Stagnation of water on the land is not just temporary puddles after rain, but a serious threat to the foundation of the house, the root system of plants and the general microclimate. Many property owners face the problem of soil overmoisture, especially if the site is located in a lowland or on clay soils. Properly designed drainage able to remove excess moisture, preserving the integrity of buildings and ensuring a comfortable stay on the territory.
The question of how to properly drain requires an integrated approach and an understanding of hydraulic principles. Errors in the planning phase can result in the system not working properly or requiring costly rework. In this article, we will discuss the main types of drainage, their installation technologies and nuances that must be taken into account to create a durable engineering network.
⚠️ Before starting any excavation work, be sure to check the location of underground utilities (gas, electricity, water supply) to avoid emergencies and fines.
Soil analysis and system type selection
The first step in creating an effective drainage system is a thorough analysis of the soil. It is the physical properties of the soil that dictate the choice of technology. If the water goes away slowly, and after the rain, puddles stand for a long time, most likely, clay or loam predominates on your site. In such cases, surface removal may not be sufficient and deeper retraction may be required. drainage.
There are two main types of systems: surface (storm) and deep drainage. The first is designed to collect water from roofs, paths and platforms. The second is laid below the level of freezing of the soil and serves to lower the level of groundwater. The choice between them often depends on the terrain and the depth of the aquifer.
To accurately determine the type of system required, it is recommended to conduct a simple test: dig a hole about a meter deep and observe it during the day. If the water appears quickly and will hold, then the groundwater level is high, and it is necessary to deep-drainage. If the water is only present after a heavy rainfall, it may be sufficient. storm-water.
- 🌧️ Surface drainage is effective for removing precipitation from hard surfaces.
- 🌊 Deep drainage is necessary for draining clay soils and protecting foundations.
- 🏗️ The combined system provides maximum protection of any type of site.
Design and calculation of slopes
The key factor in the successful operation of any gravity system is the correct slope of the pipes. Water should move by itself, without stagnation, but not too quickly so that solid particles do not settle on the bottom. The optimal slope is in the range of 2 to 5 millimeters per linear meter of the pipe. This value seems insignificant, but its observance is critical.
When designing the track, it is necessary to take into account the terrain of the site. Pipes are laid in the direction of natural water flow - from higher points to lower ones. If the relief is flat, the slope is created artificially due to the depth of the trench.
What to do if the terrain is flat?
If the natural elevation difference is absent or insufficient, it may be necessary to install a drainage well-storage with the subsequent pumping of water. Also sometimes used method of soil filling to create an artificial slope in the right direction, but this is a time-consuming process.
The amount of materials is calculated on the basis of the plan. The diagram shall indicate cornering points, observation wells and water discharge points. Turning the pipe without observation wells is not recommended, since it is in these places that blockages most often occur, and cleaning without access will be impossible.
- 📐 The slope of 2-5 mm per meter is the standard for pipes with a diameter of 110 mm.
- 🔄 Rotating wells are mandatory when changing the direction of the route by more than 15 degrees.
- 📏 The distance between the observation wells in straight areas should not exceed 30-40 meters.
Required materials and tools
The quality of the materials used directly affects the life of the system. The main element is perforated pipes. For deep drainage, corrugated pipes of low-pressure polyethylene are most often used (PAP) or polyvinyl chloride (PVC), wrapped in geotextile. This material prevents the germination of roots and siltation of holes.
Besides the pipes, you'll need rubble. It is best to use granite crushed stone of medium fraction (20-40 mm), as it has high strength and does not follow with time. Limestone is not recommended for use because of its ability to dissolve and cement, which can lead to blockage of the system.
☑️ List of required materials
Also, you can not do without sand to create a cushion and align the bottom of the trench. Tools will be required standard for earthworks: shovels, roulette, pegs and cords for marking. To seal the bottom of the trench and filling, a vibrating plate may be needed, although in small areas you can do with manual tramping.
| Materials | Appointment | Important characteristics |
|---|---|---|
| The corrugated pipe | Water transportation | Ring Stiffness Class SN4 or SN8 |
| geotextile | Filtration | Density 150-200 g/m2, needle-piercing |
| Crushing | Drainage backfill | Granite, 20-40 mm fraction |
| Lookout well | Audit and cleaning | Diameter 315-500 mm, with bottom valve |
Technology of installation of deep drainage
Installation of the deep system begins with the marking of trenches according to the project. The width of the trench should be sufficient to accommodate the pipe, the layer of rubble and ease of operation. The depth depends on the level of groundwater and the depth of freezing, but usually ranges from 0.8 to 1.5 meters.
After excavation of the soil, the bottom of the trench is carefully tamped and filled with a layer of sand 10-15 cm thick. The sand is leveled with compliance with the project slope. Then geotextiles are laid on the sand so that the rubble pillow can be completely wrapped with its edges afterwards. This creates a kind of “candy” or “trough” for the filter.
⚠️ Attention: Geotextile should be stacked with a margin in width so that the edges can be wrapped over the rubble. The cover of the canvases should be at least 15-20 cm.
A stained beam is placed on the floor of the slab, which is covered with a slab. It is important to ensure that the perforation (holes) is directed downwards if a modern filter pipe is used, or evenly distributed. The joints of the pipes are connected by couplings that ensure tightness, but at the same time leave the possibility of water movement.
The pipe is laid on the rubble, then covered with rubble from all sides, after which the geotextile is wrapped, creating a closed filtering loop.
Surface (storm) drainage device
Surface drainage, or stormwater, solves the problem of rapid removal of water from the surface. It can be point and linear. Point drainage is installed under the drain pipes, near the door pits and watering cranes. Linear is a network of channels, closed by grids that collect water from large areas.
Installation of linear drainage requires digging trenches of less depth than for a deep system. The main thing here is to ensure unimpeded flow of water into the main collector or storm sewerage. Channels are installed on a concrete cushion to fix and prevent surfacing when filled with water.
An important element of the system are sand traps. They are installed at the beginning of the system or before entering the main pipe. Inside the sand trap, the flow rate drops and the sand, leaves and debris settle to the bottom without clogging the main pipe. Regular cleaning of sand collectors is the key to the long-term operation of the entire system.
- 💧 Point rain receivers are installed in places of maximum accumulation of water.
- 🛣️ Linear trays are mounted along the paths and access roads.
- 🍂 Sand catchers require cleaning 2-3 times a season to prevent blockages.
Final stage: filling and maintenance
After laying the pipes and checking the slopes, a reverse filling is made. First, the pipe is completely closed with rubble, then the edges of the geotextiles are wrapped. On top of the geotextile pours a layer of sand, which is shed with water for sealing. The upper layer (20-30 cm) is covered with fertile soil if lawn is planned, or left under the powdering of rubble / gravel.
Maintenance of the drainage system does not require complex manipulations, but it should be regular. Once a year, preferably in autumn, it is necessary to open observation wells and check the level of bottom sediments. If the silt layer exceeds 20-30% of the well height, it must be removed by pump or manually.
To extend the life of the system, install a return valve at the exit of the observation well, which will prevent water from entering the reservoir or general sewerage back into the pipes during floods.
If you notice that the water has stopped going or the water in the wells is above normal levels, this is a signal of a blockage. In this case, a special wire rope with a yarsh or washing the system with water under high pressure is used. Timely cleaning will avoid expensive repairs and reworking of trenches.
Frequently Asked Questions (FAQ)
How deep should a drainage trench be digging?
Depth depends on the target. To protect the foundation, the pipe must lie below the sole of the foundation, but above the depth of freezing (usually 0.8–1.2 m). For drainage of the site, the depth can be less, about 0.6-0.8 m, to collect the topwater.
Can asbestos or ceramic pipes be used?
Use of old materials is not recommended. Asbestos is fragile and complex in installation, and ceramics have short segments and many joints where leaks and overgrown roots are possible. Modern polymer pipes are flexible, durable and easier to install.
Do I need to insulate the drainage pipes?
In most cases, deep drainage does not freeze, since the water in it moves or stands at the level of groundwater, which have a plus temperature. However, if the pipe comes to the surface at the dumping site, this area is better to insulate or make a heating cable.
How often should the drainage system be cleaned?
Preventive check is recommended once a year, best in late autumn after leaf fall or early spring. If the system is designed correctly with sand collectors, a major cleaning may be required every 3-5 years.
Where can I dump water from the drainage?
Water can be discharged into storm sewers (if there is a permit), into the nearest body of water, ravine or on the relief outside the site. Discharge of household wastewater into the central sewerage is prohibited without approval, as this creates an overload of treatment facilities.