What is site drainage?

Drainage on a property is a system of engineering structures designed to remove excess moisture from the soil. The primary purpose of drainage is to protect the property, house, garden, buildings, and utilities from overwatering, flooding, foundation damage, mold, and mildew.

Drainage is especially important for areas with clay soils, where water accumulates after rain or snowmelt and drains slowly or does not drain at all.

Why is drainage necessary?

Here are the main reasons why installing drainage is not a whim, but a necessity:

• Protection of the foundation of the house and buildings. Over-watered soil can damage foundations, especially due to frost heaving. This leads to cracks, subsidence, and collapse.
• Prevention of flooding and stagnant puddles. Drainage carries away excess water from heavy rains and spring floods, eliminating puddles, mud, and dampness.
• Preservation of the garden, lawn, and bedsExcess moisture is detrimental to plants, tree roots, shrubs, and fruit trees. Constant moisture promotes rot and mold and mildew growth.
• Extending the lifespan of paths, surfaces, and blind areasWater washes away paths, concrete and wooden surfaces, reducing their strength.

Types of drainage and their features

1. Surface drainage

It is an open system of ditches, gutters and storm drains that collects rainfall from the ground surface and directs it into collectors or beyond the site boundaries and drains the water.

Typically installed around the perimeter of buildings, along paths and areas, and in areas where water actively accumulates.

Examples of surface drainage elements:

• storm drains;
• linear trays;
• gratings;
• drainage ditches.

2. Deep (closed) drainage

This is a more complex system, in which perforated drainage pipes wrapped in geotextile and filled with crushed stone are laid in the ground. Moisture enters through the holes in the pipes, from where it is drained into drainage wells, reservoirs, or storm drains.

Deep drainage is needed if:

• the site is located in a lowland;
• there is a high groundwater level nearby;
• the house has a basement and a cellar;
• the soil on the site is clayey or does not absorb water well.

How drainage works – the operating principle

The drainage scheme as a whole looks like this:

• water is collected (through funnels, trays or perforated pipes);
• is diverted along a slope to the discharge point (collector, inspection well, drainage pit);
• If necessary, a pump is connected if the drain cannot flow away by gravity (to prevent stagnation of water).

How to choose drainage for your site?

The choice of drainage for a summer cottage depends on the following factors:

• soil type (clay, sandy, fertile);
• terrain (flat, with slopes);
• location of buildings and communications;
• groundwater level;
• the presence of storm drains and other utility networks;
• area and dimensions of the site.

Stages of drainage installation

• Design: it is important to correctly calculate the slope, depth, diameter of pipes, location of wells and trays.
• It is necessary to determine where the drains will be located.
• Marking and digging trenches (or ditches) - usually 70-120 cm deep.
• Laying geotextiles, cushions of layers of sand and crushed stone.
• Installation of perforated pipes, installation of wells, connection of channels.
• Filling with crushed stone, covering with geotextile, backfilling with soil.

Mistakes to Avoid

• Lack of slope - water will stagnate.
• Too shallow a depth - pipes may be damaged in frost.
• Ignoring groundwater may lead to flooding problems in the future.
• Use of unsuitable materials - cheap plastic, clay, poorly draining crushed stone.

Where drainage is most often needed

• Plots in a lowland or on a slope.
• Houses with basements, ground floors, and heated floors.
• Areas near forests, swamps, and bodies of water.
• At high GWL (groundwater level).
• If the area is constantly damp, there are a lot of puddles, and the soil has poor absorption.

Conclusion

A properly designed drainage system reliably protects your home, garden, paths, and basements from moisture and damage. However, drainage isn't simply digging a ditch or laying a pipe; it's a complex engineering task that requires consideration of soil, slope, topography, pipe depth, and many other factors. In addition to removing excess moisture, a drainage system can be part of the overall site design and used to divert wastewater from septic tanks, which is especially important for country houses and suburban homes without centralized sewerage systems.

If drainage is installed incorrectly, it won't work effectively, and you'll only waste time, effort, and money. Therefore, it's best to entrust this work to professionals who will take into account all the nuances and specific features of your site.

Please share any questions or drainage issues you've had in the comments, share your experiences, and forward this article to friends who might find this information useful.

Need reliable drainage in St. Petersburg? Don't waste time – contact the specialists who know how to install a drainage system properly and for a long time.