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 yard 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 a similar system.
What is a drainage system?
A drainage (drainage) system is a complex of aboveground or underground channels designed to drain excess moisture. In other words, this is an artificially created watercourse, thanks to which water located on the surface of the soil or inside it is discharged outside a certain area. Only three main tasks are assigned to drainage:
- reduction to the design value of the groundwater level;
- collection and removal of melt water;
- collection and removal of water resulting from prolonged rainfall.
Is drainage needed?
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 don't need drainage systems. But if your house or cottage is located in the middle latitudes, where winters are snowy, and spring and autumn rainy, you can not do without them. And the point here is not only that excess moisture creates certain inconveniences and does not affect the plants growing in the plot in the best way.
Water, penetrating into the slots of the foundation of the house, can freeze, expanding them and thereby destroying the foundation of the structure. Groundwater, approaching the lower point of the foundation, can contribute to the subsidence of 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 buildings 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 with a depth of more than 1.5 meters, regardless of the presence and level of groundwater;
- all buildings and premises located in the zones of capillary humidification, if they are used in harsh humidity and temperature conditions.
Based on what is the calculation of the drainage system
The device of drainage systems and storm sewers is based on data:
- soil characteristics and soil structure;
- average amount of water falling out in the form of precipitation;
- groundwater location level depending on the season.
You can get such information by contacting the department (department) of land resources of the region (district).
Types of drainage systems
The device of drainage and drainage systems involves the use of three types of structures:
Each of the structures under certain conditions can quite effectively cope with the removal of excess moisture.
Outdoor drainage
The installation of drainage systems of the open type is the simplest and most common type of drainage of the site. The main element of such drainage is open channels (ditches) dug around the perimeter of the site. Usually they have a width of 0.5 m 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 it.
Wastewater collected in the surface discharge circuit flows from it into the gutter, which takes them out of the site into a specially provided drainage basin or into a central storm sewer.
The walls of each channel are reinforced 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 with an appropriate size grate from above.
It is worth noting that, due to its design, such a drainage system cannot be used to lower the groundwater level. It is effective only for the removal of water falling out in the form of precipitation, and in areas located on the slope.
The cost of an open drainage system is minimal. The construction of such a design without taking into account the design will cost you about 1000-1200 rubles per linear meter.
Indoor drainage
If groundwater comes too close to the surface, a better solution would be to organize a closed drainage. Its design provides for laying a system of trenches 0.3-0.4 m wide at a depth of up to 1.5 m. They are excavated under a slope in the direction of the drainage well. Closed drainage, in addition to channels located around the perimeter, usually also provides 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. Special drainage pipes wrapped with geotextiles are laid on top of such a “pillow”. From above, the pipe is again filled with large gravel, forming the upper water-bearing layer. The ball of soil or turf completes the design.
What is a drainage 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 done on its own. Today, everything is much simpler. Plastic structures almost replaced asbestos and ceramics. A modern drainage pipe is a reliable and durable element that is easy to assemble 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, clay or loamy soil are wrapped with geotextile before installation. This is to ensure that soil particles do not clog holes through which moisture seeps. In other words, geotextiles serve as a kind of filter.
The cost of building a closed drainage system is much higher. Here you will have to pay 1,500-2,000 rubles per linear meter. The estimate for the drainage system also includes the cost of pipes and geotextiles. On average, a running meter of the pipe will cost 40 rubles, and geotextiles - 30 rubles / m. n. The construction of a collector well with a depth of 3 and a diameter of 1 meter costs about 400 thousand rubles.
Backfill drainage
The device of the drainage system on the site with your own hands is best done using a backfill drainage system. Structurally, it differs from the closed one in that no pipes are used here. Their role is played by large rubble or broken brick. Top layer - crushed stone of small fraction and turf. The depth of the trenches and the location of the channels are the same as that of the closed drainage.
Water, seeping from the surface into a ditch or rising from a lower level, enters the canal and moves obliquely towards the drainage well. Given that free space forms between large gravel, water practically does not encounter any resistance on its way, so the effectiveness of such a drainage system is in no way inferior to a closed type drainage system. But the prices for the installation of the drainage system of the filling type are significantly lower, because this does not include the cost of geotextiles, pipes and their installation.
Wall drainage of buildings
If it is established that groundwater comes 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 roughly determined by measuring the distance from the surface to the water in a normal well. Do not forget to take into account at the same time that in spring the level will necessarily rise due to melt water.
The device drainage system drainage from the foundation of buildings begins with the determination of the depth of its lower point. In other words, we need to find out how deep the foundation goes into the ground. The drainage system is recommended to be located at a depth of at least 0.5 m from the lower point of the base of the building. Only in this case, groundwater will be discharged before they reach the foundation.
The drainage system around the house begins with the excavation of 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 bias 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 drainage system of the foundation is built on the same principle as closed drainage, i.e. using special perforated pipes wound in geotextiles.
To protect the foundation of buildings, it is not enough to use only drainage. Be sure to complement it, a drainage system should be equipped that will divert water to stormwater. 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, drainage simply will not be able to cope with its task, which will cause significant overmoistening of the soil around the foundation.
Slope calculation
The efficiency of water diversion 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 bias? The minimum normalized value of this value for clay soils is 2 mm, and for sand - 3 mm for each 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 of the drainage system is taken, starting from its highest point and to the drainage well. If, for example, its length is 20 meters, then the minimum design slope should be 0.4 m, and practical - 1-1.5 m.
Common errors in the construction of drainage systems
When constructing drainage systems, the following errors are most often made:
- wall drainage device without drainage system ;
- the use of drainage pipes in a geotextile winding in sandy or loamy soils;
- use in designing drainage systems of liquid levels instead of level and theodolite;
- installation of storm drains instead of drainage wells.