Drainage of surface water from the site. Discharge of surface and ground water

An integral part of a private house or cottage is a storm drainage system, which provides an aesthetic appearance to the residential building and the area adjacent to it. It also prevents premature destruction of the foundations of buildings and the roots of plants growing on the site. For an inexperienced person in the field of "water disposal" this moment may seem like a dark forest. In this article we will look at everything point by point: drainage of surface, storm and melt water, from buildings and site.

For creating storm sewer aka the drainage system surface waters Basic knowledge in construction and data about the territory being developed are required. Storm sewerage is gravity-flow, i.e. is arranged at an angle and includes the following elements:

1. Roof drainage;
2. Drainage drainage system;
3. A sewer or drainage discharge point.

Roof drainage receives precipitation at the roof level, through trays, gutters, funnels and sends it to the surface drainage system.

Design of a surface water drainage system

For design you need to know:

• the average amount of precipitation (both in the form of rain and in the form of snow, melt water), you can find this out in SNiP 2.04.03-85;
• roof area;
• the presence of other communications and facilities in the territory being developed.

For design, it is necessary to decide in what places they will be located. drainpipes and how many there will be. A diagram is drawn up that shows the differences in elevation of the surface of the site and the buildings on it. The diagram indicates the location of all storm sewer elements, including pipes, inspection wells and water discharge points. During design, the amount of required materials and their costs are also calculated.

Drainage of water from the roof

The roof drain material is varied: steel, copper, steel with polymer coating, aluminum, etc. Plastic is especially popular. It is economical, resistant to damage, is a sound-insulating material, airtight, and light in weight and installation. To properly design a roof drain you will need:

1. Metal bracket;
2. Hairpin with a special nut;
3. Adjustable mount;
4. Gutter bracket;
5. Tip;
6. Connecting coupling;
7. Knee;
8. Funnel plug;
9. Gutter plug;
10. Corner element;
11. Funnel;
12. Gutter connector;
13. Gutter;
14. Drain pipe.

The quantity and type of each element depends on the perimeter of the roof and the amount of pumped liquid, because too powerful a drainage system is irrational from the point of view of financial costs, and a weak one will not cope with the task. Need to find best option. The figure shows required dimensions, characteristic of middle zone Russia.

Installation of a water drainage system from the roof of a house

Installation is carried out after developing the design of the entire drainage system and reading the instructions supplied by the supplier store (each system has its own design features that must be taken into account). General installation sequence and work performed:

1. Installation begins with attaching the bracket from the side of the rafter wall or frontal board, taking into account the slope of the gutters.
2. Then the gutters themselves are laid using special plates and fastened to each other using the cold welding or rubber seals. The cold welding method is preferred for joining gutters due to its resistance to deformation.
3. An additional bracket is installed in corner connections and connections with funnels.
4. The pipes are installed, maintaining a distance of 3-4 cm from the wall. The vertical brackets are attached at a distance of 1.5-2 m. The drain itself should be located half a meter from the ground surface.

Tips from the professionals:

• The gutters begin to be laid from the funnel so that the edges of the gutter are below the edge of the roof.
• If you use a pipe to collect gutters from three directions (if the roof non-standard shape), it is necessary to provide tees instead of standard funnels.
• The distance between the brackets should be no more than 0.50-0.60 m.
• It is recommended to mark the slope of the gutters in advance. For example, a guideline can be a rope stretched from the starting point to the ending point.
• Plastic ebbs are mounted at a temperature of + 5°, otherwise the material will crack when cutting. Flashings made from other materials can be installed at any ambient temperature.

Construction of a surface water drainage system

Surface water drainage system or surface drainage consists of point drainage systems and linear channels.

Point drainage They are small wells locally connected to roof drainage. The trays are laid below the freezing level of the pipes. The installation of such drainage is similar to the installation of a roof drain. A trench is being prepared (lower than the freezing depth of the pipes, you can find out everything in the same SNiP) at a slope towards the collector. Sand is poured in a layer of 20 cm. Pipes are laid using fittings. If the sealing is maintained, the pipes are backfilled.

Linear channels come in two types - open or closed, equipped with grates or meshes to retain large debris. The gratings should be predominantly made of metal, because... withstand heavy loads (especially in places at the entrance to the garage).

Advice from professionals. To effectively collect surface water, a comprehensive arrangement of storm and point drainage is necessary. In case of heavy precipitation, the bulk of the water will be drained by surface drainage.

You can see what the process of installing a surface water drainage system looks like in the video:

Deep drainage system is provided if the area where the site is located is prone to prolonged rains. Such a system will protect the site from erosion, protect trees from premature death (due to rotting roots), and protect the foundation from the destructive effects of water.

Groundwater drainage system

Drainage groundwater differs from the systems described above in that it is installed at a greater depth and in the case of groundwater close to the surface of the earth, which can flood a basement or underground garage. Drainage is combined with storm water, and storm water pipes are laid higher than the drainage. It is necessary to understand the difference between stormwater and drainage. Storm drainage for drainage of rain, melt water and floods, and deep drainage for drainage of groundwater and possible flooding. Surface and deep drainage are connected using special node connections for the accumulation of excess water in one place and its subsequent disposal, recycling or reuse. Drains are installed parallel to each other.

This is important: during heavy rainfall, water in large quantities passes through the storm drain in a short time. When such a flow of water enters the groundwater drainage system, this water flows from the pipes into the ground, thereby not draining it but flooding it, that is, it begins to perform the opposite function. Therefore, the surface water drainage system should be connected to the groundwater drainage system no earlier than the places where the water drainage and not drainage pipes pass, if you look at the direction of water movement into the systems. Soil drainage is carried out in places where perforated pipes are laid. Water is drained through sealed pipes.

According to the method of groundwater extraction, they are divided into: vertical, horizontal and combined drainage. Vertical drainage consists of vertical ribbed wells lowered into the groundwater layer. They are equipped with pumps and filters, respectively, for cleaning and pumping groundwater outside the territory. This scheme is quite complicated both in installation and in operation.

Horizontal drainage consists of perforated pipes laid at the optimal pumping outlet depth in dug ditches lined with crushed stone. Ditches are dug throughout the site in a herringbone pattern.

The installation of drainage, regardless of the type of site, begins with the arrangement drainage well in the farthest part of the site, away from the house. You can use ready-made plastic wells.

In places corner connections inspection wells are installed to facilitate communication maintenance.

The depth of drainage is selected based on its objectives: if the goal is to collect groundwater to protect the basement, then the depth should correspond to the level of the basement floor; if the goal is to drain abundant water that sinks into the ground, the depth corresponds to the depth of the foundation.

Pipes are wrapped special material() to prevent sand and gravel from getting into the pipes, with which the pipe is covered with a layer of 20-30 cm. After this, the pipe can be covered with ordinary soil. Unlike vertical drainage, water collected through holes in pipes is discharged by gravity and not by pumps.

Horizontal drainage is more popular than vertical or even combined drainage due to its cost-effectiveness and ease of installation.

You can read more about the design of the groundwater drainage system in the article:

Discharge of collected water

Excess water is removed outside the site, into a ditch or reservoir. If this is not possible, then a well or reservoir is installed within the site, from where the water can be reused.

Advice:

It is recommended to lay drainage in ditches with V-shaped walls with a wall slope of 30◦ in the cross section of the ditch. Width 50 cm. Recommended ditch slope1-3 cm per meter of length. Wells can be equipped from any material that is not subject to corrosion.

Maintenance of drainage systems

Maintenance of the above systems is not difficult if they are properly designed and constructed. Main points in service:

1. Once every ten years, use a pump to thoroughly flush the pipes to prevent deposits on their walls.
2. Regular visual inspection of wells, collectors and cleaning if necessary.

The shelf life of a properly designed, installed, and maintained drainage system is on average fifty years, or even much more.

Tips from the professionals:

1. Be sure to check that the pipes are laid on a slope. The slope should be away from the house.
2. If it is impossible to install a gravity drainage system, a pressure outlet equipped with a pump is installed.
3. Do not forget about optimal design and price = quality.Very often you want more, better, but the budget does not always allow you to realize your plans. That's why It is recommended to design, compare the project with prices, make purchases and install in accordance with the recommendations given here.

The planning of areas for development and other needs must be carried out taking into account the effective removal of precipitation using a drainage system, storm channels and drainage systems. If rain or melt water stagnates, this will contribute to the destruction of the coating and other negative consequences.

Why are surface waters dangerous?

Surface water is formed from atmospheric precipitation: snow, rain, hail, etc. This moisture can cause problems on a site (construction site, country house), ranging from elementary stagnation of water from unpleasant smell and ending with a violation of the integrity of the foundations of nearby buildings. The troubles do not end there; dampness can also penetrate into buildings and provoke the spread of fungus and increased humidity. There is also a danger for sidewalks and road surfaces: cracking, heavy icing, subsidence of the road surface. The root system of plants can rot from excess precipitation, the fertile layer will be washed away, and a violation of the thermal regime will create conditions for the expansion of moss and mold.

To avoid all these negative phenomena, we need an excellent surface water drainage system.

This system comes in two types:

• point;
• linear.

Branches are also divided into open and closed. The second option is more used for draining sediment from entire city blocks. The point method is the simplest; it is most often used when there is a small amount of falling moisture, which is collected in local modules (for example, water flowing from roofs). Linear system more complex and consists of many elements: gutters, trays, ditches, wells, etc. Moisture is quickly collected from a large area and immediately sent to the central drainage collector.

Materials

The materials used are concrete, plastic and earth embankments, ditches and trenches as a temporary solution to the sediment problem. Elements of the surface water drainage system are installed at an angle, which facilitates the rapid collection and discharge of unnecessary moisture. If on site high humidity through underground waters, then drainage system is designed comprehensively, taking into account atmospheric phenomena and the influence of underground sources. Often, sand, dirt, and debris can get into drainage channels and trays with water, and therefore special traps are installed.


These devices prevent the system from becoming clogged and stopping performing its direct functions. When drawing up a general design for the drainage of surface water, a number of factors must be taken into account: the amount of precipitation, the area of ​​the site, the presence of groundwater, the level of humidity, and the slope.

As a result of the action of solar energy, water constantly evaporates from the earth's surface. The largest amount of moisture on the globe evaporates from the surface of the seas and oceans (88%) and much less (12%) from the surface of the land. Evaporated moisture is transported by air currents. When it encounters cold air currents, it condenses and falls onto the surface of the ocean or land in the form of rain and snow. Precipitation that falls on the surface of the land partially evaporates, partially seeps into the ground, and the rest of the precipitation flows down the slopes to the lowest places on the surface, feeding streams, rivers and large rivers, which carry this flow back into the seas and oceans. When the closed cycle of moisture movement (ocean - atmosphere - ocean) is incomplete, a small water cycle occurs in nature. With a complete closed cycle (ocean - atmosphere - land - ocean), a complete water cycle occurs in nature (Fig. 1). Areas in which the entire amount of precipitation evaporates (there is no runoff) are called drainage-free areas (deserts, semi-deserts).

With constant circular circulation of water between land and ocean, the total amount of precipitation X falling on the land surface is equal to the amount of evaporation losses Z, underground runoff Y 1 and surface runoff Y 2 The water balance equation can be expressed by the formula

X = Z + Y 1 + Y 2

Or, taking the total drain Y = Y 1 + Y 2

Fig.1. Scheme of circular circulation of water in nature

1-evaporation from the ocean surface; 2 - precipitation falling into the ocean; 3 - precipitation falling on land; 4 - evaporation from the land surface; 5 - infiltration; 6 - underground drain; 7 - river flow into the ocean

In our country there is a positive water balance: i.e. the average annual precipitation exceeds the average annual amount of moisture evaporation. This is confirmed by the presence in the country of a developed network of large and small rivers and their tributaries, i.e. there is a constant river flow from the land surface. The exception is certain arid areas, where the average annual amount of precipitation is less than the average annual amount of moisture evaporation from the land surface.

A number of conditions contribute to the acceleration of the formation of water droplets in the atmosphere, of which it should be noted that the air basin is clogged with combustion products emitted into the air by pipes industrial enterprises, as well as city dust. Observations have established that short intense showers often occur over industrial areas and the centers of large cities, while in suburban and nearby rural areas no precipitation is observed at this time.

The amount of precipitation falling on the soil surface is measured in linear and volumetric units. In linear units, the average annual and average monthly amount of precipitation H, mm, characteristic of a given climatic region, as well as the intensity of individual rains i, mm/min are measured. In technical calculations, the volumetric unit of measurement of the amount of precipitation g expressed in l/s per 1 hectare is used. To move from one unit of measurement to another, use a dependency

where: k = 166.7 - volumetric conversion factor, i.e. volume of precipitation, l/s, falling on an area of ​​1 hectare with rain intensity of 1 mm/min; k =0.001·10000·1000/60= 166.7 l/s per 1 ha, here 0.001 is the height of the sediment layer, m; 10,000 - area of ​​1 hectare, expressed in m; 1000 - volume of 1 m, expressed in l; 60 is the number of seconds in 1 minute.

The characteristics of the rainfall are recorded by recording instruments - rain gauges, which mark the height of the layer of precipitation h, mm, that fell over a period of time t, min. The amount of precipitation falling per unit time determines the intensity of rain. Average rain intensity, mm/min,

Each rain is characterized by intensity (i or g), the amount of precipitation that fell per unit of time, the duration of the rain and the probability of its occurrence, i.e. the probability of recurrence of such rain over a given observation period of years. In practice, when calculating a storm sewer network, the probability of recurrence of rain intensity of a given duration is taken as c = 1 year, c = 3 years, c = 5 years, c = 10 years, even more rare repetition.

There is a certain relationship between the intensity of rain and its duration, which is expressed by the formula

g - rain intensity, l/s per 1 ha; t - rain duration period, min; A and n are parameters depending on the climatic region of the settlement and the accepted period c.

From the above dependence it follows that longer rains have lower intensity, and vice versa.

Atmospheric precipitation affects the operating conditions and improvement of urban areas. Total amount of precipitation falling on earth's surface throughout the year varies widely. The largest amount of precipitation on the globe was recorded in Cherrapunji (India, Assam state): the average long-term annual amount here was 11,013 mm, the maximum per year was 16,305 mm (1899) and 24,326 mm (1947). In the central part of the European territory of Russia, the average annual precipitation gradually decreases when moving from west to east. U western borders In Russia, the average annual precipitation reaches 650-700 mm per year, gradually decreasing eastward to 500-400 mm per year. On the western slopes of the Ural ridge, the average annual precipitation increases again to 600-700 mm per year.

On Far East the decrease in precipitation occurs from the Pacific coast to the eastern slopes of the Ural Mountains. The greatest amount of precipitation per year in Russia falls on the eastern shore of the Black Sea, as well as in the Altai mountains, on the slopes facing Pacific Ocean. In the Altai mountains, the influence of a barrier that has arisen is felt - high mountains in the path of the movement of winds carrying large reserves of moisture from the ocean.

Formation of surface runoff and its organization

The formation of surface runoff depends on the terrain conditions, and the flow rate depends on the size of the catchment area of ​​the basin and the nature of the use of its territory. The boundaries of the drainage area of ​​the basin are determined by topographically taking into account the terrain and carry them along watershed ridges located at the intersection of two slopes, one of which faces the main thalweg of a specific drainage area. The main thalweg of the basin has access to larger thalwegs, streams and rivers.

Storm runoff and spring snowmelt runoff are formed within the drainage area. In urban planning practice, the organization of surface runoff is considered within relatively small catchment areas (300, 500, 1000 hectares), in which the largest costs will be generated by storm runoff. In an undeveloped area located in natural conditions runoff, the main directions for drainage of surface runoff will be the thalwegs of small basins. In the process of development and improvement of urban areas, the natural drainage system is disrupted. Instead, they create an organized closed system drainage

The main collector of the pool is located in a strip free from urban development, i.e. within the “red lines” and streets or a technical strip specially allocated for these purposes, which is located in the direction of the main thalweg (Fig. 2). This condition must be taken into account in the planning and development of urban areas. At the same time, favorable conditions are created for the placement of main underground utility lines (storm and fecal sewerage, etc.).

To drain surface runoff from the side slopes of the pool, a lateral network of drains is designed in accordance with the street layout.

Fig.2. Scheme of an organized (closed) drainage system

1 - main collector of the pool; 2 - lateral network; 3 - inspection wells; 4 - rainwater wells; 5 - watershed line; 6 - designed ditches; 7 - existing thalweg on an undeveloped area

The organizing drainage system is the trays of intra-block driveways and city streets, ensuring the flow of surface runoff into a closed storm sewer network. In the practice of planning and development of urban areas there are various cases formation of surface runoff, the conditions of formation depend on the size of the built-up area and the nature of its use.

First case. Surface runoff is formed within the completely built-up catchment area of ​​the basin. At the same time, natural drains (streams and small rivers), flowing and stagnant reservoirs (ponds) located within the built-up area are abolished. Polluted surface runoff coming from built-up and landscaped areas can no longer be used to feed open watercourses and reservoirs. Instead of the abolished natural system drainage system, a closed network of urban storm sewerage is arranged, which should ensure the removal of surface runoff from the area of ​​​​residential microdistricts, as well as intra-block and city passages.

Surface runoff from a closed storm sewer network is released into flowing watercourses (rivers) or special coastal canals, which divert the surface runoff for clarification outside the urban area into a system of technical reservoirs of settling tanks, from which the clarified runoff enters the rivers (Fig. 3).

Second case. Surface runoff is formed within a large drainage area, significantly larger than the area of ​​the built-up area. In this case, the lower part of the pool is used for development, and its upper part remains in natural conditions.

According to the conditions for the formation of surface runoff, the total drainage area of ​​the basin can be divided into two private areas - F 1 and F 2 (Fig. 4). Within the drainage area F 1, runoff is formed under natural surface conditions. Within the catchment area F2, surface runoff is formed within the built-up urban area, which corresponds to the first case (see Fig. 4). The runoff generated within the catchment area F1, which is located in a suburban environment, will flow along the natural thalweg of the basin to the border of urban development, and then through the urban area it is passed through an underground collector to the point of release into a flowing watercourse (river). The cross-section of the city collector must ensure the passage of the calculated flow rate coming from the drainage area of ​​the basin F 1 and the flow rates generated within the development of the territory F 1 .

Fig.3. Scheme of organization of surface runoff within a built-up area

1 - city border; 2 - main boundary of the pool; 3 - watershed ridge; 4 - main collector of the pool; 5 - coastal channel; 6 - technical settling ponds; 7 - emergency spillways

To reduce the cross-sectional dimensions of the city collector in the thalweg of the basin at the boundaries of urban development, it is advisable to provide for the installation of a regulating tank - a reservoir. In terms of planning, such a reservoir is used for various purposes (boating, sport fishing, etc.), including as a container for accumulating surface runoff formed in suburban conditions on area F. Dimensions of the reservoir area, water surface marks and the edges of the slope and bank are determined taking into account the use of the reservoir as a regulating tank.

Fig.4. Scheme of organization of surface runoff in a built-up lower part of the basin; the upper part of the pool is preserved in natural conditions

1 - city border; 2 - main boundary of the pool; 3 - watershed ridge; 4 - main thalweg of the pool; 5 - den; 6 - bypass drain; 7 - designed regulating capacity; 8 - private boundary of the pool; 9 - main collector of the pool; 10 - coastal collector; 11 - emergency spillway; 12 - technical settling ponds; F 1 - undeveloped area of ​​the pool; F 2 - built-up area of ​​the pool

Third case. Urban development retreats from the bank of the river to a considerable distance. There remains an undeveloped area between the river bank and the urban development boundary. Such conditions arise when the floodplain part of the river turns out to be unsuitable for urban construction: the coastal part is flooded with flood waters, the surface of the soil layer is swampy and has unfavorable geological conditions (peat, silt deposits). The organization and removal of surface runoff from a built-up urban area is carried out using a closed drainage system (as in the first case). Stormwater runoff from the head of the city sewer is passed through a combined drainage system consisting of an open drainage channel and a closed drainage pipe. The length of this path can be significantly longer compared to the length of the main city sewer (Fig. 5).

Fig.5. Scheme of organization of surface runoff with a built-up upper part of the basin

1 - city border; 2 - main boundary of the pool; 3 - watershed ridge; 4 - main collector of the pool; 5 - private boundary of the pool; 6 - open channel; 7 - spillway collector; 8 - emergency spillway; F - built-up area of ​​the pool; F - undeveloped area of ​​the pool

For the general improvement of the floodplain part of the territory, it is necessary to drain it with the installation of shallow drainage channels and an open drainage channel. Due to sanitary conditions, an open canal cannot be used to pass through contaminated storm drainage coming from the storm sewer network. To receive and remove surface runoff coming from urban areas, it is advisable to install an accompanying drainage collector located next to the open drainage channel. Thus, for complete engineering improvement of the floodplain part of the city, it is advisable to design combined system drainage system, consisting of open and closed channels. For economic reasons, the cross-section of the drainage drain is planned taking into account the passage fixed costs, entering the city drainage network (industrial iodine, runoff from street irrigation, drainage outlets, etc.), and rainwater is given only by frequent rains. During the period of rain floods, less frequent

repeatability, when the outlet drain overflows, the open channel and the outlet drain will work together.

In cities and towns, a closed drainage system is installed to drain surface runoff. For summer cottages, small villages and park areas, you can design an open drainage system consisting of concrete trays, ditches and reinforced drainage channels (Fig. 6). At street intersections and entrances to courtyards, ditches are replaced with shallow crossing pipes. The depth of the ditches should be no more than 0.8-1 m. The minimum width along the bottom of the ditch is 0.4 m

Fig.6. Scheme of an open drainage system

1 - cuvettes; 2 - moving pipes; 3 - inspection wells

The advantage of an open drainage system should be considered the ability to quickly install it at a low cost of money and building materials. However, such a system also has a number of significant shortcomings, the main of which are the need for a device large number crossing pipes and bridges, as well as a decrease in the sanitary level in residential areas, especially with slight slopes.

At open system drainage system, the width of the streets between the “red lines” in relation to the calculated width is increased by the width required to accommodate the ditches. Organized runoff from road gutters and intra-block driveways enters storm drainage wells. The length of the free path of the water flow from the watershed point to the first rainwater wells is taken to be 75-250 m, depending on the slopes of the road tray and the size of the drainage area in this drainage section. The filling height of the roadway trays should not exceed 8-10 cm with a side height of 15 cm. The amount of water passing through the tray depends on the filling of the tray and the slope along the road tray.

The storm sewer network consists of the main basin collector and connections to the side drainage network. The main collector of the pool is installed to replace the abolished thalweg of the pool. The main collector route is located within the “red lines” of a street, boulevard or technical strip allocated for laying main underground communications.

For operational reasons, it is advisable to locate the route of the storm sewer network outside the carriageway of the streets, so that when connecting the side network the road surface is not destroyed. For normal operation of the storm sewer network, inspection wells are installed at corners of turns, at points where the lateral network is connected, as well as at places where pipe sizes and slopes change. To receive organized runoff, rainwater wells are installed in road gutters and at street intersections. At the same time, they strive to create convenient conditions for the movement of pedestrians and vehicles, as well as to meet the requirements of the general improvement of the territory and the protection of city structures from the harmful effects of surface water.

The main attention should be paid to protecting street intersections, city and transport areas, as well as pedestrian routes from surface runoff. The distance between rainwater wells installed in road trays is on average 50-60 m. The layout of these wells at street intersections, depending on the direction of drainage, is shown in Fig. 7. In addition to rain and melt water, discharges are accepted into the closed storm sewer network drainage water, as well as conditionally clean water (i.e., not requiring special treatment before being discharged into drains) from industrial enterprises in agreement with the sanitary inspection authorities.

Fig.7. Schemes for placing rainwater wells at street intersections

Gutter designs

With an open drainage system, cross-sections of streets are made taking into account the intended level of improvement of the urban area.

A typical cross-section of a road with shoulders and ditches is shown in Fig. 8. Surface runoff from the roadway, as well as from the adjacent territory, is diverted into ditches located along the roadway. The ditches are constructed using earthen ones, with their slopes reinforced with stone or concrete slabs, as well as from ready-made reinforced concrete blocks with vertical walls.

Fig.8. Typical cross-section of a road with shoulders and ditches

1 - carriageway; 2 - curb; 3 - earthen ditch

The total width of the street between the “red lines” is reduced (while maintaining the overall dimensions of the main elements of its division) due to the strip required for the construction of slope ditches of a general profile (Fig. 9).

Fig.9. Scheme of open drainage on roads with trays

1 - roadway; 2 - road flow; 3 - paved ditch; 4 - prefabricated reinforced concrete ditch; 5 - bypass tray; 6 - side stone

The dimensions of the main outlet channel with an open drainage system are determined by calculation. With improved types of road surfaces, a closed drainage system is installed - the ditches are replaced with reinforced concrete pipes and laid at a depth that ensures that the drains do not freeze (Fig. 10).

Fig. 10. Scheme of closed drainage on roads with improved surfaces

1 - rainwater well; 2 - inspection well; 3 - drainage pipe; 4 - outlet from the rainwater well; 5 - side stone

Surface water from the road trays flows into rainwater wells, the flow from which flows into the main network of drains. Stormwater and inspection wells are constructed from prefabricated reinforced concrete blocks. Their sizes are assigned based on the operating conditions of the network (Fig. 11, 12). For design reasons, prefabricated inspection wells are arranged in three types depending on the diameter of the pipes

Fig. 11. Scheme of rainwater well

1 - working chamber; 2 - bottom; 3 - sandy base; 4 - outlet from the rainwater well; 5 - sealing the hole with concrete; 6 - cast iron grate; 7 - side stone

On large collectors, special necks are installed on which cast iron hatches are installed. For laying a storm sewer network, round reinforced concrete pipes and prefabricated rectangular channels are used, and when installing collectors large sizes design atypical prefabricated structures.

Fig. 12. Schemes of prefabricated inspection wells depending on the diameter of the pipes

a - 300-500 mm; b - 600-700 mm; c - 800-1100 mm; 1 - floor slab; 2 - neck ring; 3 - support ring; 4 - hatch with cover; 5 - hole for laying pipes; 6 - working chamber

When laying pipes large diameter and their laying depth is insufficient, instead of one, two pipes of smaller diameter are laid, having the same total drainage capacity (Fig. 13).

Fig. 13. Scheme of laying two pipes side by side

1 - reinforced concrete pipe; 2 - concrete base; 3 - preparation from crushed stone

The minimum backfill above the top of the drain pipe structure is taken to be at least 1 m. Laying round pipes with sealing of quarter and socket joints is shown in Fig. 14.

Fig. 14. Scheme for laying a round pipe with sealing the socket joint and detail

1 - reinforced concrete pipe; 2 - concrete base; 3 - preparation from crushed stone; 4 - pipe socket

Sanitary and technical condition of surface runoff and protection of open watercourses from pollution

Surface runoff formed within a built-up and landscaped urban area is significantly different in sanitary condition from runoff formed under natural surface conditions. The surface of an undeveloped area is usually occupied by meadows, arable lands, forests or other vegetation; under these conditions, surface runoff is formed as slightly polluted.

When a territory is developed for urban planning purposes, the nature of the use of the territory changes dramatically: residential development appears, complexes of industrial enterprises are built, city streets are equipped with roads for vehicle traffic. Communal zones, car depots, various small or large enterprises, etc. are being created. The air basin of cities is polluted by waste combustion products entering the air from the chimneys of industrial enterprises, as well as from the exhaust pipes of vehicles. As a result, water falls on the surface of the urban area. a large number of industrial dust and soot, and when vehicles move, residues of petroleum products, lubricants and other substances remain on the roadways of streets and roads. The listed contaminants are washed away by irrigation and rainwater from the surface of low-permeability coatings and enter the storm sewer network.

The concentration of rainwater runoff pollution with suspended and ether-soluble substances will depend on the sanitary and technical condition of various areas of the urban area and the amount of precipitation falling on the surface. In the central areas of the city in areas of new residential development with high level improvement and good operation of the territory, the pollution of rainwater runoff will be less than in industrial zones and on roads with heavy traffic.

In addition to rain and melt water, as well as water from watering and washing streets, the storm network receives discharges from car parks from car washes, lightly contaminated waste water from industrial enterprises, as well as discharges from snow melters.

Modern production consumes a large amount of water, which is taken from lakes, large and small rivers. After finishing technological process water in the form of polluted industrial waste is sometimes discharged into the same lakes and rivers. Depending on the nature of production, waste water may contain mineral suspended matter and waste various materials, biological waste, chemical and radioactive products. Amount of clean water consumed, m, during the production of 1 ton of certain types of products:

Rental - 1.5-10

Sugar - 13-16.5

Coke - 1.5-30

Sulfuric acid - 60-139

Leather - 82-110

Rubber (synthetic) - 250

Thin cloth - 300-600

Artificial silk - 1000-1500

Kapron- 2500

As can be seen from the data presented, for the production of 1 ton of new materials, the consumption of clean water sometimes increases many times.

In the established practice of designing a storm sewer network, each drainage basin corresponds to a separate outlet of the main drainage collector. With an increase in the area of ​​the built-up area, the number of separate drainage basins discharging polluted runoff into flowing water bodies will correspondingly increase. Simultaneously with the increase in the area of ​​the built-up territory, the sanitary and hygienic condition of large and small rivers flowing within the urban area is deteriorating. Small rivers located within the developed area, deprived of natural sources of food, are turned into sewers and are enclosed in underground pipes.

As part of projects for planning and development of urban areas, as well as projects for the reconstruction of old cities, a general scheme for the development of a storm sewer network is being developed. To protect open flowing watercourses from pollution, measures are planned to clarify surface runoff before discharging it into these watercourses. The choice of measures to protect urban watercourses from pollution must be economically justified and technically justified. It depends on the size of the area being built, natural features, as well as on the nature of industrial and other structures located within the urban development area. To improve the sanitary and technical condition of open watercourses located within the built-up area, the following is provided:

a) switching existing waste and industrial water outlets to the sewerage sewer outlet (semi-separate network) with subsequent treatment of contaminated wastewater at treatment facilities;

b) local and cluster treatment of industrial waters on the territory of industrial enterprises;

c) measures to prevent surface water pollution: a well-organized service for the operation of industrial and car park areas, as well as the territories of oil depots and other contaminated areas;

d) cleaning the bottom of reservoirs from sediments of silt and dirt and replacing the excavated soil with sand.

With a separate sewerage system, if, due to the conditions of the existing development, it is impossible to lay a drainage collector outside the urban area, as well as for economic reasons, clarification of surface runoff is carried out at structures located within the urban area. In this case, technical reservoirs - settling tanks - are installed at the mouth areas of individual collectors or a combined group of them. With a centralized surface runoff treatment system, runoff from the main collectors of individual basins is released into coastal canals, through which the polluted runoff is transported to treatment facilities located outside the urban area.

More convenient in technical and economically should be considered a combined system for protecting flowing watercourses from pollution, developed taking into account the local characteristics of the developed area. In less polluted sections of the river, when it enters urban territory, they are limited to improving sanitary and hygienic conditions in the river, performing the work listed in points a, b, c and d. Below this section, taking into account the local characteristics of the territory, structures are installed to clarify surface runoff before release it into open urban watercourses. In the lower section of the river, located within the industrial and communal zones, they arrange centralized system protection of open watercourses with the removal of polluted runoff to treatment facilities located outside the urban area. The boundaries of individual zones when applying the same solutions will depend on the nature of the layout and development of the territory. The main types of recommended structures for clarification of surface runoff are stationary shield barriers located in the coastal part of the river bed (Fig. 15); settling ponds (Fig. 16) and closed structures.

Fig. 15. Scheme of a stationary shield barrier

1 - rainwater collector; 2 - distribution chamber; 3 - supply pipeline; 4 - floating boom; 5 - reinforced concrete canopy; 6 - panel shutter

The type of structure for clarification of polluted runoff is taken depending on the size of the catchment area of ​​the basin, the nature of the development and planning conditions of the territory, taking into account the development of storm sewers. Stationary shield barriers are installed directly in the riverbed along its bank, when, due to the conditions of existing development and other features of the territory, it seems possible to install other standard structures. Settling ponds are installed at the mouths of drains. Closed treatment facilities are created within a built-up and landscaped area in the presence of drainage basins with an area of ​​less than 300 hectares.

Fig. 16. Scheme of a settling pond at the interface with a reservoir

1 - rainwater collector; 2 - distribution chamber; 3 - compartment for retaining oil and petroleum products; 4 - water intake well; 5 - container for settling oil and petroleum products; 6 - receiver of oil and petroleum products; 7 - settling tank section; 8 - semi-submerged panels; 9 - collapsible dam; 10 - dividing dam; 11 - access road

Operating principles of structures installed to clarify polluted surface runoff

The purpose of surface runoff clarification structures is to capture solid products and ether-soluble substances washed into the storm network from road and other surfaces located within the built-up area.

Solids from the runoff settle in sections of the settling tank. Ether-soluble substances (residues of petroleum products) are captured using hydraulic valve and post-treatment filters, the designs of which are made depending on the types of structures. Within large green areas, settling ponds are also installed, equipped with drainage structures with devices for catching residual oil products. Such settling ponds can simultaneously serve as containers for regulating surface runoff. The ponds are located on the main thalwegs of the drainage basins.

When operating structures constructed to clarify surface runoff, it is necessary to ensure timely removal of retained oil product residues from the surface of individual compartments, and solid sediment from the settling sections of structures. Lifting of solid waste and loading it into vehicles is carried out mechanically, and removal of oil products from the surface of individual compartments and draining them into storage tanks is carried out using a rotating slotted pipe mounted in the structure.

When constructing a structure for surface water treatment, it is necessary to allocate a place for the disposal of solid waste, and also to decide on the method of disposal of retained petroleum products. Without this, it is impossible to start operating the structure. For solid waste disposal, the remaining quarry openings or other areas are used, the runoff from which will not flow into open watercourses. The solution to this problem in each individual case will depend on local conditions and must be agreed with the sanitary authorities. If the remaining petroleum products cannot be disposed of, they are burned in special furnaces or subject to deep burial.

The constructed structure is equipped with access roads, which must provide Good work operational transport with designated areas for stopping fire engines. To protect against pollution of the surrounding area and for fire-fighting purposes, the area allocated for the device treatment facilities, fenced with green spaces.