, a simple channel is used, which has the required slope.

Pipes

Pipe Ø also affects the distance between wells. Let's find out this nuance.

When laying the sewer system, the following values ​​\u200b\u200bof the dimensions of the sewer pipes must be taken into account:

• 0.15 m for an intra-quarter network for domestic or industrial purposes;
• 0.20 m for the street sewer network;
• 0.25 m for street storm water.

If in a settlement the volume of wastewater is >300 m3 per day, then the smallest diameter for the intra-quarter and street network is 150 mm.

Sanitary protection zones

Another important aspect worth mentioning is the sanitary protection zones that affect the location of sewer wells. The parameters are determined by the performance and the type of structure used.

It is clear that such information does little for a simple developer in terms of practical application. Therefore, I will explain the parameters that must be adhered to when designing autonomous sewerage private household.

For example, let's take its productivity equal to 15 cubic meters per day:

• For the section of underground filtration of wastewater, the sanitary protection zone will be 15 m;
• For a trench filtering drains or a sand and gravel filter - 25 m;
• At least 5 m should be from the foundation to the septic tank and at least 8 m to the filter well.

The diagram indicates 3 meters - this is the minimum distance from the sewer to the foundation of the cottage. But we are talking about a nodal well!

Legal and legal liability

In legislation Russian Federation penalties are provided for violations of the requirements of SNiP for the design and installation of external sewerage, as well as a measure of responsibility.

The following persons are responsible for compliance with the rules and regulations:

1. design organizations - established responsibility for the correctness of plans, drawings and all preliminary calculations for the design of an external sewer network;
2. customers and developers - the responsibility for the preparation for operation of the installed sewer network has been established. This includes: personnel moments, the correct selection and operation of equipment, commissioning processes, etc.;
3. Research Institute - established responsibility for the issued data on climatic conditions in the region where the installation of the sewer network is carried out;
4. construction and installation organizations - full responsibility is established for compliance with all norms and rules during construction and installation works and testing of the completed structure.

When checking and identifying violations for these categories of persons, a decision is made to bring them to administrative, disciplinary and, in case of serious consequences, even criminal liability.

In the course of investigations of accidents related to the malfunctioning of the sewer network or its breakdown, specific perpetrators are identified and the degree of guilt of each of them is established.

Do not think that the responsibility lies only with those who design and build objects of state and municipal outdoor sewerage systems.
Any citizen who is engaged in independent design and installation of an autonomous sewer network is also responsible for violating the requirements of SNiP and environmental laws.

Negligence or inaction of the responsible person, non-compliance current rules and norms, which led to an accident or breakdown or interfere with the normal operation of the sewer pipeline, is also classified as a violation with all of the above consequences for a particular culprit.

The vast majority of owners of suburban real estate have to equip the system for storing and disposing of wastewater on their own. In order for everything to work properly and not have to dismantle the system, you must follow a set of rules for installation. One of them is the distance between the sewer wells.

Inspection sewer wells according to SNiP should be installed at a certain distance from each other.

These elements are needed in the system in order to control the external drain line.

It consists in free access to . Inspection tanks are mounted on straight flat sections of the main, in places where several pipes intersect, at system turns, etc.

Through the inspection wells, the system is serviced, blockages are removed and damaged elements and parts of the pipeline are replaced.

For each type of well, its own set of rules and a formula for calculating the distance.

SNiP 2.04.03-85 contains all the rules for installing sewers. Where to install wells, what distance is acceptable for a particular pipe diameter.

The larger the cross section of the sewer pipe, the greater the distance between the wells. This difference in footage is due to the throughput of pipes. At the highway assembled from elements of large diameter, it is high. Blockages appear less frequently. The load is less, as a result of which repairs are required less often.

Varieties of revision wells and the permissible distance between them

Lookouts

Installed for free access and maintenance of the system. The distance between is indicated in the table.

Swivel

Mounted in places where pipes form a turning angle

• The distance between wells is calculated according to straight line pipeline.
• The length of the segment is indicated in SNiP. If you do not meet the requirement, you will have to install an additional well.

Variable

Structures are required in areas with a change in the height of the pipe laying

• SNiP did not establish standards for the distance between these structures, but the following requirements apply
• One difference cannot be more than 3 meters. If the slope is more than this footage, then a stepped overflow system with wells is created.
• With a difference of 50 cm, the well can be replaced with an overflow

nodal

Used at the junction of pipes. The distance depends on the nozzle diameter.

If the pipeline is laid below 3 meters from the soil level, then pipes with a diameter of at least 1.5 m are used. This is necessary so that you can go down into the well along with the equipment, identify malfunctions and fix it. A narrow well would be inappropriate in this case.

When arranging an external sewer line, it should be taken into account that the distance from the sewer to the source with drinking water must be at least 30 meters.

If a cesspool acts as a septic tank

The distance from the sewer wells to the water supply system is increased to 50 meters.

Proper installation of the sewer line is very important, but maintenance and control of pipes and their connections also affects the operation of the system.

Revision wells are installed at a certain distance in order to be able to easily make repairs, eliminate blockages, replace failed elements or lay a new line without leading heavy land works. Wells allow you to replace elements by dragging pipes with a special cable from one well to another.

For example: there is a blockage. It was not possible to eliminate it using chemicals. The second option to get rid of the blockage is to use a plumbing cable. But the cable is only 15 meters long. Having identified the area with a blockage, it is possible to work with the cable. If there are no wells, then you will have to do a hydrodynamic pipe cleaning.

Hydrodynamic pipe cleaning

It is an excellent prevention. Water supplied under strong pressure not only eliminates the blockage, but also washes away all deposits from the walls of the pipeline.

It should be noted that the use of bacteria for septic tanks also has a fruitful effect on the wastewater system. The amount of sediment in the septic tank is reduced, there is no smell. If the bacteria are flushed through the toilet, the pipeline is protected.

The sewerage system will work clearly and properly if it is installed in accordance with all the rules and regularly inspected and prevented.

Note!

To avoid mistakes during the installation of revision wells, it is better to contact a specialist. He will make the calculation without errors and give the necessary recommendations.

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Regulatory documents are very difficult to master, especially for non-professionals. To understand all the requirements for engineering networks, you need to spend a lot of time processing a large amount of material. It is also quite problematic to find exactly the information you need on the web: often the search results turn out to be completely different from what they should be.

This article will describe all the information that relates to sewer systems, the main types of sewer wells, their parameters and requirements for structures will be considered.

Sewer systems of private houses

In arrangement suburban areas often used autonomous systems sewers, which are distinguished by the presence of a large number positive qualities. Some systems turn out to be more economical than using a central collector, while others turn out to be the only possible solution to the problem of sewerage.

For the normal functioning of the external sewage system and the provision of quality service, the design of the system must be arranged in accordance with the norms and rules displayed in the relevant documents.

The installation scheme of the sewer system and its operation largely depend on factors, which include:

• topographic indicators of the selected territory;
• types of soils located on the site;
• the presence of water sources near the site;
• layout of engineering underground networks that are already present on the territory.

The sewerage device can be quite simple: simplest design consists of a single piece of pipeline that transports wastewater to a pit or septic tank located outside the building. You need to know how far from the house to make a septic tank. The simplest septic tank can be made from car tires stacked vertically on top of each other: the effluents will still be filtered, and the solid fractions will be periodically pumped out by the sewage machine. This design is well suited for installation in suburban or small urban areas. In order for the sewer to work normally, it is enough for it to provide a constant slope and periodically pump out.

It is much more difficult to arrange a sewer system on a site with a difficult terrain, or on which there is a source of drinking water. In this case, the sewage system must comply with the sanitary requirements that apply to septic tanks or waste storage tanks. In addition, the device of the system can be complicated by connecting to it drainage system and storm drainage. See also: "".

This design consists of several separate pipelines, so a large number of wells will be required for its operation. To ensure the operability of the system, you need to either contact the specialists, or carefully study all the nuances associated with the requirements for sewage.

Types of sewer wells

The main document that defines design features sewer elements and the distance between sewer wells - SNiP 2.04.03-85 “Sewerage. External networks and structures”. The document contains a large number of requirements, but there is no need for owners of private houses to study them all - it is enough to deal with the problem of local drainage (read also: ""). The main thing you need to know is that any sewer system requires intermediate wells, and they will be installed depending on various factors.

Distance between manholes according to SNiP

Manholes should be installed in such situations:

• in the presence of an extended pipeline running in a straight line;
• if there are turns or bends in the pipeline, as well as when the diameter of the pipes changes;
• in the presence of branches of the structure.

The function of manholes for sewers is to monitor the system and the ability to gain access to its interior for maintenance.

Determines the distance between the SNiP sewer wells, and according to it, the following rules must be followed:

• with a pipe diameter of 150 mm, wells are installed every 35 meters;
• 200-450 mm - 50 m;
• 500-600 mm - 75 m.

A further increase in the diameter of the pipes allows you to increase the maximum distance between the sewer wells even more. However, the likelihood of such a design appearing in a summer cottage is extremely small, because the volume of effluents produced by 3-4 people does not require wide pipes. The use of large pipes can be justified if absolutely all wastewater passes through the sewer: precipitation, bath water, and direct waste from a residential building.

As a rule, when arranging private sewer systems, pipes with a diameter of 100 mm are used. When using them, the distance between the sewer wells is defined by SNiP as 15 m. In the event that the sewer does not have bends, branches, and the diameter of the pipeline does not change throughout its length, then the distance can be increased to 50 m.

Rotary wells for sewerage

This type of wells is absolutely identical to inspection wells in its purpose and design, with the only difference that rotary wells are mounted in places where the direction of the pipeline changes. Sharp bends with big angles Turns are usually the most clogged areas, so they need to be given special attention. It is this function that rotary wells perform.

The distance between the rotary sewer wells is usually calculated based on the length of the straight sections between the bends of the pipeline. If the pipeline section is longer than specified by the regulatory document, then it must be equipped with inspection wells to ensure a sufficient level of control over the operation of the system.

Drop wells

Installation of sewerage on a site with difficult terrain is a rather troublesome business. If the territory has a noticeable slope, then the slope of the pipeline will also be appropriate, which is absolutely impossible to allow: wastewater moving at high speed will gradually settle on the walls of the sewer system, thereby clogging it and rendering it unusable.

Regulatory documents in this case speak of the need to install differential wells, which are installed in steps and compensate for the high speed of waste transportation, saving the structure from blockages (more: "").

In this case, SNiP does not determine the specific distance between sewerage wells, but imposes some design requirements:

• firstly, the height of one drop must be less than three meters;
• secondly, with drops up to 0.5 m deep (when using pipes with a diameter of up to 600 mm), drop wells can be replaced by inspection wells using drains.

You should always remember that any sewer system ends with a spillway point, in which the final well is necessarily located, requiring an inspection hatch.

Other regulations

In addition to the standards described above, which are often a problem for owners of private plots due to their inaccessibility, there are others that must also be followed in order to avoid problems with the functioning of the sewer in the future. For example, the minimum distance from the sewer well to the building should be 3 m, and the maximum - 12 m, regardless of the type of well used. The distance from the house to the sewer well is a rather important indicator that must be observed. It is important to consider the distance from the cesspool to the well. In addition, it is important to always remember the existence of sanitary standards that determine the removal of elements of sewer systems from reservoirs, water sources, vegetable gardens and orchards.

Conclusion

Installing a sewer system on your own site is not a big problem. All installation work related to laying pipelines and arranging sewer facilities are quite simple, and any homeowner can do them (read also: ""). About all types of work, you can find other articles on this site, and then everything will become very clear.

Details 29.12.2011 13:10

Page 2 of 6

6.3. Manholes

6.3.1. Inspection wells on gravity sewer networks of all systems should be provided for:
at the points of connection;
in places of change of direction, slopes and diameters of pipelines;
on straight sections at distances depending on the diameter of the pipes: 150 mm - 35 m, 200 - 450 mm - 50 m, 500 - 600 mm - 75 m, 700 - 900 mm - 100 m, 1000 - 1400 mm - 150 m, 1500 - 2000 mm - 200 m, over 2000 mm - 250 - 300 m.
The dimensions in terms of wells or chambers on sewer networks must be taken depending on the pipe of the largest diameter D:
on pipelines with a diameter of up to 600 mm - length and width 1000 mm;
on pipelines with a diameter of 700 mm or more - length D + 400 mm, width D + 500 mm.
The diameters of round wells should be taken on pipelines with diameters: up to 600 mm - 1000 mm, 700 mm - 1250 mm, 800 - 1000 mm - 1500 mm, from 1200 mm and more - 2000 mm.
Notes. 1. The dimensions in terms of the wells on the turns must be determined from the condition of placing the turning trays in them.
2. On pipelines with a diameter of not more than 150 mm and a laying depth of up to 1.2 m, wells with a diameter of 600 mm are allowed. Such wells are intended only for the input of cleaning devices without people descending into them.

6.3.2. The height of the working part of the wells (from the shelf or platform to the ceiling, as a rule, must be taken as 1800 mm; if the height of the working part of the wells is less than 1200 mm, their width can be taken equal to D + 300 mm, but not less than 1000 mm.
6.3.3. The manhole tray shelves should be level with the top of the larger diameter pipe.
In wells on pipelines with a diameter of 700 mm or more, it is allowed to provide a working platform on one side of the tray and a shelf at least 100 mm wide on the other. On pipelines with a diameter of more than 2000 mm, it is allowed to arrange a working platform on consoles, while the size of the open part of the tray should be taken at least 2000 x 2000 mm.
6.3.4. In the working part of the wells, the following should be provided:
installation of hinged ladders for descending into the well (portable and stationary);
fencing of the working platform with a height of 1000 mm.
6.3.5. Dimensions in terms of rainwater wells should be taken on pipelines with a diameter of up to 600 mm inclusive - with a diameter of 1000 mm; on pipelines with a diameter of 700 mm or more - round or rectangular with trays 1000 mm long and a width equal to the diameter of the largest pipe, but not less than 1000 mm.
The height of the working part of the wells on pipelines with a diameter of 700 to 1400 mm inclusive should be taken from the pipe tray of the largest diameter; on pipelines with a diameter of 1500 m and more, working parts are not provided.
Shelves of trays of wells should be provided only on pipelines with a diameter of up to 900 mm inclusive at the level of half the diameter of the largest pipe.
6.3.6. The necks of the wells on the sewerage networks of all systems should be taken, as a rule, with a diameter of at least 700 mm.
The dimensions of the neck and the working part of the wells at turns, as well as on straight sections of pipelines with a diameter of 600 mm or more at distances of 300–500 m, should be sufficient to lower the devices for cleaning the network.
6.3.7. The installation of hatches must be provided at the same level with the surface of the carriageway with improved coverage; 50 - 70 mm above the ground in the green zone, and 200 mm - in a non-built-up area. If necessary, hatches should be provided with locking devices. The design must ensure the operating conditions, taking into account the loads from the transport, the safe entry and exit of personnel.
6.3.8. In the presence of ground water with a calculated level above the bottom of the well, it is necessary to provide waterproofing of the bottom and walls of the well 0.5 m above the groundwater level.

6.4. Drop wells

6.4.1. Drops up to 3 m high on pipelines with a diameter of 600 mm or more should be taken in the form of weirs of a practical profile.
Drops up to 6 m high on pipelines up to 500 mm in diameter inclusive should be carried out in wells in the form of a riser or vertical walls-spreaders, with a specific wastewater flow rate per 1 linear meter. m of the wall width or the circumference of the cross section of the riser is not more than 0.3 m3 / s.
Above the riser, it is necessary to provide a receiving funnel, under the riser - a water pit with a metal plate at the base.
For risers with a diameter of up to 300 mm, it is allowed to install a guide elbow instead of a water pit.
Note. On pipelines with a diameter of up to 600 mm, drops up to 0.5 m in height are allowed to be performed without an overflow well by draining in a manhole.

6.4.2. On rainwater sewer collectors with a drop height of up to 1 m, it is allowed to provide overflow wells of a spillway type, with a drop height of 1 - 3 m - a water-cutting type with one grate of water-cutting beams (slabs), with a drop of 3 - 4 m high - with two water-cutting grids.

6.5. rainwater inlets

6.5.1. Storm water inlets should be provided:
in the trays of streets with a longitudinal slope - on long sections of slopes, at intersections and pedestrian crossings from the side of the tributary surface water;
in low places that do not have a free flow of surface water - with a sawtooth profile of street trays, at the end of long sections of slopes in courtyards and parks.
In low places, along with storm water inlets with gratings in the plane of the roadway (horizontal), it is allowed to use storm water inlets with a hole in the plane of the curb stone (vertical) and a combined type with horizontal and vertical gratings.
In trays of streets with a longitudinal slope, it is not recommended to use vertical and combined storm water inlets.
6.5.2. The distances between the storm water inlets with a sawtooth longitudinal profile of the gutter are assigned depending on the values ​​of the longitudinal slope of the gutter and the depth of water in the gutter at the gutter (no more than 12 cm).
The distances between the storm water inlets on a section of streets with a longitudinal slope of one direction are established by calculation based on the condition that the width of the flow in the tray in front of the grate does not exceed 2 m (with rain of design intensity).
With a street width of up to 30 m and the absence of rainwater from the quarters, the distance between the storm water inlets can be taken according to table 6.

Table 6

Greatest distances between storm water inlets

Street slope The greatest distances between storm water inlets, m
Up to 0.004 50
More than 0.004 to 0.006 60
More than 0.006 to 0.01 70
More than 0.01 to 0.03 80

With a street width of more than 30 m, the distance between the storm water inlets is no more than 60 m.
6.5.3. The length of the connection from the storm water inlet to the manhole on the collector must be no more than 40 m, while it is allowed to install no more than one intermediate storm water inlet. The connection diameter is assigned according to the estimated water inflow to the storm water inlet with a slope of 0.02, but not less than 200 mm.
6.5.4. It is allowed to connect to the storm water inlet downpipes buildings and drainage networks.
6.5.5. The connection of a ditch (tray) to a closed network should be provided through a well with a settling part.
At the head of the ditch it is necessary to provide gratings with gaps of not more than 50 mm, the diameter of the connecting pipeline - according to the calculation, but not less than 250 mm.

6.6. siphons

6.6.1. The projects of siphons through water bodies used for domestic and drinking water supply and fishery purposes must be coordinated with the bodies of sanitary and epidemiological supervision and protection of fish stocks, navigable watercourses - with the management bodies of the river fleet.
6.6.2. When crossing water bodies, siphons must be received in at least two working lines.
Each line must be checked for the passage of the estimated wastewater flow, taking into account the allowable backwater.
At wastewater flow rates that do not provide the design (non-clogging) speeds, one of the lines should be taken as a reserve (non-operating).
When crossing ravines and dry valleys, it is allowed to provide siphons in one line.
6.6.3. When designing siphons, it is necessary to take:
pipe diameters not less than 150 mm;
the depth of the underwater part of the pipeline to the design marks or possible erosion of the bottom of the watercourse to the top of the pipe - at least 0.5 m, within the fairway on navigable water bodies - at least 1 m;
the angle of inclination of the ascending part of the siphons - no more than 20 ° to the horizon;
the distance between the siphon threads in the light is at least 0.7 - 1.5 m, depending on the pressure, as well as the technology of work.
6.6.4. Gates shall be provided in the inlet and outlet chambers of the siphons.
6.6.5. The layout mark at the chambers of the siphons, when they are located in the floodplain part of the water body, should be taken 0.5 m above the horizon high waters 3% security.
6.6.6. The places where siphons cross water bodies should be marked with appropriate signs on the banks.

6.7. Road crossings

6.7.1. Crossing by pipelines of railways of I, II and III categories on stages and highways I and II categories should be carried out on cases.
Under railways and roads of other categories, it is allowed to lay pipelines without cases, and pressure pipelines must be provided from steel pipes, and gravity - from cast iron.
6.7.2. The places of crossings over railways and roads must be agreed with the relevant organizations in the prescribed manner.
When developing a transition project, the prospect of laying additional tracks should be taken into account.
6.7.3. Crossings of pressure sewer pipelines under roads are designed in accordance with SP 31.13330.
At the same time, in the event of an accident on the pipeline, wastewater should be drained from the case into sewer networks, and in their absence, measures should be taken to prevent them from entering water bodies or onto the terrain (emergency tanks, automatic shutdown of pumps, switching pipeline fittings, etc. ).
6.7.4. In order to maintain the required slope when laying a gravity pipeline, an appropriate concrete block with guide structures should be provided in the case.
6.7.5. It is allowed to use the upper zone of the steel case for placing electric cables or communication cables in the corresponding pipes.
6.7.6. In some cases, after pulling through the pipes, filling the space between the pipes and the case with cement mortar is allowed.
6.7.7. The wall thickness of the steel case should be determined based on the calculation, taking into account the depth, and for cases laid by puncture or punching, taking into account the necessary force developed by the jacks.
6.7.8. Steel cases must be provided with adequate anti-corrosion insulation of the outer and internal surfaces, as well as sacrificial protection against electrochemical corrosion.

6.8. Outlets and storm drains

6.8.1. Outlets into water bodies should be placed in places with increased flow turbulence (narrows, channels, rapids, etc.).
Depending on the conditions for the discharge of treated wastewater, coastal, channel or dispersal discharges should be taken. When discharging treated wastewater into the seas and reservoirs, it is necessary to provide for deep-sea outlets. It is allowed to release completely treated wastewater by inlet to absorption sites located in the zone of the underflow of the water body.
6.8.2. The locations of releases must be coordinated with the bodies of sanitary and epidemiological supervision and the protection of fish stocks, and in navigable areas - with the fleet management bodies.
6.8.3. Pipelines of channel and deep-water outlets should be designed, as a rule, from steel pipes with reinforced insulation and laid in trenches.
The design of the outlets must be taken into account the requirements of navigation, the modes of wave action levels, as well as geological conditions and channel deformations.
6.8.4. Storm drains should be provided in the form of:
releases with caps in the form of walls with postcards - with unfortified banks;
holes in the retaining wall - in the presence of embankments.
In order to avoid flooding of the territory in the event of periodic rises in the water level in the water body, depending on local conditions, it is necessary to provide special gates.

6.9. Network ventilation

6.9.1. Exhaust ventilation of household sewage networks should be provided through risers internal sewerage buildings. In some cases, with appropriate justification, it is allowed to provide for artificial exhaust ventilation of networks.
6.9.2. Special exhaust devices should be provided in the inlet chambers of the siphons, in manholes in places of a sharp decrease in the flow rate of water in pipes with a diameter of more than 400 mm, in differential wells with a drop height of more than 1 m and a water flow rate of more than 50 l / s, as well as in extinguishing chambers head.
6.9.3. When ventilation emissions are located within sanitary protection zones, residential areas, as well as large crowds of people, measures should be taken to clean them.
6.9.4. For natural exhaust ventilation of outdoor networks that discharge wastewater containing volatile toxic and explosive substances, at each outlet from the building, exhaust risers with a diameter of at least 200 mm should be provided, located in the heated part of the building, while they should be connected to the external chamber of the hydraulic seal and be displayed above the maximum roof height by at least 0.7 m.
6.9.5. Ventilation of sewer channels and collectors of large sections, including those laid in a mountain or shield way, is taken according to special calculations.

6.10. Drain stations

6.10.1. Reception of liquid waste (sewage, slops, etc.) delivered from non-sewered buildings by sewage transport, and their processing before being discharged into the sewer network, should be carried out at drain stations.
6.10.2. Drain stations should be located near sewer collectors with a diameter of at least 400 mm, while the amount of wastewater coming from the drain station should not exceed 20% of the total estimated flow through the collector.
It is prohibited to place drain stations directly on the territory of urban wastewater treatment facilities.
6.10.3. At the discharge station, it is necessary to ensure the reception (unloading) of special vehicles, washing them, diluting liquid waste to a degree that allows them to be discharged into the sewer network and further to treatment facilities, as well as the retention of large mechanical impurities.
6.10.4. Dilution of liquid waste is provided, as a rule, with tap water through a tank with a jet break.
Water is supplied for washing vehicles in the receiving compartment with hoses during unloading, for dilution in channels and receiving funnels, in grating compartments and when creating a water curtain.

6.11. Snow melting points

6.11.1. It is allowed to install at sewer facilities of snow-melting points that use wastewater heat to melt snow and ice removed from the streets, with the discharge of the resulting melt water into a gravity sewer.
6.11.2. Snow melting points should be designed on the basis of the general scheme of their location, taking into account the proximity of the main areas to be removed from snow, the availability of points for supplying wastewater and removal of melted water, accessibility relative to the road network, ease of access and organization of oncoming traffic of trucks, the possibility of queues during periods after heavy snowfalls, distance from housing, etc.
6.11.3. The composition of the snow melting point should include:
snow melting chambers (one or more);
devices and mechanisms for supplying and crushing snow;
a platform for intermediate storage of snow;
a platform for temporary storage of the extracted waste;
industrial premises.
6.11.4. Imported snow must be crushed before being fed into the snow melting chamber, while separating large heavy inclusions (fragments of the road surface, large stones, tires, etc.). For this purpose it is allowed to use:
special separator-crushers;
gratings through which snow is forced by caterpillar bulldozers.
6.11.5. It is allowed to use one of the following methods of supplying wastewater to melt snow:
selection from a gravity sewer (using a specially created pumping station with submersible pumps);
outlet from the gravity pipeline to the bypass line;
supply from the pressure pipelines of the sewage pumping station.
It is allowed to lay special pressure pipelines to the snow melting point.
6.11.6. When taking wastewater from a gravity sewerage system, it is necessary to calculate the minimum hourly inflow of wastewater, taking no more than 50% for the needs of the snow melting point. When sampling from pressure pipelines, it is necessary to ensure the speed in them after the sampling point, which provides a self-cleaning mode of wastewater movement.
6.11.7. Snow melting chambers are allowed to be located:
above the surface, with pressure supply of waste water into them;
at the level of occurrence of channels from which waste water is discharged into the bypass.
6.11.8. volume and internal organization snow-melting chambers must ensure the melting of the snow fed into them with the release of settling and floating inclusions from it. The task of the snow melting point is to separate from melt water inclusions that are not typical for domestic wastewater, in order to avoid the deposition of coarse inclusions in channels and collectors and overloading the grates with large floating objects. The design of snow melting chambers should ensure the retention of such inclusions with their subsequent unloading and removal.
6.11.9. When calculating the snow melting chamber, it is necessary to determine: the volume of the snow melting zone and the flow rate of waste water supplied for melting (by thermal engineering calculation), the volume of the accumulation zone of settling and floating inclusions, the frequency of cleaning the chamber.
6.11.10. Unloading of the delayed inclusions is recommended to be carried out by grabs. When substantiating, it is allowed to use special mechanical equipment (scrapers, bucket elevators, etc.).
6.11.11. To prevent excretion unpleasant odors the surface of the snow melting chamber must be covered with removable plates.
6.11.12. The garbage removed from the snow melting chamber should be taken to the waste disposal site.

7. Rain sewer. Estimated rainwater flow

7.1. Conditions for diversion of surface runoff
from residential areas and enterprise sites

7.1.1. Surface runoff from urban areas with a significant load from pollutants should be diverted to treatment facilities, i.e. from industrial zones, high-rise residential areas with heavy traffic of vehicles and pedestrians, major highways, shopping centers, as well as rural settlements. At the same time, the diversion of surface runoff from industrial sites and residential areas through rain sewers should exclude the ingress of household wastewater and industrial waste into it.
7.1.2. With a separate system of surface runoff from residential areas, treatment facilities should, as a rule, be located at the mouth sections of the main rainwater sewer collectors before being released into the water body. Places of wastewater discharge into a water body must be coordinated with the authorities for regulating the use and protection of water, the sanitary and epidemiological service and fish protection.
7.1.3. When establishing the conditions for the organized discharge of surface wastewater into water bodies, the environmental and sanitary requirements for the protection of water bodies in force in the Russian Federation should be taken into account.
7.1.4. If there are centralized or local treatment facilities in the city’s rainwater sewerage system, surface runoff from the territory of enterprises of the first group, upon agreement with the water supply and sewerage authorities (WSS), can be directed to the city’s rainwater network (drain) without prior treatment.
Surface wastewater from the territory of enterprises of the second group, before being discharged into the rain sewer of a settlement, as well as when they are jointly discharged with industrial wastewater, must be subject to mandatory preliminary treatment from specific pollutants at independent treatment facilities.
7.1.5. The possibility of receiving surface wastewater from the territories of enterprises into the municipal sewerage system of cities and towns (for the purpose of joint treatment with household wastewater) is determined by the conditions for receiving wastewater into this system and is considered in each specific case if there is a reserve capacity of treatment facilities.
7.1.6. The systems for discharging surface wastewater from the territories of settlements and industrial sites should take into account the possibility of infiltration and drainage water entering the collector network from associated drains, heating networks, common collectors of underground utilities, as well as unpolluted wastewater from industrial enterprises.
7.1.7. To prevent pollution of water bodies by melt runoff in winter period from the territories of settlements with a developed network of roads and heavy traffic, it is necessary to provide for the organization of cleaning and removal of snow with deposition to "dry" snow dumps or its discharge into snow melting chambers with subsequent removal of melt water into the sewer network.
7.1.8. Removal of rain and melt water from the roofs of buildings and structures equipped with internal drains, should be provided in the rain sewer without treatment.
7.1.9. The disposal of surface wastewater to treatment facilities and water bodies should be provided, if possible, in a gravity mode along lower sections of the runoff area. Pumping of surface runoff to treatment facilities is allowed in exceptional cases with appropriate justification.
7.1.10. On the territory of settlements and industrial enterprises, closed systems for the disposal of surface wastewater should be provided. Diversion through an open system of drains using various kinds of flumes, ditches, ditches, ravines, streams and small rivers is allowed for residential areas with low-rise individual buildings, villages in rural areas, as well as park areas with the construction of bridges or pipes at intersections with roads. In all other cases, appropriate justification and agreement with the authorities is required. executive power authorized in the field of environmental protection and ensuring sanitary and epidemiological supervision.
Discharge for treatment of surface runoff from roads and road service facilities located outside settlements is allowed to be carried out by trays and cuvettes.

7.2. Determination of average annual volumes
surface wastewater

7.2.1. The average annual volume of surface wastewater generated in residential areas and enterprise sites during the period of rainfall, snowmelt and washing of road surfaces is determined by the formula

where, and - the average annual volume of rain, melt and irrigation water, respectively, m3.
7.2.2. The average annual volume of rain and melt water flowing from residential areas and industrial sites is determined by the formulas:

where F is the collector runoff area, ha;
- precipitation layer, mm, for the warm period of the year, determined according to SP 131.13330;
- layer of precipitation, mm, for cold period year (determines the total annual amount of melt water), or the water reserve in the snow cover by the beginning of snowmelt, is determined according to SP 131.13330;
and - the overall coefficient of rain and melt water runoff, respectively.
7.2.3. When determining the average annual amount of rainwater flowing from residential areas, the total runoff coefficient for the total runoff area F is calculated as a weighted average of the partial values ​​for runoff areas with different types of surface according to table 7.

Table 7

Runoff coefficient values
for different types of surfaces

┌──────────────────────────────────────────────────┬──────────────────────┐
│ Type of surface or runoff area │ Overall factor │
│ │ drain Psi │
│ │ d │

│Roofs and asphalt concrete pavements │ 0.6 - 0.7 │
├──────────────────────────────────────────────────┼──────────────────────┤
│ Cobblestone or crushed stone pavements │ 0.4 - 0.5 │
├──────────────────────────────────────────────────┼──────────────────────┤
│City quarters without road surfaces, small │ 0.2 - 0.3 │
│ squares, boulevards │ │
├──────────────────────────────────────────────────┼──────────────────────┤
│Lawns │ 0.1 │
├──────────────────────────────────────────────────┼──────────────────────┤
│Quarters with modern buildings │ 0.3 - 0.4 │
├──────────────────────────────────────────────────┼──────────────────────┤
│Medium cities │ 0.3 - 0.4 │
├──────────────────────────────────────────────────┼──────────────────────┤
│Small cities and towns │ 0.25 - 0.3 │
└──────────────────────────────────────────────────┴──────────────────────┘

7.2.4. When determining the average annual volume of rainwater flowing from the territories of industrial enterprises and industries, the value of the total runoff coefficient is found as a weighted average value for the entire runoff area, taking into account the average values ​​of the runoff coefficients for different types of surfaces, which are equal to:
for waterproof coatings - 0.6 - 0.8;
for soil surfaces - 0.2;
for lawns - 0.1.
7.2.5. When determining the average annual volume of melt water, the total runoff coefficient from residential areas and enterprise sites, taking into account snow removal and water losses due to partial absorption by permeable surfaces during thaws, can be taken within 0.5 - 0.7.
7.2.6. The total annual volume of irrigation water, m3, flowing from the runoff area is determined by the formula

where m is the specific water consumption for washing road surfaces (as a rule, 0.2 - 1.5 l/m2 per wash is taken);
k - average number of washes per year (for middle lane Russia is about 150);
- area of ​​hard coatings subjected to washing, ha;
- runoff coefficient for irrigation water (taken equal to 0.5).

7.3. Determination of estimated volumes
surface wastewater when discharged for treatment

7.3.1. The volume of rainwater from the calculated rain, m3, discharged to the treatment plant from residential areas and enterprise sites, is determined by the formula

where F - runoff area, ha;
- the maximum layer of precipitation for rain, the runoff from which is treated in in full, mm;
- average runoff coefficient for design rain (defined as a weighted average value depending on the constant values ​​of the runoff coefficient for different types of surfaces according to table 14).
7.3.2. For residential areas and industrial enterprises of the first group, the value is taken equal to the daily layer of precipitation from low-intensity, often recurring rains with a period of a single excess of the calculated intensity P = 0.05 - 0.1 years, which for most settlements of the Russian Federation provides acceptance for cleaning of at least 70% of the annual surface runoff.
7.3.3. The initial indicators are:
data of long-term observations of weather stations for precipitation in a particular area (at least 10 - 15 years);
observational data at the nearest representative weather stations.
A weather station can be considered representative of the area of ​​flow under consideration if the following conditions are met:
the distance from the station to the catchment area of ​​the object is less than 100 km;
the difference in elevation between the catchment area above sea level and the meteorological station does not exceed 50 m.
7.3.4. In the absence of long-term observational data, the value for residential areas and industrial enterprises of the first group can be taken within 5–10 mm as providing acceptance for treatment of at least 70% of the annual volume of surface runoff for most territories of the Russian Federation.
7.3.5. The maximum daily volume of melt water, m3, in the middle of the snowmelt period, discharged to treatment facilities from residential areas and industrial enterprises, is determined by the formula

where F - runoff area, ha;
- total coefficient of melt water runoff (assumed 0.5 - 0.8);
- a layer of sediments of a given frequency;
a - coefficient taking into account the unevenness of snowmelt, can be taken as a = 0.8;
- the coefficient taking into account snow removal should be approximately equal to:

where is the area of ​​the total territory F cleared of snow (usually from 5 to 15%).

7.4. Determination of the estimated costs of rain and melt water
in rainwater collectors

7.4.1. Rainwater flow rates in rainwater sewer collectors, l/s, that discharge wastewater from residential areas and enterprise sites, should be determined by the method of limiting intensities according to the formula

where A, n are parameters characterizing respectively the intensity and duration of rain for a particular area (determined according to 7.4.2);
is the average runoff coefficient, determined in accordance with the guidelines in 7.3.1 as a weighted average depending on the value for various kinds watershed surfaces;
F - estimated runoff area, ha;
- estimated duration of rain, equal to the duration of the flow of rainwater over the surface and pipes to the design section (determined in accordance with the instructions given in 7.4.5).
Rain water flow for hydraulic calculation of rain networks, l/s, should be determined by the formula

where is the coefficient taking into account the filling of the free capacity of the network at the time of the onset of the pressure regime (determined according to table 8).

Table 8

Fill Factor Values
free network capacity at the time of occurrence
pressure mode

Exponent n Beta coefficient
< 0,4 0,8
0,5 0,75
0,6 0,7
0,7 0,65
Notes. 1. With terrain slopes of 0.01 - 0.03, the indicated values
the beta coefficient should be increased by 10 - 15%, with terrain slopes
over 0.03 - take equal to one.
2. If the total number of lots on the rain collector or on the lot
wastewater inflow is less than 10, then the beta value for all slopes
it is allowed to reduce by 10% with the number of sections 4 - 10, and by 15% - with
number of sites less than 4.

7.4.2. Parameters A and n are determined based on the results of processing long-term records of recording rain gauges of local meteorological stations or according to the data of the territorial departments of the Hydrometeorological Service. In the absence of processed data, parameter A can be determined by the formula

where is the intensity of rain for a given area with a duration of 20 minutes at P = 1 year (determined according to Figure B.1);
n is the exponent determined from table 9;
- the average amount of rain per year, taken according to table 9;
P - rainfall, years;
y - exponent, taken according to table 9.

Table 9

Parameter values ​​n, y to determine
estimated flow rates in storm sewer collectors

┌─────────────────────────────────────────────────┬────────────┬─────┬────┐
│ District │ Value n │ m │ y │
│ │ at │ r │ │
│ ├──────┬─────┤ │ │
│ │P >= 1│P< 1│ │ │

│Coast of the White and Barents Seas │ 0.4 │0.35 │ 130 │1.33│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│North of the European part of Russia and Western Siberia │ 0,62 │0,48 │ 120 │1,33│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Plain areas of the west and center of the European │ 0.71 │0.59 │ 150 │1.33│
│parts of Russia │ │ │ │ │
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Highlands of the European part of Russia, western │ 0.71 │0.59 │ 150 │1.54│
│slope of the Urals │ │ │ │ │
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Lower Volga and Don │ 0.67 │0.57 │ 60 │1.82│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Lower Volga region │ 0.65 │0.66 │ 50 │ 2 │
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Windward slopes of European uplands │ 0.7 │0.66 │ 70 │1.54│
│ parts of Russia and Northern Ciscaucasia │ │ │ │ │
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Stavropol Upland, northern foothills │ 0.63 │0.56 │ 100 │1.82│
│ Greater Caucasus, northern slope of the Greater Caucasus │ │ │ │ │
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Southern part of Western Siberia │ 0.72 │0.58 │ 80 │1.54│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Altai │ 0.61 │0.48 │ 140 │1.33│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│North slope of the Western Sayan │ 0.49 │0.33 │ 100 │1.54│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Central Siberia │ 0.69 │0.47 │ 130 │1.54│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Hamar-Daban ridge │ 0.48 │0.36 │ 130 │1.82│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Eastern Siberia │ 0.6 │0.52 │ 90 │1.54│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Basins of the Shilka and Argun rivers, valley │ 0.65 │0.54 │ 100 │1.54│
│r. Middle Amur │ │ │ │ │
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Basins of the rivers of the Sea of ​​Okhotsk and Kolyma, northern │ 0.36 │0.48 │ 100 │1.54│
│part of the Lower Amur lowland │ │ │ │ │
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Coast of the Sea of ​​Okhotsk, Bering river basins │ 0.36 │0.31 │ 80 │1.54│
│ seas, central and western parts of Kamchatka │ │ │ │ │
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│East coast of Kamchatka south of 56°N │ 0.28 │0.26 │ 110 │1.54│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Coast of the Tatar Strait │ 0.35 │0.28 │ 110 │1.54│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Area about. Khanka │ 0.65 │0.57 │ 90 │1.54│
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│River basins of the Sea of ​​Japan, about. Sakhalin, │ 0.45 │0.44 │ 110 │1.54│
│Kuril Islands │ │ │ │ │
├─────────────────────────────────────────────────┼──────┼─────┼─────┼────┤
│Dagestan │ 0.57 │0.52 │ 100 │1.54│
└─────────────────────────────────────────────────┴──────┴─────┴─────┴────┘

7.4.3. The period of a single excess of the design intensity of rain must be selected depending on the nature of the sewage facility, the conditions for the location of the collector, taking into account the consequences that may be caused by rainfall exceeding the calculated ones, and taken from tables 10 and 11 or determined by calculation depending on the conditions of the location of the collector, intensity rainfall, catchment area and runoff coefficient for the exceedance limit period.

Table 10

Period of a single excess of the calculated intensity
rain depending on the value

┌────────────────────────────────────┬────────────────────────────────────┐
│ Conditions for the location of collectors │ Single excess period │
│ │ calculated rain intensity P, │
│ │ years, for settlements │
│ │ at the value of q │
│ │ 20 │
├──────────────────┬─────────────────┼──────────┬────────┬────────┬───────┤
│ On driveways │On highways │< 60 │60 - 80 │80 - 120│ > 120 │
│local value │ streets │ │ │ │ │

│Favorable │Favorable │0.33 - 0.5│0.33 - 1│0.5 - 1 │ 1 - 2 │
│and average │ │ │ │ │ │
├──────────────────┼─────────────────┼──────────┼────────┼────────┼───────┤
│Unfavorable │Average │ 0.5 - 1 │1 - 1.5 │ 1 - 2 │ 2 - 3 │
├──────────────────┼─────────────────┼──────────┼────────┼────────┼───────┤
│Especially │Unfavorable │ 2 - 3 │ 2 - 3 │ 3 - 5 │ 5 - 10│
│ unfavorable │ │ │ │ │ │
├──────────────────┼─────────────────┼──────────┼────────┼────────┼───────┤
│Special │Special │ 3 - 5 │ 3 - 5 │ 5 - 10 │10 - 20│
│ unfavorable │ unfavorable │ │ │ │ │
├──────────────────┴─────────────────┴──────────┴────────┴────────┴───────┤
│ Notes. 1. Favorable conditions for the location of collectors:│
│the pool with an area of ​​no more than 150 hectares has a flat relief with an average slope│
│surface 0.005 or less; the collector passes through the watershed or│
│ in the upper part of the slope at a distance from the watershed no more than 400 m. │
│ 2. Average conditions for the location of collectors: a pool with an area of ​​more than │
│150 ha has a flat relief with a slope of 0.005 m or less; the collector passes
│ in the lower part of the slope along the thalweg with a slope of 0.02 m or less, at │
The area of ​​the basin does not exceed 150 hectares. │
│ 3. Unfavorable conditions for the location of collectors: collector │
│passes in the lower part of the slope, the basin area exceeds 150 hectares;│
│the collector passes through a thalweg with steep slopes at an average level│
│ slopes over 0.02. │
│ 4. Particularly unfavorable conditions for the location of collectors: collector │
│ removes water from a closed low place (hollow). │

Table 11

Period of a single excess of the calculated intensity
rain for the territory of industrial enterprises
at values

┌──────────────────────────────────────┬──────────────────────────────────┐
│ Short-term result │ Single excess period │
│ network overflow │ calculated rain intensity P, │
│ │years, for the territory of industrial │
│ │ enterprises with values ​​q │
│ │ 20 │
│ ├───────────┬──────────┬───────────┤
│ │ Up to 70 │ 70 - 100 │ Over 100 │

│Technological processes enterprises │0.33 - 0.5 │ 0.5 - 1 │ 2 │
│ are not violated │ │ │ │
├──────────────────────────────────────┼───────────┼──────────┼───────────┤
│Technological processes of the enterprise │ 0.5 - 1 │ 1 - 2 │ 3 - 5 │
│ violated │ │ │ │
├──────────────────────────────────────┴───────────┴──────────┴───────────┤
│ Notes. 1. For enterprises located in a closed basin,│
│the period of a single excess of the calculated rain intensity follows│
│determine by calculation or take equal to at least 5 years. │
│ 2. For enterprises whose surface runoff may be polluted│
│specific pollution with toxic properties or organic│
│substances that cause high values indicators of COD and BOD│
│(i.e. enterprises of the second group), single excess period│
│calculated rain intensity should be taken taking into account environmental│
│the consequences of flooding for at least 1 year. │
└─────────────────────────────────────────────────────────────────────────┘

When designing rainwater drainage for special structures (metro, railway stations, underpasses), as well as for dry areas, where values ​​are less than 50 l / s (from 1 ha), at P = 1, the period of a single excess of the design intensity should be determined only by calculation taking into account the limiting period of exceeding the design rain intensity specified in Table 10. In this case, the periods of a single excess of the design rain intensity, determined by calculation, should not be less than those indicated in Tables 11 and 12.

Table 12

Limit period for exceeding rain intensity
depending on the location of the collector

The character of the pool
serviced
collector Limiting period of exceeding the intensity
rainfall P, years, depending on conditions
collector location
good-
pleasant average unfavorable
especially pleasant
unfavorable
pleasant
Territory of quarters
and driveways of the local
values ​​10 10 25 50
Main streets 10 25 50 100