GB2507967A

GB2507967A - Rainwater ground collection system

Info

Publication number: GB2507967A
Application number: GB1220472.3A
Authority: GB
Inventors: Oscar Berkeley
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-11-14
Filing date: 2012-11-14
Publication date: 2014-05-21
Anticipated expiration: 2032-11-14
Also published as: GB2507967B; GB201220472D0

Abstract

The invention relates to a rainwater collection system 2 comprising a three dimensional cellular member 4 in the form of a cellular array of holes 6 extending through the thickness of the array, wherein the holes are preferably in the form of an hexagonal honeycomb structure. The honeycomb structure is filled with aggregate/gravel material 7 so as to form a reinforced ground surface 9. A flexible impermeable membrane 14 extends beneath the cellular member so as to collect the rainwater which has fallen onto the reinforced ground surface and propagated through the aggregate material filling the holes of the cellular member. The cellular member is preferably made from a polymer and the impermeable membrane from butyl rubber. The collection system forms a reinforced ground surface suitable for use as a driveway or path.

Description

RAINWATER COLLECTION SYSTEM.

The present invention relates to a rainwater collection system and to a method of installing a rainwater collection system. In particular, the present invention relates to a rainwater collectjon system comprising a reinibreed ground surthce, such as a driveway or path, and. an associated installation method.

It is known to produce driveways and paths in the domestic or commercial built environment which are adaj.ited to collect or harvest rainwater for subsequent use, A known rainwater collection system includes concrete block permeable paving, incorporating an array of specially shaped concrete blocks shaped to form special gaps between each block of the array so that rainwater failing onto the array, which may be laid as a driveway or a path, falls down through the gaps and soaks into a sub-base. An impermeable membrane liner may he located beneath the sub-base so that water collects in the sub-base, and a drainage pipe system may communicate with the sub-base to conduct th.e collected water away to a tank for storage and subsequent use, That known system is expensive to install, because the concrete blocks of the permeabk paving are specially shaped, having profiled sides, typically incorporating a plurality of outwardly extending nubs. Consequently. the blocks are expensive as compared to conventional concrete paving blocks which have straight sides and abut along common edges. Also, the cost of installation is hice',h, because the blocks must be laid individually.

Furthermore, the known system suffers from the problem that only a small proportion of the entire surface area of the array of concrete block permeable paving is actually permeable. this being provided by the gaps between the blocks. This limits the ability to collect large volumes of rainwater in short periods of time, and increases rainwater run-off from the surface, reducing the rainwater collection or harvesting efficiency. Furthermore, the gaps can become clogged with debris, again reducing water collection or harvesting. The known system provides an inconsistent efficiency depending upon the rainfall volume and the maintenance of the system. Some commercially available blocks have intenneshing profiled sides, but this reduces the gap width and ftrther reduces water collection.

There is therefore a need in the art for a low cost rainwater collection system, also known as a rainwater harvesting system, comprising a reinforced ground surface, such as a driveway or path, which has a lower capital cost and a Lower cost of installation than the known concrete block permeable paving system.

There is also a need in the art for a rainwater collection or harvesting system comprising a reinforced ground surface, such as a driveway or path, which has a higher rainwater collection or harvesting efficiency than the known concrete block permeable naving system.

There is furthermore a need in the art Thr a rainwater collection or harvesting system comprising a reinforced wound surface, such as a driveway or path, which has a more consistent water collection efficiency than the known concrete block permeable paving system.

It is accordingly an aim of this invention to provide a rainwater collection or harvesting system, and associated installation method, which at least partially overcome at least some of these significant disadvantages of the known rainwater collection or harvesting system.

The present invention accordingly provides a rainwater collection system comprising: a. a three dimensional cellular member in the form of a layer having a cellular array of holes extending through the thickness of the layer; b. aggregate material filling the holes of the cellular member, the aggregate material and the cellular member defining a reinforced ground surface; and c. a flexible impermeable membrane extending beneath the cellular member and configured to collect rainwater which has fallen onto the reinforced ground surface and propagated through the aggregate material.

Optionally, the three dimensional cellular member has a honeycomb structure. Typically, the holes are substantially hexagonal in crosssection, although other cell shapes, such as circular, may he used. Optionally, the three dimensional cellular member is composed of a polymer.

In some embodiments, the rainwater collection system may further comprise a water permeable layer at least partly, or wholly, covering a lower surface of the three dimensional cellular member. The water permeable layer may be. composed of a grid or mesh, for example of plural interconnecting modules of injection moulded polymer. Alternatively, the water permeable layer may be composed of a textile.

Typically, the rainwater collection system flirther comprises a first layer of sand separating a lower surface of the three dimensional cellular member and the fiexibte impermeable membrane, and optionally a second layer of sand adjacent to a lower surface of the flexible impermeable membrane, Typically, compacted hardcore material is adjacent to a lower surface of the second layer of sand, In some preferred embodiments, the flexible impermeable membrane comprises huty! rubber.

PreferaHy, the flexible impermeable membrane is inclined at an angle to the horizontal to define a. water flow direction therealong towards a downstream portion thereof Typically. a rainwater collection pipe or tank is provided at the downstream portion.

Typically, the aggregate material comprises gravel.

The present invention farther provides a method of installing a rainwater collection system, the method comprising the steps of: i laying a flexible impermeable membrane over a ground area: ii. disposing over the flexible impermeable membrane a three dimensional cellular member in the form of a layer having a celiuar array of holes extending through the thickness of the layer; and iii. filling aggregate material into the holes of the cellular member, the aggregate material and the cellular member defining a reinforced ground surface and the flexible impermeable membrane extending beneath the cellular member and configured to collect rainwater which has fallen onto the reinforced ground surface and propagated through the aggregate material, Optionally, the method further comprises the step, between steps i. and iii., of iv. providing a water permeable layer at least partly, or wholly, covering a lower surface of the three dimensional cellular member.

Optionally, the method fti-ther comprises the step, between steps i. and ii. ot v, laying a first layer of sand over the tiexihie impermeable membrane thereby to separate a lower surface of the three dimensional cellular member and the flexible imperriteahe membrane, Optionally, the method further comprises the step, before step i., of: vi. laying a second layer of sand over which a lower surface of the flexible impermeable membrane is laid in step i, Optionally, the method further comprises the step, before step vi,, of: vii, laying a compacted hardcore material over which the second tayer of sand is laid in step vJ.

Optionally, in step i. the flexible impermeable membrane is laid so as to he nchned at an angle to the horizontal to define a water flow direction therealong towards a downstream portion thereof.

Optionafly, the method further comprises the step, before step ii., of: disposing a rainwater collection pipe or tank to collect water flow at the downstream portion.

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates a vertical cross section through a rainwater collection system in accordance with a first embodiment of the present invention; and Figure 2 illustrates a plan view of the cellular member of the rainwater collection system of Figure 1.

Referring to Figure 1, there is shown a vertical cross section through a rainwater collection system, designated generally as 2, in accordance with a first embodiment of the present invention.

The rainwater collection system 2 comprises a three dimensional cellular member 4 in the firm of a layer having a celMar array of holes 6 extending through the thickness of the layer.

The three dimensional cellular member 4 has a honeycomb structure, preferably with the holes 6 being substantially hexagonal in cross-section as showi in Figure 2 which is a plan view of the three dimensional cellular member 4. However, other cell shapes may be used.

such as circles, with the circles being interconnected by being mounted on a lower water permeable mesh, Typically. the three dimensional cellular member is composed of a polymer, such as a polyolefin, for example polypropylene. The three dimensional cellular member may comprise a geocefl material available in commerce under the trade mark Terram from Fibereweb Geosyntheucs Ltd of Maldon, Essex, UK or under the trade mark Ground Guards from Greensward Engineering of Leeds, UK.

Aggregate material, designated by the reference numeral 7, fills the holes 6 of the cellular member 4. For clarity of illustration, the aggregate material 7 is shown in only one of the cells 6 in Figure 1. Typically, the aggregate material 7 comprises gravel, although other aggregate material may be provided having the desired aesthetic appearance and durability.

The aggregate material and the cellular member define a reinforced ground surtlice 9. The cellular member 4 holds the aggregate material 7 within the cells 6 and provides a durable reinforced ground surface S.The aggregate material 7 permits rainwater falling on the surface 9 to propagate downwardly through the aggregate material 7 in the cells 6.

A water permeable layer 10 at least partly, typically wholly, covers a lower surface S ot' the three dimncnsiona.l cellular member 4. In some embodiments, the layer 1 0 may be composed of a mesh or grid, which may be comprised of a plurality of interconnected injection mnoukted modules, such as panels, optionally of a polymer such as a polyolefin such as polyethylene or polypropylene, Alternatively, the layer l 0 may be composed of textile, such as a polymeric geotextile material, for example a geotextile material available in commerce under the trade mark l'erram from Fihereweb Geosynthetics Ltd of Maldon, Essex, UK.

The water penneable layer 10 permits rainwater to pass downwardly therethrough but prevents earth, sand or other material, or weeds, from passing upwardly therethrough into the cells 6 and prevents the aggregate material 7 front passing downwardly therethrough into the lower layers of the rainwater collection system 2. The water permeable layer 10 is adapted to separate the aggregate material 7 from material beneath the water permeable layer 10 during use of the rainwater collection system over an extended period, thr example at least one year, optionally at least 10 years. c.

A first layer of sharp sand 12 is located beneath the water penneable layer 10. A flexible impermeable membrane 14 extends beneath the first layer of sharp sand 12, and also the cellular member 6, and is configured to collect rainwater which has thilen onto the reinforced ground surface 9 and propagated through the aggregate material 7 filling the holes 6 of the cellular member 4. Typically, the flexible impermeable membrane 14 comprises butyl rubber.

The flexible irnpermeahk membrane 14 i.s inclined at an angle to the horizontal to define a water flow direction therealong towards a downstream portion thereof. A rainwater collection pipe or tank, noL shown, is provided at the downstream portion of the flexible impermeable membrane 14 at the level of the flexible impermeable membrane 14 to collect water from the flexible impermeable membrane 14.

The first layer of sand 12 separates the lower surfhce $ of the three dimensional cellular member 6 and the water permeable layer 10 from the flexible impermeable merrbrane 1 4.

The sand layer 12 absorbs and retains any water which has passed through the water permeable layer 10, allowing the water to drain slowly through and along the sand layer 12 and along the impermeable membrane 14.

This sand layer 12 also spreads any load applied to the ground surface ¶, for example from a ehicle, and reduces the risk of inadvertent puncturing of the flexible impermeable membrane 14, for example by the cellular member 6.

A second ayer of sharp sand 16 is laid beneath the flexible impermeable membrane 14, and so adjacent to a lower surface of the flexible impermeable membrane 14, Again, the second layer of sand 16 reduces the risk of inadvertent puncturing of the flexible impermeable membrane 14.An optional additional protective underlay (not shown) may be provided beneath the flexible impermeable membrane 14. This underlay may be above the sand layer 16 or may even replace the sand layer 16 in some embodiments.

A layer of compacted hardcore material I 8 is laid beneath and adjacent to the second layer of' sand 16 to provide a solid base for the driveway or path. A sub grade base layer 20 may be provided beneath the compacted hardcore material 1 8.

When the rainwater collection system of Figures 1 and 2 is installed, initially the sub grade base layer 20 is provided over a ground area having tile required shape and dimensions for the reinforced ground surface, such as the driveway or path. The layer of compacted hardcore ma.teria.l 18 is laid above the sub grade base layer 20 to provide a solid base thr the driveway or path. Then the second layer of sand 1 6 is laid. Optionally, a protective underlay is then laid.

The flexible impermeable membrane 14, cut to the required shape and dimensions, is laid over the second layer of sand 16 or protective underlay. The flexible impermeable membrane is laid so as to he inclined at an angle to the horizontal to define a water flow direction therealong towards a downstream portion thereof A rainwater collection pipe or tank is disposed at the downstream portion to collect water flow at the downstream portion.

The first layer of sand i2 is laid over the flexible impermeable membrane 14. The water permeable layer 10 is laid over first layer of sand 12. The layer 10 may at least partly cover, hut typically wholly covers, the lower surface of the three dimensional cellular member 6 which is disposed over the water permeable layer 10.

Finally, the aggregate material 7 is filled into the holes 4 of the cellular member 6. The aggregate material 7 and the cellular member 6 define a reinforced ground surface 9 and the flexible i.ni.perrneahle membrane 1.4 extends beneath the cellular member 6. The flexible impermeable membrane 14 is configured to collect rainwater which has fallen onto the reinforced ground surface 9 and propagated through the aggregate material 7 filling the holes 4 of the cellular member 6.

The preferred embodiments of the present invention can provide a rainwater collection system which has low capital and installation costs since the flexible impermeable membrane, the three dimensional cellular member and the aggregate material are inexpensive, particularly as compared to concrete block permeable paving, and can he laid quickly over a large surface area of desired shape and dimensions. The flexible impermeable membrane can be cut to the desired shape and dimensions. The three dimensional cellular member may he in the form of a single unitary layer to cover the desired shape and dimensions. Alternatively, the three dimensional cellular member can comprise an assembly of a number of individual modules connected together or abutting each other.

The aggregate mate!ial can he selected from a wide variety of decorative aggregates, such as gravels or stone ehippings, providing a wider choice of the final aesthetic appearance of driveway or part than is available using the known concrete block permeable paving.

Furthermore, the aggregate material, together with the cellular member, defines a reinforced ground surface which has substantially uniform water absorption properties. Water runoff is reduced as compared to the known concrete block permeable paving Also, the continuous waterahsorhing ground surface does not become locally blocked by debris, therefore reducing maintenance to maintain maximtm water harvesting as compared to the known concrete block permeable paving.

Any polymeric matetials used in the rainwater harvesting system are preferably UV stabilised, \Tarious modifications to the illustrated embodiment of the invention will be readily apparent to those skilled in the art,

Claims

CLAIM S1, A rainwater collection system comprising: a. a three dimensional cellular member in the form of a layer having a cellular array of holes extending through the thickness of the layer; b. aggregate material filling the holes of the cellular member, the aggregate material and the cellular member defining a reinforced, ground surface; and c. a flexible impenneahie membrane extending beneath the cellular member and configured to collect rainwater which ha.s fallen onto the reinforced ground. surface and propagated through the aggregate material.
2. A rainwater collection system according to claim i wherein the three dimensional cellular member has a honeycomb structure.
3. A rainwater collection system according to claim I or claim 2 wherein the holes are substantially hexagonal or circular in crosssection.
4. A rainwater collection system according to any foregoing claim wherein the three dimensional cellular member is composed of a polymer.
5. A rainwater collection system according to any foregoing claim further comprising a water permeable layer at least partly, or wholly, covering a tower surface of the three dimensional cellular member, wherein the water permeable layer comprises a grid or mesh, or a textile layer, adapted to separate the aggregate material from material beneath the water permeable layer during use of the rainwater collection system over an extended period.
6. A rainwater collection system according to any foregoing claim thither comprising a first layer of sand separating a lower surface of the three dimensional cellular member and the flexible impermeable membrane.
7. A rainwater collection system according to any foregoing claim further comprising a second layer of sand adjacent. to a lower surface of the flexible impermeable membrane. 9.
8. A rainwater collection system according to clai.m 7 further comprising compacted hardcore materia' adjacent to a lower surthee of the second layer of sand.
9 A rainwater collection system according to any foregoing claim wherein the flexible impermeable membrane comprises huwi rubber.
10. A rainwater collection system according to any foregoing claim wherein the flexible impermeable membrane is inclined a an angle 10 the horizontal to define a water flow direction therea]ong towards a downstream portion thereof
11. A rainwater collection system according to claim 10 further comprising a rainwater collection pipe or tank at the downstream portion.
12. A rainwater collection system according to any foregoing claim wherein the aggregate material comprises gravel.
13. A method of installing a rainwater collection system, the method comprising the steps i. laying a flexible impermeable membrane over a ground area: ii. disposing over the fiexihk impermeable membrane a three dimensional cellular member in the form of a. layer having a cellular array of holes extending through the thickness of the layer; and iii. filling aggregate material into the holes of the celluar member, the aggregate material and the cellular member defining a. reinforced ground surface and the fiexibk impermeable membrane extending beneath the ceflular member and configured to collect rainwater which has fallen onto the reinforced ground surface and propagated through the aggregate material.1 4 A method according to claim 13 wherein the three dimensional cellular member has a honeycomb structure.15. A method according to claim 13 or claim 14 wherein the holes are substantially hexagonal or circular in crosssection.16. A method according to any one of claims 13 to 15 wherein the three dimensional cellular member is composed of a polymer.17. A method according to any one of claims 13 to 16 further cornpnsing the step.between steps i. arid iii. of: iv, providing, a water permeable layer at east partly covering a lower surface of the three dimensional cellular member.18. A method according to any one of claims 13 to 17 further comprising the step, beiween steps i. and ii. of: v. laying a first layer of sand over the flexible impermeable membrane thereby to separate a lower surface of the three dimensional cellular member and the flexible impermeable membrane.19. A method according to any one of claims 13 to 1 8 thrther comprising the step, before step i., of: vi, laying a second layer of sand over which a lower surface of the flexible impermeable membrane is laid ITI step i.20. A method according to claim 19 further comprising the step, hefbre step vi., of: vii.laying a compacted hardcore material over which the second layer of sand is laid in step vi.21, A method according to any one of daims 13 to 2(1 wherein the flexible impermeable membrane comprises butyl tubber.22. A method according to any one of claims 13 to 21 wherein in step i. the flexible impermeable membrane is laid so as to be inclined at an angk to the horizont& to define a water flow direction therealong towards a downstream portion thereof 23. A method according to claim 22 further comprising the step, before step ii., of: chsposmg a rainwater coliection pipe or tank to collect water flow at the downstream portion.24, A method according to any one of claims 13 to 23 wherein the aggregate material comprises gravei.25. A rainwater collection system substantially as hereinhefbre described with reference to the accompanying drawings.26. A method of installing a rainwater collection system substantially as hereinbefore described with reference to the accompanying dravingt