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Title:
UNDERGROUND TANK SYSTEM AND METHOD OF MANUFACTURING AN UNDERGROUND TANK SYSTEM
Document Type and Number:
WIPO Patent Application WO/2021/229403
Kind Code:
A1
Abstract:
An underground tank system is disclosed. The system comprises a plurality of panels including at least a pair of side panels, an end panel and a top panel. The panels are configured to be assembled substantially underground so as to define an internal water receiving zone between the panels. The side panels and the end panel are provided with angled slots permitting water to travel into or out of the water receiving zone. A tank network, a kit for manufacturing the underground tank system, and a method of manufacturing and assembling the underground tank system, are also disclosed.

Inventors:
PILLAY MORGAN RUNGEN (ZA)
Application Number:
PCT/IB2021/053944
Publication Date:
November 18, 2021
Filing Date:
May 10, 2021
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
PILLAY MORGAN RUNGEN (ZA)
International Classes:
E03F1/00; B28B7/00; E03B11/00
Attorney, Agent or Firm:
EDWARD NATHAN SONNENBERGS INC (ZA)
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Claims:
CLAIMS

1 . An underground tank system which comprises a plurality of panels including at least a pair of side panels, an end panel and a top panel, wherein the panels are configured to be assembled substantially underground so as to define an internal water receiving zone between the panels, and wherein the side and end panels are provided with angled slots permitting water to travel into or out of the water receiving zone, the slots in each of the side and end panels being angled between about 40° and about 80° relative to an axis which extends along a height of the panel.

2. The system according to claim 1 , wherein the water receiving zone has a substantially rectangular cuboidal shape.

3. The system according to claim 1 or 2, wherein the slots are substantially cylindrical.

4. The system according to any one of the preceding claims, wherein the slots are provided substantially across an entire area defined by each side panel and/or substantially across an entire area defined by the end panel.

5. The system according to any one of the preceding claims, wherein the system is an infiltration system and wherein the slots are angled so as to allow water to egress the water receiving zone via the slots while substantially preventing particles including sand and/or rock from entering the water receiving zone.

6. The system according to any one of claims 1 to 4, wherein the system is an agricultural tank system, and wherein the slots are angled so as to allow water to ingress the water receiving zone via the slots and the system further comprises a barrier component substantially preventing particles including sand and/or rock from entering the water receiving zone.

7. The system according to any one of the preceding claims, wherein the slots in each of the side and end panels are set at an angle of about 60° relative to the axis which extends along the height of the panel. 8. The system according to any one of the preceding claims, wherein the system includes the pair of side panels, a pair of end panels and the top panel, the system having a modular design which allows additional side panels, top panels and/or intermediate panels to be added to the system to modify its dimensions and thus a volume of the water receiving zone.

9. The system according to any one of the preceding claims, wherein the panels of the system are manufactured primarily from cementitious material by means of casting in suitable moulds.

10. The system according to claim 9, wherein the top panel includes a removable lid, wherein lifting of the lid is facilitated by a handle element and/or lifting arrangement incorporated into the lid during a casting process.

11. The system according to claim 10 which includes the lifting arrangement, wherein the lifting arrangement is configured to be located in a mould for the lid during the casting process, and wherein the lifting arrangement includes a shield and a lifting element, the lifting element being configured to mate with the shield such that, after casting and curing, at least a part of the lifting element is held captive within the cementitious material, while another part of the lifting element is exposed and located within or adjacent to a cavity defined by the shield, such that the exposed part of the lifting element can be used to lift the lid, in use.

12. A tank network which includes a plurality of the underground tank systems according to any one of claims 1 to 11 , the systems being interconnected by means of pipes, wherein the pipes provide fluid communication between the water receiving zones of adjacent tank systems via inlet/outlet holes in the end panels of the adjacent tank systems.

13. A kit for manufacturing an underground tank system, wherein the kit includes moulds designed for casting the panels of the underground tank system according to any one of claims 1 to 11 , such that, after casting and curing, the panels can be assembled to define the underground tank system, and wherein the kit includes inserts configured for defining the angled slots in the side and end panels during a casting process, each insert including a plurality of tubes and caps for sealing off ends of the tubes. 14. The kit according to claim 13, which further comprises reinforcing material including wire mesh and steel bars, the reinforcing material being configured to be received in one or more of the moulds prior to casting.

15. The kit according to claim 14, which includes at least one wire holder which is configured to receive a wire mesh junction of the wire mesh, wherein the wire holder is designed to retain the wire mesh junction substantially centrally in one of the moulds, when taken along a vertical axis or direction of the mould, and to support the wire mesh junction at a desired height above a bottom surface of the mould. 16. The kit according to claim 15, wherein the wire holder includes a set of receiving formations at opposite ends thereof, wherein each set of receiving formations is configured to accommodate a different thickness of wire, and the receiving formations being defined by legs of the wire holder which are also used to support the wire holder in an upright condition.

Description:
UNDERGROUND TANK SYSTEM AND METHOD OF MANUFACTURING AN

UNDERGROUND TANK SYSTEM

Field of the invention

The invention relates, generally, to underground tank systems. More specifically, the invention relates to an underground tank system, including but not limited to an infiltration tank system. The invention also relates to a kit for manufacturing such a tank system and to a method of manufacturing such a tank system.

Background to the invention

Various systems are used to dispose of unwanted water, such as surface runoff, storm water, waste water and grey water, by allowing it to soak slowly into the ground, thus dissipating into the groundwater. These systems are known commonly referred to as infiltration systems.

Infiltration systems are used to prevent flooding during heavy rainfall and otherwise deal with excess water in situations where the volume or flow rate of water is too high for surface water drainage systems to cope with (or where there is no surface water drainage system).

One example of an infiltration system is known as a soakaway. A soakaway is constructed by digging a hole in the ground and filling the hole with stone, rubble, plastic (e.g. plastic crates) and/or other elements. It is designed to allow water to filter through it and soak into the ground.

Another commonly used infiltration system is known as a French drain. A French drain is essentially a trench filled with gravel or rock and containing a perforated pipe that redirects water from a particular area. The Inventor has experience with conventional soakaways, French drains and similar infiltration systems and has identified a number of drawbacks in these systems. Some of these drawbacks are highlighted below.

Firstly, conventional systems may be fairly tightly packed and only small air pockets are present, e.g. between the stones or pieces of rubble in the system. As a result, the system may lack adequate space to receive water and thus be unable to handle large volumes of water or rapidly flowing streams of water (e.g. during heavy rains).

Secondly, the Inventor has found that some of the conventional systems, particularly French drains, require a fairly large installation area. This may make it infeasible for certain applications.

Thirdly, conventional systems are difficult to modify once installed. For instance, it may be difficult to lengthen, add onto or otherwise alter a soakaway or French drain once the system has been installed in the ground. These systems also cannot be effectively cleaned after installation.

The Inventor has identified a need for a system that may be useful in addressing the above and other issues while also being relatively easy to manufacture and install.

The term “underground tank system” should be interpreted broadly in the context of this specification. Embodiments of the invention may be applied not only to infiltration systems, but also to other underground tank systems like septic tanks, grease and fat tanks, attenuation tanks, sand, oil and grease traps, agricultural tanks, and the like.

Summary of the invention

Broadly, according to a first aspect of the invention, there is provided an underground tank system which comprises a plurality of panels including at least a pair of side panels, an end panel and a top panel, wherein the panels are configured to be assembled substantially underground so as to define an internal water receiving zone between the panels, and wherein the side panels and the end panels are provided with angled slots permitting water to travel into or out of the water receiving zone, the slots in each of the side and end panels being angled between about 40° and about 80° relative to an axis which extends along a height of the panel.

The underground tank system may be a so-called “panelled tank”. The slots may be substantially cylindrical slots.

The water receiving zone preferably has a substantially rectangular cuboidal shape when the panels are assembled underground.

In some embodiments, the tank system may be an infiltration system. In such embodiments, the slots are angled so as to allow water to egress the water receiving zone via the slots while substantially preventing particles such as sand and/or rock from entering the water receiving zone.

In alternative embodiments, the tank system may be an agricultural tank system. In such alternative embodiments, the slots are angled so as to allow water to ingress the water receiving zone via the slots and the system further comprises a barrier component substantially preventing particles such as sand and/or rock from entering the water receiving zone.

The slots may preferably be angled between about 45° and about 75°, more preferably between about 50° and about 70°, around more preferably approximately 60°, relative to the axis (Z-axis) which extends along the height of the relevant panel.

The tank system may include the pair of side panels, a pair of end panels and a top panel. The tank system may have a modular design, allowing additional side panels, top panels and/or intermediate/central panels to be added to the system to modify its dimensions and thus the volume of the water receiving zone.

The panels may be manufactured/constructed primarily from cementitious material, e.g. by means of casting in suitable moulds.

The top panel may include a removable lid. Lifting of the lid may facilitated by a handle element and/or lifting arrangement incorporated into the lid during the casting process. At least one of the panels, e.g. one of the end panels, may be provided with an inlet/outlet hole which operatively exposes or provides fluid communication to the water receiving zone.

In some embodiments the slots may be provided substantially across an entire area defined by each side panel and/or substantially across an entire area defined by each end panel.

Broadly, according to a second aspect of the invention, there is provided a tank network which includes a plurality of the underground tank systems which are interconnected by means of pipes, wherein the pipes provide fluid communication between the water receiving zones of adjacent tank systems via inlet/outlet holes in panels of the adjacent tank systems.

Broadly, according to a third aspect of the invention, there is provided a kit for manufacturing an underground tank system, wherein the kit includes moulds designed for casting the panels substantially as described above, such that, after casting and curing, the panels can be assembled to define the underground tank system.

The kit may include inserts configured for defining the angled slots in the side and/or end panels during the casting process. Each insert may include a plurality of tubes and optionally caps for sealing off ends of the tubes.

The kit may include reinforcing material, e.g. wire mesh and steel bars, configured to be received in one or more of the moulds prior to casting.

The kit may further include at least one wire holder, or wire spacer. The wire holder may be configured to receive a wire mesh junction of the wire mesh.

The wire holder may be designed to retain the wire mesh junction substantially centrally in the mould, when taken along a vertical axis or direction of the mould, and/or to support the wire mesh junction at a desired height above a bottom surface of the mould. The wire holder may include a set of receiving formations at opposite ends thereof, wherein each set of receiving formations is configured to accommodate a different thickness/diameter of wire. The receiving formations may be defined by legs of the wire holder which are also used to support the wire holder in an upright condition.

In use, the legs not being used to receive the wire mesh junction may be located at a bottom of the wire holder to support it in the upright condition, while the other set of legs may be located at the top of the wire holder.

The kit may include the lifting arrangement referred to above, which is configured to be located in a suitable mould during the casting process, e.g. a mould for the lid of the tank system.

The lifting arrangement may include a shield, or cup, and a lifting element, e.g. a stainless steel wire lifter. The lifting element may be configured to mate with the shield such that, after casting and curing, at least a part of the lifting element is held captive within the cementitious material, while another part of the lifting element is exposed and located within or adjacent to a cavity defined by the shield, such that the exposed part of the lifting element can be used to lift the lid, in use.

Broadly, according to a fourth aspect of the invention, there is provided a method of manufacturing and assembling an underground tank system, the method comprising: providing a kit substantially as described above; casting the panels using the moulds in the kit; digging a hole or trench in the ground; and assembling the panels in the hole or trench so as to define the underground tank system.

The method may include, prior to the casting step, inserting one or more of the inserts, the reinforcing material, the wire holder and the lifting arrangement into one or more of the moulds.

Assembling the panels may include securing edges of the panels to each other, e.g. using cementitious material. Brief description of the drawings

The invention will now be further described, by way of example, with reference to the accompanying drawings.

In the drawings:

Figure 1 is a perspective view of an exemplary embodiment of an underground tank system according to the invention, wherein the exemplary embodiment is employed as an infiltration system;

Figure 2 is an end view of the tank system of Figure 1 ;

Figure 3 is a top view of the tank system of Figure 1 ;

Figure 4 is a side view of the tank system of Figure 1 ;

Figure 5 is a top view of one of the side panels of the tank system of Figure 1 ;

Figure 6 is a front view of the side panel of Figure 1 ;

Figure 7 is a cross-sectional view of the side panel, taken along line A-A in Figure 6;

Figure 8 is a perspective view of an embodiment of an insert which may be used in the construction of a panel for an underground tank system according to the invention;

Figure 9 is an end view of the insert of Figure 8;

Figure 10 is a top view of the insert of Figure 8;

Figure 11 is a front view of the insert of Figure 8;

Figure 12 is a perspective view of an embodiment of a cap for the insert of Figure

8;

Figure 13 is a front view of the cap of Figure 12;

Figure 14 is a bottom view of the cap of Figure 12;

Figure 15 is a perspective view of an embodiment of a wire holder which may be used in the construction of a panel for an underground tank system according to the invention;

Figure 16 is a first end view of the wire holder of Figure 15;

Figure 17 is a side view of the wire holder of Figure 15;

Figure 18 is a second, opposite end view of the wire holder of Figure 15;

Figure 19 is an exploded perspective view of a lifting arrangement which may be incorporated into a panel or lid of the underground tank system; Figure 20 is a perspective view of the lifting arrangement of Figure 19; Figure 21 is a top view of the lifting arrangement of Figure 19; Figure 22 is a side view of the lifting arrangement of Figure 19; Figure 23 is an end view of the lifting arrangement of Figure 19; Figure 24 is a side view of a body of the lifting arrangement of Figure 19; Figure 25 is a photograph illustrating an example of the manner in which inserts and caps may be utilised in the construction/manufacturing of a panel according to the invention;

Figure 26 is a photograph illustrating an example of the manner in which wire holders may be utilised in the construction/manufacturing of a panel according to the invention;

Figure 27 is a photograph illustrating an example of the manner in which an underground tank system according to the invention may be lengthened by adding addition panels thereto; and

Figure 28 is a photograph illustrating an example of the manner in which adjacent underground tank systems according to the invention may be connected to each other to form an underground tank network;

Figure 29 is a side view of another embodiment of the tank system in which the slots substantially cover the side panels and end panels; and

Figure 30 is an end view of the other embodiment of the tank system shown in

Figure 29.

Detailed description with reference to the drawings

The following description of the invention is provided as an enabling teaching of the invention, is illustrative of the principles of the invention and is not intended to limit the scope of the invention. It will be understood that changes can be made to the embodiments described, while still attaining beneficial results of the present invention. Furthermore, it will be understood that some benefits of the present invention can be attained by selecting some of the features of the present invention without utilising other features. Accordingly, those skilled in the art will recognise that modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances, and are a part of the present invention. Figures 1 to 4 show an embodiment of an underground tank system 10 according to the invention. In this example embodiment, the system 10 is designed and assembled to function as an infiltration system which can be used in various applications, including domestic, commercial and industrial applications.

The system 10, when assembled underground, forms a rectangular cuboidal “tank”. The tank consists of a pair of opposing side panels 12, a pair of opposing end panels 14 and a top panel 16 which includes a disc-shaped lid 18. The interior of the tank is empty/hollow, with a rectangular cuboidal water receiving zone defined internally between the panels 12, 14, 16. The system 10 has an open bottom.

The panels 12, 14, 16 and lid 18 are all manufactured by casting them using cementitious material in suitable moulds. For instance, the cementitious material may be mortar or concrete and it may be reinforced, e.g. with wire, mesh or the like. The panels 12, 14, 16 are installed in a hole/trench in the ground and secured to each other, again using a cementitious material.

The dimensions of the panels 12, 14, 16, including the length of the side panels 12, may be varied to cater for different applications and requirements (e.g. to provide an infiltration system with a suitable volume for the application). The following are examples of dimensions of embodiments of the invention:

• 1040 mm (length) x 640 mm (width) x 640 mm (height)

• 1000 mm (length) x 1040 mm (width) x 1040 mm (height)

It should be appreciated that this “modular” design allows the system 10 to be modified, and in particular to be lengthened. For instance, as shown in the photograph of Figure 27, a further pair of side panels and a further top panel can be added to provide a longer infiltration tank system 32.

Referring to Figures 1 and 2, the end panels 14 are each provided with a circular hole 20 in an upper region of the panel 14. The hole 20 exposes the internal water receiving zone and can be used to provide fluid communication between another component and the internal water receiving zone. As shown in the photograph of Figure 28, these holes 20 are configured to receive pipes 22 so that a plurality of the systems 10 can be interconnected to form an infiltration tank network 24. The holes 20 can thus be used as inlets/outlets between the water receiving zones of connected systems 10 in the network. In this way, a continuous soakaway-type network can be installed.

With the lid 18 in position, the top panel 16 is solid, as is evident from Figures 1 and 3. However, it will be appreciated that the top panel 16 can be opened to provide access to the interior of the system 10 by lifting the lid 18. Lifting of the lid 18 is facilitated by a pair of handle elements 30. The handle elements 30 are defined by lifting arrangements incorporated into the lid 18 prior during the casting process. This aspect of the system 10 is described in greater detail with reference to Figures 19 to 24 below.

The side panels 12 and end panels 14 are each provided with a plurality of slots 26. The slots 26 are angled and substantially cylindrical in shape. The slots 26 are arranged in sets of three (see the circled portion 28 in Figure 2). Each set 28 has two slots that are aligned vertically and a third slot, located between the first two slots and positioned slightly higher than the first two slots. The sets 28 of slots 26 are in turn arranged in rows and columns across the panels 12, 14 as shown in Figures 1 , 2, 4 and 6.

In the embodiment of Figures 1 to 4, a part of one or more of the panels may be devoid of slots to allow room for a logo and/or branding. These parts are indicated by reference numerals 96 and 98 in Figures 1 , 2 and 4 and exemplary “SHADAI” branding is shown in Figures 25 to 28. However, this is shown merely as an example and it should be appreciated that different logos and other indicia can be included on the panels (in any suitable zone) and/or that the slots may extend across substantially an entire panel with the panel being devoid of indicia or substantially solid zones. As an example, in the alternative embodiment of Figures 29 and 30, in which like reference numerals refer to like features in the embodiment of Figures 1 to 4, the system 92 has additional slots 94 in the panels 12, 14 which are of the same dimensions and angle as the slots 26. In other words, instead of leaving a space for logos or branding, the slots 26, 94 are provided substantially across an entire area defined by each side panel 12 and each end panel 14. The Inventor has found that covering substantially the entire panel 12, 14 with slots 26, 94 as shown in Figures 29 and 30 may improve the infiltration and overall effectiveness of the system 92.

Returning to the first embodiment which was described with reference to Figures 1 to 4, Figures 5 to 7 provide a further illustration of the side panel 12, and specifically the configuration and angle of the slots 26. As is best shown in Figure 7, the slots 26 are set at an angle relative to the three axes (X, Y and Z) defined by the panels 12. In this example embodiment, the slots 26 extend at an angle of approximately 60° relative to an axis “Z” which runs along or extends parallel to the height of the panel 12 (see Figure 7). The axes “X”, Ύ” and “Z” are shown in Figures 5 to 7, with “X” running along the length of the panel 12, Ύ” running along with width of the panel 12, and “Z” running along the height of the panel 12.

When the system is used as an infiltration system, as is the case in the example described with reference to the drawings, the slots 26 are angled so as to extend downwardly from an inner face (see face “B” in Figure 7) to an outer face of the panels (see face “A” in Figure 7). The inner face is the face adjacent to the internal water receiving zone. Accordingly, when used as an infiltration system, the angle of 60° referred to above is the angle between the inner face “B” and the axis Z / height of the panel 12.

The Inventor has found that the angled slots 26 act as a “self-gravitation” type of conduit. The angle has been specifically selected so as to allow water to exit the water receiving zone inside of the system 10 effectively via the slots 26, while not allowing particles such as sand/gravel/rocks to enter the system 10 via the slots 26. While 60° is preferable, other acute angles may also be employed.

In other applications, the system 10 may be used as an agricultural tank. In such an application, the panels 12, 14 are essentially installed “upside-down” so that the slots 26 are angled so as to extend upwardly from the inner face to the outer face. Accordingly in such an implementation the acute angle referred to above would be the angle between the outer face “A” and the axis Z / height of the relevant panel. In this way, external ground water can flow into the interior of the system 10 via the downwardly angled slots (when viewed from the perspective of the ground water’s travel direction). The system 10 may have a barrier component, e.g. it may be wrapped or in shade cloth or other suitable material to prevent sand (and other particles) from entering the water receiving zone. In this application, water entering the system 10 can be piped or pumped, e.g. to an above-ground storage tank or irrigation system.

The slots 26 may be formed in the panels 12, 14 by using inserts such as the insert 34 shown in Figures 8 to 11 .

In this example embodiment, the insert 34 is made from plastic and is injection moulded with six cylindrical tubes 36 that are held together by a network of horizontal spines 38. The tubes 36 are set at a 60° angle relative to the lengths of the spines 38 so that, during the casting process, they define the angled slots 26 in the panels (as an example, the angle is indicated in Figure 9). The tubes 36 are arranged to define two of the sets 28 as shown in Figure 2. This is illustrated by the circled part 68 in Figure 2.

The spines 38 are provided with a pair of triangular legs 40 at a bottom of the insert 34 and three pairs of spaced apart protrusions 42 at a top of the insert 34. The legs 40 ensure that the insert 34 is stable during casting and the protrusions 42 define a channel for receiving a reinforcing element such as a suitable reinforced/reinforcing wire.

The insert 34 has been designed to conform to the sizing of the gaps in the reinforcing mesh typically used in the Inventor’s moulds (see Figure 25). The arrangement of the tubes 36 in two sets or rows of three also allows the insert 34 to be cut/broken up into smaller pieces, e.g. into two sets of three tubes 36 which are still stable when positioned in a mould. This may be useful when it is necessary to form slots in corners or other desired areas of a panel where a full insert 34 would not fit.

The tubes 36 have open ends which can be capped with plastic or rubber caps, an example of which is shown in Figures 12 to 14. The cap 44 shown in Figures 12 to 14 has a head portion 46, or flanged end, and a neck portion 48. The neck portion 48 is configured to be received inside of the tube 36 and thus has an external diameter which allows it to fit inside of the tube 26. The head portion 46 has a diameter which is greater than the inner diameter of the tube 36 so as to substantially seal off one of the ends of the tube 36. The cap 44 is also designed at the 60° angle to match the angle of the tubes 36 of the insert 34.

In use, a plurality of the inserts 34 (with caps 44) can be placed into a mould designed to form one of the panels 12, 14. An example of this is shown in Figure 25, in which an end panel such as the panel 14 is being constructed.

The inserts 34 may be attached to wire mesh 48 using a tie strap or a tie wire to prevent movement during the concrete/mortar pouring and vibration process. As mentioned above, the cap 44 shown in Figures 12 to 14 is shaped to conform to the 60° angle of the tube 36. The caps 44 operatively cover the open ends of the tubes 36 to prevent cementitious material and/or debris from entering the tubes 36 during pouring or vibration.

The panels may be made with 3 mm / 4 mm reinforced welded mesh 48. The mesh may be pre-welded with, for example, 100 mm 2 openings between the mesh elements. Bars may be added, e.g. 6 mm round steel bars 50, as shown in Figure 25. Preferably, the panels are cast to a minimum of 40 MPa concrete/mortar strength. Once the cementitious material is cured, at least the caps 44 (and optionally also the tubes 36 if possible/feasible) are removed, thus exposing the slots 26 as described above. Although not described above, it will be appreciated that the hole 20 and suitable branding/indicia may also be formed in the panel 14 by inserting suitable inserts into the mould during the casting process and removing such inserts at the appropriate time if required.

A wire holder 52 or wire spacer, an example of which is illustrated in Figures 15 to 18, may be used during the casting process to keep the reinforced wire substantially centrally positioned in the mould, thus maintaining strength and durability of the tank system 10. Preferably, the wire holder 52 is employed to support the wire at a desired height above a bottom surface of the mould, i.e. to keep the wire at a desired height along a vertical axis/direction of the mould.

In this example embodiment, the wire holder 52 is designed to accommodate two common sizes of reinforced wire. The holder 52 has a first end 54 and a second end 56, with four spaced apart legs 58, 60 being located at each end 54, 56. Each set of legs 58, 60 is connected to and extends axially away from a body portion 62 of the holder 52.

The free ends of the legs 58, 60 are configured such that the wire holder 52 can stand upright on both of its ends 52, 54, i.e. both sets of legs 58, 60 are capable of supporting the wire holder 52 in an upright position in a mould.

In each set of legs 58, 60, adjacent legs are evenly spaced apart to define receiving zones for wire of a particular thickness. However, the spacings employed in the respective sets of legs 58, 60 differ. The legs 58 at the first end 54 are spaced apart so as to accommodate a first common thickness (diameter) of reinforced wire, e.g. 3 mm, while the legs 60 are spaced apart so as to accommodate a second common thickness of reinforced wire, e.g. 4 mm. This design allows the holder 52 to simply be turned over / upside-down, to allow for a different wire thickness to be accommodated. The regions between the legs 58, 60 define a plus-shape or X-shape so as to accommodate a wire mesh junction (i.e. the point where a mesh wire extending along the X-axis meets a mesh wire extending along the Y-axis). The plus-shapes or X- shapes are indicted by the broken lines 64 and 66 in Figures 16 and 18 respectively, and an example of the use of such wire holders 52 is shown in the photograph of Figure 26.

As mentioned above, lifting of the lid 18 away from the top panel 16 is facilitated by a pair of handle elements 30. The handle elements 30 are defined by lifting arrangements 70 incorporated into the lid 18 prior to the casting process. An example of the arrangement 70 is illustrated in Figures 19 to 24.

The lifting arrangement 70 includes an injection moulded, hollow, plastic shield 72, or cup, which is semi-disc shaped with an open top 74 and an internal cavity 76. Opposite sides of the shield 72 are each provided with a rounded depression 78 and spaced apart, vertically extending parallel ridges 80 defining a channel 82 there between. The depressions 78 are located in upper surfaces of the shield 72 and the ridges 80 protrude from the respective sides of the shield 72. The depressions 78 and the channels 82 defined between the ridges 80 are configured to receive a lifting element 84 in the form of a stainless steel “wire lifter” or “lid lifter”.

The shield 72 is specifically designed to snugly receive the lifting element 84 and to expose a central part 86 thereof post-casting such that the central part 86 defines the handle element 30 referred to above and shown in Figures 1 and 3.

The lifting element 84 is press bent into the shape shown in the drawings (best shown in Figure 19). The lifting element 84 has a first end 88 and a second end 90 which, when the lifting element 84 is received by the shield 72 (see Figures 20 to 23), protrude laterally away from respective sides of the shield 72. These ends 88, 90 are operatively located in the casting zone, i.e. the zone filled with cementitious material in the mould, and may further be secured to the reinforcing mesh for added strength.

The shield’s internal cavity 76 is not filled with cementitious material, while the immediately surrounding areas, including the zones occupied by the ends 88, 90, are. In this way, after casting and curing, the cavity 76 and the lifting element’s central part 86, which extends laterally across the cavity 76, are exposed, while the lifting arrangement 70 is firmly secured in the panel due to the configuration of the ends 88, 90. This permits easy opening of the lid 16, e.g. for maintenance, cleaning or the like.

It is envisaged that the lifting arrangement 70 may be applied outside of the underground tank environment. For instance, it may be used in conventional manhole covers and lids.

Embodiments of the present invention may provide numerous advantages. The tank system described herein provides an empty/void internal chamber with more holding capacity than conventional systems. It may thus act as a storage tank during heavy rains or the like and can be drained if necessary. The tank system is relatively easy to manufacture and install, and can also be accessed and cleaned after installation. Furthermore, an easy, modular “add on” system is provided, as described with reference to Figure 27.

It will be appreciated that the term “underground”, which is used in this specification, may denote both a system which is located completely under a ground level and one which is partially under the ground level. For instance, the top panel and lid may be located above a ground level to allow the system to be easily accessed for maintenance, cleaning, etc.

While the examples described with reference to the drawings relate mainly to a panelled infiltration system and a panelled agricultural tank system, other applications of aspects of the invention are envisaged.

Instead of making use of the angled slots described above, the side panels and end panels may be substantially solid, in which case the tank system may be used as a septic tank, grease and fat tank, attenuation tank, and/or a sand, oil and grease trap. Aspects of the invention such as the wire holder and the lifting arrangement may still be employed in these embodiments without employing the angled slots.

For instance, when the tank is used as a storm water attenuation tank, the wire holder and lifting arrangement may still be used and the hole in the end panel (similar to the hole 20 in the drawings) can be provided near a bottom of the end panel.

In some cases, the tank may be provided with intermediate or central panels between the end panels. This may define a plurality of compartments within one tank. Openings may provide fluid communication between the compartments, e.g. a large, square opening may be employed.

It will be apparent from the above that the Inventor has developed a highly versatile panelled tank system which can be used in a variety of applications.