Land and Field Drainage

Why Drain? – Good drainage helps maximise profits!

Wet land will not produce to its potential and allow farmers to maximise crop yield and extend the grazing season. Poorly drained land costs more as a result of higher fuel costs, increased labour and greater use of fertilizers, chemicals and seeds.

Excessive water replaces air in the soil depriving roots of vital oxygen. Removing surplus water from the land improves soil structure and prevents problems caused by waterlogging as well as having direct benefits in terms of higher yields. Free draining soils enhance seed germination as a result of greater warming which allows greater crop establishment and improvimprovese yields.

The cost of land drainage has fallen significantly over the years and the use of natural materials such as clay has added benefits as with good management, clay pipe systems can last indefinitely.

W.T. Knowles’ products for field and land drainage include clay pipes, junctions, gullies and other accessories.

Pipes used for Land Drainage

Land Drains

• KALD1 – 75mm Diameter 300mm Long – Pack Size 300
• KALD2 – 100mm Diameter 300mm Long – Pack Size 240
• KALD3 – 150mm Diameter 300mm Long – Pack Size 102
• KALD4 – 225mm Diameter 300mm Long – Pack Size 64

Land Drain junctions

Single junctions 45° Oblique

• KALJ1/1 – junction 75×75 Obl
• KALJ2/1/1 – junction 100×75 Obl
• KALJ2/1 – junction 100×100 Obl
• KALJ3/1/1 – junction 150×75 Obl
• KALJ3/1 – junction 150×100 Obl
• KALJ4/1 – junction 150×150 Obl
• KALJ5/1 – junction 225×100 Obl
• KALJ6/1 – junction 225×150 Obl
• KALJ7/1 – junction 225×225 Obl

Single junctions 90 ° Square

• KALJ1/2 – junction 75×75 Sq
• KALJ2/1/2 – junction 100×75 Sq
• KALJ2/2 – junction 100×100 Sq
• KALJ3/1/2 – junction 150×75 Sq
• KALJ3/2 – junction 150×100 Sq
• KALJ4/2 – junction 150×150 Sq
• KALJ5/2 – junction 225×100 Sq
• KALJ6/2 – junction 225×150 Sq
• KALJ7/2 – junction 225×225 Sq

Double junctions 45° Oblique

• KALJ1/4 – Double junction 75×75 Obl
• KALJ2/1/4 – Double junction 100×75 Obl
• KALJ2/4 – Double junction 100×100 Obl
• KALJ3/1/4 – Double junction 150×75 Obl
• KALJ3/4 – Double junction 150×100 Obl
• KALJ4/4 – Double junction 150×150 Obl
• KALJ5/4 – Double junction 225×100 Obl
• KALJ6/4 – Double junction 225×150 Obl
• KALJ7/4 – Double junction 225×225 Obl

Double junctions 90 ° Square

• KALJ1/3 – Double junction 75×75 Sq
• KALJ2/1/3 – Double junction 100×75 Sq
• KALJ2/3 – Double junction 100×100 Sq
• KALJ3/1/3 – Double junction 150×75 Sq
• KALJ3/3 – Double junction 150×100 Sq
• KALJ4/3 – Double junction 150×150 Sq
• KALJ5/3 – Double junction 225×100 Sq
• KALJ6/3 – Double junction 225×150 Sq
• KALJ7/3 – Double junction 225×225 Sq

Pipes for Outfalls and ditches

• KRP0/6 – Pipe 75mm 0.6mm Trad – pack Size 72
• KRP1/6 – Pipe 100mm 0.6mm Trad – pack Size 56
• KRP1/9 – Pipe 100mm 0.9mm Trad – pack Size 56
• KRP2/6 – Pipe 150mm 0.6mm Trad – pack Size 30
• KRP2/9 – Pipe 150mm 0.9mm Trad – pack Size 30
• KRP3/6 – Pipe 225mm 0.6mm Trad – pack Size 16
• KRP3/9 – Pipe 225mm 0.9mm Trad – pack Size 16
• KRP4/6 – Pipe 300mm 0.6mm Trad – pack Size 9
• KRP4/9 – Pipe 300mm 0.9mm Trad – pack Size 9
• KRP5/6 – Pipe 375mm 0.6mm Trad – pack Size 5
• KRP5/9 – Pipe 375mm 0.9mm Trad – pack Size 5
• KRP6/6 – Pipe 450mm 0.6mm Trad – pack Size 4
• KRP6/9 – Pipe 450mm 0.9mm Trad – pack Size 4

Note: Pipes from 100mm diameter to 450 diameter

Methods of Land Drainage

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  Illustration 1: Simple lateral drainage scheme with outflows into a ditch. Arrows show direction of flow

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  Illustration 2: Here laterals are connected to a main drain leading to a ditch. Size is dependent on the area and gradient of the field. Arrows show direction of flow.

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  Illustration 3: Though simple schemes are always advisable, the terrain often makes a more complex layout unavoidable as this sample.

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  Illustration 5: An example of an inlet headwall installed.

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  Illustration 6: Scheme showing inspection chambers at main junctions for ease of maintenance. Note vitrified clay bend before outfall.

Outfalls to Dykes

Outfalls from laterals discharging individually into dykes can be liable to damage by mechanical ditchers. To obviate this possibility such outfalls should be constructed from pipes which can be removed or retracted during ditch maintenance operations. It is not usual to provide headwalls for individual outfalls to laterals.

On mains discharging into dykes where the outfall is a minor stream maintained by the farmer, the standard type of headwall should be of GRC or concrete slab construction or a small wall of brick or concrete. Mains discharging into streams which are the responsibility of Water Authorities and internal Drainage Boards should have headwalls constructed to the specification laid down by the Authority. Approval should be obtained from the Authority before the job strats and on completion. Typical headwalls are shown in the opposite illustrations.

Different schemes require differing types of headwall and inspection chambers.

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  Inspection chamber with silt trap in minium 6in (150mm) thick concrete blocks set on minimum 4in (100mm) thick concrete slab.

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  Inspection chamber with slit trap

Under Drain Outfalls

A properly constructed outfall of a type suitable for the particular location is to be providedwhenever a drain pipe discharges into an open channel. The last 5ft (1500mm) length of drain pipe is to be of a rigid type. Its invert at the outfall should be al least 6in (150mm) above the normal water level wherever possible.

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  Sloping brickwork headwall

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  Inlet headwall construction with silt trap and grating of the type to be used in schemes shown in illustration 5

Further information is available in the technical section or by contacting W T Knowles on 01422 372833.