GB2232865A - Apparatus for watering and draining soil - Google Patents

Abstract

The apparatus comprises a conduit which embodies three parallel ducts, an inner primary duct 1, an intermediate secondary duct 2 and an outer duct 3. The ducts 1 and 2 are perforated pipes, pipe 1 running within pipe 2 and contacting one side of the inner wall thereof, and the outer duct of a water permeable material such as cardboard, contained by a mesh 10 for stability, and filled with a porous or water permeable mineral or biological infill material 9. In use a plurality of ducts are laid end to end and side by side on a water impermeable base, the ducts 1 connected by a manifold for water supply and drainage, and the assembly covered with soil or plant growth medium. The apparatus may be used in undulating as well as flat terrain. <IMAGE>

Description

Apparatus for Watering and Draining Soil 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.

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 sump/absorption layer over the selected area possible.

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 lightweight 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.

The invention is primarily based on the principle that moisture rises slowly to the surface by the well known means of capilliary 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 to the 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 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 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 and3or 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.

A preferred embodiment of the invention, as applied the irrigation and drainage of e.g. a golf green, will now be described by way of example with reference to the accompanying drawings, wherein: 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; 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; Figs. 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 duct: 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.

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 1", while the secondary duct 2 is 2", and the outer duct 3 is of 9" diameter; the preferred ratioof diameters being 1:2:9.

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 providefor 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 1/8" wide, 1/2" longnd are spaced at intervals of about 1".

L 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 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 waterLinwardly 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 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 excede 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 sustantially 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 capilliary 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 12" 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 conected 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 around 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 makes ducts 1 and 2 free from blockages or plugs caused by slime or soil sediment. Further more, 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 vent/overflow 4; for example there may be two such combined vent/overflows, 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 crossjoint has a plastic weld 30 or is cast in situ, 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.

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, in situ, 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 capilliary action. The trough 55 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 minimising 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 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 m 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 obtaine-d 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 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 collectÇors, orfor oil slick collectors by separating the oil from sea water quickly and economicaly.

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.

Claims (18)

Claims

1. Apparatus for watering and draining a selected area, comprising a conduit embodying three parallel ducts, an inner primary duct which extends within a secondary duct, in turn extending within an outer duct; the inner duct being connect able 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.

2. Apparatus according to Claim 1 wherein 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 lies along one inner wall surface of the secondary duct.

3. Apparatus according to Claim 1 or 2 wherein the ducts are normally of circular cross-section, the outer duct being of sufficiently resilient material to be deformed to a bulged cross-section under its own weight and that of the external soil, but is sufficiently rigid to return to its initial cross section

4. Apparatus according to any preceding Claim wherein the conduit is formed in sections which are connectable end to end with the inner duct of each section extending beyond the end of the secondary duct for coupling to the inner duct of the next adjacent section, and the secondary and outer ducts of each section being closed by a bulkhead wall.

5. Apparatus according to any preceding Claim, wherein an electrical heating cable is provided in the inner duct to heat the irrigation water.

6. Apparatus according to Claim 2 wherein the soil comprises a layer of sand in which flecks or scraps of paper or plastics mesh or woven or unwoven fibrous material are embedded in the sand to enhance the rooting properties of plants growing in the layer.

7. Apparatus according to any preceding Claim wherein a cross-pipe feeds irrigation water to the inner duct, and comprises an outer drainage pipe and an inner irrigation supply pipe, the inner pipe having a spigot which passes out through the drainage pipe and opens into the inner duct.

8. Apparatus according to any preceding Claim, wherein a water impervious layer of material is embedded below an area to be irrigated and drained by the apparatus, and one or more conduits are laid over the impervoius layer, and connected to water supply and drainage manifolds, and buried under soil the upper surface of which supports plant growth.

9. Apparatus according to Claim 8 including a reservoir substantially covering the water distribution network formed by the conduits, the network including a supply pipe through which water can flow to the inner ducts of the conduits, permitting surplus irrigation water to be collected in a sump formed within the outer duct to overflow into the secondary duct for drainage.

10. Apparatus according to Claim 8 wherein the water impervious layer comprises a layer of synthetic plastics, concrete or asphalt.

11. Apparatus according to Claim 9 wherein the outer ducts are porous.

12. Apparatus according to Claim 9 wherein the reservoir is formed by a solid porous material encasing filter material holding 50% air and 50% solids compacted and covered with a fabric mesh for stability.

13. Apparatus according to any preceding Claim embodying a low pressure water recirculation system.

14. Apparatus according to any preceding Claim wherein the conduit is provided in lengths convenient for carriage and handling.

15. Apparatus according to Claim 13 wherein the conduits are laid. below banks, inclines and undulating terrain.

16. Apparatus according to Claim 13 wherein the conduits are laid in linear or circular arrays.

17. Apparatus according to Claim 13 wherein the apparatus is installed in an area where rain fall or overhead irrigation are restricted.

18. Irrigation and drainage apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.