Types of storm sewers
In SNiP 2.04.03-85 of the Russian Federation it is clearly stated that sewage-stormwater can be arranged in two ways
The design of a sewer storm drain with a drainage system for the foundation of the building. In this case, all rain or snow melt water will drain from the built blind area of the building into special drainage wells. There the water is purified. Such a system for draining drains from a roof or platforms is quite economical, but there are two significant drawbacks to the design:
- Potential drain cleaning costs;
- Icing during the cold season. Therefore, most likely, you will have to install a heating system.
In the second case, the sewerage is also mounted externally. For this, a tray decorative system is used. The gutters are placed along the intended trajectory, connected into a single system of connecting vessels and covered with decorative gratings. Such a system is most often used in the construction of domestic storm sewers. However, gutters can also be combined in the cold season.
The third method of installing a storm sewer system is internal. In this case, special storm water inlets are mounted under the roof sewers, which divert water into the sewer pipes.
Important: in any of the cases, it is necessary to entrust the design of storm sewers to professionals. Otherwise, communication, mounted "by eye", threatens with serious problems for residents or owners of the facility put into operation.
SNIP
The construction of schemes requires compliance with all the rules prescribed in SNiP 2.04.03-85, this document takes into account the needs of the owners and regulates the rules that must be taken into account when conducting sewer networks. This document is a necessary and useful instruction that cannot be neglected when upgrading an old site or building a new one.
SNiP for storm sewers contains all the necessary calculations for the performance of work, system design. It also contains recommendations on the basic rules of operation. Today, the most popular types of stormwater are:
- Point sewerage system
- Linear system
The value of the minimum slope of storm sewers according to SNiP
An accurate calculation is necessarily carried out before the stormwater device. This is necessary in order to draw up an accurate layout of the pipeline, as well as to determine how much material is required.
The minimum slope of storm sewers according to SNiP
So, the minimum slope of the SNiP storm sewer depends on the diameter of the pipes being laid.
There is a special table in which the slope values \u200b\u200bare prescribed for pipes of different sections, you can also use the online calculator to calculate the sewer slope.
If we take the average values, then we can determine that:
- pipe DN 110 should go with a slope of about 20 mm per 1 m;
- DN 150 - this value is reduced to 8-10 mm;
- DN 200 - the required slope is 7 mm per linear meter.
If pipes with a diameter of 50 mm are used, then for them the optimal drop should be no more than 30 mm / m. Thus, an optimal drainage rate is ensured.
The depth of the storm sewer, according to SNiP
The depth of the storm sewer system is also prescribed by SNiP, but this is more like a recommendation.
The depth of occurrence is determined depending on the climatic conditions of a particular region.
For example, collection of pipes smaller than DN 500 is carried out at a depth of at least 300 mm from the level of soil freezing. The larger the diameter, the deeper the pipes are laid.
Storm sewer networks types and system calculation
When erecting absolutely any object, it is necessary to take care not only of the reliability of the foundation and roof, but also of the quality removal of rain or melt water from the site. For this, gravity storm sewers are used, which is a complex engineering network designed taking into account all the important parameters of the facility. At the same time, the depth of the storm sewer must be observed in accordance with SNiP and GOST. Otherwise, the work of communication will be at least ineffective, and in the worst case, it will harm the environment.
Important: the rainwater drainage system from the site must fully comply with the parameters of the object:
- The total area of coatings and sites from which it is necessary to remove rain or melt water;
- Floor covering material.
At the design stage of storm sewers, it is necessary to comply with all the norms prescribed in SanPiN
At the design stage of storm sewers, it is necessary to comply with all the standards prescribed in SanPiN 2.1.5.980-00, GOST 3634-99 and SNiP 2.04.03-85. Only in this case, the approval of the construction of a water drainage system from the site and its subsequent construction will be carried out as quickly as possible.
It will be necessary to provide the technical task to the regulatory authorities, which is drawn up in accordance with GOST 19.201-78. It contains detailed information about the purpose of the communication, the deadlines for its construction, methods of control over construction and technical requirements for the finished system.
In addition to the project documentation, it is worth attaching working papers in accordance with GOST 21.604-82 “Water supply and sewerage. External networks”, which will provide information in the form of drawings of the frontal and longitudinal profile of the finished communication, a plan of the entire designed network indicating its specific sections and all statements regarding the scope of installation work. We read below about what a storm sewer is and the norms for its construction in accordance with GOST and SNiP.
Waste water volume calculation
In order for the system to divert water from the object to work as efficiently as possible, it is necessary to accurately calculate the average amount of precipitation.
In order for the system of water diversion from the object to work as efficiently as possible, it is necessary to accurately calculate the average amount of precipitation that falls on a particular area during the month. To do this, you can use the formula taken from SNiP 2.04.03-85:
Here the indicators are the following data:
- Q is the average volume of rain or melt water. which will need to be removed from the site;
- q20 is the intensity of rain or snowfall in a particular region of Russia. The data are registered in the SNiP tables for each specific locality;
- F is the total area of all roofs and platforms from which storm or snow runoff will be discharged;
- Ψ is the correction factor. which allows you to achieve the most accurate calculations on the average volume of water for diversion. This indicator completely depends on the type of coating from which the liquid will be discharged.
The coefficient indicators are also spelled out in the tables of SNiP 2.04.03-85 and have the following wording:
- Roofs of any type - the coefficient is 1;
- Platforms and paths made of asphalt - coefficient 0.95;
- For sites and objects made of concrete - the coefficient is 0.85;
- For crushed stone with an admixture of bitumen - a coefficient of 0.6;
- And for simple gravel in its pure form - 0.4.
Thanks to the use of such a formula, it is possible to calculate as accurately as possible the volumes of rain or melt snow water that will "attack" the object in each of the seasons.
Professional design
Not everyone can carry out an independent calculation of storm water.
In addition, if the owner of a private residential area has the right to make a mistake, he can design a sewer at his own peril and risk.
To organize even a small enterprise, to draw up plans for the improvement of urban or courtyard areas, carefully calculated, technically sound projects are required that fully comply with all existing sanitary and building standards.
Such design and survey work is carried out by special organizations, having state certification for the implementation of activities of this kind
.
When contacting specialists, the customer presents them with a number of documents that will form the basis of the terms of reference:
- Topographic map of the area from which storm water is to be diverted.
- Geological survey data containing information about the nature of soils at the site.
- General building plan.
-
If you plan to discharge to a centralized collector system
- technical conditions for water utility services for connection. - Sanitary standards for water treatment, if it is supposed to be discharged into natural water bodies or drainage fields.
- Possible wishes of the customer on the organization of the accumulation of collected water.
The result of the work of designers is a package of documents, which includes:
- General information about the equipped site and storm sewers.
- A detailed schematic diagram of the storm drain.
- A scaled drawing-plan of the site with reference to the locations of all stormwater elements. In fact, it is a ready-made installation instruction for further work.
- Detailed specification of the equipment required according to technical specifications.
- Full estimate for the purchase of the required materials and construction, installation and commissioning.
The finished storm sewer project is subject to mandatory approval by the water utility enterprises, state technical supervision bodies, the sanitary and epidemiological service, and the environmental control service in charge of the state of water resources.
Only after the full approval of the project in all controlling instances, it is possible to proceed to its practical implementation.
Some design organizations take over the entire process of coordinating the project they have developed.
The design process is complex, but there are no trifles in this matter.
In order for the storm sewer to fully fulfill its functions, so as not to incur penalties for violations of environmental legislation, it is better to entrust the development of the project to experienced specialists whose qualifications are not in doubt.
Slope trays why and why
Gutters are gravity-fed systems that, in order to function properly, need to create a constant, uniform slope towards the receiving collector. The entire range of characteristics of stormwater, as well as domestic sewage, is described in SNIP 2.04.03-85. This document regulates materials, technical requirements, as well as methods for hydraulic calculation and calculation of wastewater volumes. Of course, the main binding in determining the volume of rainwater is to the region, the intensity of precipitation in it, as well as the coverage around the storm channel. The minimum slope of the tray depends on this, which is 3 millimeters per meter of the highway.
However, this value is a minimum and depends on the coverage around flumes, as well as on the catchment area. The higher the area, and the worse the surface absorbs water, the higher the hydraulic section and the slope of the system. Do not forget that here, in the storm sewer, water is often discharged from the roofs of houses. Therefore, in this case, the system must have a large throughput.
The creation of storm sewers is largely associated with a large amount of earthwork. To minimize excavation work, the industry produces a tray with an internal slope, which greatly simplifies the installation of the entire system. These products already have the necessary slope. At the same time, the tray itself remains its characteristic shape, and only the inner chute is subjected to slope.In addition, the use of such conduits significantly reduces the risk of errors and subsequent improper operation of storm sewers. Such trays are often made of plastic, as it is quite easy to control its shape during production. However, the concrete tray with a slope, which is also produced, is no exception in this series. Such gutters are created by vibrocompression, which allows achieving high geometric accuracy, including the minimum required slope.
Much, when determining the required slope of the system, depends on the roughness of the inner surface of the tray. The lower it is, the less resistance is experienced by the flowing water flow, which means that its speed and the throughput of the entire system are higher. The leader here, of course, are plastic trays with minimal surface roughness. This means that the slope of storm trays from such gutters can be done less.
However, do not forget that any storm drainage system is not only trays. Also, an obligatory element of the system is sand traps, which work as small sedimentation tanks, in which a suspension of large fractions settles. To minimize the frequency of cleaning sand traps, it is not uncommon for trays to be equipped with gratings that protect the entire system from large debris.
Collector installation rules
When arranging a network of pipes or storm sewer trays, some rules must be observed
- Thus, the communication device requires not only the laying of a sand and gravel cushion in the trench, but also the pouring of concrete mortar to securely fix the collector.
- The entire system during the device must be equipped with special sand traps that will purify the water from small debris and prevent silting of the entire network. Such tanks are mounted at the site of water entry from storm water inlets or gutters into a common sewer pipe.
Important: Sandbox baskets require regular cleaning. In the presence of tortuous communication at all turns, it is worth placing inspection wells
By the way, they can also play the role of sand traps. If the construction of a straight network with a length of more than 10 meters is carried out, then on each segment of 10 m, an inspection well is also installed.
In the presence of tortuous communication at all turns, it is worth placing revision wells. By the way, they can also play the role of sand traps. If the construction of a straight network with a length of more than 10 meters is carried out, then on each segment of 10 m, an inspection well is also installed.
https://youtube.com/watch?v=mYqthJUxyLc
Depth of storm sewer
This parameter depends on the geological conditions in a particular region and the experience of operating engineering networks. It is regulated by SP32.13330.2012 (in an updated version). Specifically for a private house, the numbers are not spelled out - the rules relate to systems arranged in a residential area.
In the absence of experience (non-canalized area, for example) in the operation of networks, they rely on the level of soil freezing, which is different in all regions.
Pipes with a diameter of less than 500 mm are laid 30 cm below the freezing depth mark. Pipes with a diameter of more than 500 mm are laid 50 cm below the freezing depth mark. It is permissible to lay pipes to a depth of 70 cm from the surface (layout). This is the distance to the top of the pipe. At the same time, thermal insulation of the pipeline and its protection from mechanical influences are provided. The depth of the collector is determined by statistical and thermal calculation. The maximum depth is not standardized - it is determined by calculations for each individual case
The materials used, the characteristics of the soil, the technologies used are taken into account.
Reality is very far from book truths. Sometimes it is impossible to follow the rules for a number of reasons.Deviations are acceptable, but any non-standard solution that is not prescribed in the rules and regulations needs the approval of the relevant authority, that is, the project must be agreed upon.
In order for the project to be approved, all applied technical solutions must be justified, and in a comparative way. That is, you need to compare the technical and economic parameters of different options and prove that either the best or the only possible one is designed.
Slope calculation for an apartment
To install a sewer system for a sink, washbasin and bathroom, you need to choose pipes with a diameter of 40-50 mm. One meter should have a slope no more and no less than 2.5-3.5 cm. The minimum value of the slope coefficient per meter is 0.012, and the normative is 0.02. For a toilet, the required slope is 85-100 mm, and for a common riser - 100 mm. To calculate the slope coefficient, the formula is used:
V*√(H/d)>K,
where K is the coefficient for plastic and glass pipes 0.5, and for others 0.6,
H is the coefficient of how quickly the pipeline is filled,
V is the speed of fluid movement along the line,
D is the inner diameter of the pipe.
To correctly set the level of the slope of the pipe in the apartment, it is enough to use a regular ruler.
How to calculate the filling level
For plastic and cast iron pipes, it is mandatory to calculate the level of filling with water. Thanks to this indicator, you can find out at what speed the water must move so that it cannot become clogged. And of course, the exact value of the slope per meter depends on such an indicator. To calculate the filling rate, you need to divide the water level in the pipe by the diameter.
The minimum indicator according to SNIPA is 0.3, and the maximum is 1. But, in practice, this occupancy is in the range of 0.3-0.6. He is the optimal one.
Slope calculation for external sewerage
For your own home, you need to know that installing a storm system is a very troublesome job. Storm sewerage consists not only of a pipeline, but also of ditches that also drain water. The minimum slope per meter of storm pipes also depends on the type and what diameter it has.
For storm sewers, pipes should be 150-200 mm in diameter, and the slope at 200 mm should be 0.007, and at 150 mm - 0.008. that is, the larger the diameter, the smaller the slope. Since the water in such a sewer in any case will pass without any difficulties. And also the slope depends on how the surface of the drainage system. If it is rough, the more you need to do it and vice versa.
For the external system, a level is used. After all the pipes are connected, thanks to the level, their correct slope is set. But it's very hard to do it alone. For such work, at least 3 people will be needed: one sets the slope, the other monitors what level the level shows, and the third, of course, manages this process.
Basic rules for calculating the slope and installing a sewer pipe:
- For a pipe that is 50 mm in diameter, 3 cm of angle is needed per meter, and if it is 110 mm in diameter, then 2 cm.
- The total length of the piping angle for both outdoor and outdoor systems is 15 cm.
- When calculating the norms for an external sewer system, according to SNiP, it is necessary to take into account how much the ground freezes.
- Using the above formulas, it is possible to calculate the correct slope of the pipe yourself, but in turn, to confirm your calculations, you need to consult with specialists.
Thus, having learned all the details about the slope, everyone will be able to carry out such work on their own. But do not forget to get all the recommendations from the experts. Use different tilt methods for apartments and private homes. Take into account all the details, do the calculations correctly. Then your system will last a very long time, it will be reliable, and you won’t have to worry about the fact that it can break through at any moment.
More materials:
- air valve for sewage 50;
- check valve sewer internal 50 mm;
- valve vacuum sewer 110 mm.
