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During rainfall, huge amounts of water accumulate on roofs and roads. It certainly needs to be taken to a ravine or drainage wells, which is what storm sewers do. Many have seen huge trays along the roads, covered with bars on top. This is the drainage system, but not the whole one. A complete storm sewer system involves the use of several elements that form the main units for collecting water.
Drainage system design
The photo shows a diagram of a system that allows you to collect water from the roof of a building. This is only part of the drainage, because the drains then need to go somewhere. The general scheme of storm sewerage consists of the following nodes:
- storm water inlets;
- pipeline;
- drainage wells;
- filters.
Each node has characteristic varieties and plays its role. Next, we will look at each element separately. This will make it easier to understand the principle of operation of the storm sewer, as well as its structure.
The video shows the structure of the drainage system:
Storm water inlets
This element of the drainage system is often called a water intake. The essence does not change from this. The design is designed to receive rain or melt water. This is where the name came from.Storm water inlets are produced in various sizes, shapes, depths, and from different materials. The top of the trays is covered with a durable grill.
Reinforced concrete trays
Concrete trays for storm drainage are used in road construction. Storm water inlets are installed to collect wastewater in places where the structure is subject to high pressure. Depending on the brand of concrete used, reinforced concrete trays come in three types:
- Lightweight storm drainage trays are produced with a wall thickness of a maximum of 2 cm. The structures are given a cubic shape. A lightweight water inlet is installed under the drain pipe from the building, and a plastic outlet is used as a connecting element.
- A heavy rainwater inlet made of concrete is designed for a load of up to 3 tons. Such water inlets are installed along small roads, in areas where passenger vehicles are expected to enter. The trays are made of fiber-reinforced concrete with a wall thickness of more than 2 cm. The top of the drainage structure is covered with a cast-iron grate with a galvanized coating.
- Main trays for storm sewers are distinguished by their collapsible design. The water receiver consists of several parts, which simplifies the process of its installation. The material for the manufacture of trays is reinforced concrete. The minimum wall thickness is 5 cm. Cast iron grates are used to cover the trays. Reinforced concrete structures can withstand heavy loads, so their installation location is highways.
In private yards, when laying drainage systems, concrete rainwater inlets are practically not used due to their large dimensions and weight, as well as the complexity of installation.And in road construction, reinforced concrete trays for storm drainage are gradually being replaced by more reliable cast-iron water inlets.
Cast iron trays
This type of storm water inlets is also used in road construction. The structures are made of SCh20 cast iron, which is resistant to heavy loads, as well as the effects of aggressive impurities in water.
Depending on the shape and permissible load, cast iron trays produce the following modifications:
- Small storm water inlets for storm sewers "DM" are produced in a rectangular shape. One tray weighs at least 80 kg, and can withstand a maximum load of up to 12.5 tons. Small water collectors are installed in the yard near apartment buildings or along a non-busy highway.
- Large-sized storm water inlets “DB” are designed for a maximum load of 25 tons. The trays have a rectangular shape and weigh a minimum of 115 kg. The installation location is large highways, parking lots and other similar places with a large number of passing vehicles.
- Round-shaped storm water inlets “DK” are installed temporarily instead of rectangular gutters when they are sent for repairs. The structure weighs approximately 100 kg and is designed for a load of up to 15 tons.
The top of the trays is covered with cast iron grates. For reliability, they are fixed with bolts.
Plastic water inlets
In private construction, the most popular are rainwater inlets made of plastic. Their popularity is due to their light weight, ease of installation and long service life. Each type of plastic tray is designed for a specific load, which is indicated by the letter marking of the product:
- A – up to 1.5 t.Storm water inlets of this class are designed for installation on sidewalks and other areas where vehicles do not enter.
- B - up to 12.5 tons. The tray can withstand the load from a passenger car, so it is installed in parking lots, near garages, etc.
- C – up to 25 tons. Water collectors can be installed at gas stations and highways.
- D – up to 40 tons. The grate of this rain inlet can easily support the weight of a truck.
- E - up to 60 tons. Similar models of water intakes are installed on sections of roads and areas with heavy traffic loads.
- F – up to 90 tons. Storm water inlets are designed for specially equipped areas for heavy equipment.
All plastic rainwater inlets are made with a pipe down or to the side for water drainage. The choice of model depends on its installation location in the drainage system. The top of the trays is covered with a plastic grid.
Water collectors made of composite materials
Two types of trays are produced:
- polymer concrete products are made of concrete with the addition of plastic;
- Polymer sand trays are based on similar materials, but sand and additives are also used as additives.
According to their characteristics, composite water intakes have found their place between reinforced concrete and plastic trays. Unlike concrete storm water inlets, products made from composite materials are lighter, have a smooth surface, but can withstand less load. If we compare trays with plastic counterparts, their composite products are heavier, but stronger. The storm inlets are covered on top with cast iron or plastic gratings.
Metal water inlets
Metal water intake trays are not very popular due to the fact that the material quickly corrodes. To increase the service life of the rain inlet, it is necessary that its walls are made of thick steel or stainless steel. This option is not beneficial in terms of cost and heavy weight. If there is a need to install a metal water inlet, then preference is given to cast iron models.
Pipes for drainage system
So, the collected water now needs to be drained into a sewer or drainage well. Pipes are used in the storm drainage system for this purpose. They are also made from different materials. Let's look at what types of storm sewer pipes there are, and which one to give preference to:
- Asbestos-cement pipes were used in the last century, and have not yet lost their popularity. Such a pipeline is resistant to corrosion, quite durable, and has a low linear expansion rate. The disadvantage is the large weight of the pipe and its fragility, which requires careful transportation and installation.
- Metal pipes are the only solution if you need to lay storm drainage in an area with heavy mechanical loads. The disadvantage is the complexity of pipeline installation, high cost and instability of the metal to corrosion.
- Plastic pipes are available with a smooth wall or corrugated. The fact that the drainage pipe is intended for outdoor installation is indicated by its orange color.Smooth-walled PVC pipes cannot be bent, so fittings are required at bends. It is more convenient to use corrugated pipes for storm drainage because of their flexibility.
In private construction, preference is given to plastic pipes. They are light in weight, do not rot, are cheap and can be easily installed by one person.
Sand trap
There are different types of sand traps for storm sewers, but they all perform the same function and have a similar design. The filter housing forms a container. Above its bottom there are feed-through pipes for connection to the pipeline. The sand trap has a filter grid that traps solid particles.
The principle of operation of the filter is simple. Water moving through the pipes enters the sand trap. Solid impurities, under the influence of gravity, pass through the grate, settling at the bottom of the container. Already purified water comes out of the sand trap and moves further through the pipes to the drainage well. The filter is periodically cleaned of sand, otherwise it will no longer cope with its duties.
Wells
The drainage of water from the storm drain goes to a ravine, drainage well or to a treatment plant. Drainage, intermediate and sewer wells have a simple design. In principle, it is a container of certain dimensions buried in the ground.
The complex device has a distribution well installed in the system to discharge wastewater of varying degrees of contamination. The design is a plastic container with one inlet and two outlets. The well is equipped with a neck, the top of which can be covered with a cast-iron hatch. There is a ladder inside for descent.
Flow distribution occurs according to the bypass principle.Dirty water enters the well through the inlet pipe. The outlet pipes are installed one above the other. Dirty liquid with heavy impurities is removed through the lower outlet and sent to treatment facilities. Less contaminated water leaves through the upper outlet and is sent through a bypass channel - the bypass - to a drainage well or other drainage point.
Let's sum it up
That's all the main components of storm sewer units. At first glance, the drainage system looks very simple, but it is not. Accurate calculations and correct installation are needed so that the storm sewer can cope with the maximum volume of wastewater.
Storm water is good. I installed plastic gutters myself last year. Now after the rain there are no puddles under the foundation. This problem is rarely paid attention to, but in vain. Then they complain that the house is cracked or there is dampness in the rooms.