High-quality arrangement of the courtyard of a private house or summer cottage is impossible without a drainage system, especially if they are located in places where the amount of precipitation is above average or groundwater comes close to the surface. Excess moisture is not only puddles and constant dirt, but also a serious danger to the foundation of buildings.
In this article we will talk about what constitutes a drainage system for a summer cottage or courtyard of a private house. In addition, we will consider what types of drainage structures are and how much it will cost to equip your site with such a system.
What is a drainage system
Drainage (drainage) system is a complex of overground or underground channels designed to remove excess moisture. In other words, it is an artificially created watercourse, due to which water located on the surface of the soil or inside it is removed from a certain area. Drainage has only three main tasks:
- reduction to the design value of the groundwater level;
- collection and drainage of melt water;
- collection and drainage of water resulting from prolonged precipitationprecipitation.
Do I need drainage
If you live in a warm region where snow is a rarity, it rains 2-3 times a year, and groundwater is located at a depth of more than 50 meters, you do not need drainage systems. But if your house or cottage is located in the middle latitudes, where winters are snowy, and spring and autumn are rainy, you cannot do without them. And the point here is not only that excessive moisture creates certain inconveniences and does not have the best effect on the plants growing on the site.
Water, penetrating into the cracks of the foundation of the house, can freeze, expanding them and thereby destroying the foundation of the structure. Groundwater, approaching the lowest point of the foundation, can contribute to subsidence of the soil under it, and this leads to the appearance of cracks on the walls of buildings.
According to the requirements of the Guidelines for the Design and Installation of Drainages (2000), the installation of drainage systems is mandatory:
- for used buried structures located below the calculated groundwater level, as well as when the floor level of the basement above it is less than 5 meters;
- used buried structures in clay and loamy soils, regardless of the presence and level of groundwater;
- technical underground (basement) premises in clay and loamy soils when they are deeper than 1.5 meters, regardless of the presence and level of groundwater;
- of all buildings and premises located in areas of capillary moisture, if theyused in severe humidity and temperature conditions.
On the basis of what the calculation of the drainage system is done
The arrangement of drainage systems and storm sewers is carried out on the basis of data:
- about soil characteristics and soil structure;
- average rainfall;
- groundwater levels depending on the season.
You can get such information by contacting the department (department) of land resources of the region (district) with a request.
Types of drainage systems
The arrangement of drainage and drainage systems involves the use of three types of their structures:
- open;
- closed;
- filling.
Each of the designs under certain conditions can effectively cope with the removal of excess moisture.
Open drain
Open-type drainage systems are the simplest and most common type of site drainage. The main element of such drainage is open channels (ditches) dug along the perimeter of the site. They are usually 0.5 m wide and are dug to a depth of 0.6-0.7 m. The edges of the ditch are cut at an angle of 30 degrees to make it easier for water to enter.
Wastewater collected in a surface diversion circuit flows from it into a gutter, which leads it off the site into a specially provided drainage basin or into a central storm sewer.
Walls of each channelreinforced with bricks or concrete. Instead of these classic materials, special modern devices can be used - trays made of the same concrete or plastic. In order to prevent branches, leaves, stones from falling into the canal, sometimes it is covered from above with a grate of the appropriate size.
It is worth noting that such a drainage system, due to its design, cannot be used to lower the groundwater level. It is effective only for the removal of water that falls in the form of precipitation, and in areas located on a slope.
The cost of an open-type drainage system is minimal. The construction of such a structure without taking into account the design will cost you about 1000-1200 rubles per linear meter.
Closed drainage
If groundwater comes too close to the surface, the best solution would be to organize closed-type drainage. Its design provides for laying a system of trenches with a width of 0.3-0.4 m at a depth of up to 1.5 m. They are dug under a slope in the direction of the drainage well. Indoor drainage, in addition to channels located along the perimeter, usually includes internal channels located throughout the area in the form of a herringbone.
The bottom of each trench along the entire length is first covered with a layer of sand, and after it - with a layer of rubble. On top of such a "cushion" special drainage pipes are laid, wrapped with geotextile. From above, the pipe is again covered with large rubble, forming the upperwater bearing layer. Completes the design with a ball of soil or turf.
What is a drain pipe
A few years ago, drainage pipes were made of asbestos cement or ceramics. Naturally, the installation of a drainage system required significant costs, and could not always be carried out on its own. Today everything is much easier. Plastic structures have practically replaced asbestos and ceramics. A modern drainage pipe is a reliable and durable element, easy to install and repair.
On sale you can find two types of pipes: ordinary plastic with perforation and corrugated. The latter are considered more durable due to the use of stiffeners.
Drainage pipes laid in sandy, clayey or loamy soil are wrapped with geotextile before installation. This is done so that soil particles do not clog the holes through which moisture seeps through. In other words, geotextile performs the function of a kind of filter.
The cost of building a closed drainage system is noticeably higher. Here, you will have to pay 1500-2000 rubles per linear meter. The estimate for the installation of the drainage system also includes the cost of pipes and geotextiles. On average, a running meter of a pipe will cost 40 rubles, and geotextiles - 30 rubles / m. The construction of a collector well with a depth of 3 and a diameter of 1 meter costs about 400 thousand rubles.
Batch drainage
Do-it-yourself drainage system on the site is best done usingbackfill drainage. Structurally, it differs from the closed one in that no pipes are used here. Their role is played by large crushed stone or broken brick. The top layer is crushed stone of fine fraction and sod. The depth of the trenches and the arrangement of the channels are the same as those of the closed drainage.
Water, seeping from the surface into the ditch or rising from the lower level, enters the channel and moves at an angle towards the drainage well. Given that free space is formed between large gravel, water practically does not encounter any resistance in its path, therefore, the efficiency of such a drainage system is in no way inferior to a closed-type drainage system. But the prices for the installation of a backfill-type drainage system are significantly lower, because this does not include the cost of geotextiles, pipes and their installation.
Wall drainage of buildings
If it is determined that groundwater is coming too close to the surface of the soil on the site, it is worth considering the organization of wall drainage. It will help protect the foundation of the task from the formation of cracks in it and subsidence of the soil under it. By the way, the groundwater level can be approximately determined by measuring the distance from the surface to the water in a conventional well. Do not forget to take into account at the same time that in the spring the level will definitely rise due to meltwater.
The construction of a drainage system for drainage from the foundation of buildings begins with determining the depth of its lowest point. In other words, we need to know how deep the foundation goes into the ground. drainagethe system is recommended to be located at a depth of at least 0.5 m from the lowest point of the building foundation. Only in this case, groundwater will be discharged before it reaches the foundation.
The installation of a drainage system around the house begins with digging trenches around the perimeter of the building at a distance of 0.5-0.7 m from the walls. So that the water does not stagnate, the channels must have a certain slope in the direction of the location of the drainage well. If the site already has a drainage system, wall drainage can be brought to it.
The foundation drainage system is built on the same principle as closed drainage, i.e. using special perforated pipes wrapped in geotextiles.
Drainage alone is not enough to protect the foundation of buildings. In addition, it must be equipped with a drainage system that will divert water into the storm drain. At the same time, it is impossible to combine the two systems in any case, this will lead to the opposite effect. In the event of a large amount of precipitation, the drainage simply will not cope with its task, which will cause significant waterlogging of the soil around the foundation.
Slope calculation
The efficiency of water drainage from the foundation and the site as a whole largely depends on the correct organization of the slope, and the larger it is, the better. What should be the slope? The minimum normalized value of this value for clay soils is 2 mm, and for sandy soils - 3 mm per linear meter of the system. But in practice, a slope of 5-7 mm per meter is most often made. For its calculation, the entire length is takendrainage system, starting from its highest point and up to the drainage well. If, for example, its length is 20 meters, then the minimum design slope should be 0.4 m, and the practical one should be 1-1.5 m.
Common mistakes when installing drainage systems
During the construction of drainage systems, the following mistakes are most often made:
- wall drainage device without drainage system;
- use of drainage pipes in geotextile winding in sandy or loamy soils;
- application in the design of drainage systems of liquid levels instead of a level and theodolite;
- installation of stormwater wells instead of drainage.
