Patent Grant
7056058
The present invention relates to the provision of structures for the adequate drainage of liquids by artificial means and has particular application in the area of landscape gardening and/or the provisions of grass standings or verges. Further embodiments of the invention relates to an improved drainage system for traffic areas such as roadways, train corridors and runways.
Known methods of draining water from relatively large surface areas where the funnelling of water directly into narrow diameter pipes is impractical or impossible, involve the use of a layer of stone or gravel capable of supporting the surface to he drained. Water from this “gravel” layer may then be allowed to percolate into the ground below, follow the lie of the land through said gravel to further conventional drainage channels or pipes or is otherwise evacuated.
Where the area to be drained is a roof-top garden for example, and the roof top is of concrete, the concrete may be covered with a water impervious membrane; the membrane serving to shed water into conventional channels, gutters or drains. Over the membrane there may he a layer of pebbles that is in turn covered by drainage structure in the form of a generally flat filter of a material known as geotextile material. Finally, a layer of soil is laid in which vegetation may be grown is applied over the filter.
The layer of pebbles facilitates drainage of water from the soil to enable adequate oxygen to reach the roots of vegetation therein, and the filter prevents the soil from clogging the layer of pebbles, which would prevent drainage. The lower impervious membrane prevents the ingress of moisture to the building or structure below.
The above described use of pebbles, or gravel or stone in place of the pebbles, bas been found to have various defects. Firstly, such a system may be expensive insofar as stones or pebbles, which are heavy, present transportation problems both in terms of moving them to the site and to lifting them when at the site. Also, the supporting structure may need reinforcing to support the pebbles or the stones. The pebbles may puncture the impervious membrane due to sharp edges and/or excessive weight. The abovedescribed system does not permit the deployment of water or power or other conduits within the system, particularly where such conduits are to be put in after the drainage system has been laid.
In European Patent No. 0244651 it set forth a drainage structure that addresses these problems, and overcomes them by providing that a drainage structure is of generally flat configuration and is cellular in nature, so that water (or other liquid or gas) can pass through it in any direction which means either in a direction transverse to the plane of the structure or in a direction in the plane of the structure.
The structure disclosed in said European Patent comprises a pair of plate members having apertures therein, held in spaced relation by means of spacer members so that there are formed cells, which are hydraulically interconnected with each other, between the plate members. When the structure is in use, it will normally be horizontal or substantially so, and to induce the water flowing through the structure to pass between the cells, the apertures of the top plate member are offset relative to the apertures of the bottom plate member.
As, also shown in the European Patent, at the lower ends of the spacer members, are connecting walls that extend between adjacent spacer members. These walls retain some water in the bases of some of the cells to a level to the tops of the walls, and in use the water eventually cascades over the walls into adjacent cells where there are apertures in the lower plate member, and the water then flows out of the apertures and out of the structure. In so cascading, the water makes some splashing, which in turn adds to the oxygenation of same, improving the quality of the draining water.
The present invention, in one form, is concerned with this aspect of the prior draining structure, and seeks to improve this oxygenation Of the draining water even further and to thereby improve its quality, although it is not necessary that the draining structure of the present invention have all of the specified features of the prior structure, even although they are preferred.
According in one form, the present invention comprises a draining structure which is generally flat in nature and is for use mainly in a horizontal or substantially horizontal disposition, and comprises top and bottom plate members which are held spaced apart by spacer members so that the structure is cellular in nature with the cells hydraulically interconnected with each other, the plate members having apertures therein which are disposed so that the apertures in the top plate member are offset relative to the apertures in the bottom plate member, and wherein there are web walls extending between adjacent spacer members at the lower plate member and form at their top edges, weirs for water which is retained by the web walls, wherein the top edges of the web walls are curved, notched or otherwise shaped or the walls have apertures, to cause the water spilling over these edges into adjacent cells at a varying velocity profile to increase the oxygenation of the water as it splashes on falling from the weir top edges.
Preferably, the web walls are provided adjacent the top and bottom plates, so that the structure is usable equally well either way up, i.e., with either plate upmost. The said edges are preferably curved edges and may be defined by circular, oval or other continuously curving shapes formed in which are webs connecting adjacent spacer members.
This form of the invention provides for better oxygenation of the water passing through the structure whereby its quality can be improved, simplifying disposal into the municipal draining system, and there is the added advantage that the web walls can be such as to provide better resistance of the structure it shear forces applied in the plane of the structure and compression forces applied transverse to the plane of the structure. Shearing can happen in use by virtue of ground movements, especially where the structure is use on sloping ground, and compression loading can occur where the structure is used in circumstances where live loads such as vehicle traffic can be expected.
As in the prior structure, the structure is preferably a one piece moulding of plastics material, although for larger areas, several of the structures can be clipped together by virtue of formations on the structures themselves, or by other means.
It is to he mentioned that the invention is not limited in its use to roof-top gardens. It can be used to provide drainage under roadways, under embankments and elsewhere where drainage is required and/or where surface erosion might be a problem. For instance in car parks or pervious roads to mitigate flood or contaminated waters from roads or highways, the structure can be used as a pervious paving combination with pervious soils and/or plants such as turf. The structure can be designed to allow heavy loads to he impressed thereon without damaging the plant material.
According another form, the present invention comprises a liquid pervious layer support which is generally flat in nature and is for use mainly in a horizontal or substantially horizontal disposition, and comprises top and bottom plate members which are held spaced apart by spacer members so that the structure is cellular in nature with the cells in communication with each other, the plate members having support areas alternating with apertures in a checkerboard arrangement, the apertures are disposed therein so that the apertures in the top plate member are offset relative to the apertures in the bottom plate member, each support area having an opening therein and wherein there are web walls extending between adjacent spacer members at the lower plate member and form at their top edges, weirs for water which is retained by the web walls, wherein the top edges of the web walls are curved, notched or otherwise shaped or the walls have apertures, to cause the water spilling over these edges into adjacent cells at a varying velocity profile to increase the oxygenation of the water as it splashes on falling from the weir top edges.
Preferably the web walls are formed on both the top and bottom plate members.
Other pervious paving on the market has been unsuccessful because of the small capacity of the pervious drainage element and the heat absorbed by the concrete that burns or dehydrates the grass. Other plastic paying does not allow the natural horizontal and vertical growth of the root system of turf. In the case of this structure it allows the natural horizontal growth of the turf root systems, protecting other materials in the system, such as the lining material, from compaction due to the road traffic.
The system will, preferably, require a drainage structure beneath the root zone at a depth of approximately 300 mm to ensure sufficient moisture capacity to allow the robust growth and recovery of the turf.
The invention also extends to a drainage system embodying a structure as aforesaid and a method of drainage using a drainage structure as aforesaid.
Presently the roadways are based upon the old Roman system of having a water impervious top layer that directs water into side gutters where it passes into underground pipes and drains, which are impervious to water, and is directed from a large catchment area into creeks, rivers and the ocean.
Thus when it rains, all of the rubbish and pollution such as oil, grease, vegetation, dog faeces, food stuffs, paper and detergents, are flushed into the drainage system and concentrated into the outfall area, such as a creek, river and the ocean. There is little or no attempt in most of the existing drainage systems to decontaminate this pollution. If any treatment is carried out, it, usually, only involves a filtering out of larger solids. This dumping of the stormwater runoff into the water ways, depletes the oxygen from the waterways, and introduces chemicals which increases, in some cases exponentially, the growth algae, both of which destroys the healthy fauna and flora of the waterways.
Further because the natural water absorbing soils and vegetation have been covered or removed and replaced by water impermeable roads, there is an increase in the amount of runoff in urban areas, than if the area was in its natural state.
Additionally the use of bitumen and concrete on the roads causes a heat sink to absorb and retain the solar energy and in a small way contribute to the heating of the planet.
The present invention, in another form, seeks to ameliorate these problems by providing a roadway or other transport corridor drainage system comprising:
at least the edge surface, of the roadway or other transport corridor, being permeable to water, such that water can flow therethrough;
a permeable drain located at least below said permeable edge surface; and
a water permeable retention tank connected to said permeable drain, such that runoff passes through the permeable surface into the permeable drain and into the permeable retention tank, where the water is stored and flows back into the soil through the walls of the tank.
The invention will now he described by way of example with reference to the accompanying drawings, in which:
A first embodiment of the present invention, as shown in
As can he seen from
Referring now in more detail to
The plate members (5 & 6) are arranged so that the apertures (12) in the top plate member (5) register with the support areas (10) in the lower plate member (6). Thereby, water flowing through apertures (10) must travel between the spacer members (7) that connect between the plate members (5 & 6) at the junctions (11), before the water can exit the lower plate member (6).
By virtue of this construction, the drainage cell (1) can be moulded in one piece in plastics material, and the construction is such that a plurality of cells (13) are defined between the plate members (5 & 6) and the spacer members (7). The spacer members (7) are angled to lie at 45° to the linear sides of the cells (13), to facilitate moulding.
Additionally, the drainage cells (13) are moulded with web walls (15) in both directions and between adjacent spacer members (7) with which the walls are integrally formed, and each wall (15) is provided with an oval aperture (16) to allow for fluid communication between the cells (13).
The apertures (16) do not extend to the surfaces of the support areas (10) in the plate members (5 & 6) so that they define flow weirs as will he explained in more detail in relation to
Referring now to
In consequence, as the water level builds up, so the water will start to cascade over the curved weir edge (17) and onto the supporting strata (9). By using a curved edge (17), the velocity profile of the water cascading over the edge (17) will be varied so that some of the water will be travelling faster than other parts. It will be travelling fastest in the region (18). By so providing a varied velocity profile for the spilling water, when it cascades and splashes onto the underlying support strata (9) as shown at (19) in
Additionally, the webs (15) form shear and compression strengthening means for the entire drainage cell (1) which will make it more resistant to shear loading in the plane of the drainage cell (1) and compression loading in the transverse direction.
A further embodiment in the form of a pervious layer support (20) is shown in
Further the pervious layer support (20) can be filled with growing medium, such that grass and other plants can he grown therein and become a “grass cell. This provides a considerable advantage, as the “grass cell” (20) can be used as a grass standing or verge, upon which motor vehicles can stand or run, as the “grass cell” (20) is also a load bearing member. According to this aspect of the invention, the structure need not be exactly according to the invention set forth above, but could be according to the drainage cell, the subject of the previously mentioned European Patent.
One of the embodiments of the grass cell is shown in
As explained, the “grass cell” (20) provides for the growing of grass, whilst the lower drainage cell (1) is provided for drainage. The same reference numerals have been used to indicate parts already described. The “grass cell” (20), filled with sand or soil of good drainage properties (22) and the grass roots (23), seats on the soil layer (3) which sits on the aggregate layer (2). A goetextile filter material (24) covers the top and bottom of the drainage cell (1).
As shown in
In the use of the arrangement shown in
The invention provides, in one aspect thereof, in a simple and effective manner, for the better oxygenation of water passing through the drainage cell (1) which is of considerable importance or environmental reasons.
In the second aspect, the invention provides a structure use wherein growing medium fills the structure and plant roots grow therein, which roots can grow along the plane of the structure as well as through the structure. Providing such an arrangement means that the roots will be well aerated, which means that water passing the root system will be well aerated. In this second aspect, the structure. need not he the same as in the first aspect, although it is advantageously so.
The added strength of the cell will make it more suitable for use in locations where the ground is sloping, or is known to be subject to ground movement, and the carrying of loads.
As indicated, the grass cells and drainage cells are suitable for use in roof-gardens.
It is preferred that the structures be moulded in one piece in plastics material, hut again this is not an essential requirement of the invention.
The spacer members maintain the plate members in generally parallel relationship, but again this is not completely essential.
Also as specified in the European parent, the drainage cell defined according to the invention has the advantage that small pools of water will collect in the lower portions of the cells below the weir edges, and this can be useful in circumstances where no water flow occurs for a prolonged period of time. The collected water can evaporate and feed the growing material located above the drainage cell. Additionally, by virtue of the construction of the structure, the maintenance of oxygen adjacent the roots of any plants above the upper plate member is maintained, and by virtue of the cellular structure free flow of water and oxygen in any horizontal direction within the drainage cell can be maintained. Additionally, service pipes for liquid and power can be inserted into the structure after it has been placed in position.
The structure can be fabricated in any suitable plastics material, but polypropylene has been found to he particularly suitable. The structure is relatively rigid and shear resistant whilst being of relatively lightweight. The structure may be of the specific dimensions mentioned in said European patent.
The structure can be used in conjunction with a filter membrane as described or in any suitable manner.
The edges of the drainage cells or the “grass cells” may be provided with tongues and groove, or with a groove (29) into which a mating pin fits to enable them to be connected with similar structures to provide a large area of coverage.
In another form the present invention relates to an improved drainage system for traffic areas such as roadways, train corridors and runways.
An existing prior art roadway drainage system incorporates a water impervious road surface that is sloped to direct water into a gutter, where the water is directed along to flow into an underground water impervious drainage system where the water is discharged into a creek, river or the ocean. As shown in
In this embodiment the lower gutter (32), road surface (32), and underlying sub-base (33), adjacent the gutter, are removed by any suitable means and is replaced by an infiltration area. A trench (34) is dug and a water impervious liner (35) is positioned against the roadway side of the trench (34), with a water permeable geotextile (24) on the curbside of the trench (34). The impervious liner (35) could be replaced with a water permeable geotextile similar to that on the other side of the trench. Placed at the bottom of the trench (34) are drainage modules (36). Generally these drainage modules (36) are hollow with perforated walls made from plastics, and are load bearing. The modules could be constructed as shown in Australian patent application no.593085, or could be constructed as shown in Australian patent application no. PQ3490, wherein the modules (36) have walls (37) composed of a lattice of thin web members (38). The modules (36) are placed, on a geotextile sheet (39), end to end along the trench, and also stacked one on top of the other to the required height, and wrapped in the geotextile sheet (39).
Suitable aggregate material such as gravel (2) surrounds the thus wrapped drainage modules (36), and a geogrid (40) that is permeable to water, is laid on top of the gravel (2). A suitable concrete edge (41) is placed against the cut existing gutter (31) and a layer of filter soil (42) is placed on top of the geogrid (40), with a honey combed supporting “grass blocks” (43) resting on the filter soil, and filled with soil and having grass (44) growing therein.
These blocks could be of any suitable dimensions and could be made of individual blocks as shown in
As shown in
Further instead of the “grass blocks” (43), “grass cells” (20), as shown in
Both “grass cells” (20) and “grass blocks” (43) are strong enough to support the weight of vehicles and pedestrians, and because of their construction prevents compaction of the soil both within the “grass cells” (20) and “grass blocks” (43) and below them. Thus allowing for the runoff to quickly percolate through the “grass cells” (20) and “grass blocks” (43).
Therefore during rain, water runs off the impervious road surface (30) and onto the “grass cells” (20) or “grass blocks” (43) of the infiltration area, where the water percolates through the soil (51), into the filter soil (42), which can be a mixture of sand and soil, where some pollutants are absorbed and broken down by bacteria. The water then percolates through the aggregate material (2) and can pass into the surrounding soil (52), or flow into the water permeable channels formed by the drainage modules (36), where the water can be temporarily stored for percolation back into the surrounding soil (52), an/or can flow along the water permeable channels to a storage area for percolation back into the soil or for supplying water for sprinkler systems or the like.
A further embodiment is shown in
As shown in
In the case of a medium density traffic area, the infiltration area extends further out into roadway, and could be up to 2.5 meters wide, as shown in
In low traffic areas the entire road could be made into an infiltration area, as shown in
The drainage cells could be of any construction, in which two substantially parallel perforated surfaces are rigidly held apart by spacer members and the like to form a hollow passageway therebetween. A suitable drainage cell is described in Australian Patent no. 593085.
This technology can readily be applied to highway situations to assist in purifying water and the air, as shown in
The above technology could also be applied to car parks, as shown in
As shown in
Other areas of the car park are constructed as shown in
Thus water percolates through the filter soil (42) where it is absorbed and the excess percolates into the percolation tanks (57). The percolation tanks (57) are located near the trees (59) to take up water that is collected in the percolation tanks (57).
The drainage cells (1) extend into other areas of the car park and are connected to feed excess water into the percolation tanks (57).
A variation of the embodiment shown in
An additional embodiment of the present invention is shown in
A detailed view is shown in
The infiltration area (58) comprises a filter soil (42) or EcoSoil (a trade mark of Atlantis Corporation Pty Ltd) shaped as a shallow ditch and covered in turf or grass (4) and with other assorted vegetation to take up water. The filter soil (42) or EcoSoil rests upon a layer of aggregate material (2). Located beneath the aggregate material (2) are drainage modules (36) wrapped in geotextile sheets (39). Drainage cells (1) extend beyond the drainage modules (36) in the infiltration area (58) to direct water into the drainage modules (36). Thus water is filtered as it passes through the filter soil (42) or EcoSoil, where water is retained for take up by the grass (4), while the excess percolates into the channels formed by the drainage modules (36), where the water flows there along, and is percolated back into the soil.
This technology could also be used with areas that are covered by concrete or the like such as driveways or car ports, as shown in
In the case of roads on hillsides, the technology can be applied as shown in
In another embodiment existing water impervious streets can be modified as shown in
Whilst this system still returns water to the river systems, the water has been purified, by passing through the grass (4) and the EcoSoil or filter soil (42), to remove all solid pollutants and to absorb other pollutants in the grass and soil where they are broken down by biological action.
Thus the present invention uses vegetation and soil to, both, filter out pollutants and to absorb runoff, and to hold the water underground for slow release back into the soil to stimulate plant growth. Thus erosion and the pollution of the waterways are reduced.
It should be obvious to people skilled in the art that modifications and alterations can be made to the above embodiments without departing from the scope and the spirit of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| PP8843 | Feb 1999 | AU | national |
The present application is a divisional application from U.S. patent Ser. No. 09/914,333, lodged Aug. 24, 2001 now U.S. Pat. No. 6,779,946.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3990247 | Palmer | Nov 1976 | A |
| 5030343 | Urriola | Jul 1991 | A |
| 5250340 | Bohnhoff | Oct 1993 | A |
| 5447389 | Olson | Sep 1995 | A |
| 5810510 | Urriola | Sep 1998 | A |
| 5848856 | Bohnhoff | Dec 1998 | A |
| 6095720 | Stark | Aug 2000 | A |
| 6736569 | Lee | May 2004 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20050100401 A1 | May 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 09914333 | Aug 2001 | US |
| Child | 10722981 | US |
