Note: Descriptions are shown in the official language in which they were submitted.
2016375
FIELD OF INVENTION
This invention relates to apparatus for watering and
draining soil, for use in selected areas of ground, including
areas with slopes or mounds, for the cultivation of turf or other
vegetation. In particular the invention is directed to the
improvement of turf required for sports grounds, and the
propagation of nursery plants, and in general is applicable to
large scale plant growing under conditions of controlled soil
humidity.
BACKGROUND OF THE INVENTION
It is difficult for example to adequately and effectively
irrigate undulating terrain such as a golf green by surface
sprinkling, particularly when the surface and subsoil have
become compacted, thereby becoming resistant to the
penetration of water. The same compacted subsoil presents
drainage problems during periods of heavy rainfall as surface
water tends to collect.
Equipment for irrigation and drainage of soil is known
which uses an impervious base lining of a trough which is
co-extensive with the area to be treated. A closely spaced
pipe grid covers this area. The known equipment is expensive
as it requires extensive excavation to place the base lining.
The present invention is intended to provide equipment
which is simpler in its construction, and which requires less
excavation work for placing it in the soil, but which nevertheless
makes the formation of a sumplabsorption layer over the
selected area possible.
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SUMMARY OF THE INVENTION
An object of the invention is to provide an improved
construction of watering and drainage apparatus in the
selected area which will improve the growing conditions for
turf or other plants to be grown in the area, and at the same
time reduce the compaction factor of the soil.
Another object of the invention is to adequately and
effectively irrigate, drain and recycle the soil water over all
the area and through the soil structure, by means of a conduit
structure which can be prefabricated off-site, which is light-
weight and portable so that the conduits can be easily and
quickly laid out in the selected configuration to suit the
topography of the area, and the crop to be grown.
The invention seeks to achieve an area of soil which
covers the conduits and is effectively drained thereby of
surface water, but also enables water to be supplied from
below so that it percolates upwardly and can enhance the
rooting of plants over the selected area. As a result, using
the apparatus of the invention, the following factors in the
growth of turf or other vegetation on the surface of the area
can be controlled to contribute to healthier plant growth;
deep root formation, easy maintenance and labour, saving of
water and prevention of flooding and drought, underground
aeration, fertilizer control, evaporation control, acceptance
of sewerage water, whilst the area is still usable even when
being watered from below.
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The invention is primarily based on the principle
moisture rises slowly to the surface by the well known
means of capillary action, and that moisture moves from
places with a high moisture content to places with a low
moisture content, and that the water content of the soil is
controlled by atmospheric temperature and humidity, and
that water is denser than air.
According tothe invention there is provided apparatus
for watering and draining a selected area, comprising a
conduit made up of three parallel ducts; an inner primary
duct which extends within a secondary duct, in turn extending
within an outer duct; the inner duct being connectable to a
water source for watering, the secondary duct being connectable
for irrigation and drainage to a sink to which drainage water
can be conducted, and the outer duct being connectable for
drainage and irrigation with a sink to which water can be
conducted.
Preferrably the secondary duct is housed in the outer
duct and retained in position by a porous or water permeable
infill within the outer duct, and the inner duct is displaced
from the axis of the secondary duct so that it contacts one
inner surface of the secondary duct.
The apparatus of the invention forms a water reservoir
equally effectively over undulating or level terrain, above a
water impervious layer which may be a sheet of synthetic
plastics covering the whole area. A distribution system of
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pipes and manifolds may connect the ducts to the water
supply and sinks.
The inner and secondary ducts may be of plastics, and
the outer duct may be of a paper product enclosed in a net of
a plastics mesh. The inner duct may be slotted, and the
secondary duct may also be slotted, and form a reservoir for
water and air with the outer duct completely filled with a wood
product such as bark or sawdust, or peat and/or porous
volcanic rock encased for example in a cardboard separator.
The filler material should allow lightweight flexibility and
percolation of water from the surface into the secondary duct
and provide for upward circulation of water to the surface
where the vegetation is growing.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a vertical cross-section of an irrigation and
drainage conduit in apparatus according to the invention;
Fig. 1A is an end view of the conduit;
Fig. 2 is a cross-section of a plurality of such conduits
in place below the soil of an area to be irrigated and drained;
Fig. 2A is a cross-section of a conduit, showing how
it may be deformed by pressure;
Fig. 2B is a cross-section of a further embodiment of
conduit;
Fig. 3 is a longitudinal section of the conduit;
Fig. 4 is a cut-away perspective view showing a plurality
of conduits in place in undulating ground;
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Fig. 4A and Fig. 4B show alternative connections of
the inner ducts of the conduits to a header manifold;
Fig. 5 shows the use of two different shapes of conduits
under different terrain;
Fig. 6 and 6A show in a partially cut-away elevation
and a sectional view respectively, the arrangement of the two
innermost ducts of the conduit;
Fig. 7 is a sectional view showing end views of an
alternative form of duct;
Fig. 8 is a further sectional view of the further dpct;
Fig. 9 is a plan view thereof; and
Fig. 10 is a sectional view of a further embodiment of
duct in place in the ground, and showing a cross-connection
to a transverse supply conduit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A preferred embodiment of the inventions, as applied
the irrigation and drainage of e.g., a golf green, a playing field,
will now be described by way of example with reference to the
accompanying drawings, wherein
Fig. 1 shows in cross-section a conduit A according to
this invention, which comprises an inner primary duct 1 and an
intermediate secondary duct 2 which is of substantially larger
diameter than the inner duct 1, and a third outer duct 3 which
is of substantially larger diameter than the second duct 2.
In this embodiment the inner duct 1 has a diameter of 2cm
while the secondary duct 2 is 5cm, and the outer duct 3 is
of 20cm diameter; the preferred ratio of diameters being 2:5:20.
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The three ducts are so connected with one another that
when conduit A is disposed substantially horizontally the
lower portion of the external surface of the inner duct 1 is
closely adjacent to the bottom portion of the inner surface of
the duct 2. The two ducts can be connected in this relationship
by means of being secured intermittently along the lengths of
the ducts. To provide for the connection of lengthwise
adjacent conduit sections with another, the outer duct 3 of
each section can terminate. Each section of outer duct has
each of its ends closed by a bulkhead-like flange. The adjacent
end portion of the inner duct 1 projects through a closely
fitting cutout in that flange 5, as can be seen in Figs.1A and 3.
Along its length, except in its exposed end portions,
the inner duct has slots 6 which open laterally through its
wall 2. These slots are preferably spaced at regular intervals
along the duct and are preferably arranged symmetrically in
relation to a vertical plane which contains the axis of both
ducts. Furthermore, the slots are preferably vertical in the
horizontal plane. Typically the slots 6 are 4mm wide, 10 mm
long and are spaced at intervals of about 2.5cm.
The wall of duct 1 has ports 7 extending through at
intervals along its length. These ports 7 are preferably
spaced regularly along the top half of the duct, arranged
symmetrically with respect to vertical and horizontal planes
along the axis of the duct 2. Preferably ports 7 have a
diameter of 2mm.
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The wall of the outer duct 3 is in its undeformed
condition when the outer duct 3 is slightly flattened by its
own weight and the weight of the inner ducts 1 and 2, to be
deformed to a quasi elliptical cross-section when buried on
site. The wall of outer duct 3 comprises unpierced walls of
water pervious material allowing moisture to penetrate either
way from the fill to the soil, and acts as a separator from
the growing medium 8 above. The interior of duct 3 is
completely filled with a compacted homogenous lightweight
inert filler material 9 allowing the free movement of soil water
inwardly and outwardly to and from duct 2. Duct 3 is
substantially covered with a fabric netting 10 to increase
the structural strength and stability of the duct wall.
As the slots 6 are at a level above the bottom of the
outer duct 3, a liquid sump 11 tends to form therein. The
highest surface level 12 of this sump is slightly above the
slots 6, but normally the surface level will not rise above
the plane 13. In practice the surface level establishes itself
at a height determined by equilibrium between flow into the
sump, and flow out of it, with the maximum only being attained
in heavy rainfall. Above the sump 11 there is an air chamber
15, as shown in Fig. 1.
During watering or irrigation, water issuing from ports
7 in duct 1 sprays through the air chamber 15 and into the
sump 11 in the outer duct. When the water level in the sump 11
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rises above the lower edges of slots 6, water flows from
these slots 6 into duct 2. The maximum height of the water
in the sump 11 during watering cannot exceed the level 14
of the upper edges of the slots 6.
The three ducted conduit A of Fig. 1 is installed by
being laid directly onto the surface to be drained and
irrigated, or instead placed in a trench. The trench can be
provided with a substantially flat bottom 16 and substantially
vertical sides 17 with an extended base area 18.
When the conduit A is laid in place, owing to the
material of its wall, outer duct 3 deforms or flattens under
its own weight and that of the ducts 1 and 2 to a flattened
ellipsoid 29 (Fig. 2A). After the conduit is placed in a trench,
the trench is partly filled with growing medium 8 over which
the filling is completed with selected soil 20, the composition
of which depends upon the plants 21 to be grown.
When a plurality of conduits are laid side by side, they
provide elongate moisture sources in the soil. The intent here
is to specify the extent of the moisture fields presented by
the ducts in a homogenous extended area with uniform moisture
content at any given time to be presented to the surface soil
20 and planting. Basically, however, it will be obvious that
the surface moisture will be increased with wider conduits, as
in Fig. 2B. The moisture from the conduits diffuses through the
soil in known manner by capillary action and moisture vapour.
In some cases it may be advantageous to install the
conduits A at a relatively shallow depth, for example in a
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30cm trench, or in humus or directly upon the surface of
humus or soil. The choice of such installation arrangements
is dependant upon climate and other local conditions, the kind
of plants to be grown, the available water supply and the type
of water, whether fresh, brackish or soiled. Therefore no
generally valid values can be set forth. A single conduit
according to this invention could be installed in a trough or
like receptacle filled with humus or soil, particularly in a small
home garden or greenhouse.
In an installation for an area of substantial width, a
plurality of conduits A will be laid in parallel with one another.
For irrigation, the inner duct 1 of several conduits will be
connected by means of a manifold into which flows water
from a suitable pumped or elevated source. For drainage or
dewatering, the manifold is connected to a suitable sink,
such as a suction source such as a pump inlet, or a location
which is at a lower elevation than the area to be drained or
dewatered.
Because of the existence of the air chamber 15 in the
secondary duct 2 above the level of the sump 11, a free
circulation is ensured for both watering and drainage so that
the drainage can be accomplished at about the same rate as
gravity flow watering. Slime or soil sediment collected ground
the outer duct 3 will settle to the air space 22 (Fig. 2) at
the bottom and between the ducts and cannot rise any
substantially higher level in the outer duct 3 and therefore
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2016375
makes ducts 1 and 2 free from blockages or plugs caused
by slime or soil sediment. Furthermore, because water from
the inner duct 1 injects into the air chamber 15 during drainage
the action of irrigation and drainage can be accomplished at the
same time. It will be apparent that the arrangement permits
watering and pressurised drainage to be accomplished as may
be desirable for large areas in addition to being suitable for
gravity flow watering and drainage.
The layout, of which over the whole area is shown in
Fig. 4, is arranged to effect distribution over the whole area
and this apparatus may consist, as shown, of a perimeter ring
pipe with a central supply pipe 23 with water inlets 24, a
suitable stopcock 25 adjacent to outlets 24 of the perimeter
drainage pipes 27. At suitable points along the drainage pipe
27 there is a combined ventloverflow 4; for example there may
be two such combined ventloverflows, one at each end of the
drainage pipe 27. Radiating from the perimeter pipe 27 are a
number of pipes 24 which connect the conduit A duct 2. All
these pipes are unperforated to allow water to drain, collect
and recycle. At each connection there may be a cross joint 28,
such as shown in Figs. 4 A and B, and this cross joint may be
of plastics tubing. The cross joint has a plastic weld 30 or is
cast insitu, and there is a through aperture 31 to provide a water
communication channel. It can be observed that water can flow
into the drainage system and out of it, and rise through the
reservoir sump 11 upwards through the soil 8 to the roots 32.
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Fig. 5 shows an alternative form wherein rounded
section conduits according to Fig. 1 are laid below an inclined
bank, whilst rectangular sectioned conduits according to Fig. 2A
are laid below a flat bed. In Figs. 7, 8, and 9 are shown
further conduits where the outer duct is composed of trays 40
in which the inner ducts 1, 2 pass and the trays are partly
filled with soil 8 while the porous fill material 9 is contained
in transverse ridged structures 41 of triangular cross-section.
In Fig. 10 is shown a cross-section of a further
embodiment of apparatus according to the invention, insitu,
and showing a connection to a cross-supply pipe. A conduit 50
comprises an inner duct 51, attached by rivets 52 to the upper
inner surface of an intermediate secondary, drainage, duct 53.
This extends axially within an outer duct 54 of considerably
greater diameter. The duct 50 is seated in a rectangular cross
sectioned trough 55 of impervious polyethylene sheeting.
The outer duct 54 has a wall of cardboard, inside a nylon mesh
sock which acts to reinforce and cover the cardboard wall, the
latter acting as a filter which is pervious to water. The ducts 51
and 53 are of plastics tube, duct 51 having apertures 56, and
duct 53 having apertures 57 which allow water rising above
respective levels 58, 59 to spill into the next outer duct.
Outer duct 54 is filled with particulate calcined aggregate
mixed with peat, which provides a medium which can absorb
water entering the duct 54 through apertures 57, and allow it
to migrate upwardly through capillary action. The trough 55
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is filled with sand in the space between the trough walls
and the conduit 50. The conduit is covered with a layer
60 of sand, in which are embedded scraps or flecks 61
of plastics or paper material, in the form of mesh or unwoven
fibrous webs. These flecks 61 allow the roots of grass 62
growing in the layer 60 to penetrate the mesh or fibres and
increase the grip of the roots in the layer 60, thus minimizing
damage by divots, boot studs or cleets, or horses hooves.
An electrical heating cable 63 extends along the bottom
of the inner duct 52, within the water in the duct, and can heat
the irrigation water to a high temperature, and thereby warm
the whole conduit and overlying soil. This can be used as
required to disperse frost or snow, or to prevent its accumulation
and to heat the soil to allow improved growth of grass.
A crossconduit 65 is provided, which has an outer
drainage pipe 66, and a smaller diameter irrigation pipe 67
within and along the bottom of the drainage pipe. The pipe 67
communicates with the inner duct 51 of the conduit 50 by
means of a spigot 68, which passes through the wall of
drainage pipe 66 and extends into duct 51. Irrigation water
passes from pipe 67 into duct 51 and excess passes through
apertures 56 into duct 53, which is used to drain excess
moisture from duct 54, or to supply water thereto through
apertures 57, depending on the prevailing hydrological
conditions. Water passes up through the medium in duct 54
into the layer 60 to be taken up by the grass, for growth and
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transpiration, and evaporates from the soil surface, when
prevailing weather is dry. Excess water from rainfall
percolates downwards, and drains from the medium in
conduit 54 into the drainage conduit 53. The build up of
water on the surface, or in the layer 60 is thus avoided, and
the formation of pools, or waterlogging is avoided.
A conduit system according to the invention can be
formed as a closed system. It can be used for carrying
fertilizer into the soil if nutrients are dissolved in water used
for irrigation, and this type of fertilization affords uniform
distribution of nutrients in the soil of the kind only otherwise
obtained by rainfall. The apparatus can also be used for
desalination in desert areas, by feeding brackish water in
through the conduit and allowing solar heat to draw distilled
water to the surface as a dew condensation to support the
vegetation on the surface. The duct 3 being moisture porous
will attract and precipitate the salts on the inner face of the
duct wall, allowing pure water to pass through, fresh water
rainwater or salt water being fed through the conduits to
irrigate an area to be cultivated, and then reversing the flow
by draining the area to carry away leached out salt.
With low pressure flow irrigation in a desert area the
pressure in the air chamber 15 is raised by daily heating and
water is thereby forced out of the sump 11 so that irrigation
is effected in a manner similar to pressure watering.
It will be apparent that the apparatus of this invention
can be used for purification of waste water by taking advantage
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of its ability to feed water out into soil or a filter bed or
the like, and to permit subsequent return flow of the water
thus fed out. Arrangements comprising the apparatus of
this invention can also be used as rain water collectors,
or for oil slick collectors by separating the oil from sea water
quickly and economically.
It will be observed that the area underlain by the
apparatus according to the invention results in a ground cell
in which the water content can be effectively controlled by
the introduction of a calculated amount of water delivered
through the conduits, while allowing surplus water to overflow
leaving a balanced area which thus neutralises the water
content and creates conditions required for the growth of the
specific vegetation, irrespective of the external atmospheric
conditions which may not always be conducive to proper growth.
Arrangements can be made for recycling of initial water supplies
by forming a sump at the tail of the drain and pumping the water
from the sump 11 back to the main inlet duct 1. If required,
an automatic control may be set to effect pumping at regular
intervals. Such recirculation would be particularly suitable for
a dry area where water is scarce. Further, the underground
watering apparatus will save water effectively.
It will be apparent that the apparatus of this invention
can be used to cover, drain and control toxic waste materials.
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