The dream of a landscaped suburban area may well become a reality. A local area with luxurious lawns, a beautiful garden, a productive vegetable garden, gazebos, patios, alpine slides - all this today can be arranged on soil of any quality and lands of any geodetic complexity, the main thing is to approach the decision correctly and not forget about such a procedure as site drainage.
This system is expensive, so in order not to get into trouble and not pay twice, you should figure out whether the existing landscape needs drainage, and if so, what type.
Why is drainage needed on the site?
What are the functions of drainage? The objectives of the system are as follows:
1. Collection of melt water.
2. Rainfall drainage.
3. Removal of groundwater beyond the boundaries of the territory.
It is not always advisable to comprehensively drain the soil by laying deep and surface drainage at the same time. Deep drainage systems are required only for swampy soil and those lands where the groundwater level is high. Linear drainage will not be superfluous anywhere. Seasonal flooding is typical for any climate zone. In addition, the quality of our soil generally leaves much to be desired. Clay soils have poor permeability, which also provokes the formation of puddles.
Linear drainage to prevent puddles
Flooded areas are death not only for plants, but also for wooden buildings and decorative structures. At best, they will have to be seriously repaired. At worst, demolish and install new ones. Both situations are financially costly, and if you consider that without drainage on the site there is a prospect of carrying out global reconstructions regularly, then it makes sense to think about preventing water stagnation.
Site deep drainage system
When site drainage is required
You will have to organize drainage from the land provided that the dacha area is located on a steep slope. To prevent storm flows from carrying away the fertile part of the soil, it will be necessary to create a surface, but not a point, but a linear drainage system with transversely broken channels capable of intercepting water and redirecting it to the storm sewer.
Drainage of a site on a slope
The reason to start installing drainage on the site with your own hands would be to place it in a lowland. In this case, it is initially a reservoir for collecting water flowing to it. In this option, drainage elements are located along the perimeter of the territory.
Drainage of a site located in a lowland
No less of a scourge are flat areas where water is poorly absorbed by the soil. This is where you need to design an entire system of point or linear drainage systems covering the entire area.
Collecting and standing puddles for a long time will tell you that the area needs to be drained. Inspect the lawn. Assess the condition of the bushes. Check if the soil is rotting. These tips are effective in already inhabited areas. On virgin lands, you will have to focus on what is happening in the area. Have the neighbors prepared a pit for the house and dug holes for the fence supports? Fabulous! Check them out. If there is an accumulation of water inside, try to figure out where it is flowing from. Ask the old-timers about the level of water in the wells over the past few years. If it turns out that groundwater lies less than a meter from the surface, then it is most likely impossible to do without installing drainage on the site.
Point drainage system
Surface drainage
“Drainage can be done with linear or point drainage”
The simplest solution. The surface system collects water from drains and the site. By providing rainfall with free flow paths, it relieves the soil from waterlogging.
Surface drainage ensures the collection of water from the site
To arrange such site drainage with your own hands, you do not need to involve specialists. There will be no large-scale work here. Drainage can be done with linear or point drainage. Point drainages are responsible for local moisture collection. This could be runoff from roofs or water from irrigation taps. To drain large areas, it is correct to lay out a linear drainage system.
Point drainage is responsible for local moisture collection
Surface drainage methods
An open drainage system can consist of either randomly generated grooves or parallel grooves. Each scheme has side inlets that carry water that enters the drainage to the central drain. Which type of surface drainage device is preferred should be chosen based on the type of soil and topographical conclusions.
Open drainage channel
Drainage in a random area
The ditches of such storm drains are adapted to collect water from soil of low permeability, where there are extensive low-lying areas of stagnation, the elimination of which by smoothing the surface is impossible or unprofitable.
By and large, random linear drainage is the prerogative of fields. The ditches scattered across the field are not very large. Most often they are quite small and do not intersect with the main drainage lines.
The purpose of the random grooves is to ensure the outflow of moisture accumulated in low-lying islands. To make random drainage of a site with your own hands, simply dig small grooves with the appropriate slope angle. The soil extracted in this case can be used to fill small lowlands.
Linear drainage will ensure the outflow of accumulated moisture
Field stormwater channels should follow through the main mass of depressions towards the natural slope of the site. This is the only way to ensure complete drainage of the area.
Drainage in a parallel area
It is rational to equip this type of drainage on flat, difficult-to-dry soils with numerous small depression flaws. The parallelism of the grooves does not mean they are equidistant. The walking distance depends on the soil conditions.
Closed drainage
Deep drainage helps reduce groundwater levels
Closed drainage structures are universal. They can drain melt and storm water no less efficiently than surface drainage. Since the system is hidden underground, it does not interfere with landscaping, which makes it quite popular among gardeners.
Vertical drainage
The main elements of this type of drainage system are wells, traditionally installed near the house. The outflow of water accumulated in them occurs using pumps.
Drainage of a site of this type is carried out only according to a professionally drawn up project. Without engineering knowledge and specific skills, it is not worth taking on the installation of drainage on the site with your own hands. Carrying out the work will require the use of specific hydraulic equipment, so leave the solution to this task to those who know exactly how to do it.
Vertical site drainage system
Do-it-yourself site drainage: main nuances
The choice of the type of drainage system is mainly influenced by the cause of flooding of the area. Clay soils, which are characterized by retention of melt and atmospheric water, can be brought into order by arranging surface drainage. Open-type drainage grooves will be quite sufficient to quickly remove excess moisture from the serviced area.
If the cause of basement flooding, erosion of the foundation, and swelling of the soil is groundwater, then the problem will have to be solved with a thorough approach, that is, by deep drainage of the soil. Both options for installing drainage on the site are available as standalone options.
Point drainage
To create a local open drainage network, drawing up a design diagram is not necessary. Its arrangement is logical in the case when flooding of the site occurs only at certain points and only when there is excessive rainfall. Sloping areas are most often susceptible to flooding: the area near the porch, gazebos. Water is guaranteed to accumulate in relief irregularities.
Places for installing point drainage
In the case where the problem area is located near the very boundaries of the land, to ensure drainage, it is rational to complete the drainage on the site with a regular dug trench that extends beyond its boundaries.
In steel cases, having noticed places of stagnation of water, they are equipped with dug-in water intakes or closed tanks. The water collected in them can later be used to water the garden.
Linear drainage
“Ensuring the uninterrupted operation of the surface drainage system occurs by calculating the correct slope of the drainage ditches”
Digging ditches across the entire site or certain corners of it is the best way to drain clay soils. Here it would not hurt to sketch out a rough plan of the future system, on which to mark all the drainage branches and the location of the drainage well to which they are planned to be connected.
Example of a linear drainage plan
Ensuring the uninterrupted operation of the surface drainage system occurs by calculating the correct slope of the drainage ditches. The process of arranging linear drainage systems will be greatly facilitated by the presence of a natural slope at the site. On flat surfaces you will have to create an inclination angle artificially. This condition is mandatory. Ignoring it will cause stagnation of collected water in drainage channels.
For linear drainage on a flat surface, create a slope angle
The quantity of channels to be laid is determined according to the absorbency of the soil. The more clayey it is, the denser the drainage network is branched. The depth of the trenches dug for drainage of the site with your own hands is about half a meter. The width of the groove depends on its distance from the storage tank. The widest will be the main branch of the drainage system, where water flows from all parts of the site.
After the drainage system on the site has been dug, they begin to check the quality of its functioning. To do this, a strong flow of water is launched through the watering hoses through the channels. Correctly supply water from several points at the same time.
The assessment takes place “by eye”. If water flows slowly and accumulates somewhere, you will have to adjust the slope and perhaps even widen the groove.
After making sure that the drainage is ideal, you can start decorating the drainage of the area. The appearance of open ditches is not aesthetically pleasing. When working on a drainage system on a site with your own hands, the easiest way is to decorate it with different fractions of crushed stone. You can put larger elements of stones at the bottom of the grooves and sprinkle small ones on top. If desired, the last layer is made from marble chips.
Decorating linear drainage
If this is not available, replace the material with decorative gravel. What does this mean? Having selected some of the fine gravel, it is painted blue, in different shades. By pouring it into the channels of linear drainage systems, you will get the illusion of running water. For a complete association with streams, plant the banks of the ditches with flowering plants. This way you will get not just a functional drainage system, but also a luxurious design element.
Channels dug along the perimeter of the site are often covered with a decorative lattice.
Decorative grating for drainage channel
Filling surface drainage with gravel is not only a matter of aesthetics. In fact, this is also an opportunity to strengthen the walls of the ditches, preventing them from collapsing, and also protect the bottom from washing out. Therefore, by using gravel backfill, you will extend the operational life of your drainage system.
Service Features
When caring for surface drainage, special attention is paid to the cleanliness of the outlet channels. Even small growths on the walls and bottom can cause a decrease in operating efficiency. Drains are inspected after every rainfall. All obstacles that appear in the way of the drain must be removed.
The drainage system needs regular cleaning
The second point will be to control the slope angle of the linear drainage elements. When smoothing it, you will have to adjust the bottom of the channel by digging or adding.
Point drainage is cleaned manually.
Do-it-yourself deep drainage of the site
If the problem of swamping is not in super clayey soil, but in nearby groundwater, then you will have to worry about developing a closed drainage system. Types of work are arranged in the following order:
1. Understand the depth of laying drainage pipes on the site. This indicator is affected by the density of the earth. The higher its numbers, the less deep the drainage. Let's look at an example. Drainage pipes are immersed in sandy soil by at least a meter; for loams this parameter is already 80 cm. In clay soils, pipes are placed no deeper than 75 cm. Why can't drains be installed higher? In addition to soil density, there is another indicator. We are talking about the depth of its freezing. The drains you lay should lie below this mark, then the pipes will not be deformed.
An example of a deep drainage device
2. Select the type of pipes. If surface drainage can be installed without any specific conductors, then for deep drainage of the area, drains will have to be purchased. What does the modern assortment offer? The drainage elements of the system are manufactured:
– made of plastic;
– ceramics;
– asbestos.
Ceramic pipes are quite expensive for installing drainage on a site, but they will last for centuries. There are estates where the closed drainage area made of ceramics has been functioning for 150 years. Asbestos-cement products, although durable, are practically not used today due to their environmental unsafety.
Inexpensive and practical perforated plastic is at the peak of popularity. As a component of deep drainage of the site, pipes from it will need additional protection from clogging with small soil particles. If this is not taken care of initially, then after a very short time the drains will become clogged and will stop letting water through.
Perforated plastic pipes for drainage
It is good to use geotextiles to insulate the drainage pipes of the site. It is only possible to avoid wrapping drains with filter material in clay soil. Here it will be enough to lay the pipe on a twenty-centimeter layer of gravel. This option will not work in loams. The pipes will have to be wrapped in geotextile fabric. The worst thing will happen to owners of sandy plots. Here, the components included in the deep drainage system of the site will have to not only be wrapped in geotextiles, but also covered on all sides with a thick layer of gravel.
Arrangement of drainage using geotextiles
If you have a goal - to make high-quality drainage of the site with your own hands and have certain skills to implement it, focus on drainage systems made of stone or brick. Their creation is more complex and costs a lot, but the operating efficiency is simply excellent.
3. Prepare a place for water intakes. Before digging, you need to decide where the drains will carry the collected water. The pipe can simply be taken out of the area and the water can be allowed to drain into a ditch dug there, or a drainage well can be built for this purpose, similar to point drainage systems. The second option is more practical. In a dry year, water from it can save the crop, and it is rarely possible to remove drainage from the site.
Water intake device
4. Excavation work begins. Digging ditches when installing drainage on the site is inclined towards the well. Each subsequent meter of the ditch deepens by 7 cm. The slope angle is controlled by a level. It is optimal to arrange system drains in a herringbone pattern. In this case, all branches of the linear drainage system will depart from one central pipe having a larger diameter.
The article is devoted to the issues of organizing drainage in a suburban area. We suggest understanding the types of drainage and the criteria for choosing a particular system. Let's look at the nuances of drainage design and talk about their main elements. We did not ignore the installation technique and the features of caring for the drainage system.
Purpose and operating principle of drainage
The volume of private construction is growing from year to year. For a number of reasons, future homeowners do not always have the opportunity to choose a plot that is ideal in hydrogeological terms, and in some regions almost all soils consist of “unfavorable” clay and loams - an example is the Moscow region. There is never just one problem; in addition to “ground” issues and high groundwater, weather troubles are added: heavy snow and its sudden spring melting, heavy autumn rains. Note that the water balance of a site can be disrupted by our own hands - during large-scale construction. This is a high-rise redevelopment of the site; storm drainage from a large roof area; waterproof yard coverings; swimming pools and ponds; artificial hills and alpine slides; massive fences on high and deep foundations that stop the water.
So, the problem of “excess water”: the soil becomes waterlogged - as a result, we have poor health of many plants, winter freezing of water and heaving of the soil with various kinds of deformations of blind areas, paths and shallow foundations, the formation of ice dams, flooding of basements, destruction of the foundation of the main building, the appearance of mold and fungus indoors, the expansion of mosquitoes and frogs. The most important thing is that you should not count on the short-term nature of some negative factors; such difficulties are systematic and tend to worsen over time.
The only way out in this situation is to make drainage for the site. Drainage is the hydraulic engineering construction of a system of artificial soil paths for draining sedimentary, groundwater and deep water outside the site. The idea is that a network of surface (ditches) or deep (underground perforated pipes) channels located at an angle is installed across the site. Water seeps into them through holes or joints and flows by gravity into a nearby reservoir or ditch (open drain) connected to a ravine, or a pit filled with rubble, where it is gradually absorbed into the ground. If direct drainage is not possible (great depth of drainage pipes, neighboring buildings, low location of the site...), then the moisture is collected in a drainage settling well, from which it is pumped out.
Storm sewers are usually not connected to the drainage system; rainwater is carried in separate lines with an identical slope parallel to the main drainage. This is not an axiom; with proper calculation, the intake of roof water by drainage is quite possible.
It must be said that drainage of the site does not exclude, but only complements the protection of buildings. Waterproofing and proper ventilation of foundations are necessary in any case, and in difficult hydrological conditions, the construction of foundation drainage is recommended. We will talk about protecting buildings in the next article.
Types of drainage
Before you begin drainage work, you will have to wisely choose the type of drainage system that is most suitable for your area.
Superficial, open drainage
The main competitor of deep pipe drainage. This system is suitable for soils that are slowly permeable, including clay and loam soils. Conventionally (!) a simple and inexpensive method of drainage, which consists in constructing a network of ditches of various widths (40-50 cm), depths (50-70 cm) and section shapes (V-shaped or trapezoidal bevel of the walls 25-35 degrees). The system usually consists of a central drain (this is the “exit channel”), side ditches and field ditches. These channels have a tree-like arrangement - preferably at right angles to each other, “from branches to trunk”. Accordingly, the central drain is larger and deeper than the side drains, and the side drain is larger than the field drain. Channels of 30-40 cm can be filled with filter material (crushed stone, broken brick, river pebbles). To collect sand and debris, special collection containers are installed at the bottom of ditches. From above, surface drains can be covered with gratings and masked with turf.
By type of placement, ditches can be parallel (chosen when the site has numerous stagnant zones) and random (if there are local but large low spots on the site). Protecting large areas of a site is called linear drainage. As an option, point drains are used for local water removal, for example, to drain a roof storm gutter from the outlet pipe.
The most justified use of surface drainage will be in areas with a large natural slope, when it is acceptable for the water to be removed within one to two days. The obvious disadvantages of this drainage method include the somewhat unpresentable appearance of the system of open ditches, serious design limitations, the need to carry out a fairly serious amount of excavation work, the need for proper placement of a large amount of raised earth (it is filled with critical low spots, laid in shafts in places designed for drainage ). Mandatory excavation works, in fact, make such drainage relatively inexpensive - hydrological surveys and topographic surveys should be carried out, the area should be carefully leveled in order to avoid reverse slopes, vegetation should be removed and controlled, and the surface should be repeatedly smoothed with a leveling plow.
Caring for surface drainage causes some difficulties. After heavy rainfall, silt build-up and other blockages may form in the system and must be monitored and removed immediately. Serious problems are caused by the overgrowing of ditches with vegetation; some species must be removed from the site altogether, for example, willow, poplar, cattail. Drains filled with filter elements are eventually covered with washed-off soil and last for about 4-8 years, then they require major repairs. Periodically, operational restoration of slopes is required (leveling and smoothing again).
Vertical drainage
This method of getting rid of flooding is rarely used. It consists of placing special prefabricated wells, wells and settling tanks at certain points on the site, usually in critical areas, mines, problem basements or near buildings. As these containers are filled, water is automatically pumped out by drainage pumps with float switches. Such a system is used when there is no required slope on the site for open drainage, and linear deep drainage through pipes is difficult due to the lack of accessible water discharge points. Such drainage, in fact, is the simplest in terms of construction and labor costs, however, for correct functioning it must be carefully designed, which is very difficult to do. A variant of vertical drainage can be considered a radial system, when prefabricated shaft wells are supplemented with wells and underground channels. Radiation drainage is rarely used in private suburban construction due to its high cost.
Deep, closed drainage
This is the leader among all types of drainage in terms of functionality and is most often used. This system is suitable for any areas with excess humidity or high groundwater levels, including those where it is not possible to build a surface drainage (no slope, dense buildings, extensive landscaping, path system, complex multi-species landscaping...). Closed drainage is durable (service life is more than 50 years) and most efficient, it is easy to care for, it allows you to solve many complex issues of landscaping and engineering problems. In clay and loamy areas, drainage pipes are laid even in the absence of obvious problems, so to speak, for prevention.
Deep drainage is of the horizontal linear type, but its point use is also possible. The main element of this drainage system are drains in the form of ceramic, asbestos-cement or polymer perforated pipes with a diameter of at least 110 mm, mounted horizontally with a slope (about 1 centimeter per meter), usually towards the natural flow of water on the site or into storage wells. The drains are usually located in a “herringbone” pattern at a depth of about one meter; they lie in the thickness of the sand-crushed stone cushion. Inspection wells are installed at pipe turns and branches. If the territory is vast and the total drainage length exceeds 300 linear meters, then a central drainage drain with a larger cross-section is used; for an area of up to 20 acres, pipes of the same size are used. Next we will take a closer look at this system as the most promising.
Other types of drainage
If there are strong inflows of water into the territory from the outside, then an interception system is built; in this case, drains are usually located along the perimeter of the site.
Accompanying drainage is used to protect extended structures, tunnels, ditches for various purposes, and all kinds of communication highways located in the ground. These drains are located along the protected area. Near buildings, so-called wall drainage is used.
To localize the “spot”, a ring system was invented, which creates a closed funnel to be processed.
Separately, it is worth noting the mole drainage, which is intended for preliminary drainage of the area. In this case, special cavities are constructed for gravitational localization of excess water.
In particularly difficult situations, or with high requirements, the problem of swamping is solved by reservoir drainage, when deep inclined layers of crushed stone and sand are installed under the entire problem area.
Depending on the specific conditions, several types of drainage can be combined.
Features of drainage design
It is advisable to carry out work on the arrangement of drainage after the completion of capital construction and the completion of large-scale work on the site, so as not to damage the drainage elements. But it is better to design the system together with the development of all other drawings.
To correctly design drainage, you will need a lot of information:
- A topographical survey is almost mandatory. An exception may be cases when the area is completely flat, but one way or another it is necessary to determine the general slope, the relationship of the drained area to the surrounding area (lowland/highland), drainage routes and places of water discharge.
- You should prepare in advance a detailed plan of the site, which indicates the catchment area, engineering specifics and mutual connection of buildings and other structures (fences, pools, basements, ponds, alpine slides, points of storm roof drains...). Particular attention is paid to underground communications.
- As a separate item, a drawing of paths, paved areas, and fences such as curbs is drawn up.
- In some situations, geological and hydrological surveys can be very useful, which will shed light on the nature of the soil, water regime and balance. Most loamy areas have similar conditions and do not need such careful exploration.
What should we get from developers as a result? First of all, we need to have a technical and, it would be nice, economic justification for this or that type of drainage. Next are the drawings. They usually indicate a water drainage plan, zonal breakdown, tied drain lines, and location points for inspection and collection wells. In difficult conditions and highly developed systems, images of vertical sections and a drainage diagram of structures will be required. A table of slopes and depths is created separately or on working drawings. At the same stage, a specification of all system elements is created (type of drains, profile and cross-section) and the required building materials are calculated based on quantity.
Organizations involved in the installation and development of drainage systems, as a rule, use the “Guide to the design of drainage of buildings and structures.” It was developed in 2000 at JSC Mossproekt. The second is “Technical recommendations for the design, installation and operation of drainages made of polyethylene pipes with a filter shell” (Laboratory of underground structures of the State Unitary Enterprise “Research Institute Mosstroy”, 2005).
It is difficult to overestimate the importance of comprehensive professional design, since errors in arranging drainage can even worsen the situation. That is why, if you have the desire and ability to construct drainage on your own, then it is better to turn to specialists for the project, especially since it is often possible to design the system even remotely (if you provide the developers with the necessary data). The average price for designing site drainage has formed on the market - it is about 15 thousand rubles with an on-site visit, 10 thousand without visiting the site (if the customer can provide the necessary information). The asking price will be about 20-25 thousand if the plot is large and the project includes the development of foundation drainage and a stormwater system.
Materials for closed drainage
The main element of deep drainage is a pipe. If previously drains were made of ceramics, clay, concrete, asbestos cement, metal, wood, stone, now they have been replaced by polymer pipes made of HDPE (low-density polyethylene) or polypropylene with a diameter of 50-650 mm. Their advantages are undeniable:
- Service life more than 50 years.
- High corrosion resistance.
- They do not accumulate deposits and are easy to wash.
- They have low hydraulic resistance.
- They have high ring strength and low weight.
- They have flexibility.
- Easy to install.
- They have perforation and a textile filter.
In average private construction, corrugated drains with an internal diameter of 110 mm and a length of up to 50 meters are usually used. Some manufacturers supply pipes not in coils, but in sections of 6/12 meters.
They can be produced either with or without perforation (for point outlets). To collect sedimentary water (overflow), polyethylene pipes with perforation only in the upper sector can be used - drainage and throughput pipes. The holes are located in the depressions between the waves, which prevents their contamination; the size of the slot perforation is about 1.5 mm.
To isolate from clogging with small particles, filters made of geotextile or coconut fiber are used. For small diameters, the pipe is wrapped on a machine; if the drain is larger than 250 mm in cross-section, then the filter is usually applied manually. On soils containing crushed stone particles, a filter winding is not needed; for sandy loamy, clayey soils, a filter is required.
A plastic drain can have one or two walls and special stiffening ribs. Single-wall pipes are suitable for most areas up to 2 meters deep. Double-walled drains with stiffening ribs are used if it is necessary to go deeper, there are special loads (road, building, high-traffic area...), a very high level of groundwater, which can freeze and create strong soil movements.
Wells are also made of corrugated polyethylene. They differ in shaft diameter and height. The following may be special: diameter, number and location of connections. The exact height of the well is obtained by trimming the shaft. The drain is connected through couplings, or the pipe enters the well directly - into the holes.
An important element of deep drainage is the filter. For these purposes, geotextiles are most often used, which are made from polymers by knitting, woven and non-woven methods. Thanks to its special structure, as well as needle-punched holes, it is not subject to silting, but filters water perfectly. In addition, this material performs a separating and protective function, it does not age, withstands the effects of aggressive chemicals, is not torn by root growth, is not eaten by rodents, and is not a habitat for mold and fungi. Often, the geotextile layer is part of drainage gratings and membranes - a synthetic roll material with surface protrusions, which is produced by extrusion. A natural analogue of geotextiles is coconut fabric, which is not much inferior to other building materials in terms of functionality and durability.
Special drainage pumps are used to pump water collected in tanks. They are not designed to raise the water column to great heights, but have good performance. They are divided into units for clean water - centrifugal ones, which cope with particles of no more than 5 mm in size and the amount of mechanical impurities no more than 5%. Dirty water pumps have a slightly different impeller, so they are capable of removing particles up to 20 mm in diameter, and the maximum impurity can reach 10% of the volume. For the most difficult tasks, there are powerful pumps with metal casings, where the maximum can reach 35 mm and 25%, respectively. The drainage units are cooled with water, so they are submersible. A clear advantage is the lower intake, which ensures complete pumping of liquid. Switching on/off is carried out automatically - by a float.
Some features of the drainage device
Installation of the system begins with excavation work. The first step is to dig trenches 20 centimeters deeper than the designed drain horizon - this distance will be needed to construct a cushion. The width is the same: from the pipe to the walls of the trench we leave 20 cm. The approximate depth is from 50 cm to 3.5 meters. It is usually recommended to lay a channel below the freezing depth - on average it is about 120 cm (to drain water from the roots of trees, they go deeper by 1.5 meters or more). The distance between drains is usually from 5 to 10 meters, selected depending on many conditions. The bottom of the trench should be arranged with a designed slope towards the collection collector; there should be no sharp stones or construction debris on it. Get ready, there will be a lot of excess soil, it is better to immediately sort it into two sides - separately the top and separately the bottom layer (make the backfill more fertile - take out the rest, or plan it).
To improve filtration and separate the backfill layers from the soil, the trench is lined with rolled geotextiles.
A sand cushion is backfilled - this is a layer of about 5 cm. Next, a layer of crushed stone is laid - approximately 15-20 centimeters (fraction 8-32 mm). It is leveled along a given slope and compacted moderately. The slope must be at least 3 degrees, in practice it turns out to be from 0.5 to 10 mm per meter of running pipe.
The next step is to lower the pipes into the trench and secure them to prefabricated collectors and wells, connecting the sections to each other. For connection, fittings, couplings, or high-temperature welding are used.
Now pipes and wells are covered with a 20-centimeter layer of crushed stone and 5-10 centimeters of sand. Carefully fill the space on the sides of the drain.
Cover the top fill with geotextile.
We backfill the soil and lay turf.
For possible preventive maintenance, an inspection well is installed at every second (many experts recommend every) sharp turn of the drain. It is also recommended to use it every 50 meters on straight sections of drainage.
In the place where the collector enters the collection well or reservoir, a check valve is installed, which will prevent the flow of water towards the site if, for some reason, the normal level suddenly rises.
Caring for the drainage system
The system should be periodically inspected through control wells, especially after heavy rainfalls and during periods of active snow melting. Particular attention is paid here to the presence of contaminants and a decrease in the speed of water flow, an increase in the level in wells. If deviations from the norm are detected, it is necessary to clean the drainage.
The system is cleaned with water under pressure. The hose is put on the pump socket, the drains are inserted inside, and pushed down the slope. The procedure is repeated from different wells. Even if no problems are found, it is recommended to carry out preventive cleaning of pipes and wells with a jet of water every couple of years. Inspection wells must be tightly closed with lids during the entire period of operation.
If the drainage of the site is well designed and correctly assembled, and the materials are selected correctly, then caring for it will not cause much trouble, the system will serve both you and your children without any problems.
Turishchev Anton, rmnt.ru
A drainage system in a private courtyard will avoid many problems with both buildings and the quality of the soil for the beds. Its design is the right decision of the owner in any case. But, the relevance of such a system is especially acute if the house has recessed parts. In such a situation, installing drainage around the house is an effective tool for protecting against flooding, which is caused by large amounts of precipitation and rising groundwater levels.
Important! According to SNiP 2.06.14-85, SNiP II-52-74, it is mandatory to install a drainage system near buildings with a significant depression, in areas with clay soil, in areas with high occurrence of groundwater aquifers, in areas located at the bottom of the slope.
Please note that the above standards are relevant for both industrial facilities and residential buildings.
What the market offers: types of drainage
Initially, please note that the drainage system is arranged according to certain rules and technologies. Depending on the tasks assigned to it, drainage can be:
- wall (vertical);
- ring (trench).
Option No. 1 Open drainage: description of the device
To drain the area, a custom ditch can be used, dug according to a certain algorithm. In principle, everything is more than simple: a drainage ditch up to half a meter wide and 0.7 meters deep is dug along the perimeter of the site. From it, water is discharged into the waste basin. Such an object can be common to several nearby households.
Important! The drainage ditch should have a slope of 30 degrees in relation to the collection point for diverted wastewater. Therefore, even at the stage of digging a ditch, a slope of 2 cm must be made for each linear meter for clay soil, and 3 cm for sandy soil.
We would like to note right away that such indicators must be met both for open drainage and for a closed system, which will be discussed further.
Option No. 2 Closed drainage: two technologies
- Closed drainage around a private house involves not only digging a ditch, but also installing a pipeline through which unnecessary moisture enters drainage wells. From an economic point of view, it is most profitable to construct such a pipeline system from PVC pipes. The most popular diameters: 63 mm, 110 mm. Moreover, it is important that the inner surface of the pipes is smooth and the outer surface is corrugated. The drainage pipeline also has holes along its entire length to protect it from soil and sand particles; it is covered in coconut fabric or geotextile material.
- A closed system for draining the area can be implemented in another way. It is very similar to the pipeline solution, but instead of laying pipes, a special water drainage channel is formed. A trench dug at a slope is half filled with coarse stone material - broken bricks, gravel, crushed stone. The second layer is the same materials, but of a finer fraction; soil is already poured on top. This technology has one serious drawback - siltation. Experts recommend eliminating it by laying an additional filter layer from the same geotextile or tecton.
Important! If closed drainage is arranged correctly, then the groundwater level does not rise above the point that is calculated in advance. At the same time, soil fertility increases.
Option No. 3 Vertical drainage
Wall drainage, as you might guess from the name, is designed to protect buildings from moisture. There is virtually no alternative to it in low-lying areas, since only such a system will once and for all eliminate questions regarding flooding of the basement floor during rainstorms or spring melting of snow.
The vertical drainage device looks like this in stages:
- A pit is dug around the perimeter of the building, the bottom of which is covered with a sand cushion. The depth of drainage around the house is determined by the height of the foundation, but in any case the recess will be 30 centimeters below the base of the structure.
- Using a laser level, measures are taken to eliminate existing differences in height and a slope is formed directed towards the drainage collector.
- The ditch is covered with geotextiles.
- The slope is checked.
- A layer of well-washed gravel is poured, making sure that the fraction is larger than the holes in the pipe. Otherwise, a problem such as blockages is guaranteed.
- Recesses are formed for laying the drainage pipeline.
- Pipe installation is in progress.
- At each turn, a vertical pipe is mounted, protected from above by a lid. In this way, channels are provided through which the wall drainage system is periodically maintained, which makes it possible to operate it effectively for many years.
- The fully installed system will be carefully checked again to ensure the correct slope.
- The drainage pipeline is wrapped with geotextile, very tightly and secured using a thin nylon cord.
- A layer of gravel 20 cm thick is poured on top.
- Another layer of geotextile is laid.
- Next comes a layer of river sand and soil.
We would like to emphasize that if the location of the site is characterized by complex hydrogeological conditions, then the optimal combination will be: vertical drainage + linear. This point is very important to take into account when deciding how to make drainage around the house yourself.
Important! Clause 5.23 of SNiP 2.06.14-85 reflects the standards for linear and trenchless drainage. According to them, preference is given to any system based on economic feasibility. If the choice fell on an open system, the depth of the ditch should be at least 4 meters. In addition, it is necessary to focus on the depth of soil freezing in a particular area.
Prefabricated drainage well
The place where drainage water is discharged can be not only a collection pool, but also a well. It can be quickly built from reinforced concrete rings, although, as an option, the walls are made of solid castings. This will require a reinforcing mesh and a cement-based mortar. In the place where pipes coming from different directions intersect, soil is selected, walls are formed, and a drainage cushion is placed at the bottom. Before you start backfilling, you need to carry out thermal insulation measures - foam plastic with a thickness of 25 cm is used.
Local drainage device
It happens that a nuisance in the form of constantly collecting water occurs only in a certain place on the site. Modern construction technologies in this regard offer a way to solve the problem, such as local drainage. It is not difficult to build an object of this type:
- A closed container or a special water intake is buried in the ground. In any case, the possibility of using accumulated water for economic purposes must be provided.
- If water stagnates on the border of the local area, then it is simply diverted to the street through a drainage ditch. In this case, installation of a water intake is not required.
You can't build without a project
So, we hope you have become familiar with the upcoming scope of work, and along the way, have figured out which of the described systems is suitable in your particular case. However, there is no point in cutting from the shoulder and first you need to develop a project for the future system. Do not ignore this stage, even if there is a need to set up a small local facility.
Important! Clause 5.20 of SNiP 2.06.14-85 states that when designing drainage, priority should be given to gravity systems. Drainage with forced pumping requires convincing justification.
The drainage project consists of:
- Schematic images of sections of the system laying - sketches.
- The calculation part indicating croquet numbers regarding the slope, dimensions of ditches, pipe sections, distances of the relative positions of the structural parts of the system.
- Indications of standard sizes of drains, wells, connecting units, etc.
It is impossible to competently draw up a project without possessing the following data:
- Average precipitation for the year.
- Features of the local landscape.
- Soil composition.
- Indicator of groundwater level.
- How close is the nearest body of water?
What materials can be used?
We decided to highlight this issue for consideration separately, since it is of most concern to non-professional craftsmen who have decided to independently install drainage around the house.
The modern market is ready to satisfy consumers with any wallet. So, the drainage pipeline can be made up of pipes:
- polyvinyl chloride;
- reinforced concrete;
- ceramic;
- concrete.
Also, pipe filters made of porous concrete or polymer concrete can be used as consumables.
In conclusion: about preparing the foundation for drainage installation
Before proceeding with the installation of wall drainage, it is necessary to prepare the foundation in a certain way. To do this, you will need bitumen-kerosene mastic - applied to the foundation from the outside. While this coating is still wet, we fix a special reinforcing mesh (possibly plaster and paint mesh) - cell size 2 x 2 mm. After the mastic hardens, after about 24 hours, the working surface is once again coated with a bituminous composition.
Groundwater can be very dangerous for the foundation and the house as a whole. Excessively moistened soil can significantly lose its bearing capacity, and subsidence soils even “sink” due to water under its own weight. To combat groundwater, drainage is installed.
Purpose and type of drainage for the foundation
To protect the foundation from water, it must be drained through a pipe system from the area near the foundation. Drained water is divided into three main types: rain, melt and groundwater. The drainage system can drain any of them, often two or three types (depending on ground conditions).
To drain rain and melt (including ground water), drainage for the foundation is shallow, that is, at those elevations where these waters need to be intercepted. Groundwater usually occurs at greater depths. If they also need to be drained, combined systems are arranged, consisting of horizontal surface drainage connected through inspection wells to the buried part of the drainage.
Diagram of a forced drainage device. Surface drainage can be connected to the system.
In relation to private construction, to protect foundations from water, there are two main types of drainage - horizontal and vertical. The first of them is often called gravity, the second – forced. As you might guess, the first of them removes water from the foundations independently, the second - with the help of one or more pumps.
Vertical drainage is rarely used in private construction on a permanent basis; it is usually used for construction dewatering in order to remove water from a foundation pit or trenches for foundation construction. Such drainage is necessary when the required foundation depth is located below the groundwater level.
Horizontal foundation drainage has become more widespread as a means of preventing watering of the load-bearing soil layer during seasonal flood waters or rainstorms. I also use it to drain rain and melt water from the roof of the house and the adjacent area.
Additionally, subtypes of drainage systems can be distinguished: surface (drained water moves along open trenches), deep (using pipes buried in the ground).
Horizontal drainage
Horizontal foundation drainage is a system of drainage pipes laid with a slight slope (almost horizontally). The drained water enters the pipes through holes in the latter, and flows away from the foundation by gravity.
To avoid clogging of the holes in the pipes, they are sprinkled with fine crushed stone and wrapped in geotextiles. This allows you to filter out small particles that can clog pipe perforations.
Discharge of storm water from the roof into a drain. The system eliminates the formation of “standing” puddles near the house.
To monitor the performance of the system, inspection wells are installed. Through them, if necessary, you can clean the system with a special steel cable.
Vertical drainage
The main difference between vertical foundation drainage and horizontal drainage is the upward movement of water vertically. Of course, this is impossible without pumps. Vertical drainage is forced, not gravity. It is usually used for construction or emergency dewatering. This type of drainage is rarely used in private construction, except during the construction period.
Unloading area
None of the drainage types can operate in isolated mode. The drained water must be discharged somewhere. The drainage system for the foundation is just a “transport” that moves water along the desired path.
The discharge zone can be an existing storm drain, a self-draining septic tank of sufficient capacity, an existing reservoir, free soil with a high filtration coefficient (for example, sand), etc.
Scheme of discharge of drained water into the storm sewer system. 1,2 – drainage pipes with a filter frame, 3 – inspection wells, 4 – free-flow (gravity) collector, 5 – pumping station in a collector well, 6 – pressure collector.
A “septic tank” for receiving drained water is equipped using special drainage modules.
Such modules form an underground receiver of sufficiently large volume, capable of receiving storm drains. After rain, over time, the water “disappears” on its own. Such modules can only be placed in soils with sufficient filtering capacity, at a sufficient distance from buildings and under conditions of low groundwater levels.
In what cases is drainage necessary?
The most vulnerable type of foundation from the point of view of the need for drainage protection is shallow foundations, for example, an insulated Swedish slab. High groundwater can “wash away” the soil under the slab and cause deformation of the building.
If foundations with a sufficient depth are used, elements such as blind areas, porches, garden paths, etc. are vulnerable to the overflow. In these cases, drainage located under an insulated blind area is preferable.
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The insidiousness of high water is that it usually occurs during the period of snow melting, when there are still frosts at night. The frozen soil creates an aquifer that seals the drainage system. To avoid this, for such foundations, drainage pipes are laid in a warm zone, where freezing is excluded during slight frost.
Drainage for the foundation is also necessary on flooded construction sites, where, in accordance with the geotechnical survey report, seasonal fluctuations in the groundwater level are observed with an amplitude that causes water saturation of the soil layer at the level of the base of the foundation. In such cases, a problem often arises in the design of the discharge zone of the drainage system.
Another case where it is necessary to protect the foundation with drainage systems is the location of the building on a slope. During heavy rainfall or intense snow melting, water flowing at high speed along the slope can cause a lot of trouble. Under these conditions, in addition to surface drainage around the building, it is advisable to install a drainage ditch along the upper perimeter of the site.
Drainage is an engineering system designed to protect the building and the surrounding area from rain and groundwater. The service life of the house, other buildings on the site, road surfaces, and whether melt and storm water will accumulate on the site depends on how efficiently the system works (deep, surface, vertical drainage).
Today, the following types of drainage are distinguished:
- horizontal,
- vertical,
- combined.
Horizontal drainage systems most in demand in suburban areas. In such systems, as a rule, water removal occurs by gravity. A simple option for this design would be to use ditches filled with drainage material. A more complex option is deep drainage using pipes in combination with drainage and filter materials.
Vertical drainage- is a complex of structures whose main task is to lower groundwater. This type of drainage system includes drainage wells equipped with hydromechanical equipment (for example, pumps) and a ground complex (water supply network, automation equipment, instrumentation, etc.). The vertical system is used for draining soils with high filtration rates, if there are well-filtering strata at the base of low-permeability soils.
Vertical drainage should be guided by the hydrogeological conditions of the site and the requirements regarding the regulation of water regime. This will avoid damage to the foundation, basements, and walls of the building.
Application area:
- suburban construction,
- construction of dams,
- construction of infrastructure (roads, railway lines, etc.).
Vertical drainage system known as wall drainage, in most cases, it is a wall panel through which water flows into a special pipe wrapped in filter material. The main task of this drainage system is to protect walls and other structures from the hydrostatic action of water. This can be achieved by constructing a cavity between the wall and the soil.
How does vertical drainage work?
Vertical drainage system devices include water-absorbing and water-reducing wells, through filters used for draining special underground structures and mining deposits.
Filter part vertical drainage system should be located in the aquifer of the soil. Water is removed using special pumping stations, switching systems, power supply, etc. Such an engineering structure is highly efficient, but is quite complex, therefore it is most often used in the construction of infrastructure facilities, dams, and in the construction of elite country mansions.
Filter wells or well system are usually located at the lowest point of the site. This makes it possible to most effectively lower the groundwater level.
Vertical drainage is incredibly durable and reliable. Compared to waterproofing, it works more effectively. However, to achieve maximum effect, experts recommend using this drainage system in combination with waterproofing. This is especially true for foundation drainage, retaining walls, and basements.
Using horizontal and vertical drainage in combination (combined system), you can not only monitor the groundwater level, but also collect moisture from the surface of the site.