Plastic infiltration units are known. Infiltration units (also known as attenuation units depending on the deployment conditions of the unit) are for the temporary storage of excess rainwater, enabling controlled discharge. They are used for managing intense rainfall run-off and for reducing the risk of flooding. When the water stored in the unit is later discharged into a water impermeable system, such as a sewer, the unit may sometimes be referred to as an attenuation unit. When the stored water is later discharged into a water permeable system, such as the ground, the unit is generally referred to as infiltration units. Where reference is made in this text to an infiltration unit, it may refer to a unit suitable for attenuation (attenuation unit) and/or infiltration (infiltration unit) .

Conventionally , plastic infiltration units may simply be stacked one on top of each other and next to each other . This has a disadvantage that no overall volume decrease is achieved. Thus , storing and transporting the units can be expensive. Further, the stacked units by virtue of their relatively large total volume may be complex to handle . Thus , manpower costs may also be large .

Whilst it may be possible to stack certain infiltration units inside one another to therefore reduce the overall volume of a stack of infiltration units, this is only possible with certain types of infiltration unit, for example, cone shaped units. Further, cone type units, once stacked and arranged together in storage, have a profile which may be hazardous for operators attempting to stand or walk on top of the stacked units. This results in a less safe working environment for operators.

It is an object of the invention to reduce the storage and transport costs of the plastic infiltration unit without compromising the total effective volume of each plastic infiltration unit. It is a further object to reduce the environmental impact of the transport of plastic infiltration units. In accordance with one aspect of the invention, there is provided a plastic infiltration unit comprising:

a top deck which extends in a plane, the top deck having an underside, at least one pillar extending in a direction from the top deck for supporting the top deck, wherein the top deck comprises at least one first integrated connector and the at least one pillar comprises at least one second integrated connector, for temporarily holding in position the plastic infiltration unit with another identical plastic infiltration unit comprising at least one another pillar, the at least one another pillar comprising at least one another second integrated connector, wherein the plastic infiltration unit and the another plastic infiltration unit are connectable, so that in a coupled arrangement, the at least one pillar of the another identical plastic infiltration unit is held in position at the underside of the top deck of the plastic infiltration unit.

In this way, a plastic infiltration unit and another (second) plastic infiltration unit can be held in position together for storage and transport in such a way that the total volume to be stored or transported is reduced. In particular, in this way, the at least one pillar of one plastic infiltration unit is accommodated in the space between, the at least one pillar and top deck of another plastic infiltration unit. The reduction in the volume to be stored or transported results in a reduction in costs and a reduction in the environmental impact of storing and transporting such units. The present invention provides the further advantage that the connectors provide a form fixing function to prevent deformation of the plastic infiltration units in transport and storage .. According to a further aspect of the invention, there is provided an assembly comprising at least two plastic infiltration units, including a first plastic infiltration unit and. a second plastic infiltration unit, wherein each plastic infiltration unit comprises a top deck which extends in a plane , the top deck having an underside, at least one pillar extending in a direction from the top deck for supporting the top deck, wherein the top deck comprises at least one first integrated connector and the at least one pillar comprises at least one. second integrated connector, for temporarily holding the first plastic infiltration unit with the second plastic infiltration unit, the at least one pillar comprising at least one another second integrated connector, wherein the at least two plastic infiltration units are connectable , so that in a coupled arrangement, the at least one pillar of the second plastic infiltration unit is held in position at the underside of the top deck of the second plastic infiltration unit. According to a yet further aspect of the invention, there is provided a method of manufacturing a plurality of plastic infiltration units comprising the steps of: producing a plastic infiltration unit according to any preceding claim with another plastic infiltration unit according to any preceding claim, using a molding process and coupling the plastic infiltration unit and the another plastic infiltration unit when the plastic infiltration unit and the another plastic infiltration unit are still warm from molding process) ..

The invention, and various embodiments thereof, will further be explained on the basis of examples, with reference made to the drawings, in which:

Fig, 1 shows a plastic infiltration unit according to an embodiment of the invention;

Fig, 2 shows a side view (along the y direction) of a. plastic infiltration unit according to an embodiment of the invention;

Fig, 3 shows a side view (along the x direction) of a plastic infiltration unit according to an embodiment of the invention

Fig, 4 shows a top view (bird's eye view) of a plastic infiltration unit according to an embodiment of the invention; Fig. 5 shows an underside view of a plastic infiltration unit according to an embodiment of the invention; Fig, 6a shows a side view (along the y direction) of a plastic infiltration unit aligned with respect to another (second) plastic infiltration unit prior to the plastic infiltration unit and the another plastic infiltration unit becoming temporarily coupled, according to an embodiment of the invention;

Fig 6b shows a side view (along the y direction) of the plastic infiltration unit and the another (second) plastic infiltration unit of Fig. 6a in a temporarily coupled arrangement, according to an embodiment of the invention;

Fig, 7 shows a detail of Fig. 6a, in particular, Fig. 7 shows the at least one first integrated connector of the plastic infiltration unit in alignment with the at least one second integrated connector of the another plastic infiltration unit prior to becoming temporarily coupled, according to an embodiment of the invention; Fig. 8a shows a detail of Fig . 6a and Fig. 7, in particular, Fig. 8a shows a first integrated connector of the plastic infiltration unit in alignment with the second integrated connector of the another plastic infiltration unit prior to becoming temporarily coupled, according to an embodiment of the invention

Fig. 8b shows the detail of Fig. 8a in a temporarily coupled arrangement according to an embodiment of the invention; Fig. 9a shows a first integrated connector located in the vicinity of the periphery of the underside of the top deck according to an embodiment of the invention; Fig, 9b shows a pair of first integrated, connectors located between the pillars of the plastic infiltration unit according to an embodiment of the invention; Fig. 10a shows a projection and a recess formed in the top deck of a plastic infiltration unit and an another (second) upended plastic infiltration unit, prior to the upper surface of the plastic infiltration unit coming into contact with the upended upper surface of the another plastic infiltration unit, according to an embodiment of the invention;

Fig. 10b shows the plastic infiltration unit and another plastic infiltration unit of Fig, 10a when the upper surface of the plastic infiltration unit is brought into contact with the upended upper surface of the another plastic infiltration unit, according to an embodiment of the invention;

Fig. 11a shows a first pair of plastic infiltration units and a second pair of plastic infiltration units aligned for stacking upon each other according to an embodiment of the invention;

Fig . lib shows a detail of Fig. 11a, in particular, Fig. lib shows the at least one projection and the at least one recess on the respective facing top decks of the first and second pair of plastic infiltration units , to prevent sliding between the first and second pair of plastic infiltration units , according to an embodiment of the invention; Fig. 11c shows the first and second pair of plastic infiltration units of Fig. 11a in a stacked arrangement , according to an embodiment of the invention; Fig . 12 shows a first pair of plastic infiltration units and a second pair of plastic infiltration units arranged according to an embodiment of the invention; Fig. 13a shows the first pair of plastic infiltration units and the second pair of plastic infiltration units of Fig . 12 , arranged according to an embodiment of the invention;

Fig . 13b shows a stack of first and second pairs of plastic infiltration units of Fig . 12 and 13a, according to an embodiment of the invention;

Fig. 13c shows the stack of pairs of plastic infiltration units of Fig . 13b being loaded for transporting, according to an embodiment of the invention;

Fig . 14a shows the first pair of plastic infiltration units of Figs. 6b, according to an embodiment of the invention; Fig. 14b shows a plurality of pairs of plastic infiltration units of Fig . 6b and 14a, arranged adjacent to one another and stacked with respect to one another, according to an embodiment of the invention; Fig . 14c shows the arrangement of plurality of pairs of plastic infiltration units of Fig . 14b being loaded for transporting, according to an embodiment of the invention.

Fig. 15 shows a cross- section of a pillar of a plastic infiltration unit according to an embodiment of the invention; Fig, 16 shows a view of a portion of a pillar of a plastic infiltration unit according to an embodiment of the invention .. In the drawings and in the detailed description hereinbelow, like reference signs denote like features. The invention is exemplified in the embodiments described below. The invention is not limited to these embodiments. In this disclosure reference is made to a plastic infiltration unit 2, also referred to as a (first) plastic infiltration unit 2. Reference is also made to another plastic infiltration unit 2 ^" , also referred to as a (second) plastic infiltration unit 2". In embodiments, of the present invention, the another plastic infiltration unit is another identical plastic infiltration unit, that is the another plastic infiltration unit and the second plastic infiltration unit are identical to the plastic infiltration unit. Yet further plastic infiltration units , for example, third to nth plastic infiltration units may also be referred to. In these embodiments , the third to nth plastic infiltration units are identical to the first and second plastic infiltration units . According to embodiments of the invention, these plastic infiltration units (first to nth) may be connected and arranged in various ways , for example, in layers and/or stacked or temporarily coupled to one another for storage and/or transportat ional reasons . Unless otherwise stated, in the embodiments shown, the plastic infiltration units described and shown are constructed in the same way, so that in terms of the features described hereinbelow, the first to nth plastic infiltration units 2, 2 ^' are the same . For example, in Figs . 1-5, a (first) plastic infiltration unit is shown . Its various features are identified. Figs . 1-5 also include a reference in brackets to another (second) plastic infiltration unit 2'. In this connection, the features of the another (second) plastic infiltration unit 2 ^' correspond to those of the (first) plastic infiltration unit 2 and are, however, indicated in the remaining figures as having a prime ( " ' " ) to distinguish the another (second) plastic infiltration unit 2 'from, the (first) plastic infiltration unit 2, In this disclosure, reference is further made to upper and lower surfaces, and undersides etc of the plastic infiltration unit. In this connection, this terminology- refers to the general, relative orientation of the various features of the plastic infiltration unit when deployed. Prom this disclosure it will be seen that during storage and transportation, for example, the plastic infiltration units may be turned upside down {upended} , inverted etc, so that they may couple with each other. The terminology is used, however, consistently, so that an underside of an inverted plastic infiltration unit is indeed located "above" an upper facing surface of the same inverted plastic infiltration unit ,

Fig. 1 shows a plastic infiltration unit according to an embodiment of the invention. Fig. 2 shows a side view {along the y direction) of a plastic infiltration unit according to an embodiment of the invention. Fig. 3 shows a side view (along the x direction) of a plastic infiltration unit according to an embodiment of the invention. Fig. 4 shows a top view (bird's eye view) of a plastic infiltration unit according to an embodiment of the invention. Fig. 5 shows an underside view of a plastic infiltration unit according to an embodiment of the invention. According to an embodiment of the invention, the plastic infiltration unit 2 comprises a top deck 4 and at least one pillar 6 extending from the top deck 4, The at least one pillar 6 supports the top deck 4. The plastic infiltration unit 2 is preferably weld free. For example, it is preferably made by injection molding from thermoplastic material. The plastic infiltration unit 2 according to the invention can be produced in a single shot. The top deck 4 and the at least one pillar 6 are thus- produced in one piece . In this way, an efficient manufacturing process is achieved. in the embodiment shown, the top deck 4 extends in a plane , for example, the xy plane shown in Fig . 1. The longitudinal direction 12 (or z direction) of the at least one pillar 6 is substantially perpendicular to the plane of the deck (the xy plane shown in Fig . 1) .

The deck of a (first) infiltration unit provides a structure into which pillars of the (first) plastic infiltration unit extend from and into which pillars of another (second) plastic infiltration unit are insertable into . The pillars are provided to support a load. The load includes a load from surrounding plastic infiltration units and the load of any water . The load is transferred via the pillars also through the deck . In this specification, the deck of a plastic infi It ration unit is referred to as a "top" deck. It is referred to as a top deck since the pillars of the same plastic infiltration unit extend from an underside of the deck . Therefore , when the plastic infiltration unit is deployed the deck is on the top of the pillars . The top deck of a first plastic infiltration unit, when deployed, however, may form the base for a second plastic infiltration unit disposed on top of (stacked on) the first plastic infiltration unit.

In this disclosure, reference is further made to upper and lower surfaces, and undersides etc of the plastic infiltration unit. As mentioned above, reference is also made to a top deck. In this connection, this terminology refers to the general, relative orientation of the various features of the plastic infiltration unit when deployed.

Further, the top deck may include an upper facing surface 28 (shown in Figs . 1-4 , 6, 7) and an underside 29 having a lower facing surface 30 (shown in Figs. 2, 3, 5, 6, 7) . In one embodiment, the pillar 6 is integratably formed in the top deck 4 so that an upper end 14 (also referred herein as the proximal end) of the pillar 6 forms a part of the top deck 4 into which, for example, in use, a lower end 16 (also referred herein as the distal end) of a second pillar is insertable when deployed, for example.

In the embodiment shown in Fig.l, the unit 1 includes six pillars. Other numbers of pillars are envisaged, for example, two, three or four, or more.

In one embodiment, the plastic infiltration unit comprises a top deck 4 which extends in a plane, for example, the xy plane, shown in the Figures. The plastic infiltration unit further comprises at least one pillar 6 extending from the top deck for supporting the top deck 4. The top deck 4 has an underside 29. The at least one pillar 6 extends in a direction 12 from the top deck 4 for supporting the top deck 4. In particular, the at least one pillar 6 extends from the underside 29 of the top deck 4.

Fig. 6a shows a side view (along the y direction} of a plastic infiltration unit aligned with respect to another (second) plastic infiltration unit prior to the plastic infiltration unit and the another plastic infiltration unit becoming temporarily coupled, according to an embodiment of the invention. Pig 6b shows a side view (along the y direction} of the plastic infiltration unit and the another (second) plastic infiltration unit of Fig. 6a in a temporarily coupled arrangement, according to an embodiment of the invention, Fig. 7 shows a detail of Fig. 6a, in particular, Fig. 7 shows the at least one first integrated connector of the plastic infiltration unit in alignment with the at least one second integrated connector of the another plastic infiltration unit prior to becoming temporarily coupled, according to an embodiment of the invention. Fig. 8a shows a detail of Fig. 6a and Fig. 7, in particular, Fig. 8a shows a first integrated connector of the plastic infiltration unit in alignment with the second integrated connector of the another plastic infiltration unit prior to becoming temporarily coupled, according to an embodiment of the invention. Fig. 8b shows the detail of Fig. 8a in a temporarily coupled arrangement according to an embodiment of the invention. Fig. 9a shows a first integrated connector located in the vicinity of the periphery of the underside of the top deck according to an embodiment of the invention and Fig. 9b shows a pair of first integrated connectors located between the pillars of the plastic infiltration unit according to an embodiment of the invention. With reference to Pigs. 1 to 9, the top deck comprises at least one first integrated connector 101 (Pigs, 1-3 , 5-3). The at least one pillar 6 comprises at least one second integrated connector 103 (Figs. 1-3, 5-8) .. The at least one first integrated connector 101 and the at least one second integrated connector 103 are provided for temporarily holding in position the {first} plastic infiltration unit 2 with another {second} plastic infiltration unit 2 ^" (Figs. 6-8, see also Pigs. 11-14 described in more detail hereinbelow) . In one embodiment, the at least one first integrated connector 101 and the at least one second integrated connector 103 connect the (first) plastic infiltration unit 2 with another (second) plastic infiltration unit 2'. The another (second) plastic infiltration unit 2 'comprises at least one another pillar 6. The at least one another pillar 6 ^' comprises at least one another second integrated connector 103' (Figs. 6 - 8) . The (first) plastic infiltration unit 6 and the another (second.) plastic infiltration unit. 6' are connectable . In a coupled arrangement, the at least one pillar 6' of the another (second) plastic infiltration unit 2 'is held in position at the underside 29 of the top deck 4 of the (first) plastic infiltration unit 6 {Figs. 6b, 8b, 11a, lie, 12-14} . As mentioned above, Figs. 6a, 7 and 8a show the {first} plastic infiltration unit 6 and the another (second) plastic infiltration unit 6 'aligned in such a manner that when brought into contact with each other, they will temporarily connect. Figs. 6b, 8b and 11-14 show the {first) plastic infiltration unit 6 and the another (second) plastic infiltration unit 6 ^' in a temporarily connected arrangement. As depicted in Figs. 6b, 8b and 11-14 , the at least one pillar 6 ^' of the another plastic infiltration unit is temporarily connectable to the underside of the top deck of the plastic infiltration, unit . In one embodiment , the connection between the (first) plastic infiltration unit 6 and the another (second) plastic infiltration unit 6 'is formed by a connection of at least one of the at least one first integrated connector 101 with at least one another second integrated connector 103" and a connection of the at least one second connector 103 with the at least one another first integrated connector 101 ' . The integrated connectors are integrally formed in the structure of the plastic infiltration, unit and the another (second) plastic the at least one first and second 101, 103 and at least one another first and second 101', 103 'integrated connectors are integrally formed in the structure of the plastic infiltration unit. In the coupled arrangement the plastic infiltration unit and the another plastic infiltration unit are transportable. Various transportational , storage and arrangements for the plastic infiltration units when not deployed are shown and discussed hereinbelow with reference, in particular, to Figs. 11-14. In one embodiment, the (first) plastic infiltration unit 2 comprises at least one second integrated connector 103 and the another (second) plastic infiltration unit 2 'comprises at least one first integrated connector 101 ^' . The at least one first and second integrated connectors 101, 103, 101', 103' are connectable, respectively, to one another, to temporarily connect the at least one pillar 6 of the plastic infiltration unit 2 to an underside 29' of the top deck of the another plastic infiltration unit 2'. In a further embodiment, the at least one first integrated connector 101, 101 'and the at least one second integrated connector 103 , 103 ' is a male and a female connector, respectively, or vice versa . In particular, the male connector is arranged to be inserted into the female connector and the female connector is arranged to receive the male connector . In the embodiments shown, the first integrated connector 101, 101 'is a male connector and the second integrated connector 103, 103 'is a female connector. The invention is not limited in this respect and the first integrated connector 101, 101" may alternatively be a female connector and the second integrated connector 103, 103 "may be a male connector.

With reference, in particular, to Figs. 8a, 9a and 9b, in one embodiment, the at least one first integrated connector 101 (101") is a male connector comprising a pin 101 {101") extending from the underside 29 (29") of the top deck 4 (4") . Further, in one embodiment, the at least one second integrated connector 103, 103" is an at least one female connector comprising an opening 103, 103" provided in a distal end 16, 16" of the at least one pillar 6, 6 ^" . Further, the at least one pillar 6, 6" may comprise a. foot 22 , 22 ' having an underside 105 ' , 105 (Figs . 8a and 8b) located at the distal end 16, 16" of the at least one pillar 6, 6 " . Further, the opening (103 (103 ^" ) may be provided in the underside 105' (105) of the foot 22, 22 " . In one embodiment , each of the at least one pillar 6 , 6 "is provided with a second integrated connector 103 , 103 ' . Further, a first integrated connector 101 , lOl ^' is provided for each of the at least one pillars 6 'of the another (second) plastic infiltration unit 2 ' . In one embodiment , the plastic infiltration unit 2 and the another plastic infiltration unit 2 'are both provided with at least one first and at least one second integrated connector ( 101 , 101 ' , 103 , 103") . The at least one first integrated connector 101, 101 'and the at least one second integrated connector 103, 103 'are located at complementary locations on the (first) plastic infiltration unit 2 and the another (second) plastic infiltration unit 2', respectively, so that when one of the plastic infiltration units 2, 2" is inverted with respect to the other plastic infiltration units 2', 2, at least one of the first integrated connectors 101, 101 'connects with at least one of the second integrated connectors 103, 103 On the other plastic infiltration unit 2, 2 ^" and vice versa. In one embodiment, a plurality of first and second integrated connectors 103, 1β3 ' , 105, 105 "are provided. In particular, there is redundancy of first and second integrated connectors 103, 103', 105, 105 ^' , provided at complementary locations, however, so that at least one first integrated connector 101, 101 Of one plastic infiltration unit connects with a second integrated connector 103, 103 'of the another inverted plastic infiltration unit 2, 2', In this way, connection between the plastic infiltration units is achieved without having to orient or align the plastic infiltration units beyond inverting one of the units and bringing the plastic infiltration units towards each other with the pillars offset with respect to one another to allow at least one of the pillars of one unit to connect with the underside of the top deck of the other unit. In this way, the time required to prepare the units for transportation or storage is reduced. In a preferred embodiment, the units are arranged so that as many as possible of the pillars of the one unit are connected with the underside of the top deck of the other unit. In this way, the connection is made stronger between the units. Further, the space occupied by the two units in total is reduced. In one further embodiment, the underside 29, 29 ^' of the top deck 4, 4 ^' comprises an outer perimeter region 107 (Fig. 9a) in which at least one first integrated connector 101 is located. Fig. 15 shows a cross-section of a pillar of a plastic infiltration unit according to an embodiment of the invention and Fig. 16 shows a view of a portion of a pillar of a plastic infiltration unit according to an embodiment of the invention.

In one embodiment, the at least one pillar 6, 6 ^' extends in a longitudinal direction 12 ( z direction) and has a longitudinal axis (z axis) . The at least one pillar 6, 6' includes a central compartment 8 extending along the longitudinal axis (z axis) and at least one additional compartment 10 extending in the longitudinal direction. The at least one additional compartment 10 may surround at least a part of the central compartment 8. Further, the at least one second integrated connector 103, 103 ^' is provided in the at least one additional compartment 10 (Figs . 8a and 8b) .

In one embodiment , the at least one integrated male connector 101 , 101 ^' may comprise a pin . The pin may comprise a first plate portion 109 and a second plate portion 111 ( Fig . 9a and 9b) . The first and second plate portions 109 , 111 may have a distal end 113 (Fig. 8a, 9a, 9b) . The first plate portion 109 may have a central region 115 extending in a direction of insertion of the pin ( Figs . 8a, 9b) . Further, the first and second plate portions 109 , 111 may taper towards the distal end 113. Further, the second plate portion ill may extend from the central region 115. Further, the first and second plate portions 109 , 111 are integrally formed. In one embodiment , the second plate portion 111 extends perpendicularly from the first plate portion 109. In one embodiment, the at least one integrated male connector 101, 101 'has a "T"shaped crosssection , In one embodiment, the at least one integrated female connector 103, 103 'may comprises a recess 103, 103 'formed in an underside 105, 105' surface of the at least one pillar 6, 6'. The recess 103, 103 'may have an at least in part circular crosssection 117 (Fig. 8a) . The recess 103, 103 may further comprise a plurality of notches 119 (Fig. 8a) extending away from the circular part 117 of the recess 103, 103'. In the embodiment shown in Fig. 8a, three notches are provided. In this way, a T-shaped male connector can be readily accommodated in the female connector in three orientations,

In one embodiment, the plastic infiltration unit 2 and the another plastic infiltration unit 2' may comprise an even number of at least four pillars 6, 6 ^' . Further, the top deck 4, 4 'of the plastic infiltration unit and the another plastic infiltration unit extend in a plane and have a quadri lateral shape (Figs . 1-5) . The top deck 4 , 4 'may have a peripheral region 13 (Figs . 1, 4 and 5) extending around the periphery of the top deck 4 , 4 ^' and four corners 121 (Figs . 1 and 4). The at least four pillars 121 are arranged in one embodiment towards the corners 121 of the top deck 4, 4 ' . Further, a plurality of first integrated connectors 101, 101 ^' are disposed on the underside 29 of the top deck 4 , 4 ^' , respectively. Further, a plurality of second integrated connectors 101 , 103 'are disposed on the at least four pillars 6, 6 ^' , respectively. Further, on the underside 29 of the top deck 4, 4 ^' in a region 123 defined between the pillars (Fig. 2) , the plurality of first integrated connectors 101 , 101 'may be are disposed in pairs . Further, in the peripheral region 13, the plurality of first integrated connectors 101, 101 ^' may be disposed singly. In this way, when the plastic infiltration unit 2 is brought into contact with an upturned another plastic infiltration unit 2", the pillars 6 of the plastic infiltration unit 2 engage with the second integrated connectors 103' of the another plastic infiltration unit 2' and the pillars 6 ^" of the another plastic infiltration unit 2 ^' engage with the first integrated connectors 101 of the plastic infiltration unit 2 (Figs . 6a, 6b, 7, 8a, 8b, 11a, 11c) . In one preferred embodiment, the plastic infiltration unit 2 and the another plastic infiltration unit 2 ^' comprise six pillars 6 , 6 ^' and twenty first integrated connectors . Further each pillar may comprise four second integrated connectors . Therefore, a unit comprising six pillars 6, 6 comprises twenty four second integrated connectors 103 , 103 ^' .

As mentioned above , in one embodiment , the plastic infiltration unit 2 and the another identical plastic infiltration unit 2" may have the same construction. In particular, the top deck 4 , 4 'may be a quadri lateral construction extending in a first direction (y ) and a second direction (x) , and having a thickness extending in a third direction {z ) . In one embodiment , the three directions (x , y and z directions ) are orthogonal with respect to each other.

Fig . 10a shows a projection and a recess formed in the top deck of a plastic infiltration unit and an another (second) upended plastic infiltration unit, prior to the upper surface of the plastic infiltration unit coming into contact with the upended upper surface of the another plastic infiltration unit , according to an embodiment of the invention and Fig . 10b shows the plastic infiltration unit and another plastic infiltration unit of Fig . 10a when the upper surface of the plastic infiltration unit is brought into contact with the upended, upper surface of the another plastic infiltration unit, according to an embodiment of the invention. In a yet further embodiment as depicted in Figs, 10a and 10b, and further depicted in Fig. lib, the plastic infiltration unit and the another plastic infiltration unit may further comprise at least one projection 201, 201 ^' and at least one recess 203, 203' for receiving the projection 201, 201'. The at least one projection 201, 201' and the at least one recess 203, 203' may be disposed on an upper surface 205, 205' of the top deck 4, 4'. In this way, when the upper surface 205, 205' of the top deck 4, 4 ^' is brought into contact with the upper surface 205, 205 'of an upturned top deck 4' of the another plastic infiltration unit 2 ^" , the at least one projection 201 on the plastic infiltration unit 2 is received by the at least one recess 203 ' of the another plastic infiltration unit 2, or vice versa. In this way, a sliding motion, between the top deck of plastic infiltration unit and the top deck of the another plastic infiltration unit is prevented ..

In a further embodiment, the underside 29 of the top deck 4 may comprise a chamfered edge 307 (Fig. 12) which is arranged to cooperate with a chamfered edge 307' of another plastic infiltration unit 2 ^' .

According to one embodiment of the present invention _. , there is provided a plurality of plastic infiltration units comprising a plastic infiltration unit 2 and at least one another (second) plastic unit 2 ' . The plurality of plastic infiltration units are temporarily coupled to one another for transporting or storage purposes. As mentioned above, various transporting and storage arrangements are shown in Figs.11-14. In one embodiment, the plurality of plastic infiltration units comprises a first pair of plastic infiltration units temporarily coupled to one another, wherein the top deck of a first plastic infiltration unit is temporarily coupled to the at least one pillar of a second plastic infiltration unit, the plurality of plastic infiltration units further comprising a second pair of plastic infiltration units temporarily coupled to one another wherein the top deck of a third plastic infiltration unit is temporarily coupled to the at least one pillar of a fourth plastic infiltration unit. In one embodiment (Figs. 11c, 13c and 14) the first pair of plastic infiltration units is stacked on the second pair of plastic infiltration units.

In a yet further embodiment depicted in Figs. 14b and 14c, a third and a fourth pair of plastic infiltration units coupled and stacked in the same manner as the first and second pair of plastic infiltration units, and arranged adjacent to the first and second pair of plastic infiltration units.

In a yet further embodiment , as depicted in Figs . 12 and 13a, 13b and 13c, the second pair of plastic infiltration units is arranged so that the at least one pillar of the fourth plastic infiltration unit is arranged to be located in a space between the top decks of the first and second plastic infiltration unit .

In a yet further embodiment , a third and fourth pair of plastic infiltration units coupled in the same manner as the first and second pair of plastic infiltration units , and arranged adjacent to the first and second pair of plastic infiltration units (Figs lib, 14c} .

In. particular, the plurality of plastic infiltration units may be strapped together using strapping bands 301 (Figs. 11a, 11c, 13a, 13b, 14b, 14c) . Further, the plurality of plastic infiltration units may be strapped together using at least one wooden beam 305 {Fig. 13b) , Alternative bundling techniques may also be envisaged,

According to a further aspect of the present invention, there is provided a plastic infiltration unit comprising; a top deck which extends in a plane, the top deck having an upper surface, wherein the top deck comprises: at least one projection and at least one recess for receiving the projection, the at least one projection and the at least one recess being disposed on an upper surface of the top deck, so that when the upper surface of the top deck is brought into contact with the upper surface of an upturned top deck of another (second) plastic infiltration unit, the at least one projection on the plastic infiltration unit is received by the at least one recess of the another plastic infiltration unit , or vice versa, to prevent a sliding motion between the top deck of plastic infiltration unit and the top deck of the another plastic infiltration unit.

The plastic infiltration units of the present invention may be arranged as an assembly. According to an embodiment of the invention, there is provided an assembly of two, or more plastic infiltration units , In one embodiment, the assembly comprises at least two plastic infiltration units , including a first plastic infiltration unit and a second plastic infiltration unit. Each plastic infiltration unit comprises a top deck which extends in a plane, the top deck having an underside, at least one pillar extending in a direction from the top deck for supporting the top deck. The top deck comprises at least one first integrated connector and the at least one pillar comprises at least one second integrated connector, to temporarily connect the first plastic infiltration unit with the second plastic infiltration unit. Each of the at least two plastic infiltration units comprises at least one pillar, the at least one pillar comprising at least one another second integrated connector, wherein the at least two plastic infiltration units are connectable , so that in a coupled arrangement , the at least one pillar of the second plastic infiltration unit is held in position at the underside of the top deck of the second plastic infiltration unit . Preferably, the assembly comprises a plurality of pairs of plastic infiltration units arranged to temporarily connect with each other . However, the assembly may also include an odd number of plastic infiltration units, whereby pairs of plastic infiltration units are coupled with one another and the odd plastic infiltration unit is disposed, for example , between the pillars of a coupled pair.

According to a yet further aspect of the present invention, there is provided a method of manufacturing a plurality of plastic infiltration units comprising the steps of : producing a plastic infiltration unit with another plastic infiltration unit, using a molding process and coupling the plastic infiltration unit and the another plastic infiltration unit when the plastic infiltration unit and the another plastic infiltration unit are still warm from molding process. In this way, the units are maintained in an optimum orientation whilst they cool. In this way, yet further, the accuracy of the production of the units is improved.

The arrangements of plastic infiltration units are not limited to those shown in the Figures.

It is of course clear that the expression "produced in one piece" is to be understood as embracing or alternatively formulated as the following expressions, and that the following expressions may be interchangeable with the expression "produced in one piece": that the top deck and the at least one pillar are at least one of monolithic , uniform and/or integral , alternatively, that the infiltration unit is free from at least one of joins, seams , and/or interfaces, further alternatively, that the material of the top deck and the material of the pillar are continuous , yet further alternatively, that the top deck and the pillar are integrally connected, and yet further alternatively, that the top deck and the pillar are free from at least one of joins, seams, and/or interfaces .

The invention is not limited to the embodiments shown and described above.