The foundation is designed to receive and distribute the load from the house. Its further operation depends on the quality of the foundation of the house. The type of foundation depends on many factors, not least of which is the presence and level of groundwater.
Often there are soils with high groundwater levels, which significantly interfere with the installation of the foundation. It is completely impossible to build a foundation with a basement in such conditions due to the constant load. But making a foundation without a basement is quite possible even with a high groundwater level, provided that the installation technology is followed.
What effect does groundwater have?
The main substance of any foundation is concrete, which receives the harmful effects of groundwater, or rather those substances that are dissolved in them. Chemicals and salts loosen the foundation and cause it to delaminate. You can tell that the base is deteriorating by the appearance of plaque, a musty smell and stains.
In soils where the groundwater level is high, you will encounter difficulties when digging a pit, since water will flow into it, eroding the bottom and reducing the bearing capacity of the soil. That is why you first need to design a drainage system that will help drain water from the base.
Another negative effect of groundwater, but now not on the foundation, but on the soil itself, is suffusion. This term refers to the leaching of all mineral compounds from the soil. If this process is detected, you will have to engage in the process of draining the area, that is, perform water reduction
At high water levels, you can use pile foundation structures, which are more adapted to such conditions.
Groundwater level: definition and dependence on freezing level
To determine the groundwater level in the area selected for construction, it is best to trust professionals who will do it correctly and using technology. If this is not possible, then you can perform the determination yourself. In this case, the person who conducted the research will be responsible for the result. Work is carried out only in autumn or spring, since during these periods the groundwater level is highest. It is necessary to cover a hole prepared in advance with a depth of 3 meters and a width of 1 meter with polyethylene to protect it from precipitation and debris. After some time, a certain amount of groundwater will accumulate in this hole, the level of which needs to be measured. If it is less than 2 meters, then there is no need to carry out additional measures when arranging the foundation. Otherwise they will be needed.
The groundwater level indicator and the level of soil freezing express a relationship that reveals whether it is necessary to take into account the type of soil when installing the foundation. According to the requirements of SNiP, if the first indicator is less than the second, then there is no need to think about the type of soil, but you can calculate the foundation, referring only to the load from the structure itself.
If a house is being built on sandy, clayey soil or sandy loam with a high water level, then the foundation in any case is laid below the freezing level with the obligatory arrangement of a drainage system.
In addition, the groundwater level in such soils is usually increased by 0.5 - 1 m, judging by the practice of building foundations in these conditions.
Important! When carrying out work on arranging a drainage system, one should take into account the fact that the soil can settle significantly.
Foundation arrangement
To create a reliable foundation for a house, you need to choose the right type and design it. Let's consider the main types of foundations and the possibility of their installation on soil with a high groundwater level:
Performing drainage on the site
A drainage system is a mandatory element of arranging a foundation on soil with a high groundwater level. Usually, a pump is used to lower the water level in a pit or trench, but if during pumping springs appear at the bottom, then the pump is not a solution, since water will constantly flow and increase its level.
There are two ways to install a drainage system.
- Open drainage. As a drainage system in this type of water drainage, drainage ditches with pipes are used through which water is discharged into the drainage ditch. Such a system will be more effective in areas located on slopes.
- Closed drainage is a system of pipes and wells that are hidden underground and clearly designed in advance. To begin with, trenches are dug, the bottom of which is covered with sand and crushed stone.
Important! Before backfilling, the trenches are covered with geofabric, which will prevent silting of the ditch.
Drainage pipes are laid on top of the prepared base; this is usually done under the groundwater level. The entire structure is covered with sand and crushed stone and then covered with soil.
Where the drainage pipes make a turn, inspection wells must be installed. Their size is determined depending on the depth of the pipes.
Advice! If, after the work has been completed, water still remains on the site, then you cannot do without consulting a geologist.
Construction of a columnar foundation
Particularly popular on problematic soil with high groundwater is a columnar foundation, which will perfectly withstand the house in such conditions. The design of this base is the most budget-friendly, which in no way detracts from its dignity.
Such a foundation is made by installing piles around the perimeter of the future building and in those places where there will be load-bearing walls. The number of pillars is determined depending on the load that will be placed on the base. A sand-crushed stone cushion is placed in each well and reinforcement is made, after which concrete is poured. The piles are buried below the soil freezing level. This is done so that the foundation rests on solid soil, bypassing the problematic one.
Important! Before installing the piles, all water is pumped out of the wells to avoid problems with the solution hardening.
After installing all the piles, their upper parts are waterproofed, and a grillage is created, which is a strip that will become a support for the walls of the house.
Thanks to the columnar base, you don’t have to worry about soil heaving in winter. The cost of installation of piles will be significantly reduced if you use individual construction technology, which is the manual preparation of wells for piles.
However, despite its prevalence among private developers, the columnar foundation has some disadvantages. First of all, it is impossible to arrange a basement or ground floor in the house. If, however, a basement is planned, then its installation will significantly increase construction costs. The second disadvantage is that each pile must rest only on solid soil, and only a professional geologist can say at what depth it is. Sometimes it happens that there is basically no solid foundation on a site, even at depth. And lastly, a columnar foundation is not suitable for houses built from heavy building material.
Floating foundation device
It can even be installed in trenches and pits that are filled with water.
This foundation, when arranged in dry trenches and pits, is erected using the following technology:
- Digging a trench with a depth of 80 cm and a width of 50 cm.
- Laying geotextile on the bottom.
- Erecting formwork in a trench to give the foundation a rectangular shape.
- Construction of a twenty-centimeter sand cushion.
- Filling gravel or crushed stone on top of the sand with a layer equal to or thicker than the layer of sand.
- Compacting the created cushion and installing side waterproofing.
- Installation of reinforced mesh with a rod diameter of 12 mm in the formwork.
- Pouring the mortar into the formwork, which should be done only in one step.
- After the concrete has completely hardened, the formwork is removed and the surface of the foundation is covered with a waterproofing mixture.
If the prepared trench or pit is filled with water, then drainage must be done, since water will not allow the concrete to harden and gain strength.
The drainage is a ditch with width and depth of 0.2 and 0.3 meters, respectively. Its installation has already been described earlier.
The rest of the work is no different from installing a floating foundation on dry soil and is carried out according to the previously described algorithm.
It is necessary to install a floating foundation clearly according to the scheme, so any deviation can lead to unpleasant consequences in the form of a poor-quality foundation, on which it will be very problematic to build a house and operate it.
How to protect the foundation from the harmful effects of groundwater
Any foundation must be protected from the destructive effects of groundwater. For this:
Groundwater is underground layers of water in the first (upper) layer from the surface of the earth, which is formed due to atmospheric precipitation, the amount of which directly depends on the season. This level is highest in the spring, when the snow begins to melt, or in the fall, due to the abundance of rain.
To build a reliable house, it is necessary to protect the structure from the influence of groundwater on the foundation.
Groundwater affects the structure of the foundation and the physical condition of the soil around it:
- due to the varied chemical composition found in water, the foundation is constantly susceptible to destruction;
- clay, earth, sand are washed away, which leads to constant subsidence of the building;
- mold, various fungi, a damp smell, white or yellowish salt stains appear.
We build a foundation with a high groundwater level
To start construction on a site with a high groundwater level, you need to properly design the foundation.
When designing a foundation, it is necessary to take into account not only the groundwater level, but also the depth of soil freezing.
Let's figure out what type of foundation is suitable for soil with a high groundwater level:
- Slab foundation. It does not need to be buried deep in the ground; the expansion of the soil in winter does not affect it. Disadvantage of a slab foundation: if the foundation is not isolated from water, it will gradually wash out a hole in the foundation and it will crack. To prevent this from happening, the slab foundation must not only be placed on a cushion of crushed stone and sand, but also isolated from the ground. Ruberoid is perfect for this.
- Brick foundation. When designing, waterproofing must be taken into account. Thanks to the design of the brick foundation, the expansion of the soil in winter will not affect it. And if you make a good blind area, then even external water will not threaten the house. The disadvantage of this type of foundation: a brick foundation requires a lot of costs for its construction.
- Columnar foundation. Even if you lay it below the freezing depth of the soil, its cost will be cheaper than other types of foundation. The disadvantage of a columnar foundation is that it is not suitable for heavy buildings.
- Shallow foundation strip foundation. It is also called floating foundation. Suitable for buildings made of heavy materials.
High groundwater - we build a house without a basement
It is not recommended to build a basement in an area with a high groundwater level. Groundwater will flood the basement and contribute to the destruction of the foundation and the structure as a whole.
If you planned to have a small basement, then it is better to build it separately from the house, insulate it and waterproof it, and build an earthen mound in the form of a hill on top. Such a basement will serve well and for a long time; it will always be dark, dry and cool.
So, when we have figured out everything with the basement, we can move on to laying the foundation. If your house is lightweight, for example, made of wood, you can lay a columnar foundation, since it is best suited for construction on an area with a high groundwater level. However, if the house is too heavy (brick, for example), then a floating foundation would be the best choice.
Floating foundation for areas with high groundwater levels
A floating foundation can be built both in dry trenches and pits, and in trenches that will be filled with groundwater.
Floating foundation in dry pits and trenches
1. It is necessary to dig a trench 80 cm deep and 50 cm wide. At the bottom you need to put material that will prevent the bedding from moving with the soil if water washes it away. For this, it is best to use geotextiles. In order to give a rectangular shape to the concrete, we erect formwork in the trench.
2. Construction of a sand cushion 20 cm thick. Gravel or crushed stone should be poured on top of this cushion. The thickness of the crushed stone layer should be equal to the thickness of the sand cushion or be thicker. For example, with a sand cushion thickness of 20 cm, the thickness of the crushed stone layer should be 20-30 cm. This will perfectly protect the foundation of the house from the influence of groundwater.
After compaction, you need to waterproof the side of the formwork and the cushion itself. This is necessary to ensure that the cement mortar does not seep into the ground.
In order for the foundation structure to be strong, it must be poured immediately. You should not fill the foundation in parts, as its strength will decrease.
3. Before pouring the solution, a reinforced frame made of reinforcement bars with a diameter of 12 mm is lowered into the formwork. Once the frame is installed, pouring can begin. It is very important that no air bubbles are created during this process. To do this, the solution must be constantly pierced with a shovel or rod, and also compacted from time to time.
Floating foundation in pits and trenches flooded with groundwater
If water begins to come out when digging a trench, then it will not be possible to make a solid foundation. Not only will the cement not completely absorb water, but it will also become completely fragile, and due to dirt, unnecessary substances will get into its mixture.
In order to be able to build a foundation in trenches filled with water, it is necessary to install drainage. The remaining construction work corresponds to the construction of a floating foundation in dry trenches and pits.
How to install drainage in soils with high groundwater levels
Drainage - removal of water from the surface of the earth and removal of underground water using a system of drainage pipes, trenches, wells, canals, pumps and other devices.
To lower the water level in the trench, it can be pumped out with a drainage pump. However, if, while using the pump, small keys appear at the bottom that push out water, then pumping should be stopped. In this case, the use of a drainage pump in certain areas will not produce results.
We offer 2 ways to install drainage:
- Open drainage is the easiest way to drain small amounts of excess melt and storm water. To install an open drainage system, drainage ditches are placed on the site, most often along its perimeter. Water from such ditches is drained into a common drain using drainage pipes. This type of drainage is most effective when the land is located on a slope.
- A closed drainage system is designed to drain and prevent the rise of groundwater using a system of underground drainage pipes. A closed-type drainage device is a carefully designed system of pipes and drainage wells laid in a trench. A filter layer of sand and crushed stone is made at the bottom of the trench, then drainage pipes are laid on it. To avoid silting of drainage pipes, it is necessary to line the trench with geotextile. In a closed drainage system, pipes are laid below the groundwater level. A drainage layer of sand and crushed stone is created on top of the pipes, which is then covered with soil and a layer of turf.
In places where drainage pipes turn, inspection wells are installed, the size of which depends on the depth of the pipes.
If it is not possible to drain the water when draining the entire area, then you need to consult an experienced geologist.
Protection of the foundation from the influence of groundwater
- Drain the entire area. After this, install waterproofing around the foundation, and upon completion of construction work, make a reliable blind area to protect the foundation from external water. For this purpose, you can also build a sidewalk along which water will flow.
- The foundation is protected with cement-sand mortar, the layer of which should be 25 mm. The mixture is applied to the surface, leveled, and then thoroughly dried. A layer of roofing felt or ordinary roofing felt is attached on top.
- Using mastic from heated bitumen and fluff lime in a ratio of one to two. If necessary, lime can be replaced with sifted dry chalk, which is mixed with regular resin in a one-to-one ratio. This molten mastic is applied to the surface in two layers, their total thickness is 8 mm.
- The foundation is insulated with two layers of roofing felt or roofing felt. When laying, an overlap of 15 cm should be ensured. When laying, care must be taken that the rolled material is not damaged or has any defects.
Soil heaving in areas with high groundwater levels
You should not miss the fact that on soil with a high level of groundwater, during the frosty period the soil will heave greatly. Therefore, to reduce the pressure of such soils on the foundation, you need to waterproof the base of your building as best as possible.
If you have to build a house on soil with a high level of groundwater, it is important to choose the right foundation and materials for its waterproofing. We recommend that you consult a specialist in this situation.
Samara is located on the banks of one of the world's largest rivers, and groundwater lies under the city at a relatively shallow depth. It is their proximity that threatens the foundation of the house with dampness, the appearance of fungus and mold. The danger lies not only in moisture, but also in chemical compounds dissolved in these waters. Their prolonged exposure - which is inevitable if the foundation comes into contact with a network of underground rivers - leads to corrosion of the building material.
Such prolonged destructive soaking sooner or later entails more global consequences - the house sags, as if “falling” into the ground. That is why many projects of houses and cottages very often turn out to be “unviable” (Samara, of course, is no exception). Neglecting such a small detail leads to fatal consequences.
What to do if the groundwater level in your area is high? Sell the land and run away? Such drastic measures will not be necessary! But you will have to give up the basement space. And in this case, you can choose one of two types of foundation:
1. Support-columnar- laid under “lightweight” wooden and foam block walls and is incredibly cheap;
2. Tape(represents a concrete strip running under each load-bearing wall) - suitable for heavy building structures, since the weight of the building is distributed evenly over such a base.
What to do if the foundation pit is already completely prepared for construction, and water suddenly appears at the bottom? There are two options here:
1. install a system for automatically pumping out and removing excess moisture;
2. ensure the outflow of water by constructing ditches along the perimeter of the building (excess water from the pit will rush to where the ground pressure is less).
These are just some recommendations for overcoming the groundwater problem. The solution is individual in each case. If you are lucky enough to find a good specialist, he, focusing on the characteristics of the soil on your site, will advise you something. All that remains is to find him. Well, everything is simple here. Type “samara cottage design” into a search engine and begin monitoring offers on the regional construction market.
The foundation plays a very important role - accepting and distributing the load from the main structure. An important factor when choosing the type of foundation is the groundwater level. When the groundwater level is high, building a foundation requires a lot of effort and material costs. In addition, laying the foundation in such conditions is carried out in strict compliance with certain rules that help reduce the impact of this negative factor.
Impact of high groundwater levels on the foundation
The basis of any foundation is a concrete solution, so the close location of groundwater has a harmful effect primarily on it. More precisely, concrete is not afraid of water itself; the destructive effect is exerted by salts and chemicals that make up soil water. As a result of their influence, the frozen solution becomes loose and begins to exfoliate. The first signs of concrete deterioration are stains and mustiness.
Another harmful effect of high groundwater is the erosion of the bottom of a trench or pit by incoming water, as a result of which the bearing capacity of the soil decreases, deformation occurs, and. This problem can be solved by constructing a drainage system and draining water.
What to consider when choosing a foundation
When choosing a foundation for building a house on a site with a high groundwater level, you should take into account various factors:
- What load will the main structure exert on the foundation? In other words, what material will be used in the construction of load-bearing walls.
- Will the house have a basement or ground floor?
- To what depth does the soil freeze in winter?
- How high does groundwater rise during a flood, and how long does it take for it to return to normal?
Taking these criteria into account, the foundation for a high groundwater level can be of several types:
- - This is a reliable structure, but unprofitable in material terms. The slab foundation can be built on the surface or deep in the ground. When planning a basement or ground floor, a monolithic slab is installed at a depth of about 2.5 meters. For greater strength, you can place a monolithic base on piles. At the same time, a structure is installed under the slab to prevent water from entering the basement.
- is the most popular option among private developers. However, it can be used with some restrictions: groundwater rises at a certain period or is located below the freezing level of the soil. The high location of groundwater allows the construction of a reinforced concrete strip in the upper layers of the soil. In this case, the load on the base must be taken into account in order to prevent its subsidence or destruction. When choosing a strip base, you should remember that in this case there will be no basement in the house.
- is one of the reliable options. Such a foundation can be made on metal, screw, reinforced concrete or bored piles. Their installation is carried out after accurately determining the depth of the dense soil layer. You can also pour the support yourself rather than using a finished product. To do this, you need to strengthen it with a reinforcement cage and fill it with concrete mortar.
Installation of a drainage system in areas with high groundwater levels
The construction of foundations, the base of which is supposed to be built below the groundwater level, inevitably leads to the use of various methods of water reduction. In other words, options are selected for removing water from a pit or trenches and keeping it at a certain distance.
Drainage involves the removal of melt and groundwater. To equip the system, drainage pipes, wells, channels, pumps and much more are used.
There are 2 ways to install a drainage system.
Open depression
You can pump out water with a drainage pump, but in this case certain conditions must be met:
- There is a reservoir nearby where the pumped water will flow.
- No visible signs of suffusion. With this phenomenon, the smallest particles of soil are carried away along with water, which leads to subsidence of the soil layers located above. The bearing capacity of such soils is very low due to constant subsidence.
Also, the open dewatering system involves a simplified version of the disposal of melt, ground and storm water. To organize such a process, it is necessary to place drainage ditches around the perimeter of the site. Water of various origins flows into them for one reason: the absence of soil resistance and capillary rise of liquid. Such systems are most effective if the site is located on a slope.
Closed drainage system
Closed drainage helps drain groundwater, thereby preventing it from rising. The basis of the system is underground pipes. A closed drainage is a carefully planned structure of pipes and wells. The system is located in a trench, the bottom of which is covered with sand and crushed stone, and also covered with geological fabric. Pipes of a closed drainage system are laid under groundwater. The top is covered with an additional layer of sand and crushed stone, which helps drain water. The entire system is covered with soil and a layer of turf.
Floating foundation in conditions of high groundwater levels
If the structure being built is too heavy, for example, a brick house, then it is better to opt for a floating foundation.
This type of foundation can be built in a dry trench or pit, or in depressions filled with groundwater.
Floating foundation in a dry trench
To arrange the foundation in these conditions, you must perform the following steps:
- They dig a trench about 1 meter deep and 0.5 meters wide and cover the bottom with geological textiles. This material will prevent the bedding from moving if water washes away the soil.
- To give the foundation a rectangular shape, formwork is made.
- Construct, the thickness of which should be 0.2 m. Gravel or fine crushed stone is poured on top of the sand. The thickness of this layer should be equal to or slightly greater than the sand cushion. Such a foundation will be a good protection for the foundation from groundwater. Each layer to be filled must be compacted thoroughly.
- The walls of the formwork and the cushion of sand and gravel are covered with waterproofing material, which will not allow the concrete solution to seep into the soil.
- Do not forget about the frame made of reinforcing bars. This design increases the reliability and stability of both the foundation and the entire house.
Floating foundation in trenches flooded with water
When the groundwater level is high, the dug pit or trench is filled with water. Under these conditions, building a reliable foundation is simply impossible. The concrete solution will absorb water, and dirt can cause unnecessary substances to enter the concrete, which inevitably leads to a decrease in its strength.
When planning the construction of a foundation in such conditions, it is important to properly organize water drainage and develop a drainage system. Otherwise, the work is carried out similarly to the construction of a floating foundation in dry trenches.
Methods to protect the foundation from the effects of groundwater
Construction of a house on a site with a high groundwater level requires mandatory work to protect the foundation from the negative impact of this factor.
- An effective system for draining water of various origins is created throughout the site. Then they make a reliable one, which will prevent external water from penetrating to the base.
- A sand-cement mortar is applied to the surface of the foundation in a layer of about 2.5 cm. The protective coating is well leveled and left until completely dry. Then the foundation is covered with roofing felt.
- Mastic is prepared using lime powder in a ratio of 1:2. The mixture is applied to the surface of the foundation in two layers with a total thickness of no more than 8 millimeters.
- Waterproofing is carried out with roofing felt or roofing felt. In this case, the material is laid in several layers, overlaying strips of 15 cm. When using this method, it is important to check the material for damage and defects.
Building a foundation with high groundwater requires careful consideration of each step, the correct choice of foundation, taking into account all positive and negative factors.
The foundation with a high groundwater level is a headache for owners of future dachas and houses. Of the total number of developers, only a small part gets plots with ideal conditions for construction.
Most of them have to deal with problems with weak or heaving soils and other inconveniences. One of these troubles is the need to build at high groundwater levels.
The influence of groundwater on the foundation would be insignificant if they did not contain solutions of various salts and other chemical compounds.
Clean water is not so terrible for concrete, but in an aggressive chemical environment it quickly deteriorates - it delaminates, becomes covered with a loose coating of a light shade, similar to plaster. Microorganisms – mold and other fungi – don’t keep you waiting either.
The main danger when building a house on the water is the process of washing out the mineral component of the soil - ascending suffusion. In this case, the stability of the soil is reduced so much that even the construction of a light building in this place becomes problematic.
The process of building a foundation for a house on soils with close water is complicated due to the loss of density of the bottom of the pit. As a result, the soil on which the foundation base must rest loses its load-bearing properties. Therefore, first of all, the developer has to deal with the arrangement of the drainage system and decide on the location of groundwater discharge.
Methodology for determining groundwater level
The answer to the question: which foundation is better for high groundwater levels can only be answered by knowing exactly how deep they lie. When clarifying this circumstance, it is not recommended to rely on the testimony of your neighbors: your site may be located lower than theirs, and the structure of the soil may differ even within the same construction site.
To determine how close underground water is to the surface, do the following:
- dig a hole with a cross-section of 1x1 meter and a depth of 3 meters. This should be done in spring or autumn. To ensure that your ore does not go to waste, do this at the location of the future cellar, cesspool or well;
- Protect the pit from seasonal precipitation by covering it thoroughly.
The research results can be assessed based on the following criteria:
- moisture has not appeared in the hole, or there is a small accumulation of it at the bottom - we can assume that groundwater lies deep enough and can be ignored when building the foundation;
- the hole is filled with water, and the distance from the surface of the earth to the mirror of the “flood” is less than 2 meters - it is necessary to change the construction site or take measures to seriously protect the foundation or high-quality drainage.
To complete the theoretical considerations on the topic “If groundwater is close, what kind of foundation is needed for a house”, we present the relationships “groundwater depth – soil freezing depth – soil types”, on the basis of which calculations are made:
- in areas where the freezing depth is less than the depth of underground water layers, the foundation is calculated only for the load from the house;
- the foundation on clay with a high water level is buried below the freezing line. Drainage measures are mandatory in this case. You will have to do the same on sandy or mixed soils;
- calculations must be carried out taking into account the correction for groundwater level - from 0.5 to 1 m upward. The expediency of this technique is proven by practice;
- another mandatory amendment is for subsidence of weak soils: even if there is high-quality drainage, the soil will definitely settle;
- if seasonal flooding occurs, it is recommended to build a house on a slab foundation or on stilts (). Pile supports must be located below the level of possible soil erosion.
Choosing a foundation type
So, if groundwater is close, what kind of foundation is needed? The most correct solution to this issue would be the construction of a floating structure. This type of foundation was developed specifically for construction on weak-bearing, bulk soils, and areas with high groundwater.
It is a monolithic concrete slab reinforced with steel rods. A slab foundation with a high groundwater level has a small thickness ().
Its device is made in the following order:
- A pit is dug 400-500 mm deep.
- The bottom of the pit is carefully leveled and then covered with layers of sand and crushed stone.
- The pillow is compacted and waterproofed using rolled materials.
- Formwork is installed along the perimeter of the future foundation.
- A reinforcing frame is assembled inside the formwork structure.
- Concrete is being poured.
The foundation is poured in mountainous areas with high water levels in stages, connecting the upper parts of the monolithic strips with powerful rand beams.
Prefabricated foundation
Well, if a developer cannot give up his dream of a spacious basement and wants to build a foundation in water, is it scary or not? Modern technologies can make this idea possible. The foundation in this case is constructed from reinforced concrete blocks () installed on a support pad (concrete slab).
The pit is dug deeper than the water level, constructing walls of polymer or steel elements around its perimeter, connected to each other with special locks. In the summer you can do without them, but if you decide to start construction in the fall, you will have to install walls. The water that will constantly accumulate at the bottom of the pit will need to be pumped out.
The bottom of the prepared pit is carefully leveled, and then for leveling it is poured with a thin layer of concrete - a footing is prepared (). Groundwater is a bad neighbor for the foundation, so simultaneously with the construction of the cushion, a drainage system is built around the perimeter of the pit.
It will consist of perforated polyvinyl chloride pipes wrapped in geotextile and a drainage well designed to accumulate water diverted from the construction area.
The formwork is mounted on the footing, then a reinforcing frame is installed in it, and pouring is carried out.
Video about pouring a TISE pile at a high groundwater level.