GB2427532A

GB2427532A - Ground drainage system

Info

Publication number: GB2427532A
Application number: GB0512752A
Authority: GB
Inventors: Michael Corban
Original assignee: A Proctor Group Ltd
Current assignee: A Proctor Group Ltd
Priority date: 2005-06-23
Filing date: 2005-06-23
Publication date: 2007-01-03
Anticipated expiration: 2025-06-23
Also published as: GB0512752D0; GB2427532B

Abstract

A drainage system 12 suitable for use under a green 10 on a golf course, comprising a composite sheet 14 for locating below the rootzone of the green, the sheet consisting of an upper permeable layer 16 and a lower drainage layer 18; a conduit 20 connected to the composite sheet for the removal or supply of water to the composite sheet; and an impermeable layer 22 for locating below and parallel to the composite sheet. The permeable layer is preferably a needle punched geotextile, and the drainage layer may comprise a polyethylene sheet having frusto-conical protrusions 36 formed by plastic deformation. The permeable layer is preferably bonded to the protrusions of the drainage layer, creating a sandwich structure. The impermeable layer may be formed from polypropylene. Advantageously, the drainage system has remotely operable control means 44,46 to control the flow of fluids through the system. The system may further comprise an underground storage tank, and a pump to recirculate fluid from the tank.

Description

Drainage System

FIELD OF THE INVENTION

The present invention relates to a drainage system, and a composite sheet for use in a drainage system, for a turfed area, particularly, but not exclusively for a green on a golf course.

BACKGROUND OF THE INVENTION

Aeration and drainage are two of the most important considerations when growing healthy turf. Both the movement of water (drainage) and air (aeration) are largely dependent on the size of voids between the particle sizes of the soil. As the soil particle size increases, so do the number of water and air migration paths through the soil. For example, clay type soils have a very small particle size which, when wet, can become very cohesive, reducing the voids between the particles for water and air to travel through, thus making it virtually impermeable. Conversely, a rounded gravel, such as pea gravel, has a much larger void ratio which makes it a very good conductor of both water and air.

Conventional turf systems, for example, for a green on a golf course, use a sand based rootzone which has rapid drainage, good aeration, deep root growth, reduced disease and reduced salts. However, there are disadvantages associated with these systems. For example, rapid drainage can be a drawback in dry weather where it is desirable to retain moisture in the soil, with the result that and increased watering of greens is necessary. Similarly, nutrients can be washed out of the soil by the rapid draining of water with the possible effect that a desired plant growth is more difficult to achieve. A further problem is ground-borne gases, which can damage the turf, can move more easily through the system to attack the roots of the turf. The presence of these gases can deplete the oxygen level within the root zone, leading to unfavourable growing conditions.

It is an object of the present invention to avoid or minimise one or more of the disadvantages associated with

the prior art.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a drainage system suitable for use under a green on a golf course, the drainage system comprising: a composite sheet adapted to be located, in use, below the rootzone of a green, the composite sheet comprising: an upper permeable layer; and a lower drainage layer; a conduit connected to at least a portion of the composite sheet for the removal or supply of fluid to the composite sheet; and an impermeable layer adapted to be located, in use, below, and generally parallel to, the composite sheet and the pipe work.

Although the present invention is particularly suitable for draining a green on a golf course, it will be understood that the drainage system could be utilised for any turfed surface for which improved drainage is required. As used herein the term fluid may be a reference to a liquid such as water or a gas (fluid) such as air.

The drainage system of the present invention, when located below the rootzone of a turfed surface, provides rapid drainage of fluid from the turf, via the composite sheet and the conduit. The composite sheet acts as a path underneath the rootzone and has superior flow rates to that of conventional drainage systems. However, fluid can also be fed through the conduit and the composite sheet into the rootzone to provide, for example water during dry conditions.

The impermeable layer assists in directing fluid to or from the conduit and prevents soluble nutrients, which may have been applied to the green, from leaching into the surrounding areas. The impermeable layer also acts as a barrier to ground-borne gases preventing gases from migrating through the soil to the rootzone of the turf.

Preferably, the conduit includes at least one aeration chamber, which in use, connects the conduit to the surface of the ground and permits air to enter the drainage system to aerate the soil.

Preferably, the permeable layer is a geotextile fabric. A geotextile is a planar product manufactured from polymeric material for use with soil, rock, earth or other geotechnical engineering related material as an integral part of man made project, structure or system.

The geotextile fabric may be a non-woven, multi filament geotextile. Alternatively, or additionally, the geotextile may be needle punched. A fabric of this type permits water to pass through but prevents fines such as silt and clay from entering the drainage layer.

The drainage layer may comprise a plurality of elements extending from a sheet, the elements defining voids therebetween to permit the passage of fluid.

Preferably, the elements are formed integrally with the sheet. Most preferably, the elements are formed by plastically deforming the sheet.

Preferably, the sheet and the elements are made from high density polyethylene.

Preferably, the elements are frusto-conical.

The permeable layer may be bonded to the drainage layer. Most preferably, the permeable layer is bonded to the elements of the drainage layer such that the elements are sandwiched between the permeable layer and the sheet of the drainage layer. Preferably, the bonded permeable layer and drainage layer construction is a pre-fabricated product such as PROVOIDTM geocomposite. PROVOIDTM geocomposite is especially useful as the geotextile can be changed for required infiltration rates.

Preferably, the intrinsic permeability of the bonded permeable layer and drainage layer construction is in the range of 0.5 to 2 x l0 m2.

Preferably, the impermeable layer is a geomembrane.

Most preferably, the impermeable layer is a polypropylene sheet. The impermeable layer may be a proprietary product such as PROLINE PPTh sheet.

The composite sheet may be flexible. Providing a flexible composite sheet allows the drainage system to follow the desired contours of the turf, particularly useful where the drainage system is to be used with a green on a golf course.

Preferably, the conduit is connected along the perimeter of the composite sheet.

Preferably, the drainage system further includes control means. Control means are provided to either increase, reduce, or even stop, the rate of drainage from the rootzone. Stopping the rate of drainage from the rootzone is useful in dry conditions or when soluble nutrients has been applied to the turf.

Preferably, the control means is adapted to prevent fluid leaving the composite sheet and entering the conduit. Preferably, the control means is in the form of barriers. Most preferably, the control means is remotely operable. Being able to control the drainage from the composite sheet into the conduit means that the flow of fluid can be increased, reduced, or even stopped as necessary.

Preferably, different sections of the drainage system can be controlled independently. On golf course greens, substantial changes in level are often a feature, by having independent control of different sections of the drainage system, the system on the upper level, for example, can be isolated to stop fluid draining to the lower level too quickly.

Preferably, the conduit is further connected to storage means. Preferably, the storage means is in the form of at least one underground tank. The drainage system may further include pump means to allow fluid in the storage means to be re-circulated onto the turf as necessary.

The impermeable layer may be provided with vertical double cuspated fin drains located below the impermeable membrane at maximum 6 linear metre centres. If the subterranean water table rises sufficiently, due to, for example, heavy rainfall, the rising water can apply pressure to the impermeable layer which may be sufficient to lift a portion of the drainage system, with subsequent damage to the turf above. Fin drains are desirable to disperse this pressure.

Another aspect of the present invention relates to the use of a composite sheet in a drainage system for a green on a golf course.

Preferably, the composite sheet is a geocomposite.

A geocomposite is a planar product comprising a number of synthetic layers, manufactured for use with soil, rock, earth or other geotechnical engineering related material as an integral part of man made project, structure or system.

Preferably, the composite sheet is adapted to be located, in use, below the rootzone of the green.

Preferably, the composite sheet comprises an upper permeable layer and a lower drainage layer.

Preferably, the composite sheet is adapted to be used in a generally horizontal plane.

A further aspect of the present invention relates to the use of a composite sheet in place of clean gravel in a drainage system for a green on a golf course.

By virtue of the present invention a drainage system can be installed below a green on a golf course which can be used to control the drainage of water from the green, aerate the green and prevent damage to the green by ground-borne gases.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example, with reference to the accompanying drawings in which: Figure 1 is a partially cut-away view of a portion of a golf green including a drainage system in accordance with an embodiment of the present invention; Figure 2 is a sectional view of the composite sheet used in the drainage system of Figure 1; Figure 3 is a sectional view through a portion of the golf green and drainage system of Figure 1 showing water being drained from the green; Figure 4 is a sectional view through a portion of the golf green and drainage system of Figure 1 showing water being retained in the soil; and Figure 5 is a sectional view through a portion of the golf green and drainage system of Figure 1 showing the green being aerated.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Figure 1, there is shown a partially cut-away portion of a golf green, generally indicated by reference numeral 10, including an drainage system 12 in accordance with an embodiment of the present invention.

The drainage system 12 is located beneath the rootzone 14 of the green 10. The drainage system comprises an upper composite sheet 14 comprising a permeable layer 16 bonded to a lower drainage layer 18.

The composite sheet 14 is connected around its perimeter to a conduit in the form of pipework 20 which is located around the edge of the green 10. The pipework 20 is 100mm diameter slotted flexible pipe. The pipework 20 and the composite sheet 14 lie over an impermeable polypropylene layer 22.

Connected to the pipework 20 is an aeration chamber 24 which has an inlet 26 located on the fairway 40 adjacent the green 10. The inlet 26 has a protective grill 28 and a cover 30. Also connected to the pipework is a drainage pipe 32 which leads to an underground storage tank (not shown) . The operation and function of the aeration chamber 24 and the drainage pipe 32 will be described in due course.

Turning now to Figure 2, there is shown a sectional view of the composite sheet 14 used in the drainage system 12 of Figure 1. The composite sheet 14 in this case is PROVOIDTM geocomposite. The composite sheet 14 comprises a HDPE sheet 34 from which frusto-conical cones 36 extend. The cones 36 were pressed out of the sheet 34 during manufacture and are integral with the sheet 34.

Between the cones 36 are voids 37 through which water and air can flow. The permeable layer 16 is bonded to the upper surface 38 of the cones and comprises a non-woven needle punched fabric.

The operation of the drainage system will now be described in connection with Figures 3-5. Firstly, referring to Figure 3 there is shown a sectional view through a portion of the golf green 10 and the drainage system 12 of Figure 1 showing water being drained from the green 10. As can be seen from Figure 3, the composite sheet 14 and the impermeable layer 18 lie in a substantially horizontal plane below the rootzone 13 of the green 10. The pipework 20 including the aeration chamber 24 and the drainage pipe 32 are located below the fairway 40 which surrounds the green 10.

The drainage system 12 further includes remotely operable control means 42 in the form of a first barrier 44 and a second barrier 46. The first and second barriers can be lowered from the position shown in Figure 3 to selectively route water or air towards or away from the green 10.

In the configuration shown in Figure 3, it is desired to drain water, indicated by the arrows, from the green 10 through the rootzone 13. The water flows through the rootzone to the composite sheet 14, passing through the permeable layer 16 and passing along the drainage layer 18 through the voids between the cones 36.

The impermeable layer 22 prevents the water draining into the sub soil 48 below the green 10. The water flows through the drainage layer 18 and into the pipework 20.

From there the water will flow around the perimeter of the green 10 until it comes to the drainage pipe 32, and will flow along the drainage pipe 32 to an underground storage tank (not shown) . As the first and second barriers 44, 46 are in a raised position, the water is permitted to flow. It will be understood by the skilled man, that the composite sheet 14 and pipework 20 will be arranged such that water will flow through the system to the drainage pipe 32 under the effects of gravity.

Referring now to Figure 4, a sectional view through a portion of the golf green 10 and the drainage system 12 of Figure 1, showing water being retained in the soil.

In this case, it is desired to retain water in the rootzone 13 because, for example, the weather is dry or soluble nutrients have been added to the green, and it is desirable they remain within the rootzone for a period of time. To retain moisture in the sub soil 13, the first barrier 44 is lowered to shut-off the flow of water through the drainage pipe 32. Once the first barrier 44 is in the lowered position, water will build up against this barrier and back-up through the system, that is through the pipework 20 and the composite sheet 14 such that water level 50 is maintained beneath the green 10.

Again the impermeable layer 22 prevents this water, and possibly the soluble nutrients, filtering away into the sub soil 48. Although the second barrier 46 is also shown in the lowered position in Figure 4, this barrier 44 has no effect in this particular operation and could be in the raised position.

Referring finally to Figure 5, this Figure shows a sectional view through a portion of the golf green 10 and the drainage system 12 of Figure 1 showing the green 10 being aerated. For aeration to occur, the second barrier 46 is in a lowered position and the cover 30 is lifted off the aeration chamber 24. In this case, air flows through the protective grill 28, which is provided to prevent small animals and leaves getting into and clogging up the system, and along the drainage pipe 32 through the pipework 20 and composite sheet 14 to aerate the sub soil 13 of the green 10. The second barrier 46 is closed to prevent air being diverted along the drainage pipe 32 towards the underground tank (not shown) Various modifications and improvements may be made to the embodiment described without departing from the scope of the invention.

Claims

S -14- * CLAIMS 1. A drainage system suitable for use under a green on a

golf course, the drainage system comprising: a composite sheet adapted to be located, in use, below the rootzone of a green, the composite sheet comprising: an upper permeable layer; and a lower drainage layer; a conduit connected to at least a portion of the composite sheet for the removal or supply of fluid to the composite sheet; and an impermeable layer adapted to be located, in use, below, and generally parallel to, the composite sheet and the pipe
2. A drainage system according to claim 1, wherein the conduit includes at least one aeration chamber, which in * *** use, connects the conduit to the surface of the ground and permits air to enter the drainage system to aerate the IS.

* 20 soil. I. * * S * * I. S

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3. A drainage system according to either of claims 1 or 2, wherein the permeable layer is a geotextile fabric.
4. A drainage system according to any preceding claim, wherein the geotextile fabric is a non-woven, multi filament geotextile.
5. A drainage system according to any preceding claim, wherein the geotextile is needle punched.
6. A drainage system according to any preceding claim, wherein the drainage layer comprises a plurality of elements extending from a sheet, the elements defining voids therebetween to permit the passage of fluid.
7. A drainage system according to claim 6, wherein the elements are formed integrally with the sheet.
8. A drainage system according to either of claims 6 or 7, wherein the elements are formed by plastically deforming * . the sheet. * .* * S S a...
9. A drainage system according to any of claims 6 to 8, wherein the sheet and the elements are made from high S. * * *: density polyethylene.
10. A drainage system according to any of claims 6 to 9, wherein the elements are frusto-conical.
11. A drainage system according to any preceding claim, wherein the permeable layer is bonded to the drainage layer.
12. A drainage system according to any of claims 6 to 10, wherein the permeable layer is bonded to the elements of the drainage layer such that the elements are sandwiched between the permeable layer and the sheet of the drainage layer.
13. A drainage system according to either of claims 11 or 12, wherein the bonded permeable layer and drainage layer construction is a pre-fabricated product.
14. A drainage system according to any of claims 11 to 13, wherein the intrinsic permeability of the bonded permeable layer and drainage layer construction is in the range of * ,*. * -5 2

0.5 to 2 x 10 m ** * * a...

I a.
15. A drainage system according to any preceding claim, wherein the impermeable layer is a geomembrane.
16. A drainage system according to claim 15, wherein the impermeable layer is a polypropylene sheet.
17. A drainage system according to any preceding claim, wherein the composite sheet is flexible.
18. A drainage system according to any preceding claim, wherein the conduit is connected along the perimeter of the composite sheet.
19. A drainage system according to any preceding claim, wherein the drainage system further includes control means.
20. A drainage system according to claim 19, wherein the control means is adapted to prevent fluid leaving the composite sheet and entering the conduit.
21. A drainage system according to either of claims 19 or 20, wherein the control means is in the form of barriers. S. * I I..
22. A drainage system according to any of claims 19 to 21, wherein the control means is remotely operable.

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23. A drainage system according to any preceding claim, wherein different sections of the drainage system can be controlled independently.
24. A drainage system according to any preceding claim, wherein the conduit is further connected to storage means.

P14 16 6GB
25. A drainage system according to claim 24, wherein the storage means is in the form of at least one underground tank.
26. A drainage system according to either of claims 24 or 25, wherein the drainage system further includes pump means to allow fluid in the storage means to be re-circulated onto the turf as necessary.
27. A drainage system according to any preceding claim, wherein the impermeable layer is provided with vertical double cuspated fin drains located below the impermeable membrane at maximum 6 linear metre centres.
28. A method of constructing a green on a golf course, the 4 S. method comprising the step of: * S.. * I * 411

installing a composite sheet in a drainage system according * S. to any one of claims 1 to 27 beneath the rootzone of a green. f * I I * .

II I 5
29. A method according to claim 28 wherein the composite sheet is installed in a generally horizontal plane.