Drainage cell

Abstract

 A drainage cell (1) for a ground water handling system, the cell comprising a through channel (25), the cell comprising one or more transverse members (5) extending from or adjacent the edge of the through channel (25) towards a base of the cell (1) for deflecting, in use, particulates or debris carried in a fluid flowing in said through channel (25).

Description

[0001] The present invention relates to a drainage cell, a drainage assembly, a support element for a drainage cell and a drainage system for ground water or storm water handling and particularly, but not exclusively, for removing silt and debris from water.

[0002] Modern building and agricultural methods are such that water which would historically drain away by natural seepage is no longer able to do so, which leads to floods, soil erosion and the like.

[0003] As a consequence, water falling as rain or formed from melting ice or flooding cannot return to the ground to form ground water. Instead, it often flows away from a locality where it is generated, depriving the ground of its beneficial effects, and overflowing normal drainage systems. This can therefore lead to flooding or erosion for example.

[0004] It is known to provide a drainage cell, which can be installed underground and which comprises perforated boundary walls. A number of such cells may be modularly assembled to provide a system for ground water attenuation. Attenuation of the water is understood to mean that the period during which water is held at a location where it arises, for dispersal into the ground at that area without flowing away therefrom, is increased. Alternatively, the water may be dispersed into a piped drainage system at a controlled rate. In this way, the water is able to disperse into the ground at a more steady rate.

[0005] The present invention seeks to mitigate or at least ameliorate the disadvantages of the known devices.

[0006] According to a first aspect of the present invention, there is provided a drainage cell for a ground water handling system, the cell comprising a through channel, the cell comprising one or more transverse members extending from or adjacent the edge of the through channel towards a base of the cell for deflecting, in use, particulates or debris carried in a fluid flowing in said through channel. Typically the fluid flowing though the drainage cell is water, but other fluids may also be used in the present device. The particulates and debris may include any form of material which is carried in the fluid, for example sand, silt, mud and other organic matter.

[0007] Preferably, the transverse members extend from substantially the edge of the through channel towards one or more lateral sides of the cell.

[0008] Preferably, the transverse members extend across the width of the cell, except across the through channel. Portions of the transverse members may partially extend into the through channel.

[0009] Preferably, the transverse members are orientated substantially orthogonal to the longitudinal direction of the through channel. Alternatively, the transverse members may be angled relative to the longitudinal direction of the through channel, i.e. at an angle less than 90°.

[0010] Preferably, the transverse members are planar. The transverse members may alternatively be ribbed, corrugated or otherwise configured to efficiently remove, in use, debris from a fluid flowing in the through channel.

[0011] Preferably, the transverse members are orientated in substantially vertical planes substantially orthogonal to the longitudinal direction of the through channel. Alternatively, the transverse members may be inclined against the direction, in use, of a fluid flowing in said through channel.

[0012] Preferably, the edges of the transverse members delimit the through channel. Portions of the transverse members may extend into the through channel and thereby serve to deflect larger debris.

[0013] Preferably, the through channel comprises a perforated channel wall. The channel wall may preferably extend fully around the channel. Alternatively, the channel wall may extend partially around the channel, for example only on the lower most side of the channel, i.e. the side nearest the base of the cell, or both top and bottom sides of the channel. The perforations in the channel wall may be slit shaped or circular apertures or any suitable form.

[0014] Preferably, the channel wall delimits the through channel.

[0015] Preferably, one or more fluid connections are provided from a side of said channel. These fluid connections may be provided from any position around the inner perimeter of the channel.

[0016] Preferably, the cell further includes an auxiliary channel fluidly connected to said through channel via said fluid connections. Fluid may therefore be removed from the through channel to flow in the auxiliary channel.

[0017] Preferably, the auxiliary channel adjoins the base of said cell. If positioned below the through channel, an auxiliary channel may serve to provide an outlet for debris and particulate matter which may have been deflected, in use, from a fluid flowing in said through channel. The base of the auxiliary channel is configured to carry a fluid flowing therethrough and may therefore be impervious to a fluid flowing through said auxiliary channel.

[0018] Preferably, the auxiliary channel has a U-shaped cross-section. The cross-section may be formed with any other suitable shape, such as semi-circular and square. The auxiliary channel may have a width which narrows towards its base. The auxiliary channel may be open at its end. The auxiliary channel may be formed in a number of sections and configured at an end of each section to connect with an adjacent section. The auxiliary channel may be formed as a single piece extending under a number of drainage cells.

[0019] Preferably, the auxiliary channel comprises reinforcing ribs. These ribs may serve to provide structural stiffness to the auxiliary channel. This ribs may be formed externally to the channel. Ribs may also be provided along the length of the auxiliary channel and extend into the auxiliary channel, i.e. into the flow of fluid in said auxiliary channel. Such ribs may serve to reduce the fluid flow rate and deflect further debris or sediment from a fluid flowing in the auxiliary channel in use.

[0020] Preferably, the cell comprises webs which adjoin adjacent transverse members.

[0021] Preferably, the webs extend from substantially the edge of the channel towards the base of the cell.

[0022] Preferably, the webs extend across the cell, except across the through channel.

[0023] Preferably, the webs are planar. Alternatively, the webs may be curved or semicircular.

[0024] Preferably, the webs are orientated in substantially vertical planes, parallel to the longitudinal direction of the through channel.

[0025] Preferably, the webs are arranged to restrict, in use, the flow of water orthogonal to the longitudinal direction of the through channel.

[0026] Preferably, one or more fluid connections extend from the channel through an external boundary of the cell. In this way water may flow from the through channel if the flow capacity thereof is exceeded.

[0027] Preferably, the transverse members and said webs form said fluid connections. Such fluid connections may be formed as square channels or conduits.

[0028] Preferably, the fluid connections extend through the base of the cell. Fluid connections provided from the through channel through the base of the cell may be used to permit, in use, sediment or debris to flow from the main through channel.

[0029] Preferably, the fluid connections extend through the top of the cell. Should the flow capacity of the through channel be exceeded, said fluid connections permit fluid to flow from the through channel. Such fluid connections may also permit fluid from an attenuation volume above the drainage cell to pass into the through channel.

[0030] Preferably, one or more lateral fluid passages are formed in the side of said through channel. Such side passages permit, in use, a fluid flowing in the through channel to flow, for example, into an attenuation volume adjacent the drainage cell.

[0031] Preferably, the opening of each lateral passage in the side of the channel is spaced above the base of the channel. This seeks to ensure that, in use, a fluid flowing in the through channel may only flow through the lateral passage when the fluid exceeds a particular depth.

[0032] Preferably, the cell comprises an attenuation volume adjacent said through channel, the attenuation volume being fluidly connected to said through channel via said one or more lateral passages.

[0033] Preferably, the through channel is formed with a circular cross-section. The cross-section of the through channel may alternatively be square or hexagonal or any other suitable shape. Preferably, the through channel is formed with a curved, in embodiments semi-circular form at the top and bottom of the channel. Between the curved forms, the channel is preferably formed with substantially parallel straight sides.

[0034] Preferably, the cell comprises vertical support elements. The vertical support elements may be formed as hollow cylinders with a circular or square cross section.

[0035] Preferably, the cell is provided with one or more perforated boundary walls. The boundary walls may be formed between adjacent support elements.

[0036] Preferably, the channel wall is formed integrally with the cell.

[0037] Preferably, the channel wall is formed as a separate part.

[0038] Preferably, the channel wall is spaced from the transverse members.

[0039] Preferably, the cell is formed of two half cells. Such a form may assist manufacture using, for example, plastics or composite materials.

[0040] Preferably, a connecting member is provided for connecting the two half-cells together, which connecting member has connecting means which connect with corresponding parts of each half cell. The connecting means may include male connections to connect with corresponding female connections.

[0041] Preferably, the half cells are provided with fixing means, to fix the cell to the connecting member. Preferably, the fixing means are provided as clips to engage with corresponding apertures in the connecting member.

[0042] Preferably, the connecting member is provided with clips to engage with corresponding apertures in the half cells. The fixing means may be provided in the support members.

[0043] Preferably, the drainage cell is configured to receive connecting members of various thicknesses to form a drainage cell of predetermined exterior dimensions. In this way, the drainage cell may be formed in a suitable dimension to fit in a matrix of drainage cells.

[0044] Preferably, an insert is provided which is configured to locate within an inner circumference of an open end of the channel.

[0045] Preferably, the insert is provided with locating means, in the embodiment a plurality of grooves, to engage with a corresponding protrusions in the open end of the channel. A pipe may be connected to the insert.

[0046] Preferably, baffling or deflecting elements, may be provided in the through channel for baffling or deflecting silt in a fluid flowing through the channel. The baffling elements preferably serve to knock silt into the base of the through channel. The baffling elements may be formed as generally vertical ribs spaced along the channel length on opposed sides of the channel which extend or project into the through channel. The vertical ribs may face into the channel. The vertical ribs may be angled relative to a transverse direction of the channel. The vertical ribs may be provided on support elements adjacent the channel. Pairs of vertical ribs may be provided on a support element adjacent the channel, the vertical ribs being angled relative to each other.

[0047] Preferably, the cell forms a module of a drainage assembly according to a second aspect of the present invention. The drainage assembly may include any number of suitable cells.

[0048] Preferably, the drainage assembly comprises a plurality of water attenuation cells including one or more drainage cells according to the first aspect of the invention or any preferable feature thereof. Geotextile membrane may be used at the external boundaries of the drainage assembly.

[0049] Preferably, the cells are provided with lateral or shear connecting means to connect adjacent and/or vertically stacked cells together. Such connecting means may include rod sections which may be inserted into corresponding holes in adjacent cells to prevent relative lateral displacement.

[0050] According to a third aspect of the present invention, there is provided a drainage cell comprising an attenuation volume, the cell comprising a channel adjoining a boundary of said cell and being fluidly connected to said attenuation volume.

[0051] Preferably, the channel is formed separately from and joined to form part of said cell. Alternatively, the channel may be formed integrally with the cell.

[0052] According to a fourth aspect of the present invention, there is provided a support element suitable for supporting a drainage cell, the support element comprising closed lateral sides, the support element including a drainage channel extending through the element, said drainage channel being configured, in use, to carry a fluid flowing in said drainage channel. To this end, the external lateral side walls of the element may be impervious to fluid to prevent the ingress of soil or water to the drainage channel. The base of the channel may be impervious to fluid such that the fluid is carried in the channel and does not pass through. The base wall of the support element may be closed in form. The support element, may, in use, be located in a channel formed in a foundation, for example a concrete foundation. The drainage channel may be open at either end to permit connection with a drainage channel of an adjacent support element. The drainage channel may be used to collect or carry debris or sediment from a drainage cell or attenuation volume fluidly connected thereto. The drainage channel may be connected to a manhole, for the collection of debris or sediment or the like. The support element may be open at its ends to permit maintenance.

[0053] Preferably, the support element includes a fluid connection, which in use, fluidly connects a drainage cell supported on said element to the drainage channel. The fluid connection may be provided by holes or apertures in the support element which correspond with the fluid conduits or outlets in a drainage cell above.

[0054] Preferably, the support element is formed as a parallelepiped. Alternatively, the support element may be formed in any suitable shape to accommodate one or more drainage cells located directly thereon.

[0055] Preferably, the drainage channel is formed as an open channel. A perforated lid may be provided across the open channel to support a cell above. Ports or slots may be provided in the side of the channel to allow water to drain down in to the channel from the side structure.

[0056] Preferably, the channel is formed with a substantially square cross section. The cross-section may be any other suitable shape, for example rectangular, circular or V-shaped.

[0057] Preferably, the width of the drainage channel increases away from a base of said channel.

[0058] Preferably, the channel width extends substantially the full width of the support element. In this way, the drainage channel provides a large are to collect fluid.

[0059] Preferably, the fluid connection is formed as a plurality of spaced through openings formed in a surface of said support element. The base of the channel may be provided without perforation. The base of the channel may also form the base of the support element.

[0060] Preferably, the through openings are formed as rectangular slits. The through openings may be performed to permit, in use, fluid flowing from a drainage cell to readily flow into the channel of the support element.

[0061] Preferably, the drainage channel is located along the middle of the support element. The location of the drainage channel may however be chosen according to, in use, a drainage cell thereabove.

[0062] Preferably, the drainage channel includes a plurality of side apertures, the lowermost part of said apertures being spaced from the base of the drainage channel. This arrangement seeks to prevent sediment or debris from flowing out of the drainage channel on either side, but permits fluid to flow into and out of the drainage channel. Preferably, an inclined channel is provided at either side of said drainage channel. The inclined channel is angled to seek to permit fluid to flow to the drainage channel. An inclined channel may be provided on either side of the drainage channel. In this way, fluid from a drainage cell or attenuation volume which may include debris, silt or sediment or the like, may flow as directly as possible, e.g. vertically down, to the support element and then to the drainage channel via the inclined channels.

[0063] Preferably, the drainage channel is configured to connect, in use, with a drainage channel of an adjacent support element For this purpose, one of the drainage channels may be formed with a male connection to engage with a corresponding female connection of an adjacent support element.

[0064] Preferably, the outer boundary of the support element comprises a plurality of spaced cylindrical supports. The cylindrical supports may be formed, for example, with a square or circular cross section to provide suitable support for drainage cells or attenuation volumes located thereabove.

[0065] Preferably, the support element includes one or more connection means for receiving a connection element for preventing, in use, lateral movement of a drainage cell located on said support element. The connection means may include apertures, for example circular holes, for receiving a cylindrical connecting rod which may be inserted in both the support element and a corresponding connection means in the drainage element thereabove.

[0066] Preferably, the drainage channel includes guide means for guiding a wheeled device along said drainage channel. The guide means may include tracks or guide rails formed in the drainage channel or adjacent thereto.

[0067] Preferably, the wheeled device includes a camera. The wheeled device may include means for cleaning the drainage channel.

[0068] A kit may be provided comprising a support element according to the fouth aspect of the invention and any preferably feature thereof and a drainage cell according to the first aspect or any preferable feature thereof.

[0069] According to a fifth aspect of the present invention, there is provided a drainage system comprising one or more drainage cells according to a first aspect of the invention or any preferable feature thereof, and/or one or more drainage cells for a ground water handling system and one or more support elements according to a fourth aspect of the present invention or any preferable feature thereof.

[0070] Preferably, the support elements are arranged horizontally adjacent the drainage cells, to form a base layer of the drainage system. In this way the base layer includes a combination of both drainage cells and support elements. The drainage cell may not be provided with a through channel in accordance with a first aspect of the invention, but may be formed as an attenuation volume. Further layers of drainage cells or attenuation volumes may be provided.

[0071] Preferably, the support elements are arranged below a base layer comprising drainage cells.

[0072] Preferably, the support elements form a base layer of the system.

[0073] According to a further aspect of the invention, there is provided a kit comprising a drainage cell according to the first aspect of the invention and a support element according to the fourth aspect of the invention. The support element may be used to provide the auxiliary channel for the drainage cell.

[0074] The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is side view of a cell of an embodiment of a first aspect of the present invention;

Figure 2 is an exploded view of the cell of Figure 1;

Figure 3 is a perspective view of the cell of Figure 1;

Figure 4 is a perspective view of a cell of a further embodiment of a first aspect of the present invention;

Figure 5 is a partially exploded view of the cell of Figure 4;

Figure 6 is an exploded view of a cell of Figure 4;

Figure 7 shows a half cell of a further embodiment of a first aspect of the present invention;

Figure 8 is an exploded view of the embodiment of Figure 7;

Figure 9 is an assembled view of the embodiment of Figure 7;

Figure 10 is a cross section through the embodiment of Figure 7;

Figure 11 is a detail view of the embodiment of Figure 7;

Figure 12 is a cross section through the embodiment of Figure 7;

Figure 13 is a cell of a further embodiment of the present invention;

Figure 14 is an exploded view of the embodiment of Figure 13:

Figure 15 is a perspective view showing an embodiment of the cell of the present invention installed in a water handling system according to a third aspect of the present invention;

Figure 16 shows a further embodiment of a cell according to a first aspect of the present invention;

Figure 17 shows a further embodiment of a cell according to a first aspect of the present invention;

Figure 18 shows an embodiment of a support element according to a fourth aspect of the present invention;

Figure 19 shows a further embodiment of a support element according to a fourth aspect of the present invention;

Figure 20 shows a schematic representation of an embodiment of a fifth aspect of the present invention;

Figure 21 shows a schematic representation of a further embodiment of a fifth aspect of the present invention;

Figure 22 a schematic representation of a further embodiment of a fifth aspect of the present invention;

Figure 23a shows an embodiment of the present invention connected to a manhole;

Figure 23b shows a further view of the embodiment of Figure 23a connected to a manhole;

Figure 24 shows a further embodiment according to a fourth aspect of the present invention;

Figure 25 shows a top perspective view of a further embodiment according to a fourth aspect of the present invention;

Figure 26 shows a bottom perspective view of the embodiment of Figure 25;

Figure 27 shows an end view of a further embodiment according to a fourth aspect of the present invention;

Figure 28 shows a top perspective view of the embodiment of Figure 27;

Figure 29a shows a perspective view of the embodiment of Figure 27 integrated with a drainage cell;

Figure 29b shows an exploded view of the embodiment of Figure 29a;

Figure 30 shows a further embodiment of a drainage cell according to a first aspect of the invention;

Figure 31 shows a view of a half cell of Figure 30;

Figure 32 shows an enlarged view of the cell of Figure 30;

Figure 33 shows a cross-sectional view of further embodiment of a drainage cell according to a first aspect of the invention;

Figure 34 shows a cross-section showing the connecting means between the two half cells of Figure 33;

Figure 35 shows a cross-section showing a further connecting means between the two half cells of Figure 33; and

Figure 36 shows a cross-section of an insert in the cells of Figure 33.

[0075] Figure 1 shows a cell generally at 1 of an embodiment according to a first aspect of the present invention. The cell has the form of a parallelepiped. The cell 1 comprises two identical half-cells 1 a, 1b. Each half-cell comprises a base 2a, 2b. The longitudinal walls of each half-cell 1 a, 1b comprise a plurality of vertical support elements 3a, 3b, which extend from the base 2a, 2b of each half-cell 1 a, 1b. The vertical support elements 3a, 3b are hollow, which serves to reduce the weight of the cell and facilitates manufacture using injection moulding techniques, for example. The vertical support elements 3a, 3b have a D-shaped cross-section, although any other suitable cross-section may be used, such as square as seen in Figure 4.

[0076] A transverse member formed as a rib 4 is provided on each side of the vertical support elements 3a, 3b and extends laterally inwardly from the base of each half-cell 1 a, 1 b such that a plurality of ribs 4 are spaced along the longitudinal length of each half-cell 1 a, 1 b. The ribs 4 are formed as planar elements and are orientated in vertical planes orthogonal to the longitudinal length of each half-cell 1 a, 1b. The edge of each rib 4 distal the base has a curved generally semi-circular edge 26a, 26b and when the two half-cells 1 a, 1 b are joined together, the semi-circular edges of the ribs 4 of the top and bottom half-cells 1 a, 1 b delimit a generally circular channel 25 through the cell 1. The through channel 25 is a channel which extends through opposed end boundary walls of the cell 1. It is envisaged that the ribs may be formed not as planar ribs, but in any other suitable form to deflect sediment, silt, debris or the like carried in a fluid flowing through the channel. Other shapes of rib are envisaged to form, for example, a square, oval or flat-bottomed channel. The channel may have a different shape in either half-cell.

[0077] Webs 5 are provided between adjacent ribs 4 on each half-cell 1a, 1b. A plurality of spaced webs 5 are provided. The webs 5 extend from the base of each half-cell 1 a, 1 b respectively. The webs 5 are planar and are orientated is vertical planes parallel to the longitudinal direction of the cell 1 and channel 25 formed therein. Each web 5 extends from the base 2a 2b of each half-cell 1 a, 1 b to a level in line with the semi-circular edge 26a, 26b of the ribs 5 and thereby also delimit the edge of the channel 25. The webs 5 and ribs 4 provide rigidity to the cell 1. In use, the cell 1 is located underground and the vertical support elements 3a, 3b, ribs 4 and webs 5 serve to resist load applied to the cell 1 and maintain the structural integrity of the cell 1 and channel 25.

[0078] In the lower half-cell 1 a, the ribs 4, which are orthogonal to the webs 5 form fluid connection in the form of rectangular ducts 7a, 7b which fluidly connect the channel 25 through the base of the cell 1 in the bottom half cell 1 a. Similarly, the ribs and webs of the upper half-cell 1b fluidly connect the channel 25 through the top of the cell 1, i.e. the base of the upper half-cell 1b. It is also envisaged that other ducts or fluid connections may be provided for fluidly connecting the channel through the base or bottom and/or top of the cell.

[0079] In order to join the two half-cells 1 a, 1 b together, a connecting member 6 is provided along the top longitudinal edge of the half-cells 1 a, 1b. The connecting member comprises a planar strip with male connecting pieces 13 on each side. The male connecting pieces 13 corresponding with and locate in the female D-shape holes in the vertical support elements 3a, 3b. Other connecting means are also envisaged, for example adhesive. Instead of D-shaped holes, the corresponding connecting pieces may have any other suitable form, for example circular or square for example.

[0080] As may be seen in the side view of the cell in Figure 1, the outermost webs 14a, 14b extend partially from the base 2a, 2b to the top of each half-cell 1 a, 1 b. In this way, the webs serve to restrict the opening between the vertical support elements 3a, 3b at the base of the cell 1.

[0081] The assembled cell 1 is shown in Figure 3. In use, water flows into the channel 25. The webs 5 serve to prevent all the fluid flowing immediately out of the cell. The ribs 4, which are positioned transverse to the normal flow of fluid through the channel 25, serve as flow retardant means and seek to encourage and deflect particulates, such as silt and debris, dispersed in the fluid to sediment and pass out of the cell through the ducts 7a. The cell 1 may form a module of a drainage system. In this way, debris and silt is removed from the fluid flowing into the cell 1, before it passes into adjoining water attenuation cells (not shown). This seeks to prevent silt being deposited in the adjoining attenuation cells and therefore prevents the volumetric capacity of the attenuation cells being reduced. The gaps between the vertical support elements 3a, 3b allow fluid to pass into adjoining attenuation cells. If the flow of water into the cell 1 is greater than the capacity of the channel 25, water may also pass out of the ducts 7b in the top half-cell into adjoining attenuation cells of the system.

[0082] The channel 25 of the cell 1 also allows an inspection device such as a remote robot camera to be passed down the channel 25 to inspect the drainage system.

[0083] Figure 4 shows a further embodiment of the present invention. The cell 101 is formed similarly to the cell 1 of Figure 1 comprising a cell 1 with a through channel 125. In addition, between adjacent support elements 103, there is provided a boundary web 108. The boundary web 108 is formed as a lattice 111 such that fluid may flow between adjacent support elements 103.

[0084] In the embodiment, the channel 125 is also provided with a channel wall 109, which extends in the longitudinal direction of the channel 125. The channel wall is provided with apertures in the form of spaced rectangular slits 110 over its full surface. The long side of the rectangular slits 110 are orientated in the embodiment shown transverse to the longitudinal direction of the channel 125. The slits 110 provide a fluid connection from the channel 125 to the ducts 107 formed by the ribs and webs. Other forms of aperture are envisaged in the channel to provide a fluid connection to the ducts. The channel may also be formed as a mesh.

[0085] As shown in Figures 5 and 6, the channel wall 109 is formed separately from the cell 101. The channel wall is formed as two corresponding half walls 109a, 109b, each with a semi-circular cross section. The semi-circular half walls 109a, 109b are formed with a flange 112a, 112b along each straight edge. The flanges 112a, 112b form a connecting member, which is provided with male connecting members 113a, 113b to engage with corresponding female holes 117 in the support elements of each of the half-cells 101 a, 101 b.

[0086] Figure 7 shows a further embodiment of a cell 201 with a through channel according to the present invention formed similarly to the embodiment of Figure 4. Instead of the D and square shaped support elements of the embodiments of Figures 1 and 4, the cell 201 comprises a plurality of hollow cylindrical support elements 203 spaced along the longitudinal boundary walls and also along and adjacent the outermost webs 214a, 214b. On the boundary walls of the cell 201, spacer elements 217 are provided between adjacent support elements 203. The spacer elements 217 generally flat corss-members which are formed between adjacent support elements 203. Between the support elements 103 and between adjacent spacer elements 217, a lattice structure 211 is provided, to allow fluid to flow between the support elements 203 of the boundary wall of the cell 201. The volume formed between the outermost webs 214a, 214b and the lattice structure 211, provides a fluid attenuation volume. Instead or the lattice structure, any other water permeable structure is envisaged.

[0087] As shown in Figure 8, the cell 201 is formed as two half-cells 201 a, 201 b. As with the embodiments of Figures 1 and 3, transverse members in the form of ribs 204 are provided orthogonal to the longitudinal direction of the channel 225 and webs 205 are provided parallel to the longitudinal direction of the channel to form ducts 207 fluidly connected with the channel and the base of each half-cell 201 a, 201 b. In the embodiment of Figure 7, the outermost lateral webs 214a, 214b extend to the top of each respective half-cell 201 a, 201 b. This increases the restriction to lateral flow of fluid from the channel 225.

[0088] The channel 225 is provided with spaced lateral passages 215 at the top of each half-cell 201 a, 201 b. These lateral passages 215 allow fluid to flow from the channel 225 if the flow of fluid into the cell 201 exceeds its capacity.

[0089] As shown in Figure 8, the two half-cells 201 a, 201 b are joined together with a planar connecting member 206 which is formed to receive the tops of the support elements 203 of each half-cell 201 a, 201 b. A curved, in the embodiment generally semi-circular channel wall 209 is formed integrally with each half cell 201 a, 201 such that when the two half-cells are joined together, a channel 225 with a substantially circular cross-section is formed.

[0090] As shown in Figures 8 and 9, an auxiliary channel 216 is provided under the base of the bottom half-cell 201a. The auxiliary channel 216 is fluidly connected to the through channel 225 via the ducts 207. The auxiliary channel 216 serves to collect silt. The flow of water through the ducts 207 into the auxiliary channel 216 carries silt out of the system to be captured by a chamber (not shown) downstream of the cell 201. The auxiliary channel 216 therefore self cleans. In addition, if needed, the silt collected may be jetted out of the auxiliary chamber 216 using a high pressure water jet, should the auxiliary chamber 216 become blocked. Further, for maintenance, water may be introduced into the auxiliary channel 216. In this way, water will then flow through the ducts and other flow paths in the system therefore serving to flush the system.

[0091] The channel wall 209 is formed integrally with and joins the ribs of each half-cell 201 a, 201 b, although it will be understood that a separate channel wall may be used as in the embodiment of Figure 3.

[0092] The auxiliary channel 216 is preferably formed as a substantially U-shaped channel. The channel may be formed with other suitable cross sections, such as square bottomed, V-shaped or semi-circular for example. The auxiliary channel 216 is connected to the cell base of the lower half cell 201a. The auxiliary channel 216 comprises a plurality of reinforcing ribs.

[0093] In the embodiment shown, the auxiliary channel 216 is open along its full length, the open channel being connected to the bottom or base of the drainage cell 201. The auxiliary channel could be closed partially along its length. The auxiliary channel could be formed integrally with the drainage cell. The auxiliary channel may be formed separately and joined to form part of the cell. In addition, an auxiliary channel may be provided within the boundary of the cell.

[0094] A drainage cell, without the through channel, may also be provided with a channel adjoining a boundary thereof. The channel may be formed according to any of the features of the auxiliary channel described.

[0095] Figure 10 shows a cross section in a vertical plane along the central axis of the cell 201 and shown the flow paths of the fluid in the cell 201. The normal flow of water into the cell 201 is in the longitudinal direction of the channel as shown by he arrow 218. The ribs, which are transverse to the normal direction of fluid flow in the channel of the cell, serve to encourage particulate material dispersed in the water to sediment. The sediment is carried by fluid though the ducts 207a into the auxiliary channel. 216. The lateral passages 215 are positioned spaced from the bottom of the channel to temporality keep fresh water, i.e. water that has come into the cell, in the channel. This serves to encourage the particles to be removed from the channel. If the flow into the cell should exceed the capacity along the channel and also the flow 219 through the lateral passages 215, the fluid may flow vertically up as shown by the arrow 220 though through the ducts 207b in the upper half-cell 201 b into adjacent flow attenuation cells (not shown).

[0096] Figure 11 shows detail of the lateral passage 215 in the outermost webs of the cell 201 The lateral passages 215 permit water to flow out of the channel 225. The lateral passages 215 are located at the joining portion of each half-cell 201 a, 201 b. Figure 12 shows a cross section along a plane parallel to the webs 214a. It can be seen that the lateral passages extend from the channel 225 to the attenuation volumes provided at either side of the cell 201.

[0097] Figures 13 and 14 show a further embodiment of the present invention. The cell 301 comprises two half-cells 301 a, 301 b. This embodiment is similar to the embodiment of Figure 7, but the channel wall 309 is formed separately from the cell 301 and formed with the connecting member 306. The channel wall 309 is located spaced from the edges 326 of the ribs 304 concentrically within the channel 325 delimited by the ribs 304. As shown in Figure 14, the channel wall has holes in the form of spaced slits 310 to correspond with the ducts 307 and also holes 328 to correspond with the lateral passages 315 formed in the outermost duct-forming webs 314 of the cell 301.

[0098] Figure 15 shows a cell 401 of an embodiment of the present invention in a ground water handling system. The drainage cell may be formed as a cell of any of the embodiments described. The system comprises a plurality of modular attention cells which form an attenuation volume 423. The drainage cell 401 forms a foundation module of the system. Water flows from a catch pit 424, for example, and flows via a pipe 422 into the channel 425 of the drainage cell 401 Overflow water flows into the attenuation volume 423. Silt and debris are collected in the auxiliary channel 416 located under the drainage cell 401.

[0099] Access to the channel 425 may be gained via the pipe 422, in order that maintenance of the system may be carried out. In addition inspection of the drainage cell 410 and attenuation volume 423 made be carried out using a remote camera, for example, which travels along the channel. Alternatively the drainage cell 401 may be located higher up in the system, depending on where the pipe 422 is connected to the attenuation volume 423, or where inspection or maintenance is required.

[0100] In the embodiment shown, the drainage cell 401 with the channel 425 comprises one cell of the system, with the other attenuation cells being provided without a channel 425. Alternatively, all the cells of the system may of the type with a channel. In this way, the system may be inspected at various locations.

[0101] The connecting member for connecting the two half-cells of the drainage cell together may be selected with a predetermined thickness to produce an assembled drainage cell of sufficient dimensions, e.g. height, to match those of adjoining attenuation cells. This enables the drainage cell to be used in a system comprising attenuation cells of different sizes. The connecting member may also be provided with connecting members which interlocks both with the drainage cell and adjacent attenuation cells.

[0102] A porous or non-porous geotechnical material may be used to cover the outer boundary of the drainage cell and/or the total attenuation volume.

[0103] The geo-membrane may be bonded, e.g. welded to the auxiliary channel 416 to form a seal between the cell and the auxiliary channel.

[0104] The ground water handling system may be flushed by the introduction of water into the structure at certain points in the system, with the outlet to the outlet pipe 422 blocked off.

[0105] When an auxiliary channel 416 is not used, water entering the drainage cell via the channel 425 will serve to self clean the channel of bult-up silt

[0106] In order to connect individual attenuation cells together, lateral connecting means such as lateral fastening clips may be used which attach between adjacent cells. Further, shear connecting means may be provided which may be inserted in corresponding holes provided in the top and bottom of vertically stacked drainage cells. The open ends of the support elements may provide suitable apertures or holes to receive the connecting means. The holes and connectors may be of any suitable cross section, e.g. circular. The connectors provide resistance to shearing between vertically stacked cells.

[0107] When a cell is not connected to a pipe at either the inlet or outlet to the channel, closure means may be provided to close the respective channel opening. Support means may also then be provided, either integrally with the closure means or forming part of the cell, by which geo-membrane material may be supported across the opening.

[0108] Figure 16 shows an embodiment of the first aspect of the present invention installed in a water handling system. The arrangement comprises a cell 201 with a through channel 225. The features of the cell 201 have been described above in relation to the embodiments of Figures 7 to 10 and will not be repeated here. In place of the cell 201, a cell in accordance with any of the other embodiments of the present invention may be used.

[0109] The cell 201 is positioned straddling a square open channel 500 formed in a concrete foundation 520. Although in the embodiment shown the foundation is formed of concrete, any other suitable material may be used.

[0110] Adjacent the cell 201, drainage cells 501 are arranged on either side. A further drainage cell 501 is located above the cell 216. Such drainage cells are known, for example, from the applicant's own application published as EP1416099 and the details of such cells will not be repeated here other than to explain their interaction with the cells in accordance with the present invention. The drainage cells 501 may comprise two separate parts joined along a central plane.

[0111] The drainage cells 501 adjacent the cell 201 are laid on top of the concrete foundation. To prevent lateral displacement, shear connectors in the form of cylindrical rods may be provided which locate in the open ends of vertical support columns 502. The drainage cell 501 located above the cell 201 may also be positioned using shear connections in the form of cylindrical rods which engage in the open ends of the vertical support columns 502 of the drainage cell 501 and the support elements 203 of the cell 201.

[0112] In the square channel 500 formed in the concrete foundation 520, an auxiliary channel 216 is laid with its open side of the channel facing uppermost against the base of the cell 201. The auxiliary channel 216 is formed with a square outer channel section that corresponds with the square channel 500 of the foundation. The auxiliary channel 216 has a substantially U-shaped channel section. Other forms of channel are envisaged such as V-shaped or semi-circular. The auxiliary channel 216 comprises a series of spaced transverse ribs 240. The base of the auxiliary channel 216 may be partially corrugated in form to aid rigidity.

[0113] Instead of being laid simply in the square channel 500 in the foundation 520, the auxiliary channel 216 may be partially laid in the foundation 520 before the concrete has cured. The ribs 240 of the auxiliary channel 216 may then partially key into the concrete foundation 520. The auxiliary channel 215 may be configured to function as described above in relation to the embodiment of Figures 9 to 10 and 15.

[0114] Figure 17 shows the auxiliary channel 216 extended beyond the end face of the cell 201. The auxiliary channel 216 may be connected to a silt collection reservoir for removal of collected silt from the system.

[0115] Figure 18 shows an embodiment of a support element 510 in accordance with a fourth aspect of the present invention. Here, the support element 510 is shown installed in an example of a system comprising a cell 201 and drainage cells 501. The cell 201 and drainage cells 501 are the same as in the embodiment shown in Figure 17 are will not be described in further detail.

[0116] Under the cell 201 a support element 510 is provided. The support element 510 is formed substantially as a parallelepiped with a drainage channel, which in the embodiment shown is an open substantially square channel 516 running along its central longitudinal length. The channel 516 has a substantially planar horizontal base wall 518 and planar substantially vertical side walls 517. In the embodiment shown, the side walls 517 are angled such that distance between the side walls 517 increases from the bottom of the channel 516 towards the open top of the channel 516. The channel 516 provides a similar function to the auxiliary channel shown in Figure 17. The base of the drainage channel 516 is configured, in use, to carry a fluid flowing though said drainage channel such that it is carried to the end of the channel. This ensures that silt of debris carried in the fluid is also carried along the channel.

[0117] The support element 510 is sized to match the foot print of the cell 201 located there upon. The support element 510 comprises two rows of spaced vertically orientated cylindrical support columns 521 either side of the central channel 516. These support columns 521 serve to support the cell 201 and/or drainage cells 501 positioned thereabove.

[0118] A plurality of support elements 510 may be placed adjacent to one another to provide an extension to the section of channel 516 which runs under the cell 201.

[0119] As shown in Figure 18, the support element is located in a square channel 531 formed in a concrete foundation 530. The depth of the channel 531 in the concrete foundation is chosen such that the uppermost planar face of the support element 510 is substantially level with the upper surface of the concrete foundation on either side of the channel 531.

[0120] The support columns 521 of the support element are open at their ends, such that shear connections, for example in the form of cylindrical connectors, may be inserted therein as well into the corresponding open ends of the support columns 203 of the cell 201 such that the lateral displacement of the cell 201 with respect to the support element 510 is prevented.

[0121] The sides of the support element 510 are closed by planar panels between adjacent support columns 521. The support element 510 is also closed on its top and bottom sides, apart from in the area of the channel 516 and the open ends of the support columns 521. Although not shown, a perforated lid may be provided across the open channel to support a cell above. Ports of slots may also be provided in the side of the channel to allow water to drain down in to the channel from the side structure of the support element.

[0122] The support element 510 may be formed using any suitable material for example injection moulded plastic.

[0123] Figure 19 shows a further embodiment of a support element according to a fourth aspect of the present invention. Here, a support element 610 is located under a drainage cell 501. The support element 610 is similar to the support element 510 shown in Figure 18. However, the channel 616 in the support element 610 has a substantially rectangular section.

[0124] Either side of the channel 616 guide means in the form of a shallow angled ledge 640 is formed spaced from the top planar surface of the support element 610. These ledges 640 may be used to provide set of tracks for a wheeled device, such as a device with a camera, which may move along the track to inspect the drainage cell 501 above. The wheeled device could alternatively include cleaning means such a brushes.

[0125] Figure 20 shows a schematic view of the operation of an embodiment of a system in accordance with a fifth embodiment of the present invention. The system comprises support elements 610 and drainage cells 501. The system shown comprises a bottom layer with two support elements 610 located adjacent a drainage cell. Directly above the bottom layer is a top layer of drainage cells 501. Although in the system shown in Figures 20 to 22, drainage cells are shown in combination with the support elements, cells in accordance with the first aspect of the invention may be used.

[0126] The channel 616 in each of the support elements 610 serves as a low flow channel in that, when there is not an excess of water in the drainage cells 501, water may flow along the channel 616 without entering the drainage cells 501. As shown by the arrows, should the flow of water in the channel 616 increase beyond the capacity of the channel 616, water will then rise and flow over the sides of the channel 616 into drainage cells 501 located either above or adjacent the support element 610.

[0127] Figure 21 shows a further schematic view of the operation of a system comprising support elements 510 and drainage cells 501 in accordance with a fifth aspect of the present invention. In the system shown, the support elements 510, are located directly underneath the bottom layer of drainage cells 501. Here, two support elements 510 are shown spaced apart. The channel 516 of each of the respective support elements 510 may serve as a low flow channel, in that when there is not an excess of water flowing into the system, water may flow along the channel 516 without entering the drainage cells 501. As shown by the arrows, should the flow of water in the channel 516 increase beyond the capacity of the channel 516, water will then rise and flow over the sides of the channel 516 into drainage cells located above the support element. In the system shown because the support elements 510 are located underneath the bottom layer of drainage elements 501, the channel 516 in each of the support elements 501 may serve to remove silt from the system.

[0128] Figure 22 shows a schematic view of a further example of an embodiment of a fifth aspect of the present invention, the system comprising a base layer comprising a plurality of adjacent support elements 510. Layers of drainage cells 501 are located directly above the base layer. This system provides for two alternative modes of operation. In the first mode of operation, water enters the system above the base layer of support elements 510. In this way, the channels 516 in the support elements 510 serve as means in which silt can collect, e.g. a sump for silt, and be removed from the system. The channels 516 in the support elements 510 can also be flushed with water to remove silt from the system. In the second mode of operation, the channels 516 serve as low flow channels as described above, with the drainage system filling and emptying via the channels 516.

[0129] Figures 23a and 23b show a drainage cell 501 which includes a support element 510 connected to a manhole 550, which is formed as a substantially vertically orientated cylindrical shaft. The drainage cell 501 and support element 510 extend through the cylindrical side wall of the manhole 550 such that the outlet from the channel 516 of the support element 510 is spaced from the wall of the man hole towards the centre thereof. A sealing interface 560 may be provided between the manhole 550 and the support element 510 and drainage cell 501. The manhole 550 may then act as a silt collection facility for silt which has passed along the channel 516.

[0130] Figure 24 shows a further embodiment of a support element 710 in accordance with a fourth aspect of the present invention. The support element 710 is formed as a parallelepiped, which a rectangular cross section. The support element 710 is open at its longitudinal ends. The planar base wall 711 of the support element 710 is solid. The side walls 712 of the support element 710 are each formed with a plurality of spaced apertures 713. In the embodiment shown, the apertures are circular in form. The top surface wall 714 of the support element 710 is formed with a plurality of spaced openings 715. In the embodiment shown, these openings are formed as rectangular slits which are orientated orthogonal to the longitudinal length of the support element 710. The apertures 813 are spaced from the base wall 711 such that silt that may collect in the support element 710 may generally remain in the volume of the support element and flow out of the support element along the inner surface of the base wall 811.

[0131] Whilst Figures 24 to 26 show typical dimensions for the support element, it should be understood that that the support element may be sized to fit the appropriate drainage cell. The support element 710 of Figure 24 may for example be sized to support a single drainage cell. The embodiments of Figures 24 and 25 may be formed of any suitable material, for example plastics, metals and composite materials. A preferred material is concrete.

[0132] Figure 25 shows a further embodiment of a support element 810 in accordance with a fourth aspect of the present invention. The embodiment of Figure 25 shares many of the features of Figure 24. The top surface wall 814 of the support element is formed with two rows of spaced openings 815. A supporting wall 816 is also provided between the top 814 and base walls 811, parallel to the side walls 812, positioned between the two rows of openings 815. The embodiment shown is configured to support two adjacent drainage cells. In the embodiment shown, the support element 810 is twice the width of the support element 710 of the embodiment shown in Figure 24.

[0133] Figure 26 shows a further view of the embodiment of Figure 25. It can be seen that the supporting wall 816, similarly to the side walls 812, is provided with a plurality of apertures 813 in the form of circular openings.

[0134] In use, the support elements 710, 810 shown in Figures 24 to 26 may be used to support drainage cell 501 located thereupon. The openings 815 permit silt to pass into the volume formed by the side walls 812 and top 814 and base walls 814. The apertures 813 ensure that water may freely flow into and out of the volume of the support element. The apertures 713, 813 are spaced from the base wall 711, 811 to seek to ensure that any silk collected passing along the inner surface of the base wall 811.

[0135] Figures 27 and 28 show a further embodiment of a fourth aspect of the present invention. Figure 27 shows a support element 910. The support element 910 is formed with a planar top wall surface 914. As visible in Figure 28, the top wall surface is formed with two rows of spaced rectangular slits 915. The slits 915 are orientated orthogonal to the longitudinal direction of the support element 910. The support element 910 also comprises two vertical walls 912 at either side of the top wall 914. These side walls are each formed with a plurality of spaced apertures 913. In the embodiment shown, the apertures 913 are formed as circular openings.

[0136] The base wall of the support element 910, the outer surface of which is parallel to the top wall 914, extends to the side walls 912. The internal surface of the base wall 930, is inclined at each side relative to the adjacent respective vertical side wall 912 such that water which falls on the internal surface is channelled towards the centre of the support element 910.

[0137] At the centre of the support element 910, between the top 914 and base walls 930, the support element 930 is formed with a rectangular box element 935. This box element 935 extends along the longitudinal length of the support element 910 and in the embodiment shown is formed integrally therewith.

[0138] The box element 935 is open at each end and provides a channel 916 for collecting silt and flushing silt from the system. The vertical side walls 936 of the box element 935, which extend between the base 930 and top walls 914 of the support element, are each provided with a plurality of spaced apertures 945. In the embodiment shown, the apertures 945 are formed as arched openings.

[0139] One end of the box element 935 may comprise a extended open end 950, which is configured to fit into the open end of a box element of an adjacent support element (not shown). This arrangement seeks to ensure the continuity and integrity of the channel 916.

[0140] The top surface wall 914 of the support element may be provided, as shown in Figure 28, with locating means 960 to connect with a drainage cell located on top of the support element. In the embodiment shown, the locating means 960 are formed as cylindrical elements which are configured to engage with the open ends of the cylindrical support elements 502 of a drainage cell 501 as shown in Figure 29a. In the embodiment shown, cylindrical locating means are provided to engage with each corner of the drainage cell located thereon. Figure 29a shows the support element 910 of Figure 28 with two drainage cells 501 located thereon.

[0141] Figure 29b shows an exploded view of the drainage cells 501 and support element 910 before assembly.

[0142] Figure 30 shows a cell generally at 1001 of a further embodiment of a drainage cell for a ground water handling system. Similarly to the embodiment shown in Figure 7, the cell 1001 has the form of a parallelepiped. The cell 1001 comprises two substantially identical half-cells 1001 a, 1001 b. Each half-cell comprises a base 1002a, 1002b. The longitudinal walls of each half-cell 1001 a, 1001 b comprise a plurality of spaced vertical support elements 1003a, 1003b, which extend from the base 1002a, 1002b of each half-cell 1001 a, 1001 b. The cell 1001 also includes two further sets of spaced vertical support elements 1003c parallel to each set of the vertical support elements 1003a, 1003b along each of the outer longitudinal walls of each half-cell. Each further set of support members 1003c is spaced inwardly from the outer longitudinal walls of each half-cell 1001 a, 1001 b. The vertical support elements 1003a, 1003b are substantially circular in cross section and are hollow, which serves to reduce the weight of the cell and facilitates manufacture using injection moulding techniques, for example.

[0143] Similarly to the embodiments of Figure 1 and 4, each half cell 1001 a, 1001 b comprises a plurality of spaced transverse members in the form of ribs 1004. The ribs 1004 extend from the base 1002a, 1002b of each half cell 1001 a, 1001 b to around the mid-point of each half cell 1001 a, 1001 b. The ribs 1004 are formed as substantially planar elements and are orientated in vertical planes orthogonal to the longitudinal length of each half cell 1001 a, 1001 b. The edge of each rib 1004 distal the base 1002a, 1002b has a curved, in the embodiment shown generally semi-circular, edge. At the mid-point of alternate ribs 1004, a further support element 1003d is provided. The further support elements 1003d have a circular cross-section and are hollow and extend from the respective base 1002a, 1002b of each half cell 1001 a, 1001 b to the curved edge of the respective rib 1004.

[0144] The ribs 1004 extend laterally inwardly such that the plurality of ribs 1004 are spaced along the longitudinal length of each half-cell 1001 a, 1001b. Connected between adjacent support elements 1003c of the set of support elements spaced inwardly of the support elements 1003a which are positioned along the longitudinal boundary walls of the cell, curved webs 1005 are provided. In the embodiment, each of the webs 1005 is generally semi-circular, the apex of which extends towards the longitudinal axis of the cell. The webs 1005 extend from the base 1002a, 1002b of each respective half-cell 1001 a, 1001 b to form a curved edge which is in line with the curved edges of the ribs 1004. The ribs 1004 extend through the apex of the webs 1005 and connect with a respective cross-member 1900 which extends between adjacent pairs of the set of support elements 1003 spaced inwardly of the boundary of the cell 1001.

[0145] In this embodiment, on the curved edges of the ribs 1004 and webs 1005, a wall 1009 is provided. The wall 1009 extends orthogonally to the curved edges of the ribs 1004 and webs 1005, but is not continuous between webs, but forms an open wall 1009, which may be described as being perforated in form and having a lattice like structure. The wall may include further sections 1300 which do not follow the edges of the ribs 1004 or webs 1005 to form a lattice structure to the channel wall 1009.

[0146] As shown in Figure 31, the half-cells are joined together with two connecting members 1006a, 1006b, each of which is formed to be inserted into the open top ends of the support elements, i.e the ends distal the respective base 1002a, 1002b of each half-cell 1001a, 1001b.

[0147] When the two half-cells 1001 a, 1001 b are joined together, a through channel 1025 is formed, which extends through the opposed ends of the cell 1001. As can be seen in Figure 30, the through channel has a cross-sectional form with a curved top and bottom and a mid-section 1150 with generally parallel straight sides. The mid-section extends from an imaginary plane parallel to the base 1002a, 1002b of each half-cell 1001 a, 1001 b which lies at generally the midpoint of each half-cell 1001 a, 1001 b. The channel 1025 is delimited by the wall 1009 at its top and bottom which extends to the upper most part of the semi-circular rib 1004.

[0148] In the mid-section, no wall 1009 is provided and in the mid-section of the channel 1025, and the channel 1025 is open between the spaced support members 1003c In the mid-section, the channel is therefore delimited by the support members 1003c. The support members 1003c adjacent the channel 1025 are provided with vertical ribs 1104 which extend inwardly toward the cntre of the channel 1025. In the embodiment shown, each support member 1003c (apart from the support members at each end of the channel) is provided with baffling elements, in the embodiment in the form of a pair of vertical ribs 1104 which are angled relative to one another and at an angle to a plane transverse to the longitudinal direction of the channel. The vertical ribs 1104 face inot the through channel and serve, in use, as baffles to baffle silt within a fluid flowing through the channel into the base of the through channel.

[0149] As may be seen more clearly in Figure 32, in the lower half-cell 1001 a, the ribs 1004 and webs 1005 form boundary walls of fluid connections in the form of ducts 1007a, 1007b which fluidly connect the channel 1025 through the base 1002a of the cell 1001 in the bottom half cell 1001 a. Similarly, the ribs 1004 and webs 1005 of the upper half-cell 1001 b fluidly connect the channel 1025 through the top of the cell 1001, i.e. the base 1002b of the upper half-cell 1001 b.

[0150] As more clearly shown in Figure 31, each of the connecting members 1006a, 1006b is formed as a ladder like frame. Each connecting member 1006a, 1006b connects into two sets of adjacent support members 1003a, 1003c.

[0151] The outer boundary wall of the cell 1001 between support elements 1003a is formed with a lattice like structure. In addition, a lattice type structure is formed on the base 1002a, 1002b of each half cell 1001 a, 1001 b between the ends of the support elements 1003a,1003c.

[0152] As can be seen in Figure 32, alternate support members 1003c adjacent the channel 1025 are provided with a pair of opposed clip parts 1100a, 1100b. The clip parts 1100a, 1100b are have a generally horizontal part which extends away from the inner edge of the support member connecting to a perpendicular part with a barbed or lipped end which is biased away from the inner edge of the support member. These clip parts 1100a, 1100b connect with the connecting member 1006 through a corresponding aperture therein. The barbed or lipped end catches under a surface of the connecting member 1006 to provide a positive connection to maintain the two half cells together. Such an arrangement is shown in more detail in the cross-section in Figure 35, which is a cross-section of a further embodiment of a drainage cell shown in Figure 33. The embodiment shown in Figure 33 is similar to the embodiment of Figure 30 and only the differences will be explained in detail.

[0153] In the embodiments of Figures 30 and 33, alternative support members 2003a, 1003a along the outer edges of the cell, are provided with receiving means 2400, 1400 in the form of an aperture to receive a respective clip part 2500a, 2500b, 1500a, 1500b. Such an arrangement is shown in cross-section in greater detail in Figure 34 in relation to the embodiment of Figure 33, where at each support member 2003a, the connecting member 2006 is provided with a single clip part 2500a, 2500b on each side, which engages with a single respective receiving means 2400 in each support member 2003. The clip parts 2500a, 2500b include a lipped or barbed part which when inserted into a corresponding receiving means 2400 in the form of an aperture engages under a surface of the receiving means.

[0154] A semicircular channel wall 1009 is formed integrally with each half cell 1001 a, 1001 b. In contrast to the embodiment of Figure 7, the shape of the channel openings at the end of the cell is not circular. Instead the channel has a semicircular form at the top and bottom with a straight section opening therebetween.

[0155] The differences between the embodiments of Figure 30 and Figure 33 will now be described. In contrast to the embodiment of Figure 30, rather than a lattice like channel wall, the channel wall has curved, in the embodiment generally oval shaped aopenings 2009. In the mid-section 2150 of the channel, the channel is not fully open between adjacent support members 2003c, but instead the channel wall 2009 extends into the mid-section and provided with openings which are generally U-shaped in form which increase in width toward the top of the respective half cell 2001 a, 2001 b.

[0156] In the embodiment of Figure 33, at the open end of the channel 2025, an insert 2600 is provided which fits the opening of the channel 2025. A pipe 2700 is connected to the insert 2600. The insert 2600 is positively connected to the opening of the channel 2025 by slots 2700, in the embodiment four spaced slots, provided around the edge of the insert 2600. Corresponding protrusions 2800 (feature 1800 in the embodiment of Figure 30) around the open end of the channel 2025 engage with the slots 2700 around the outer circumference of the insert 2600.

Claims

1. A drainage cell for a ground water handling system, the cell comprising a through channel, the cell comprising one or more transverse members extending from or adjacent the edge of the through channel towards a base of the cell for deflecting, in use, particulates or debris carried in a fluid flowing in said through channel.

2. A drainage cell according to claim 1, wherein the transverse members extend from substantially the edge of the through channel towards one or more lateral sides of the cell.

3. A drainage cell according to 1 or 2, wherein the edges of the transverse members delimit the through channel.

4. A drainage cell according to any one of claims 1 to 3, wherein the through channel comprises a perforated channel wall.

5. A drainage cell according to claim 4, wherein the channel wall delimits the through channel.

6. A drainage cell according to any one of claims 1 to 5, wherein one or more fluid connections are provided from a side of said channel.

7. A drainage cell according to claim 6, wherein the cell further includes an auxiliary channel fluidly connected to said through channel via said fluid connections.

8. A drainage cell according to any one of claims 1 to 7, wherein one or more lateral fluid passages are formed in the side of said through channel.

9. A drainage cell according to claim 8, wherein the cell comprises an attenuation volume adjacent said through channel, the attenuation volume being fluidly connected to said through channel via said one or more lateral passages.

10. A drainage cell according to claim 4 or any claim dependent thereon, wherein the channel wall is formed integrally with the cell.

11. A drainage cell according to claim 4 or any claim dependent thereron, wherein the channel wall is formed as a separate part.

12. A drainage cell according to any one of claims 1 to 11, wherein the cell is formed of two half cells, and a connecting member is provided for connecting the two half-cells together, which connecting member has connecting means which connect with corresponding parts of each half cell.

13. A drainage cell according to claim 12, wherein the half-cells are provided with clips to engage with corresponding apertures in the connecting member.

14. A drainage cell according to claim 12 or 13, wherein the connecting member is provided with clips to engage with corresponding apertures in the half cells.

15. A drainage cell according to any one of the preceding claims, wherein an insert is provided which fits around an inner circumference of an open end of the channel.

16. A drainage cell according to any one of the preceding claims, wherein the channel is provided with generally vertical ribs for baffling or deflecting silt in a fluid flowing in said through channel.

17. A drainage assembly, wherein the drainage assembly comprises a plurality of water attenuation cells including one or more drainage cells according to any one of the preceding claims.

Drawing