Field of the Invention

[0001 ] The present invention relates to a drainage system. More particularly, the drainage system of the present invention is intended for use in the management and attenuation of stormwater at source.

[0002] The present invention further relates to both a method and apparatus for the collection and/or reticulation of stormwater. More particularly, the apparatus of the present invention is modular in construction.

Background Art

[0003] Presently, stormwater in urban environments is typically collected at the edge of a paved surface, such as a roadway, and directed along a kerbing system into a subsurface drainage reticulation system. The stormwater is directed to either a detention system, a retention system or to outfall. In such an arrangement sediment and pollutants accumulate and concentrate in the water collected. Further, the natural water cycle is also adversely affected.

[0004] None of the well known prior art methods of urban stormwater management effectively manage that stormwater at its source.

[0005] The present invention has as one object thereof to overcome substantially one or more of the abovementioned problems of the prior art, or to at least provide a useful alternative thereto.

[0006] The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia or any other country or region as at the priority date of the application.

[0007] Throughout the specification and claims, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Disclosure of the Invention

[0008] In accordance with the present invention there is provided a drainage system comprising a filter portion and a drainage cell portion, the filter portion being arranged to filter stormwater that in turn flows under gravity to the drainage cell portion, wherein the filter portion is positioned so as to receive stormwater runoff from a paved surface.

[0009] Preferably, the paved surface is a roadway or similar.

[0010] Still preferably, the filter portion is arranged so as to extend at least in part along a kerb provided adjacent the paved surface.

[001 1 ] Yet still preferably, the filter portion is arranged directly above the drainage cell portion.

[0012] Preferably, a layer of free-draining sand is also provided below the drainage cell.

[0013] In one form of the present invention the filter portion is provided in the form of a porous resin bound aggregate.

[0014] Preferably, the resin bound aggregate of the filter portion is provided in prefabricated modules or portions. The drainage cell portion is preferably also formed of a plurality of drainage cells.

[0015] The or each drainage cell is preferably of approximately the same width as the filter portion positioned thereabove.

[0016] In one form of the present invention there is further provided one or more additional drainage tanks connected to the drainage cell. In an embodiment, the additional drainage tanks are arranged alongside or underneath the or each drainage cell, whereby water to be distributed may pass from the or each drainage cell to the one or more drainage tanks. In an embodiment, a layer of free-draining sand is also provided below the one or more tanks. [0017] Preferably, both the drainage cells and drainage tanks comprise a rigid skeleton and a porous sheet material provided about at least a portion thereof.

[0018] In accordance with the present invention there is further provided a method for the collection and/or reticulation of stormwater, the method comprising the method steps of:

a. Directing stormwater run-off from a paved surface toward a kerb; b. Facilitating the stormwater run-off to collect against the kerb whilst simultaneously flowing under gravity downwardly through a filter portion provided thereat;

c. The bulk of the stormwater passing though the filter portion in turn passing into a drainage cell portion from which at least a portion thereof may pass directly into surrounding soil.

[0019] In an embodiment the method further comprises storage water collected in a tank while the water drains form the drainage cell and/or from the tank into surrounding soil.

[0020] In accordance with the present invention there is still further provided an apparatus for the collection and/or reticulation of stormwater, the apparatus a filter portion and a drainage cell portion, the filter portion being arranged to filter stormwater that in turn flows under gravity to the drainage cell portion.

[0021 ] Preferably, the filter portion is arranged directly above the drainage cell portion.

[0022] In one form of the present invention the filter portion is provided in the form of a porous resin bound aggregate.

[0023] Preferably, the resin bound aggregate of the filter portion is provided in prefabricated modules or portions. The drainage cell portion is preferably also formed of a plurality of drainage cells.

[0024] The or each drainage cell is preferably of approximately the same width as the filter portion positioned thereabove.

[0025] In one form of the apparatus of the present invention there is further provided one or more additional drainage tanks, the additional drainage tanks being arranged alongside the or each drainage cell, whereby water to be distributed may pass from the or each drainage cell to the one or more drainage tanks.

[0026] Preferably, both the drainage cells and drainage tanks comprise a rigid skeleton and a porous sheet material provided thereabout.

Brief Description of the Drawings

[0027] In order to provide a better understanding, embodiments of the drainage system of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a partially cut-away top plan view of the drainage system of an embodiment of the present invention;

Figure 2 is a vertical cross sectional view through A-A of the drainage system of Figure 1 , shown in position relative to a road pavement or surface and a kerb; Figure 3 is a vertical cross sectional view through B-B of the drainage system of Figure 1 ;

Figure 4 is a side view through of an alternative drainage system of an embodiment of the present invention;

Figure 5 is a plan view of a first embodiment of a resin bound aggregate block of an embodiment of the drainage system of the present invention;

Figure 6 is a plan view of a second embodiment of a resin bound aggregate block of an embodiment of the drainage system of the present invention;

Figure 7 is a plan view of a third embodiment of a resin bound aggregate block of an embodiment of the drainage system of the present invention;

Figure 8 is a plan view of a fourth embodiment of a resin bound aggregate block of an embodiment of the drainage system of the present invention; and

Figure 9 is a transverse cross sectional view of the block of Figure 5, through an anchor.

Description of Embodiments of the Invention

[0028] In Figures 1 to 3 there is shown, a drainage apparatus 10 comprising a filter portion, for example a plurality of porous, resin bound aggregate blocks 12, and a drainage cell portion, for example a plurality of moulded plastic cells 14. It is preferred that the resin bound aggregate be formed of about 10mm round aggregate, with substantially no fines, that allows water flow through substantially the entire surface area of the block. The moulded plastic cells 14 have a rigid moulded plastic skeleton with the cells formed therein, and with the cells being interconnected. The filter portion is arranged to filter stormwater that in turn flows under gravity to the drainage cell portion, wherein the filter portion is positioned so as to receive stormwater runoff from a paved surface, such as a roadway 16, best seen in Figure 2. The paved surface may take other forms than a roadway 16, such as an outdoor recreation area. The roadway 16 may be formed of various materials, such as asphalt, concrete, paving bricks etc.

[0029] The blocks 12 are rectangular in side profile, as shown in Figure 3. In one example form, the preferred width of the blocks 12 is about 100 mm, whereas the height is preferably about 90 mm. Alternatively, the blocks may be 50mm x 150 mm in end view. The blocks 12 may come in various lengths, as described below.

[0030] As can be seen with reference to Figure 2, the blocks 12 have a spacer 40 on each lateral side and are arranged so as to extend at least in part along the length of a kerb 18 provided adjacent the paved surface of the roadway 16. As such, the blocks 12 as are provided between the roadway 16 and the kerb 18, with the spacers 40 in this embodiment bordering the kerb 18 and the pavement 16. In this manner the fall of the roadway 16 directs stormwater that falls thereon toward the kerb 16 where it passes contacts the upper surface 12A of the block 12 and then passes into and through the porous resin bound aggregate blocks 12, without significant longitudinal flow along the length of the kerb 16.

[0031 ] The relatively narrow surface of the blocks 12 that is presented adjacent both the roadway 16 and kerb 18 minimises any risk of such having to bear any significant weight from traffic or parked vehicles, although preferably they are able to bear vehicle loads. The blocks 12 may readily be removed after installation thereby allowing cleaning or replacement thereof, which in turn maximises the efficiency of the filtration performed thereby.

[0032] The blocks 12 may be arranged so as to stand directly on top of a narrow upper edge 22 of one or more cells 14, such that water filtering downwardly under gravity from the roadway 16 through the blocks 12 can pass directly into the cells 14 therebelow. [0033] The cells 14 are of about the same width as the blocks 12, as shown in Figures 1 and 2, but in this embodiment are approximately oval shaped or thereabouts in profile, as best seen with reference to Figure 3. It is to be understood that the shape of the cells 14 in profile may be altered, without departing from the scope of the present invention.

[0034] In one embodiment the pavement 16 is on a compacted road base 42, which in turn is on compacted earth 44 (such as sand). As can be seen with reference to Figures 1 and 2, a lining, for example a plastic sheet 24, may be provided between the roadway 16 and the blocks 12 and cells 14. The sheet 24 may also extend inwardly of the edge of the footprint of the pavement 16 between compacted earth 44 and surrounding earth/soil 46 on which the pavement 16 is constructed. The sheet 24 both prevents ingress of soil into the cells 14, and also protects the roadway 16 and the compacted earth 44.

[0035] The cells 14 have a layer of porous sheet material, such as geotextile material 26 provided over at least a portion thereof so as to limit the ingress of soil into a cavity or dispersion volume defined by the moulded plastic form of the cells 14. This maximises the surface area available for the dispersion of water that flows into the cells 14 out from the cells into the surrounding soil/earth 46. The interconnection of cells causes a delay in the drainage (so that it is gradual) so as to prevent undue underground erosion.

[0036] In one form of the invention, a plurality of drainage tanks 28 may further be provided to work in conjunction with the cells 14, the tanks 28 being arranged in alignment with and adjacent or in this embodiment below the lower edge of the cells 14, as shown in Figures 2 and 3. In this manner water may pass from the cells 14 into the tank 28 providing still further dispersion volume and surface area for water dispersion, thereby increasing the capacity of the drainage apparatus 10.

[0037] The tanks 28 may be provided in the form of moulded plastic panels that engage together to define a volume, in known manner. A layer of geotextile material 30 is provided about the exposed upper and side surfaces of the tanks 28, as shown most clearly in Figure 2, again to prevent ingress of soil into the tanks 28. The geotextile material 30 may be continuous and/or integrally formed with geotextile material 26. In an embodiment the geotextile 26 material may be fixed to the surface of the cells 14. In an embodiment the geotextile 30 material may be fixed to the surface of the tanks 28.

[0038] A plurality of the tanks 28 may be provided and arranged end to end extending along all or only a portion of the length of the cells 14, as best seen with reference to Figures 1 and 3. The tanks 28 are arranged so as to extend on the side of the cells 14 remote from the roadway 16 (under the kerb 16). In this manner the tanks 28 are not subject to direct loads from the roadway 16.

[0039] A layer of free-draining sand 32 is provided within the earth 46, below the cells and/or, if present, the tanks 28, as shown in Figures 2 and 3. Preferably the sand 32 is provided in a layer that is at least 150 mm deep. The provision of this layer of sand 32 increases the ability of the apparatus 10 and system of the present invention to disperse water that may be received thereby, particularly in a storm downpour event.

[0040] The apparatus 10 of the present invention may be installed prior to the creation of the roadway 16 and the kerb 18, although it is to be understood that with some excavation of existing structures, the apparatus 10 may be retro-fitted.

[0041 ] Referring to Figure 4, in which there is an alternative of the system 100 shown. In this alternative, the system 100 is arranged to receive water flow from a down pipe 50. Underneath the downpipe outlet is a block 12, this time of a suitable shape to capture the flow from the down pipe 50. For example, it may be round or square in plan view. The cells 14 are arranged to extend horizontally underneath the block 12, and may extend horizontally beyond the perimeter of the block 12. The cells 12 are on top of a tank 28. The sides of the tank 28 are covered in geotextile 30. The top of the cells 14 is covered in geotextile 26. Thus water from the down pipe 50 can be filtered by the block 12. Filtered water from the block 12 enters and is distributed in the cells 14. Water can be drained into the surrounding earth through the geotextile 26, and can also enter the tank 28, where it can also be drained into the surrounding earth through the geotextile 30.

[0042] The present invention further provides a system that comprises the apparatus 10 of the present but that also contemplates the manner in which the apparatus 10 interacts with the paved surface and kerb to direct stormwater into the apparatus 10. [0043] The apparatus 10, the system and the method of the present invention are envisaged to provide a largely uninterrupted or uninhibited pathway for stormwater from a paved surface to pass, by gravity, with a coarse filtering step, into a drainage or dispersion volume for attenuation of same.

[0044] Referring to Figure 5, an elongate block 120 of resin bound aggregate is shown, which is suitable for a straight section of pavement. The length may be for example 1000mm. However where the pavement is curved, shorter lengths of block 122, 124 and 126 can be used, as shown in Figures 6, 7 and 8. These may be for example 250mm in length. Block 124 has a flat end 130 and a concave end 132. For a 100mm width block, the radius of the concave end is 50mm. Block 126 has a convex end 134 and a concave end 132. For a 100mm width block, the radius of the convex end 134 is 50mm. Block 126 has a convex end 134 and a flat end 130. The convex end 134 is able to nest in the concave end 132 with the length of the blocks are at an angle to each other. Where a number of such blocks are used a curve of sorts can be constructed of angled flats formed by the blocks 122, 124 and 126.

[0045] Block 120 may have two anchors, such as Reid eye anchors 142, spaced along its length. Blocks 122, 124 and 126 each have one anchor 142. The anchor(s) provide a lug as an attachment point for lifting the block out for inspection, cleaning or replacement. The anchor(s) may have an eye for receiving a reinforcing bar, such as a galvanised metal bar 140, extending along part of the length of the respective block. The reinforcing bar 140 distributes the lifting force along the at least a portion of the length of the block.

[0046] It is envisaged that the system, apparatus and method of the present invention can provide "triple bottom line" benefits relative to competing methods of the prior art. Further, the present invention should provide benefits in terms of both capital and operational expenditure relative to the methods of the prior art.

[0047] It can be seen with reference to the above description that the system, apparatus and method of the present invention minimises 'longitudinal' surface water flows, minimises the transport of stormwater pollutants and increases, relative to the prior art, rates of stormwater collection immediately at source. [0048] Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.