Negative consequences of a high water level at the site, drainage options, arrangement of drainage systems in operated areas. Lowering the water level at the site is a protection from gravity-free gravity water, which is close to the surface and belongs to the first water horizon. Periodic flooding is caused by natural sources of groundwater supply - lakes, rivers, as well as precipitation and melting snow. We will talk about how to lower the water level at the site in our article.
The reasons for the increase in the water level at the site
Many summer residents are faced with the problem of excess moisture in the exploited areas, which becomes the cause of many troubles. Water not only complicates gardening and gardening work, but can also destroy buildings. Ignoring excess moisture can lead to such unpleasant consequences:
- Premature death of trees due to the fact that their root system is constantly wet and experiencing oxygen starvation.
- In some cases, groundwater changes the properties of the soil. Shale loses its stability when wet. Sandy soils quickly release water and require draining before starting construction. Certain varieties of sandy soils turn into quicksands. Some clays are swollen and difficult to mine.
- During rain or flood, the site becomes impassable.
- Subsidence of the country house due to leaching of the soil under it, because the ground becomes loose and fragile and shrinks unevenly. The walls of buildings are deformed, cracks appear.
- Also, cement is washed out of concrete, which reduces the bearing capacity of the base. The foundation cannot withstand heavy wall loads.
- During the construction of the summer cottage, groundwater fills the foundation pit and trenches. They interfere with the arrangement of basements.
- Excessive moisture leads to an increase in the cost of arranging a summer house and caring for it, as well as the cost of construction work. Additional equipment and workers will be needed.
Protection of the site from excess moisture is a whole range of measures, including the arrangement of a system of gutters and receiving wells. The essence of all methods consists in collecting water from atmospheric precipitation from the surface of the soil and from the depth into special pipelines or containers and bringing them out of the exploited area.
Work to reduce the level of groundwater at the site can be performed at any stage of exploitation of the usable area. For example, when building a country house, it is necessary to get rid of water before starting the construction of the foundation.
There are many options for reducing waterlogging in soils. Their choice is influenced by the following factors:
- Soil water resistance;
- Required dehumidification depth;
- Duration of dewatering;
- Conditions for the movement of groundwater;
- Proximity to the site of buildings.
On clay soils, open systems are recommended. If small areas are flooded during certain seasons of the year, drainage is formed only in this place.
The most problematic places are located on flat areas - on the cut of the summer cottage drain, near the porch and terrace, or on the ground with uneven relief. It is enough to dig in barrels or other containers near them, where water will drain. It is then used for watering or poured into a safe place.
You can determine the depth of groundwater using various methods:
- Geobotanical method. Based on observations of the prevailing plants in the plots. To do this, you need tables that indicate the vegetation common on various wet soils. In reference books, you can also find signs of waterlogging of the soil.
- By the water level in the nearest wells. Measure the distance from the surface to the water mirror, and then transfer the dimensions to the desired location.
- Drilling a well 2 m deep and monitoring it. The periodic appearance of water in it indicates a high location of water in a given area.
Ways to reduce the water level at the site
To solve the problem, it will be necessary to carry out a fairly large amount of land work to create ways to drain and collect excess water. Below we will consider the basic designs that can cope with the task at hand.
Storage pool
This method of lowering the water level on the site is considered traditional, it has long been used by our ancestors. The reservoir is usually equipped at the very bottom, but you can dig it in another place. To preserve the root system of trees, it is placed in the center of the estate, to protect the cellar from dampness - next to the house.
The pond can be of any shape and can be used for decorative purposes. The storage pool is filled through drainage wells, as well as from atmospheric precipitation.
The main requirement for the container is tightness. To remove water from it, a drain pipe is provided, which goes at an angle to the nearest slope, ditch or ravine. If there is no slope, the contents are removed by the pump, which starts automatically after the float sensor is triggered.
The walls of the pool are made of brick or concrete, which are erected at a distance of 20-25 cm from the slopes of the pit. The remaining gap is filled with oily, soft clay. The walls should be 15-20 cm higher than the estimated groundwater level. The bottom is laid out from the same material as the walls.
All surfaces are plastered with sand-cement mortar, and then sealed with bitumen. The bottom can be not plastered, but covered with 2-3 cm of coarse gravel, and then 5-7 cm of sand or fine gravel. The pool may be left open for geese and ducks or covered with concrete slabs with a hatch through which water is taken for household needs.
If the drive did not help get rid of the moisture in the basement, it is allowed to equip another one in the middle of the front garden. The capacity of the pond should be larger, because it collects groundwater from the entire site, as well as rainwater from the roof and ground surface.
Small drives can be made from old metal and plastic drums. It is convenient to take moisture from them for irrigation.
Open drainage system
Open drainage of an area with a high water table allows only 30-50 cm of dry land below the surface to be provided. It consists of trenches up to 0.7 m deep, made with a slope of several degrees so that moisture moves by gravity. The width along the bottom is 0.6 m, and in the upper part - up to 1.5 m. If the pit is dug on fine-grained soil, it is covered with rubble with sand 10-15 cm thick, which prevents the slopes from slipping.
Usually the open system is used as an addition to swimming pools. Water seeps through the walls of the trench and moves by gravity outside the exploited area or to the collection point.
An open system has several disadvantages:
- Water enters the ditch through the walls, liquefying the soil and reducing their strength.
- The wet bottom of the cut makes it difficult to work on the site.
- The movement of liquid weakens the walls of the trench, and also negatively affects the strength of the foundations of adjacent buildings.
If it is impossible to ensure the movement of subsoil water by gravity, they equip pits, from which it is pumped out by a diaphragm pump. This option is often used at the construction stage of a country house, for example, for draining pits. In this case, it is necessary to choose the right equipment: the pumps must pass fine particles through themselves - stones, silt, debris.
Closed drainage system
This design has a more complex structure than an open system - it includes drain pipes. If the problem area is large, it is recommended to make a plan for the location of channels, manholes and reservoirs for collecting water. Also in the project, the highest and lowest places are marked, because the liquid flows from top to bottom. When equipping a closed drainage system, use our recommendations:
- Dig a trench with an inclination towards the removal of the liquid. The angle of inclination of the bottom is 7 cm at a length of 1 m. If the area is flat, it is necessary to dig in a container to a certain depth, where the liquid will be drained.
- The number of ditches depends on the moisture content of the soil. On clay soils, they can be placed quite often.
- Near buildings, a trench is dug around the perimeter of the building and in places where there is no heavy load.
- The excavation depth depends on the type of soil. For sandy soils - at least 1 m, for loams - 0.8 m, for clays - 0.7 m, but the pipe must necessarily lie below the freezing level. In this case, it will not deform from the remnants of frozen water.
- It is recommended to place the trenches in the form of a herringbone, when they all converge to one central one leading to the drain. The width of the main ditch is performed more than all others.
- The bottom should be free of sharp drops so as not to break the pipes.
- Check the prepared system for auto-draining. To do this, pour water into the pit at different points and control the flow rate. Increase the angle of the bottom if necessary.
- First pour a layer of rubble and sand into the trench, and then place the pipe. Pottery pipes, perforated or ordinary asbestos, can be used as drainage, having previously made cuts in it with a width of 1 mm and a length of 5 cm every 20 cm. Instead of finished products, you can use bundles of brushwood smeared with clay.
- The individual elements of the system are laid in a trench and then assembled using adapters and tees.
- If pipes are used, be sure to provide manholes to clean them. They are mounted near the most problematic areas - at bends and places of narrowing.
- Cover the drain with a layer of moss or peat to protect the drainage from overhead soil. Geotextiles can also be used. Filter elements are mandatory if the soil is sandy or loamy. The fabric should be of low density, otherwise the liquid does not penetrate well into the pipe.
- A layer of sand (10 cm), crushed stone (10 cm) and waterproof material with a thickness of at least 0.5 m is poured on top, which protects the system from moisture entering from the outside.
- The remaining space is filled with earth with a mound, which after a short period of time will sag and level with the soil surface.
- The closed drainage system can be decorated to give it an aesthetic appearance. Pour coarse gravel onto the pipe, smaller fractions on top, and then cover everything with marble chips or decorative gravel. Plant greenery around the edges of the hole.
Drill holes
This option is used to drain the area during construction work. It is able to significantly reduce the high water level at the site, but this will require drilling rigs, pumps and other special equipment. The use of wells allows not to weaken the foundations of the nearest buildings.
The essence of the method lies in the formation of a funnel-shaped surface of groundwater with a slope towards the location of the deep-well pump. The longer the device operates, the larger the funnel diameter. After a while, stabilization occurs: the size of the drained area does not increase, however, after turning off the pumps, the water rises to its original place. The purpose of using wells is to remove liquid from the surface during the execution of underground works during the construction of a building.
To drain the area with a high level of groundwater, ejector wellpoints are also used, which are capable of lowering moisture to a depth of 20 meters. The kit includes water lifters with wellpoints placed inside, distribution pipes and pumps. Ejector lifters are driven by the flow from the pumps. Moisture from the wellpoints enters the tray and then into the circular container. Wellpoints are also installed at the edges of the work site. They can have a linear arrangement, contour, ring, etc.
The vacuum method of dewatering is used in areas with difficult hydrogeological conditions - soil with low permeability, low fluid loss and inhomogeneous soil composition. The essence of the method is to create a stable vacuum outside the systems. They are based on a vacuum dehumidification unit with wellpoints.
How to lower the groundwater level at the site - watch the video:
The lowering of the groundwater level provides a comfortable operation of the land plot, however, intensive pumping can lead to a violation of hydrogeological conditions - springs can dry out or the soil can sink. Therefore, such work should be accompanied by an analysis of the consequences of drainage measures.
