Site drainage, storm drain
Water nourishes all life on Earth. And if the question of how Life originated still causes fiery debate, then the assertion that
Water + Sun = basis of existence biosystems, accepted unconditionally.
However, everything is good in moderation, and sometimes, excess moisture has a devastating effect on the environment. Taking into account the format of my site, I will take, for example, the land plot on which the house is being built.
Oversaturation of the soil with water can lead to rotting of the root system of plants, slow but sure destruction of the foundation, dampness of the walls, followed by loss of strength (if the waterproofing is outdated).
As a result, the level of air humidity in the area and in the house may exceed the permissible norms and housing will become an incubator for pathogenic bacteria.
And just walking around the site, where, due to prolonged rain, it will squish underfoot for another week, and the earth is a dirty mess, you see, it is extremely unpleasant.
There is no need for drainage (drainage) of the site only on soils with deep groundwater. But even the fact that such a site is located on a hill does not guarantee the absence of flood waters in the spring.
How to determine if your property needs drainage if you have recently acquired it and do not yet have sufficient information.
look around grass cover on the site: if the grass grows in clumps framed by sandy areasand not a solid turf, then it is likely that in the spring groundwater comes to the surface and erodes it.
Dig a hole about 60 cm deep and fill it to the top with water. If the water has not completely gone in two days, then the soil on the site has poor moisture permeability and, at a minimum, a storm drain is needed.
Well, what if the soil is heavy and the level of groundwater reaches a depth of 1.5 m, then deep drainage around the house is also required.
Another important parameter is plot slope. Imagine what will happen to your home and landscape during the spring snowmelt or prolonged rains, when water rushes from above in a continuous stream.
Excess moisture in the area can be formed for two reasons:
- due to precipitation and snowmelt (seasonal)
- due to the high level of groundwater (may be permanent or associated with the spring flood period).
In the first case, surface drainage (drainage) is used, in the second — deep. Both options will be discussed later in the article.
But the most important question is not so much how to divert water from the site, but where to «dump» it.
In many settlements, ditches are being built along the roads. Their direct purpose is to receive storm drains and melt water.
At the same time, you can use the collected water for irrigation, so it makes sense to get storm sewers and collect sediment in the well.
Sediment water that has passed through the drainage system is chemically clean and suitable for technical use.
Two options are possible here: drainage using crushed stone dumping (more on this later) or a watercourse from ready-made systems with water discharge into a ditch or a catchment well.
On long sections of paths, platforms, terraces and flat roofs, linear drainage is used.
DRAINAGE FOR LINEAR DRAINAGE — a gutter with a grate.
It is buried below the paving level.
The water flows through the gutter into the storm sewer.
There are no special requirements for the installation of gutters: docking is carried out with a tongue-and-groove connection.
To prevent the sand from being carried away by the stream into the sewer, a sand trap is mounted in the watercourse — a gutter with a low bottom line, sand from the stream will settle in it.
The drainage channel does not carry a mechanical load.
But the grille performs not only a decorative function — it must be designed for a certain load (for a pedestrian zone or a roadway).
The chute is made from:
- concrete (cheaper, but short-lived),
- fiber-reinforced concrete (reinforced with fiberglass),
- polymer concrete (reliably and for a long time),
- steel (galvanized and stainless steel),
- PVC, HDPE (high-density polyethylene), polypropylene — frost-resistant and impact-resistant materials (made by European manufacturers, they are not inferior in strength to metal).
The width of the drain is chosen based on the estimated volume of the catchment.
The standard for a private yard is a width of 100-130 mm. But in places of more intense accumulation (the lower part of the exit to the garage or exit from the yard), this parameter is increased to 200 mm.
The depth is standard, and for balconies, terraces, flat roofs, where the height of the base is limited, shallow drains are used.
As for the choice of pipes, a material with a diameter of 110 mm is usually used for storm sewers. With a smaller diameter in heavy rainfall, the throughput may decrease.
NUANCE: if the pipe diameter does not match the size of the outlet, use standard adapters.
The basis for the drains is a layer of concrete on a sand and gravel cushion. For concrete (and its derivatives) gutters, a simply compacted cushion is sufficient.
Installation of a linear system begins with a sand trap, which can be located both in the center and at the edge of the drainage line.
Next, the trays are connected in sequential order. Depending on the model and manufacturer, they are fastened together with a tongue-and-groove connection and (or) a sealing compound (specify when purchasing).
Water is drained through plastic pipes, preferably through U-shaped a water seal to prevent unpleasant odors from escaping the storm sewer.
Pipes are laid with a slight slope or in steps to avoid stagnant water.
The end of the pipe is brought out either into the well, or connected to the main pipe, which brings the drain into the ditch. To avoid soil erosion, a divider (grid) is mounted at the outlet of such a pipe.
You can offer several options for plastic pipes:
- smooth — an excellent option for a drain with deep pipes, turns are carried out using elbows, and connections are made through couplings;
- corrugated without perforation — perfectly bend, have a large length, corrugation creates additional stiffeners;
- corrugated with perforation — this pipe option is used for deep drainage, not storm sewers.
Places where pipes are laid to a shallow depth should be protected from mechanical stress.
On the at the outlet of the drainpipe, under the street tap, in the lowland part of the artificial landscape, it is enough to make a point drainage.
In this case, it is possible to quickly “take away” moisture only with the help of pipes.
At the point of collection of water, a storm water inlet is installed on a concrete base. It is wise to purchase a removable filter basket for it, which will trap debris and protect pipes from clogging.
From the storm water inlet, a pipe exit (with a slope) leading to the drainage well.
To prevent an unpleasant odor from returning from the pipe, an air lock is made at the outlet of the storm water inlet: a U-shaped pipe section is inserted.
From above, the container for receiving water is closed with a protective grill.
It can be made of reinforced concrete rings, monolithic (which is very laborious) or plastic.
I will dwell on the latter in more detail.
The basis for the catchment elements of storm sewers is chosen concrete on a sand and gravel cushion. The installation depth corresponds to the height of the plastic container.
From above, the well is covered with a lid: plastic for an impassable zone or metal if it is located on the territory of a pedestrian zone or road.
It is extremely convenient to work with a plastic container, since it can be easily processed with available tools.
For example, in order to connect a pipe to the well, it is enough to drill a hole of the appropriate diameter with a puncher, insert a rubber seal and connect the adapter.
SURFACE DRAINAGE SLOW AREA
If you have Since the site has problems with the removal of melt water and precipitation, then surface drainage is indispensable.
The simplest solution for home on a flat area, the creation of a slight slope (about 2-30) away from the house with a drainage ditch around the perimeter. We are talking about a blind area with a drainage system.
As for the rest of the site, here the issue is resolved in different ways.
On permeable soils, drainage is not necessary — water will easily go into the ground anyway.
In all other cases, it is still advisable to build a drainage in the form of a ditch.
It is difficult to manage with one ditch, because several of them are made and connected into a system.
The width of the ditch should be equal to 30 cm or more, and the depth should not be less than 50 cm.
In order for the drainage structure to be safe and aesthetic, geotextiles are laid at the bottom of the ditch, the cavity is filled with rubble, covered with the free edges of the geo-web overlapping each other and masked with a turf layer (a litter of coarse sand is made under it).
Thus, you will get a drainage layer that does not look different from a lawn.
Excess melt water will accumulate in the crushed stone «pipe», and then gradually be spent back into the ground.
If your house is located on a plot with a slope, then there is a high probability of flooding of its low-lying part and the foundation of the house. In order to avoid such a situation, drainage ditches are dug in the direction perpendicular to the slope, receiving the flow of water and taking it away from the house and the site.
As can be seen in the diagram, if the house is located in the upper part of the slope, then on the side where the soil is higher, they dig a drainage ditch that protects the foundation of the house from flooding.
Please note that the ditch is located perpendicular to the slope line and has access to the main line, where all branches of the drainage system converge.
For a quick outflow of water, the bottom of the auxiliary ditches is made with a slope towards the main branch.
At the bottom of the site, the water should have an outlet into the ditch.
This drainage system can exist in the open.
But if the view of a site pitted with ditches plunges you into despondency, I recommend using the deep drainage option on the site (read on).
When the house is located at the bottom of the land plot, then an approximate diagram of a linear drainage system is shown in the figure on the right.
In areas that need to be drained, an open linear drainage system is too reminiscent of trenches on a battlefield. Therefore, their owners prefer to use a closed drainage system.
The layout of the ditches remains the same:
- for sites with a natural slope, these are branches converging to the main branch, which, in turn, has access to a ditch or a water collector (well);
- for flat areas, the bottom of the drainage ditches should have a slope towards the main branch, and that towards the catchment area.
The ditches are filled according to the following scheme:
- geotextiles are laid on the bottom,
- make crushed stone backfilling of the bottom,
- drainage pipes are laid on top (for the main branch, a larger diameter is chosen), pipes are joined using standard splitters,
- make a full backfill with rubble and lightly tamp,
- the edges of the geotextile are wrapped on crushed stone with an overlap on each other,
- soil is poured on top and tamped down (you should get a small hillock, which will sag over time).
The catchment well is installed in the lowest part of the land allotment.
DRAINAGE AROUND THE HOUSE
The most effective foundation waterproofing is deep drainage along the perimeter of the building. This engineering system is mounted at the construction stage simultaneously with the backfilling of the foundation. Otherwise, the foundation will have to be dug out.
Depending on the intensity of groundwater, the number of catchment wells is selected: they can be installed at each corner of the building, or you can get by with two.
The depth of the pipes is chosen slightly below the level of the base of the foundation.
A drainage pipe is a corrugated plastic sleeve with holes for receiving water, wrapped with geotextile or a bulk winding made of coconut fiber.
The latter option for arranging a drainage system is most preferable, since it eliminates the use of crushed stone backfill (in any case, so the manufacturers say).
Drainage wells are installed in the corners of the house.
You already know how to install a well and connect pipes to it.
What else to read on the site:
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