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P R E P A R E D B Y :

B E R N A L , L E I Z E L

Water Drainage Structure

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The Need for Drainage

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WHAT IS DRAINAGE?

It is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need

drainage to improve production or to manage watersupplies.

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Drainage Structure

A system of drains intended to collect and draw off groundwater from structures. It is used to prevent the seepage ofwater to reinforce foundations to reduce filtration pressureon the structure and to protect foundations from erosion by

seepage.

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Two Types of Drainage

Surface drainage

It is the removal of excess water from the surface of the land.This is normally accomplished by shallow ditches, also calledopen drains. The shallow ditches discharge into larger and

deeper collector drains.

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Two Types of Drainage

Subsurface drainageThe removal of water from the rootzone. It is accomplished by deep opendrains or buried pipe drains.

Deep open drainsThe excess water fromthe rootzone flows intothe open drains. Thedisadvantage of thistype of subsurface

drainage is that itmakes the use ofmachinery difficult.

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Two Types of Drainage

Subsurface drainage

Pipe drains

Pipe drains are buried pipes with openings through which the

soil water can enter. The pipes convey the water to a collectordrain

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Local System of Drainage Structures

Bed Drainage StructureIt is achieved through the use of a so-called filtration bed, which is laid inthe foundation of the structure,

directly on the water-bearing soil. Beddrainage of structures completelyprotects the building not only fromseepage of groundwater but also fromcapillary moisture. It is widely used inprotecting underground structures

built on loose soil of low permeability,as well as in draining high-temperature shops, heating systems,and flues into which no moistureshould penetrate.

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Local System of Drainage Structures

Layer Drainage StructureIt consists of drainpipes with filtration cushioning layers. The pipes arelaid on water-resistant soil outside the structures to be protected. Thistype of drainage is used only when the foundation of the structure being

protected is located on water-resistant soil.

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Local System of Drainage Structures

Circular DrainageStructure

It is constructed along the outlines ofa building or area in which a numberof structures are located. Theoperation of circular drainage of

structures is based on lowering thelevel of groundwater within theprotected contours, ensuringprotection against seepage intounderground installations andbuilding units. Circular drains areplaced at a certain distance from thebuilding; as a result, the drains maybe laid after the structure has beenerected. In this sense, circulardrainage of structures is advantageousin comparison with bed drainage,which is laid as the structure is beingerected.

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Horizontal Drainage Structure

(a) bed drainage, (b) pipedrains for circular drainage; (1) originallevel of groundwater, (2) loweredlevel of groundwater,

(3) filtration bed for bed drainage, (4) drainpipe,(5)filtration cushioning layer, (6) level of basement floor

Horizontal drainage uses pipe ortunnel drains, ditches, and gutters.

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Horizontal Drainage Structure

Pipe Drain - A combination of drainpipes with one or more sheetsof filtration cushioning layers of sand and gravel

Tunnel drain - Are pipes of large cross section, usually made ofsectional reinforced concrete, with water intake openings and acushioning layer.

Ditches- Mainly used in areas of small settlements, where the

maintenance of groundwater at depths of up to 1.5 m is permissible.Under conditions of firm soil, ditches are made in the form of slopingtrenches; in soft soil, gutters of sectional reinforced concrete are used.

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Vertical Drainage Structure

Vertical drainage with trap water discharge:(1) trap piping, (2) absorption tube of trap, (3)removal of air to vacuum pump, (4) dischargeof water to pumping unit, (5) air collector, (6)tubular wells, (7) intake chamber, (8) tunnel

Vertical drainage ofstructures is a system ofwells joined by a sewageconduit, through which

water is pumped out by asingle unit or by aseparate pump in eachwell. Sometimes thesewer is equipped with a

trap, by means of whichwater sucked in from thewells enters the sewer