Soils are a reservoir of groundwater. Depending on the nature of occurrence, distribution area and time of existence, groundwater is classified into several types.
Verkhovodka- temporary accumulations of groundwater, usually at a shallow depth from the surface. It is formed above layers of water-resistant rocks in soils permeable to water. For example, if a clay lens lies among the sandy loam environment, then a perch water may appear above it in the rainy season or during a flood. In the dry season, water from the perch evaporates or seeps into deeper layers. Verkhovodka can also form without a waterproof layer, for example, in loams that are poorly permeable to water.
If you do not provide for measures to waterproof the foundation of the future structure or do not divert water from the top water, then it will bring big trouble. Remember, even if during construction, which is usually done in the dry season, there was no water in the ground, it is likely that it will appear in a rainy spring or autumn.
Varieties of groundwater: a - top water; b - groundwater; c - interstratal waters; g - artesian; 1 - soil layer; 2 - permeable layer; 3 - waterproof layer; 4 - aquifer
It is better to check the presence of perched water in the rainy season or immediately after the snow melts using a test well up to 3 m deep. If water comes out in the well, watch it during the dry period. It is clear that if there is a perch in the well, then the water level will drop significantly or the water will disappear altogether. If the water in the well remains in dry land, without lowering the level, then this is most likely groundwater.
ground water
- groundwater horizons that are constant in time and significant in area of distribution, located on the first water-resistant layer of rocks from the surface. The upper level of groundwater lies at different depths - from 1 to 50 m. The level of groundwater can rise or fall due to changes in the amount of precipitation, fluctuations in the level of rivers, lakes, ponds, the waters of which are fed by the aquifer. Groundwater is not pressurized. They are used for the water supply of the estate, and with the appropriate quality - for drinking. They, however, create significant difficulties in construction if they lie at a shallow depth.
Interstratal waters- aquifers that lie between two water-resistant layers and therefore do not have a free surface. They are non-forceful and forceful. Non-pressure waters lie between strictly horizontal layers of aquicludes and are quite rare. Pressure waters lie between inclined water-resistant layers or between layers of a cup-shaped form. Pressure waters are called artesian, and the area of their distribution is called an artesian basin.
Most often, interstratal waters lie at a considerable depth and do not pose a danger to construction. However, in some cases, the upper aquiclude, which forms, as it were, the ceiling of the aquifer, is located not far from the surface. In this case, when digging a foundation pit (trenches, pits), the aquifer often turns out to be opened, and then reliable waterproofing of the foundation is necessary.
During construction within the boundaries of urban development or near large industrial enterprises, technogenic groundwater is also encountered. This is groundwater, similar in properties to perched water, but formed as a result of leakages into the soil of effluents from enterprises, water inflow from large and small water conduits, as well as water seeping from disturbed water pipes. The occurrence of such waters is irregular and unpredictable. It happens that they appear for a very short time, but it happens that their presence becomes quite long, for example, due to constant leaks. All this makes it necessary during construction in such places to waterproof foundations and other underground parts of buildings, even if, according to hydrogeological data, groundwater occurs here at great depths or is not present at all.
The quality of water is highly dependent on aquifers of various depths. Therefore from right choice the location of the future source of water depends on the life of the well or well and the quality drinking water. Groundwater is divided into perched water, groundwater and interstratal water.
Verkhovka is used as an additional source of water for watering the garden. But even such use is not always justified, so with oversaturation chemicals, the opposite effect may be observed - the garden will not give the expected harvest.
ground water
The main source of water that a person can use is groundwater, which occurs at a depth of up to 10 m. The depth of groundwater depends largely on the relief. Therefore, in the same area there may be different levels of occurrence.
Hence the answer to the question: Why does a neighbor have 5 rings 100 meters from me, and I need to make 7. Groundwater is considered a permanent aquifer, but it strongly depends on the regularity of precipitation. And in dry weather, the water can "leave". Water from such a layer must be subjected to additional purification for its subsequent use as drinking water.
To understand why this happens, it is necessary to follow the process of water purification.
So, during precipitation, moisture seeps through permeable rock, encountering almost no resistance on its way, so the degree of its purification is very small. It cannot be said that the water is completely unpurified, but only coarse filtration takes place, during which only large particles remain in the soil, and everything that has dissolved in the water remains in it. This forms a layer called "Ground Water".
Since the layers lie unevenly, and in some places their difference is very significant, springs may appear. The higher the spring is located, the higher the likelihood that groundwater has broken through.
Expert Tip: In some areas, the water from this layer is so polluted that high-quality cleaning at home is simply impossible. Therefore, only testing the water in the laboratory will help determine the contamination of the aquifer, and, if necessary, select best option filtering system.
Interstratal waters
More pure water located in the interstratal layer, the depth of which is from 10 to 100 m.
The peculiarity of the layer is that from here we get water ready for drinking without additional purification, because. the layer is protected on both sides with waterproof layers. Interstratal waters accumulate slowly, as they are located at a greater depth, and therefore are cleaned more efficiently. This is facilitated not only by a large layer, but also by the high density of the soil. The water-resistant layer not only reliably separates interstratal water from groundwater, but part of the moisture still seeps through it, while being effectively cleaned. The bulk of the water enters the interstratal space in those places where the reservoir comes to the surface. The farther from this place the water is taken, the cleaner it is.
Another factor influencing the fact that this aquifer does not replenish quickly is the overpressure created in it. This is especially felt when the well is equipped in a lowland. In this case, water can even gush.
The source of springs located in the lowlands is most often interstratal waters. Often, interstratal waters are saturated with minerals that will benefit a person only if they are moderately consumed in the body. Water saturated with minerals cannot be constantly drunk and cooked from it.
Comparative analysis of interstratal and groundwater
Thanks to the comparison table, you can more clearly see the difference between groundwater and interstratal water.
|
Factor |
ground water |
Interstratal waters |
|
Depth |
Less than 10 m |
10 to 100 m |
|
Usage |
As process water |
Almost everyone was faced with the need for plumbing on their summer cottages. Waters that are very close to the earth's surface can help with this, but they are also a big problem when building your home, namely, they create difficulties during the solution of laying the foundation. Verkhovodka can occur quite unexpectedly, so it is important to take into account all the factors that prevent this phenomenon. In addition to perched water, groundwater can also be found on the site, with the help of which water can already be extracted not for simple domestic needs, but for drinking use. What is perch: definitionHow is water extracted from underground? There are several definitions of groundwater in the world, and one of them is perched water. Its water cover is closest to earth surface among the rest. They are formed by seepage of water from surfaces, as well as water from the atmosphere. Water lingers at such a distance due to leaks in the lenses and layers. The formation of perched water can also occur due to the accumulation of condensate near rocks. The nature of formation is mainly seasonal, that is, when it is dry, perched water disappears, and in rainy weather or when snow melts, it appears in full. By the way, perched water is also water that forms in places where swamps progress, due to an excess of swamp life. Verkhovodka is most widespread in loess rocks. Where else can top water come from?V modern world verkhovodka - a sewer break or water leakage from water pipes and other water-related objects (the same pool). Thus, this place may become partially swampy, or the basement, foundation will be flooded near the standing building. Most often, top water is fresh water, minerals are practically absent, but if the water is dirty, then the content, for example, of iron will be overestimated. In the latter cases, the use of such water for drinking is strictly prohibited.
To prevent the formation of perched water, they can often improve the area by planting plants that would delay the melting of snow, or create special bridges that are resistant to water pressure. The construction of special outlets to ponds, wells, and rivers is also widespread. If an area with predominantly desert areas needs to be filled with water or a special lens made of perched water, then usually ditches or small pits are created into which atmospheric water is drained. This forms a good source of fresh water supply. How does groundwater affect farmingAs already mentioned, the appearance of the perch is seasonal. Nowadays, many people move to live outside the bustle of the city, closer to nature, where the problem of groundwater will await them. What it consists in: the foundation structure can float if, for example, the construction of a house is in the area where the top water is located. It may be absent during the construction period, therefore, together with specialists, it is necessary to assess the situation that may form during the rainy season or during the spring snowmelt. Useful tips for those who found a perch on their site and do not know what to do with it:  Drilling processOne of effective ways to search for water located near the surface of a land plot, is drilling. It is reconnaissance in nature, which means that the very moment of performing this operation is important. That is, such an event should be performed during periods of the greatest accumulation of water in the subsoil. Suppose, after drilling, it turns out that the top water does not increase in height by more than two and a half meters from the surface layer, then you can design a tape foundation with an average depth. It is important to consider the number of planned floors.
In the case of greater flooding of the soil with water (they may already be groundwater) and an increase in the depth of the perch, the foundation should consist of a monolithic support, similar to an inverted bowl. How to choose a place for water intakeThe moment of creation of the well is very interesting. Verkhovodka is the closest option for developing a local or personal water supply. First of all, the seeker of such a source needs to be sure that the water is suitable for use in domestic activities. What you need to check before installing your water supply channel:  Plus, to install perch water supply details, you need to remember about protection with filters. Human dangerThe danger of groundwater perched water is just for construction. Therefore, for all foundations in such an area, it is necessary to make additional waterproofing. Probably, many have heard about the destruction of foundations to such an extent that cracks, starting from the very bottom, literally divided the house into several parts. Also, top water reduces the stability of the soil itself, in certain moment the house may just start to go underground. Dampness in the basement will gradually move along the walls into the upper compartments of the structure, and this is a rather unhealthy factor, since the formation of mold will no longer be stopped. What is ground waterThe name of the waters that go inland from the perch is groundwater. Most often they are a solid water layer and do not have any waterproof layers on top. The groundwater level is determined by drilling and installing a well at the depth where the first manifestations were discovered. Groundwater differs greatly from artesian water in that it is more susceptible to changes in the atmosphere. Forests, steppes and forest-steppe regions may have predominantly fresh groundwater, but already in dry steppes and semi-deserts, the waters will be saline. A large concentration of groundwater is found in the reclaimed layers of valleys located within the nearest rivers. Lowlands and ravines slosh groundwater, creating natural spring formations that feed lakes and ponds.
How can I lower the water level of the perch?If a situation has occurred that requires an urgent lowering of the perch water, then you can use two effective ways: digging channels, that is, creating a surface drainage from a flood site, and creating a drainage system. What drainage can be used: 
Groundwater is formed by filtering atmospheric precipitation through the soil cover or the waters of rivers and lakes through their channel. Further movement of water and accumulation in the form of underground pools depend on the structure of the rocks through which it flows. In relation to water, all rocks are divided into permeable and waterproof. The former include sand, sandy loam, gravel, pebbles, fractured chalk and limestone. Water fills the pores between rock particles or cracks and moves due to the laws of gravity and capillarity, gradually filling the aquifer. Water-resistant rocks are represented by continuous occurrences of granite, dense sandstone and limestone or clays. Layers of permeable and impervious rocks occur, alternating with greater or lesser regularity. Underground waters occur to a depth of 12-16 km. According to the conditions of occurrence, perch water, groundwater and artesian waters are distinguished (from the name French province Artois, lat. Artesium, where they were mined in the 12th century), which differ significantly in hygienic characteristics. Underground fresh waters suitable for drinking water supply occur at a depth of 250-300 m or more. Verkhovodka. Groundwater, which lies closest to the earth's surface, is called perched water. The reason for the appearance of perched water is the presence of deposits under the soil in the form of lenses that create a local aquiclude. Atmospheric waters accumulating on this aquiclude form a perch above the level of the actual groundwater. The diet of the perch is unstable, as it completely depends on the precipitation that falls in a limited space. In warm and hot areas, due to evaporation, the mineralization of perch water is sometimes so high that it makes it unsuitable for drinking. Due to the surface occurrence, the lack of a waterproof roof and the small volume, the perch is easily polluted and, as a rule, it is unreliable in sanitary terms and cannot be considered a good source of water supply. ground water. The water that accumulates in the process of filtration on the first water-resistant layer from the surface of the earth is called groundwater, in the well it is set at the same level as in the underground layer. It does not have protection from waterproof layers; the area of water supply coincides with the area of their distribution. The depth of groundwater varies from 2-3 m to several tens of meters. This type of water source is characterized by a very unstable regime, which entirely depends on hydrometeorological factors - the frequency of precipitation and the abundance of precipitation. As a result, there are significant seasonal fluctuations in the standing level, flow rate, chemical and bacterial composition of groundwater. In addition, the composition of groundwater depends on local conditions (the nature of pollution of surrounding objects) and the composition of the soil. Their stock is replenished due to infiltration of precipitation, or river water during periods of high level; the possibility of groundwater ingress from deeper horizons is not ruled out. In the process of infiltration, water is largely freed from organic and bacterial pollution; while improving its organoleptic properties. Passing through the soil, the water is enriched with carbon dioxide and decay products of organic and other substances, which mainly determines its salt composition. Under natural conditions, groundwater is not polluted and is quite suitable for drinking water supply if its mineralization does not exceed the taste threshold. However, if the soil layer is thin and, moreover, polluted, it is possible to pollute the groundwater during its formation, which is an epidemic hazard. The more massive the pollution of the soil of a populated area and the closer to the surface the water lies, the more real the danger of its pollution and infection becomes. The flow rate of groundwater is usually small, which, along with a variable composition, limits their use for centralized water supply. Groundwater is used mainly in rural areas in the organization of well water supply. Interstratal groundwater. Interstratal waters lie between two water-resistant layers, are isolated from atmospheric precipitation and surface groundwater by a waterproof roof, due to which they have the greatest sanitary reliability. Depending on the conditions of occurrence, they can be pressure (artesian) or non-pressure. Their distinguishing feature is the occurrence below one, two or more layers of water-resistant rocks and the absence of nutrition from the surface directly above them. In each interstratal aquifer, a feeding area is distinguished, where the horizon comes to the surface, a pressure area and a discharge area, where water flows onto the surface of the earth or the bottom of a river or lake in the form of ascending springs. Interstratal water is extracted through boreholes. The quality of well water is largely determined by its distance from the boundary of the supply area. The sanitary advantages of deep groundwater are very high: they rarely require additional quality improvement, they have a relatively stable chemical composition and natural bacterial purity, are characterized by high transparency, colorlessness, absence of suspended solids, and are pleasant to the taste. The chemical composition of groundwater is formed under the influence of chemical (dissolution, leaching, sorption, ion exchange, sedimentation) and physicochemical (transfer of substances from filter rocks, mixing, absorption and release of gases) processes. About 70 were found in groundwater chemical elements. Their disadvantage is often a high salt content and, in some cases, an increased content of ammonia, hydrogen sulfide and a number of minerals - fluorine, boron, bromine, strontium, etc. Fluorine, iron, hardness salts (sulfates, carbonates and magnesium and calcium bicarbonates). Less common are bromine, boron, beryllium, selenium, and strontium. A characteristic feature of interstratal waters is the absence of dissolved oxygen in them. Nevertheless, microbiological processes have a significant impact on their composition. Sulfur bacteria oxidize hydrogen sulfide and sulfur to sulfuric acid, iron bacteria form nodules of iron and manganese, which are partially dissolved in water; some types of bacteria are able to reduce nitrates with the formation of nitrogen and ammonia. The chemical salt composition of various groundwater horizons fluctuates, their mineralization sometimes reaches high limits, and then they are unsuitable for water supply to populated areas. The farther the water intake site (borehole) is from the boundary of the feeding or unloading zone and the better the protection against the penetration of overlying waters, the more characteristic and constant chemical composition interstratal waters. The constancy of the salt composition of water is the most important sign of the sanitary reliability of the aquifer. The formation of groundwater composition is greatly influenced by natural and artificial factors. Changes in the salt composition of the water of a deep-water artesian well should be considered as a sign of sanitary problems. The reason for these changes may be: a) water inflow from the overlying horizon, in particular groundwater, with insufficient density of the insulating layer, flow along the walls of the well, through abandoned wells, during quarrying, with irrational exploitation of the horizon, water withdrawal exceeding its water abundance, accompanied by a change in salinity; b) filtration of river water through ravines in the water-resistant bed of the channel; c) contamination through the wellhead. In some cases, bacterial contamination of the water is also possible. One of the causes of groundwater pollution is industrial wastewater, which is infiltrated from reservoirs, tailings and sludge storages, ash dumps, etc. in case of inadequate waterproofing. Infiltration of industrial pollution is also observed in filtration fields, which until recently were used to neutralize industrial wastewater. Penetration of sewage through impermeable horizons is facilitated by surfactants present in most industrial wastewater. During the operation of a well in a certain part of the aquifer, as a result of the suction action of water-lifting devices, a zone of low water pressure develops. The degree of reduction depends on the power of the water lift, the height of pressure in the horizon before its operation and the water content of the horizon. The pressure decrease reaches its greatest value around the well, gradually decreasing as it moves away from it. The volume of water-bearing rock, which is affected by the suction effect of the water lift during its operation, received the name "depression funnel" due to its characteristic shape. The presence and size of the depression funnel change the hydrogeological conditions in the aquifer, reducing its sanitary reliability, since it becomes possible for water to flow from the overlying and underlying aquifers through cracks and hydraulic windows in the aquifers separating them. The territory on the earth's surface, corresponding to the boundary of the depression funnel, can serve as a source of groundwater pollution to the greatest extent, which is taken into account when organizing the zones of sanitary protection of the water source. Due to the protection from surface pollution, the constancy of composition and a sufficiently large flow rate, interstratal waters are highly valued from a sanitary point of view and, when choosing a source of domestic and drinking water supply, have an advantage over other water sources. Quite often, interstratal waters can be used for drinking purposes without pre-treatment. The only fundamental limitation of their choice as a source of domestic and drinking water supply is the insufficient water content of the horizon compared to the planned capacity of the water supply. To print Vladimir Marchenko 07/14/2015 | 24601 The presence of groundwater on the site can force you to abandon the construction of capital structures. To prevent this from happening, learn more about underground sources. Without information about groundwater, its composition, level of occurrence and other properties, it is impossible to plan the construction of long-term buildings and structures, arrangement reservoirs, organization water supply and sewers. The presence of groundwater can spoil any work and lead over time to the destruction of the structure. To prevent this from happening, you should know how to determine the level and characteristics of groundwater.
What is ground water?In fact, groundwater is a liquid that accumulates in the upper layers of the soil. The sources of groundwater formation are:
The depth of groundwater depends on the terrain and the presence of water bodies near your site. In swampy or lowland areas, groundwater is practically on the surface - 1-2 m, or even a few centimeters from it. Types of groundwaterThe groundwater level can change throughout the year. It reaches its minimum values in winter. At this time, the soil freezes and becomes impervious to precipitation. In addition, the snow melts only closer to spring, depriving groundwater of the main source of filling. Within private households, two types of groundwater are usually present. 1. Verkhovodka(autochthonous, "local" groundwater). They occur at a depth of 0.5 to 3 m in "spots" in depressions or between soil layers. In dry weather or cold winters, perched water almost disappears. But with the resumption of rains and an increase in the humidity of the earth, it reappears.
Sometimes these underground waters are formed in places of leaks in the water supply, sewerage or constant draining of the liquid. The water in the top water is fresh, slightly mineralized, usually not suitable for drinking. It is often contaminated with toxic metals, causing the concrete to rapidly degrade. 2. Non-pressure groundwater(allochthonous, "external" waters). They occur at depths of 1 to 5 m and are relatively constant. It is non-pressure groundwater that gives builders the bulk of the inconvenience, since it is constantly replenished due to precipitation, nearby rivers and lakes, condensate, and sometimes artesian wells. How to determine the level of groundwater?Before starting any work on the site associated with penetration into the ground, it is necessary to determine the groundwater level (GWL). It is especially important to take into account geological exploration data at. But to know what processes occur at a depth of 1 to 5 m, it is also necessary when drilling wells and wells, arranging cellars, and even before planting plants. Groundwater close to the surface affects the chemical composition of the soil, its level of acidity and moisture. Determine the level of groundwater in early spring when it reaches its maximum value. You can independently determine the depth of occurrence in several ways.
Well drilling as the most reliable way to determine groundwater levelThe higher the groundwater is located, the harder it will be to build long-term buildings and structures. And given that the foundation often occupies a large area, the groundwater level must be measured in several places. On the site in this case (as well as in any other) it is better to use test well drilling technique.
To do this, take an ordinary garden drill and make 3-4 wells 2-2.5 m deep along the perimeter of the proposed construction site. If water does not appear at the bottom of the wells within 2-3 days, then it is at a sufficient depth and you can safely design a solid structure. How to distinguish perched water from groundwater?It’s good if you didn’t come across either groundwater or perched water while drilling test wells. In this case, you can safely begin construction. Worse, if the wells are filled with water. But before you decide to build, you need to understand what kind of liquid it is - perched water (i.e. temporary accumulation of water) or groundwater (relatively permanent, occupying a large area, accumulations of water).
It is not easy to do this without seeing a complete picture of the relief. In the hot season, the top water "leaves" and a false impression is created that the soil is dry and with low level moisture. However, after a couple of days with prolonged downpours, water may appear on the site. If this happened to you, you should know that it is perch water on the site, and not groundwater. Also pay attention to the nature of the relief. Plots located in lower slopes(catchment point) or on the slope itself, but having obstacles for water flow in the form of road elements, walls, etc., are the best suited for the formation of perched water. To determine the presence and "pattern" of perched water will help specialists who make measurements several times during the year. High water level - why not build a house?It is quite difficult to influence natural processes, including the presence of groundwater in the area. V different regions adopted their building codes, which regulate the GWL, at which it is possible to start or, on the contrary, to stop the construction of capital structures. For the construction of a foundation of any type, the conditions under which the groundwater level is below the freezing depth of the soil are considered optimal. In this case, the latter should contain a minimum amount of clay and dusty (non-fluffy) particles. The foundation must be laid below the freezing point of the soil.
According to SNiP, there should be at least 0.5 m between the lowest point of the foundation and groundwater. How to understand that groundwater is destroying the foundationThe concrete base "undermines" not so much the liquid as the salts, sulfates and other compounds dissolved in it. They lead to the formation of the so-called "cement bacillus", which dissolves and loosens the concrete. You can understand that concrete is affected by groundwater by the following signs:
If something similar is observed on the foundation or in the basement, we can safely say that the groundwater has interacted with the foundation of the house. We build a house without a basementThe simplest and reliable way getting along with groundwater consists in constructing a building without a basement - for example, a simple wooden house. And if the basement is needed only for storing seamings and harvest, next to the house you can make a storage "under the hill". For heaving soils or soils with a large freezing depth, a columnar or pile foundation is suitable. If a massive building is planned, it is better to build a shallow strip foundation(MZLF), or "floating foundation". In areas with a high level of groundwater, 0.5 m of sand can be poured under the future foundation of the house. What to do with groundwater on the site?
You can "fight" with the level of groundwater. The most popular measures for lowering GWL are: 1. Surface drainage (open way dewatering) - water seeping through the bottom or slopes of the pit enters the ditches-water collectors and is pumped out from there by pumps. The option is not suitable if soil particles are constantly washed out with water, due to which it sags. 2. Pipeless drainage. To organize it, a trench is dug around the perimeter of the site, groundwater actively begins to drain into it, since there is no soil resistance. Water can be pumped out with a pump, for example, into a pond located on the site. To strengthen the walls of the ditch, it can be covered with gravel or crushed stone. 3. Pipe drainage– in addition to the previous method, perforated and corrugated pipes made of synthetic materials, which are laid on the bottom of the ditch and are also covered with bulk materials. Water pipes should ideally be discharged outside the site. 4. Usage wellpoint installations. Such systems bring groundwater to a depth of 4-5 m. The pump pumps out groundwater, and they go through a pipe to a great depth. 5. Ejector Wellpoints. A sophisticated version of the previous system. Water passes through a complex of pipes, pumps and filters and is also discharged to a depth of up to 20 m or to a drain.
Do not try to design and build a drainage system on your own, entrust it to specialists.
Groundwater - dangerous, but frequent a natural phenomenon, from the neighborhood with which not a single owner of the site is insured. Construction in the presence of soil should be carried out with extreme caution and only after a thorough study of the composition of the soil and groundwater. Similar articles
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