FIELD

[0001] The present invention relates to a modular drainage assembly and to a drainage unit for constructing the drainage assembly. In particular, but not exclusively, the invention relates to an underground modular drainage assembly for transporting water and/or sludge or for storing the same.

BACKGROUND

[0002] Various water drainage systems exist which employ channels, gutters and drains for directing water. Most conventional drainage systems employ concrete pipes or metal components. Such concrete and metal systems, however, tend to be relatively expensive to manufacture and laborious to assemble. To address the drawbacks of concrete and metal drainage systems attempts have been made to develop drainage components made of plastic materials. The use of plastic drainage components has, however, in the past been restricted due to the inability to support loads of relative high magnitude.

OBJECT

[0003] It is an object of the present invention to provide an alternative modular drainage assembly and an associated drainage unit which address or at least ameliorate one or more of the above problems associated with conventional drainage systems. It is also an object of the invention to provide an alternative assembly for storing water and alternative storage tanks for storing sludge used during the production of biogas.

SUMMARY

[0004] In a first aspect there is disclosed herein a drainage unit for constructing a modular drainage assembly, the drainage unit comprising: an elongate collapsible support structure longitudinally extending between a first end and a second end, the support structure defining an inner passage for transporting a viscous substance; and a first and a second load bearing member adapted to be held in a face-to-face arrangement within the inner passage of the support structure, each load bearing member including a load bearing member framework adapted (i) to support a load applied to the support structure and (ii) to allow the passage of the viscous substance therethrough, wherein the support structure includes a load bearing member attachment formation operatively associated with a complemental support structure attachment formation on each of the load bearing members so as to secure the load bearing members within the inner passage, the load bearing member attachment formation adapted to engage the support structure attachment formation so as to secure the first load bearing member at the first end of the collapsible structure and the second load bearing member at the second end.

[0005] Preferably the load bearing member attachment formation is adapted to enable attachment of the load bearing members at a position between the first end and the second end of the elongate structure.

[0006] Preferably the support structure comprises two opposing lateral support members and two opposing transverse support members.

[0007] In a preferred embodiment the support members are identical.

[0008] Preferably each support member includes a support member framework to support a load applied to the support structure.

[0009] Preferably the load bearing member attachment formation comprises a plurality of cavities and the support structure attachment formation comprises a plurality of protrusions, wherein the protrusions of the support structure attachment formation is adapted to be received by the cavities of the load bearing member attachment formation.

[0010] Preferably the load bearing member attachment formation comprises at least one cavity sized for receiving a protrusion of a support structure attachment formation of a load bearing member of a first drainage unit as well as a protrusion of a support structure of an attachment formation of a load bearing member of a second drainage unit located adjacent the first drainage unit.

[0011] Preferably the at least one cavity has a substantially circular cross-section. [0012] Preferably the protrusion of the first drainage unit and the protrusion of the second drainage unit each has a substantially semi-circular cross-section such that the protrusions are adapted to be located side-by-side in the at least one cavity.

[0013] Preferably the load bearing member framework and the support member framework comprise a plurality of load bearing cells.

[0014] Preferably each load bearing cell includes a curved perimeter wall.

[0015] Preferably the curved perimeter wall encloses a load distribution framework adapted to distribute load applied to a load bearing cell along the curved perimeter wall.

[0016] Preferably the load bearing member framework and the support member framework comprise a plurality of parallel, laterally spaced apart pillar members.

[0017] Preferably the load bearing member framework and the support member framework comprise a plurality of parallel, laterally spaced apart transverse members.

[0018] Preferably the pillar members and transverse members define a plurality of cell cavities, each cell cavity enclosing a load bearing cell.

[0019] Preferably each load bearing member defines a flow aperture, each load bearing member adapted to be configured relative to adjacent load bearing members so that their respective flow apertures align to form a flow passage.

[0020] Preferably the collapsible support structure and load bearing members are produced from a plastics material.

[0021] Preferably the collapsible support structure and load bearing members are produced by a plastic injection moulding process.

[0022] Preferably the plastics material is polypropylene.

[0023] Preferably the first or second load bearing member defines a membrane filter attachment formation operatively adapted to hold a membrane filter.

[0024] According to a second aspect there is disclosed herein a modular drainage assembly comprising a plurality of drainage units in accordance with the first aspect, wherein the drainage units are aligned side-by-side to provide a drainage assembly for transporting a viscous substance. [0025] Preferably the modular drainage assembly is enclosed within a geotextile.

[0026] According to a third aspect there is disclosed herein a drainage system comprising a modular drainage assembly according to the second aspect enclosed within a non-porous geotextile, the drainage system including an exhaust assembly for extracting biogas that has built up in the drainage assembly.

[0027] Preferably the exhaust assembly includes (i) an extractor fan in fluid communication with the drainage assembly and (ii) an exhaust conduit assembly in fluid communication with the extractor fan.

[0028] Preferably the exhaust conduit assembly is in fluid communication with a combined power and heat converter.

[0029] Preferably the exhaust assembly includes an activation system operatively associated with the extractor fan and adapted to activate and deactivate the extractor fan.

[0030] Preferably the activation system includes a timer and the extractor fan is activated responsive to time measurements taken by the timer.

[0031] Preferably the activation system includes an emergency trigger for activating the extractor fan.

[0032] Preferably the emergency trigger comprises a mechanical diaphragm trigger switch which will activate the exhaust fan when biogas pressure levels in the drainage system exceeds a pre-set value.

[0033] Preferably the drainage system includes an alarm system adapted to alert personnel to hazardous levels of biogas in the drainage assembly.

[0034] Preferably the alarm system includes a warning light source and/or warning signal.

[0035] Preferably the drainage assembly is in fluid communication with a manhole having a manhole lid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Preferred embodiments of the invention will be described hereinafter, by way of examples only, with reference to the accompanying drawings. [0037] In the drawings:

[0038] Figure 1 is a schematic perspective view of a first embodiment drainage unit for constructing a modular drainage assembly;

[0039] Figure 2 is a schematic perspective view of a support member of a support structure of the drainage unit;

[0040] Figure 3 is a schematic perspective view of an embodiment load bearing member of the drainage unit of Figure 1;

[0041] Figure 4 is a schematic perspective view of a support member of Figure 2 attached to load bearing members of Figure 3;

[0042] Figure 5 provides a schematic explanation of the attachment of the support member and load bearing members of Figure 4;

[0043] Figure 6 is a schematic perspective view of a second embodiment drainage unit for constructing a modular drainage assembly for providing an open water channel;

[0044] Figure 7 is a schematic perspective view of a top support member of a support structure of the drainage unit of Figure 6;

[0045] Figure 8 is a schematic perspective view of a third embodiment drainage unit for constructing a modular drainage assembly;

[0046] Figure 9 is a schematic perspective view of a support member of a support structure of the drainage unit of Figure 8;

[0047] Figure 10 is a schematic perspective view of a fourth embodiment drainage unit for constructing a modular drainage assembly;

[0048] Figure 11 is a schematic perspective view of a support member and a load bearing member of the drainage unit of Figure 10;

[0049] Figure 12 is a schematic perspective view of a fifth embodiment drainage unit for constructing a modular drainage assembly used in sewers; [0050] Figure 13 is schematic perspective front and rear views of a load bearing member of the drainage unit of Figure 12;

[0051] Figure 14 is a schematic front view of the load bearing member of Figure 13;

[0052] Figure 15 is a schematic cross-sectional view of the load bearing member at the line B- B in Figure 14;

[0053] Figure 16 is a schematic front view of the load bearing member of Figure 13 having a filter member attached thereto;

[0054] Figure 17 is a schematic representation of a first embodiment drainage system incorporating embodiment drainage units;

[0055] Figure 18 is a schematic perspective view of a further embodiment load bearing member; and

[0056] Figure 19 is a schematic representation of a second embodiment drainage system. DESCRIPTION OF PREFERRED EMBODIMENTS

[0057] Figure 1 shows an embodiment drainage unit, generally indicated with the reference numeral 10. The drainage unit 10 is adapted to be used with a plurality of other similar drainage units to construct an underground modular drainage assembly for transporting or storing a viscous substance, in this instance water. The constructed drainage assembly (not illustrated in Figure 1) will be enclosed within a non-permeable geo-textile to prevent leakage of the transported water. The constructed drainage assembly can also be enclosed with a water permeable geo-textile. A water permeable geo-textile may, for example, be employed in those instances where it is required to allow drainage of water to reduce mosquitos from breeding or deterring other unhealthy conditions. The embodiment drainage unit 10 comprises a collapsible support structure 12 and two load bearing members 14. An individual load bearing member 14 is shown in Figure 3.

[0058] The embodiment support structure 12 is elongate and longitudinally extends between a first end 11 and a second end 13. The support structure 12 comprises two opposing lateral support members 16 and two opposing transverse support members 16. The support members 16 are all of identical configuration. A free standing support member 16 is shown in Figure 2. The support structure 12 defines an inner passage 18 for transporting the viscous substance. As mentioned the viscous substance to be transported in this embodiment is water. The support members 16 each include a support member framework 20 to support a load applied to the support structure 12.

[0059] The drainage unit 10 comprises two load bearing members 14 held in a face-to-face arrangement within the inner passage 18 of the support structure 12. The load bearing members 14 are located respectively at the first and second ends 11, 13 of the support structure 12. Referring to Figure 3, each load bearing member 14 includes a load bearing member framework 22. The load bearing member framework 22 is adapted (i) to support a load applied to the support structure 12 and (ii) to allow the passage of a viscous substance therethrough.

[0060] Referring to Figures 2 and 3, each support member 16 of the support structure 12 includes a load bearing member attachment formation 24. The load bearing member attachment formation 24 is operatively associated with a complemental support structure attachment formation 26 on each of the load bearing members 14. The load bearing member attachment formation 24 is adapted to engage the support structure attachment formation 26 so as to secure the load bearing members 14 within the inner passage 18 formed by the support structure 12. The structure of the load bearing member attachment formation 24 is so adapted that the two load bearing members 14 can respectively be secured at the first and second ends 11, 13 of the support structure 12. The load bearing member attachment formation 24 is further adapted such that the load bearing members 14 can be adjusted so as to be secured at a position between the first and second ends 11, 13 of support structure 12. For added strength more than 2 load bearing members 14 can be secured within the passage 18.

[0061] The embodiment load bearing member attachment formation 24 comprises a plurality of cavities 28 and the support structure attachment formation comprises 26 a plurality of protrusions 30. The protrusions 30 of the support structure attachment formation 26 is adapted to be received by the cavities 28 of the load bearing member attachment formation 24. In this embodiment the cavities 28 and protrusions 30 engage by the protrusions 30 clipping into position (snap-locking) within the cavities 28. The protrusions 30 have a semi-circular cross-sectional shape, the purpose of which is discussed below.

[0062] Referring to Figure 3, the load bearing member framework 22 (and the support member framework 20 shown in Figure 2) comprises a plurality of load bearing cells 32. Each load bearing cell 32 includes a curved perimeter wall 34. Each curved perimeter 34 wall, in turn, encloses a load distribution framework 36 adapted to distribute a load, applied to the load bearing cell 32, along the curved perimeter wall 34.

[0063] The load bearing member framework 22 and the support member framework 20 each further comprise a plurality of parallel, laterally spaced apart pillar members 38. The load bearing member framework 22 and the support member framework 20 also comprise a plurality of parallel, laterally spaced apart transverse members 40. The pillar members 38 and the transverse members 40 define a plurality of cell cavities 42. Each cell cavity 42 houses a load bearing cell 32.

[0064] The load distribution framework 36 of each load bearing cell 32 includes a central load distribution member 50 and load distribution members 52 outwardly extending from the central load distribution member 50 towards the curved perimeter wall 34. It will be noted that the shape of the curved perimeter wall 34 of loading bearing cells 32 located towards the centre of the load bearing members 14 are substantially elliptical / oval in shape. The shape of the load bearing cells 32 located towards the perimeter of the load bearing member 14, in turn, has a shape which is substantially a half-oval / half-elliptical.

[0065] As shown in Figures 2 and 3, both the load bearing members 14 and the support members 16 include round holes 54. The purpose of the holes 54 is to facilitate ease of attachment to the drainage unit 10 of pipes for feeding water into the drainage unit 10. The load bearing members 14 also include outwardly extending connectors 56 for location in complemental non-illustrated connector apertures on the support members 16. The connectors 56 serve to provide added strength for the connection between the load bearing members 14 and their associated support members 16.

[0066] The collapsible support structure 12 and load bearing members 14 are produced by an injection moulding process wherein a plastics material, in this embodiment polypropylene, is formed to the desired shaped. It will, however, be appreciated that a range of materials could be employed to produce an embodiment drainage unit.

[0067] Figure 4 provides an example of how the load bearing members 14 and the support members 16 can be employed to construct different configured drainage assemblies wherein different drainage units are attached in a side by side configuration. Figure 4 in particular depicts a half-constructed drainage assembly 60 comprising a support member 16 having two load bearing members 14.1, 14.2 attached to opposing sides at a first end 11 of the support member 16. A single load bearing member 14.3 is located towards the centre of the support member 16 between the first and second ends 11, 13. It will, of course, be appreciated that a large number of different configurations can be constructed with the load bearing members 14 and the support members 16.

[0068] Referring to Figure 5, the load bearing member attachment formation 24 comprises at least one cavity 28 sized to receive a protrusion 30.1 of the load bearing member 14.1. The at least one cavity 28 is further sized also to receive a protrusion 30.2 of adjacent load bearing member 14.2. As shown, the at least one cavity 28 has a substantially circular cross-section whereas the protrusion 30.1 of the first load bearing member 14.1 and the protrusion 30.2 of the second load bearing member 14.2 each has a substantially semi-circular cross-section. That configuration allows the protrusions 30.1 and 30.2 to be adapted / sized to be located side-by-side in the at least one cavity 28. The effect of this is that the drainage units of which the load bearing members 14.1 and 14.2 respectively are a part of share / have a common support member 16, thus saving costs by eliminating one support member 16.

[0069] Figure 6 shows a second embodiment drainage unit 70. The drainage unit 70 differs from the unit 10 in that an opening 72 is defined in the drainage unit 70. Regulations in India require flow channels to have an open top. The opening 72 is formed in that the operative upper support member 16, shown in Figure 7, defines the opening 72.

[0070] Figure 8 shows a third embodiment drainage unit 80, similar to the first and second embodiments 10, 70 in that it comprises a collapsible support structure 12 having a number of side members 16 in the form planar panels. Two face-to-face opposed load bearing members 14 are located at opposite longitudinal ends of the support structure 12. The drainage unit 80 differs from the first and second embodiment drainage units 10, 70 in that a flanged coupling 82 is attached to one of the side members 16. As shown in Figure 9, the side member 16 to which the flanged coupling 82 is attached defines a flow passage 84 through which water (or another flowing substance) is introduced into the drainage unit 70.

[0071] Figure 10 shows a fourth embodiment drainage unit 90. The drainage unit 90 is cube- shaped and includes a collapsible support structure 12 having opposing lateral support members 16 and opposing transverse support members 16. The drainage unit 90 further includes two face- to-face opposed load bearing members 14. One support member 16 and one load bearing member 14 are depicted in Figure 11. Each load bearing member 14 defines a flow aperture 94. As shown, the load bearing members 14 are adapted to be configured relative to adjacent load support members 16 so that their respective flow apertures 94 align to form a flow passage 96. In this embodiment the flow passage is defined by a curved support wall / arch 95 to provide added structural strength.

[0072] In this embodiment the support structure attachment formation 26 of the load bearing member 14 comprises a number of oblong projections 98 operatively associated with a complemental load bearing member attachment formation 24 on each of the support members 16. In this embodiment the load bearing member attachment formation 24 is provided by a number of protrusions 100 which define recesses 102 in which the oblong projections 98 are sized to click (snap). A number of prongs 104 are provided in the recesses 102 and are operatively associated with holes 106 in the oblong projections 98 so as to secure the projections 98 within the recesses 102.

[0073] Figure 12 shows a fifth embodiment drainage unit 110. The drainage unit 110 is cube- shaped and includes a collapsible support structure 12 having support members 16 and two face- to-face opposed load bearing members 14. One load bearing member 14 is depicted in Figure 13. Each load bearing member 14 in this embodiment includes a curved support arch 112 to provide the drainage unit 110 with structural strength. To secure a membrane filter 113 (shown in Figure 16) to the load bearing members 14, a membrane filter attachment formation, here in the form of a number of hook-shaped projections 116, is provided. The projections 116 are adapted to pierce the membrane filter 113 and hold it in position.

[0074] The purpose of the membrane filter is to remove microbiological contaminants, oil, mould, fungus, bacteria, algae, animal faeces, insect body parts, plant parts or any other living or other once-living organisms from the viscous substance being transported. Examples of membrane filters which can be used for water filtration include anopore inorganic membranes, cellulose nitrate membranes, mixed cellulose ester membranes, nylon and polyamide membranes, polyether-sulfone membranes, polypropylene membranes, PTFE membranes, regenerated cellulose membranes and track-etched polycarbonate membranes.

[0075] Referring to Figures 14 and 15, the load bearing member framework 22 of the load bearing member 14, shown in Figure 13, has a gradually sloping face 115. This is particularly visible in Figure 15 where sides 117 are shown to taper inwardly from the perimeter of the load bearing member 14 towards the opening 119. The purpose of the sloping face 115 is to reduce friction imparted by the bearing member 14 on less viscous substances such as sludge.

[0076] Figure 17 shows a plurality of modular drainage units 10 placed in a longitudinal side- by-side arrangement to provide a modular drainage assembly 130, here in the form of a drainage channel. Two of the drainage units 10 have a membrane filter 113 attached at one of their ends and held by projections 116. The membrane filters 113 are located adjacent a manhole 132 through which personnel can gain access to the membrane filters 113 so as to clean them and replace as required. The manhole 132 is closed with a lid 134. The manhole 132 and lid 134 includes a rubber seal 136. The modular drainage units 10 are enclosed within a geo-textile 138. It is pointed out that the drainage units 10 are not connected to each other in the longitudinal direction so as to allow them to be aligned around a corner / bend.

[0077] Another embodiment load bearing member 14 is shown in Figure 18 which includes an opening 150. This embodiment load bearing member 14 is particularly suitable for use in applications where the drainage assembly is not required to withstand high loads, for example when employed as a storm water assembly. Having the opening 120 means less plastic is required for producing the load bearing member 14 and consequential material cost savings.

[0078] Figure 19 shows a modular drainage assembly 200 comprising a plurality of drainage units, here the drainage unit 110 of Figure 11, aligned longitudinally side-by-side to transport viscous substance. The drainage assembly 200 is in fluid communication with a storage area 202 constructed with a plurality of drainage units 110. The drainage assembly 200 and storage area 202 is enclosed within a non-porous geotextile 204 to deter leakage. In this embodiment the drainage assembly 200 and storage area 202 are employed to transport and store sewage and forms part of a drainage system 206. The drainage system 206 includes an exhaust assembly 208 for extracting methane gas (biogas), generated by the transported sewage, which has built up in the drainage assembly 200.

[0079] The exhaust assembly 208 includes two extractor fans 210 in fluid communication with the drainage assembly 200. The extractor fans 210, in turn, are placed in fluid communication with an exhaust conduit assembly 212. The exhaust conduit assembly 212 feeds methane gas to a combined power and heat converter 214. In this embodiment the combined power and heat converter is produced by Helbio S. A. In the combined power and heat converter 214 methane gas is filtered and then converted into hydrogen with a reformer. Persons skilled in the art will be aware of the fact that a reformer is a device enabling chemical synthesis to produce hydrogen gas from methane by employing a catalyst. The formed hydrogen is thereafter fed to a fuel cell where chemical energy is converted to electricity through a chemical reaction of positively charged hydrogen ions with oxygen or another oxidising agent. Electricity so generated can be loaded to an electricity supply grid 216.

[0080] The exhaust assembly 208 includes activation systems 218, each operatively associated with one of the extractor fans 210. The activation systems 218 are adapted to activate and deactivate their respective extractor fan 210. In this embodiment each activation system 218 includes a non-illustrated timer wherein the extractor fan 210 is activated responsive to time measurements taken by the timer.

[0081] Each activation system 218 includes an emergency trigger 220 for activating its associated extractor fan 210. In this embodiment the emergency trigger 220 comprises a mechanical diaphragm trigger switch which is adapted to be activate the exhaust fan 210 when methane pressure levels in the drainage system 206 exceeds a pre-set value.

[0082] The drainage system 206 includes an alarm system 222 adapted to alert personnel to hazardous levels of methane in the drainage assembly 200. The alarm system 222 includes a warning light source 224 and warning siren 226.

[0083] The drainage assembly 200 is in fluid communication with two manholes 228 each having a manhole lid 230. Each manhole lid 230 is fitted with a lock 232 to deter unauthorised, and potentially lethal, access to the drainage assembly 200.

[0084] By providing storage units employing curved structures in the load bearing member framework it is possible to achieve desirable structural strength in the drainage units whilst reducing the amount of plastic raw materials used.

[0085] Although the invention is described above in relation to preferred embodiments, it will be appreciated by those skilled in the art that it is not limited to those embodiments, but may be embodied in many other forms.