AU2006279239A1 - Storage of water, rainwater or grey water or other liquids beneath a concrete floor slab - Google Patents

Description

WO 2007/016721 PCT/AU2006/001025 1 STORAGE OF WATER, RAINWATER OR GREY WATER OR OTHER LIQUIDS BENEATH A CONCRETE FLOOR SLAB 5 Field of the Invention This invention relates to a liquid storage method and a construction for storing liquids. It relates particularly but not exclusively to the storage of rainwater and/or grey water beneath a concrete floor slab of a building. 10 Background of the Invention With growing world population there is an ever increasing need for fresh water. Unfortunately, in arid countries such as Australia the amount of rain fall which 15 provides the necessary fresh water is in some instances inadequate, particularly in drought years. Despite a lack of fresh water resources, a large amount of useable water, such as water from domestic baths and showers, is lost through being flushed down sewerage 20 lines. Apart from presenting problems of disposal, the water could much more usefully be used for a range of useful purposes such as watering domestic gardens, etc. In addition, much rainwater is lost through stormwater drains. In times of heavy rain, 25 the disposal of rainwater through stormwater drains can be problematic leading to localised flooding in the most extreme instances. Again, this wasted water could more profitably be used for domestic or other purposes if it could be stored rather than being allowed to run away down the drains. 30 Finally, increasing population means that the ratio of catchment area per human is decreasing placing even more burden on the water supply.

WO 2007/016721 PCT/AU2006/001025 2 Thus, there is a need for a storage system which is suitable for storing grey water and/or rainwater. Furthermore, it is preferred that the storage system be one which is relatively simple to construct, can be sited in locations where it is not an eyesore and can be readily accessible in times of need. 5 Disclosure of the Invention The invention provides a method of creating a liquid storage reservoir under a floor cast from a settable material comprising the steps of, 10 creating a mould form for casting of the settable material, the mould form having a shape including an area for casting of flooring, and a trough for moulding a beam extending under the flooring, disposing a void forming material in the mould form in the sub-floor space to create a liquid storage cavity for the liquid storage reservoir, 15 disposing the liquid storage reservoir in the cavity before or after casting of the settable material, and connecting a pump module to the liquid storage reservoir, the pump module being adapted to direct liquid into the liquid storage reservoir and to pump liquid from the liquid storage reservoir. 20 Suitably, the settable material may comprise concrete. It may include reinforcement as is known in the art. For example, reinforcement may comprise steel bar and/or mesh and/or rod. Additionally or alternatively, the material when set may include integrally formed ribs and/or beams or other structural features to improve the 25 structural integrity of the flooring. The void forming member may itself comprise the liquid storage reservoir. It may comprise one or more modules. Where it comprises a plurality of reservoir modules, the reservoir modules may be interconnected so as to allow liquid to flow between 30 reservoir modules. The reservoir modules may also be rigidly secured together. The modules may comprise generally squat containers formed by a process such as rotational and/or blow moulding of plastics. Typically, their depth dimension will be WO 2007/016721 PCT/AU2006/001025 3 substantially less than their length and breadth assuming they are of square or rectangular shape. They may typically have a holding capacity of 400 to 900 litres. The reservoir modules may comprise, four ribbed side walls, 5 a bottom panel, a ribbed top panel, and at least one support member extending between the top and bottom panel. The ribs may be formed as elongate recesses on the walls or top panels. The reservoir 10 modules may comprise a step formed on each of the four ribbed side walls. They may comprise four formed hollow support members extending between the top and bottom panel. The hollow support members may be formed integrally with the reservoir modules or they may be added after moulding of the reservoir modules. They may comprise columns. 15 Alternatively the reservoir modules may comprise containers formed of flexible membranes. Typically, each rigid module may be located so that a bottom panel of a module is 20 supported by the ground and the top panel of the module supports the underneath of the cast settable material such as concrete. In order to be able to bear the weight of the concrete, each module may include stiffening or reinforcement. The ends of the columns may be open. Barrier material may be installed between the 25 upper surface of the module and the settable material. The barrier material may comprise plastic sheet. It may comprise material impermeable to termnnites. It may provide some thermal insulation. Alternatively or additionally, the barrier material may be installed so that it is 30 interposed between the bottom panel of the module and the ground on which it rests. A supply pipe may extend through a lateral opening in a perimeter beam of the floor. It may extend to a pump module from an outlet of the liquid storage reservoir.

WO 2007/016721 PCT/AU2006/001025 4 Typically, the supply of liquid may be by way of drainage from guttering, such as guttering from roofs and/or household use such as shower effluent etc. The pump module may act to direct drainage liquid into the liquid storage reservoir and to pump liquid therefrom on demand. 5 The pump module may comprise filtering means for removing debris from liquid being directed into the liquid storage reservoir. Treatment means as are known in the art may be used to treat water which is drawn 10 from the liquid storage reservoir to make it suitable for its intended purpose. The treatment means may be incorporated in the pump module. Preferred aspects of the invention will now be described with reference to the accompanying drawings. 15 Brief Description of the Drawings Figure 1 shows a plan "x-ray" view of a section of concrete slab incorporating a liquid storage reservoir according to the invention; 20 Figure 2 shows the section Z-Z taken on the slab of Figure 1; Figure 3 shows an isometric view of an edge section of a slab along the lines of the slab shown in Figure 1; Figure 4 shows an isometric view of one and a half storage modules for use with the invention; 25 Figure 5 shows a plan view of a pump module for use with the invention; Figure 6 shows the section A-A taken on Figure 5; Figure 7 shows the section B-B taken on Figure 5; Figure 8 shows a flow diagram of a storage reservoir according to the invention; 30 Figure 9 shows an isometric view of a tank module for use with the invention; Figure 10 shows an isometric partial x-ray view of an installed liquid storage reservoir according to the invention; WO 2007/016721 PCT/AU2006/001025 5 Figure 11 shows an elevational cross sectional view of a floor and liquid storage reservoir; Figure 12 shows a plan view of a liquid storage reservoir; Figure 13 shows an elevational view of two tank modules; and 5 Figure 14 shows an elevational partially cut away view of a tank module. Detailed Description of the Preferred Embodiments The various elements identified by numerals in the drawings are listed in the 10 following integer list. Integer List 1 Slab assembly 15 2 Cast slab 3 Ground level 5 Reservoir assembly 9 Pump module 12 Perimeter beam 20 13 Reinforcement 14 Floor 15 Perimeter step 16 Intermediate beams 17 Opening 25 18 Thickening 20 T-brace 21 Depending bar reinforcement 23 Sub-floor space 24 Forming material 30 25 Reservoir module 26 Reinforcing pillars 27 Bottom lug 28 Top lug WO 2007/016721 PCT/AU2006/001025 6 29 Hole 30 Pin 31 Rebate 32 Connecting spools 5 33 Inlet 34 Drive pin 36 Mounting plate 37 Housing 38, 38a Inlet pipe 10 39 Supply pipe 40 Overflow pipe 43 Filter 45 Offtake pipe 46 Pump 15 47 Sheath 48 Sheath 49 Cover 50 Distribution pipe 51 Cap 20 52 Opening 53 Outlet 60 Reservoir module 61 Sidewall 63 Rib recess 25 64 Central rib recess 65 Step 66 Recess 67 Hole 70 Pipe 30 72 Air vent 74 Sloped region 75 Top panel 76 Bottom panel WO 2007/016721 PCT/AU2006/001025 7 77 Parallel recessed ribs 78 Parallel recessed ribs 80 Cap 82 Ground 5 83 Sand layer 84 Concrete 85 Perimeter beam 86 Formwork 87 Plug 10 88 Brick wall 89 Air pipe 90 U clip 91 Open regions 92 Hollow column 15 93 Intermediate beam Referring to Figures 1 to 3 of the drawings, there is shown a slab assembly generally designated 1 which comprises a cast slab 2 of concrete. 20 The slab has been cast so that the floor of the slab 14 sits above ground level 3 supported by a series of intersecting cast intermediate beams 16 and a perimeter beam 12. A reservoir assembly 5 sits in the sub-floor space 23 defined between a pair of 25 parallel ribs. Where the parallel ribs are spaced wider than the reservoir assembly, this area may be left void or used to accommodate further reservoir capacity. The floor 14 of the cast concrete slab includes reinforcement 13 in the form of conventional steel reinforcement as is known in the art eg. rod or mesh reinforcement. 30 It is to be noted that the thickness of the floor in the general region of the reservoir assembly including the region surrounding reservoir assembly may be increased relative to the rest of the floor 14 to compensate for the reduction in the number of WO 2007/016721 PCT/AU2006/001025 8 ribs which have been omitted to allow for the disposition of the reservoir assembly 5 in the sub-floor space 23. The perimeter beam 12 is formed with a perimeter step 15 as is conventional in cast 5 slabs for buildings and in this particular embodiment may include an opening 17 reinforced on its underside with a region of thickening 18 and on its upper side with a T-brace 20 and depending bar reinforcement 21. The opening 17 is an optional feature if the reservoir assembly utilises a flexible membrane as it will allow removal of a void forming member after casting and replacement with a flexible membrane. 10 Where the reservoir assembly is a rigid construction as shown in Figure 4 it may be positioned prior to casting and so there is no need for the opening 17. A pump module 9 is mounted on the external vertical face of the perimeter beam 12 across the opening 17. 15 Forming material 24 such as polystyrene foam or cardboard or simply a build up of earth or sand or excavation of trenches is provided to form the intermediate beams 16. Referring to Figure 4, a reservoir module generally designated 25 may be used alone 20 or in combination with similar reservoir modules to form the reservoir assembly 5 beneath the floor of the slab. The reservoir assembly effectively acts as a mould form for creating the sub-floor space 23 in which it is located when the concrete is cast. It may be in direct contact with the pump in the casting operation or it may be covered with an impermeable sheet such as one made of plastic provided on its top surface or 25 alternatively, an impermeable sheet may be located beneath the reservoir assembly. Each reservoir module may typically be manufactured from a semi-rigid plastic like material such as PVC, polyethylene, polypropylene or any other material which is resistant to corrosion. Typically it may have been manufactured by rotational 30 moulding, blow moulding, injection moulding or any other form of fabrication suitable for the selected material.

WO 2007/016721 PCT/AU2006/001025 9 The reservoir module includes supports in the form of reinforcing pillars 26 formed during the moulding operation or inserted later. Typically these may be tubular pillars with open ends on both upper and lower faces of the reservoir module. 5 Bottom lugs 27 and top lugs 28 are provided on opposed sides of each reservoir module and are arranged so that holes 29 in the lugs align when reservoir modules are pushed together side to side. In this way, it is easy to secure adjacent modules together using pins 30. 10 The outer edges defining the reservoir assembly may optionally be secured via drive pins 34 pushed through the holes 29 and into the ground. Rebates 31 are provided in the sides of the reservoir modules. The rebates are arranged to receive connecting spools 32 which extend between adjacent reservoir 15 modules so as to allow communication of fluid between the various modules making up the reservoir assembly. Where there is not an adjacent reservoir module, the rebates 31 will be closed. This may be by way of a plug inserted into the rebate. Alternatively, the rebate may be closed as part of the manufacturing operation and holes may be drilled in the closed rebate to fit the connecting spools 32 when 20 required. A supply pipe 39 is arranged to connect with the inlet 33 of at least one of the modules. The supply pipe is arranged to extend through the opening 17 in the case of a flexible membrane. Otherwise it may be covered with a sheath 47 to protect the 25 supply pipe which extends directly through the concrete of the perimeter beam. Alternatively it may extend beneath the perimeter beam. Similarly, an offtake pipe 45 provided with a sheath 48 extends through the outlet 53 of the reservoir assembly for purposes to become apparent. 30 It is noted that the use of sheaths 47 and 48 leaves open the option of being able to cast concrete around the pipes 39 and 45 rather than passing them through an opening 17 as is shown in Figure 3.

WO 2007/016721 PCT/AU2006/001025 10 Referring to Figures 5, 6 and 7, it can be seen that the pump module 9 may be mounted on the perimeter beam via a mounting plate 36. It includes inlet pipe 38 for receiving liquid from a source such as drains for storm water or grey water. The inlet pipe passes through the walls of the housing 37 of the pump module and 5 communicates with the litter trap 43 for removal of debris and larger particulates. It exits as inlet pipe 38a from the litter trap and communicates with supply pipe 39 for directing the liquid into the reservoir assembly. An overflow pipe 40 also communicates with the inlet pipe 38 and is arranged at a 10 raised level above the level of the reservoir assembly so that excess liquid will drain away to waste when the reservoir assembly is filled. A pump 46 is arranged in the housing. This connects with the offtake pipe 45 to direct liquid from the reservoir assembly into the distribution pipes 50 as and when 15 required. A removable cover 49 having an opening 52 and an cap 51 for sealing the opening are provided to allow easy access to the litter trap so that it can be emptied periodically as and when required. The following is a typical range of steps which may be undertaken in preparing a 20 typical concrete slab with a reservoir assembly according to the invention. Pre-slab construction works 1. Excavate the void space between the slab thickening ribs to a depth of 600mm below the underside of the concrete slab. 25 2. Placement of the reservoir module(s) into the excavated place on a 25mm bed of sand or similar non-abrasive material. 3. Connect additional module(s) as required to meet capacity desired. 4. Placement of a protective cover over the top of the reservoir assembly if deemed necessary. 30 5. Secure the perimeter of the reservoir assembly by placing sand in the void between the edge of the vessel and the edge of the excavation ensuring that the connecting pipes are not placed under stress.

WO 2007/016721 PCT/AU2006/001025 11 6. Connect the inlet pipe to the mechanical connection on the reservoir wall and extend through the concrete perimeter beam's space. 7. Connect the reservoir's outlet pipe (pump suction pipe) to the mechanical connection on the reservoir's wall and extend through the concrete 5 perimeter beam's space. Connect this pipe to the other vessel(s) if more than one vessel is involved in the installation. 8. Place the protective sleeve(s) and cover(s) over the connection pipes. After concrete slab has cured 10 9. Remove the protective covers from the inlet and outlet pipes. 10. Place the pump module on a bed on free draining, non-compacting material and secure it to the edge of the concrete slab. 11. Connect the pipe penetrations with flexible joints. 12. Connect the reticulation piping. 15 13. Connect the electrical connection. Referring to Figure 9 a typical reservoir module 60 for use with the invention may comprise a rotational moulded plastics module which is rigid and can act as a replacement for an expanded polystyrene pod in a waffle slab without effecting the 20 integrity of the slab. A number of these reservoir modules can be linked together to enable water storage in as many tanks as there are waffle pods. Where the reservoir modules are used in this type of situation, they may have a capacity of about 660 litres per module. 25 The reservoir modules comprise four side walls 61 having rib recesses 63 and a central rib recess 64 which give structural strength to the side walls. Each of the walls is formed with a step 65 which is interrupted by the various rib recesses. Furthermore, additional recesses 66 may be provided underneath parts of 30 the step. These again lend strength to the module.

WO 2007/016721 PCT/AU2006/001025 12 Holes 67 are provided in the step to allow adjacent modules to be bound together by means of a U shaped clip 90. Alternatively, a drive pin 34 may be used to anchor the side wall to the ground 82. 5 To enable connection of the reservoir module to an adjacent module a pipe 70 which can connect with a corresponding pipe of an adjacent module is provided, thereby allowing free flow of liquid between connected modules. An air vent 72 is used to permit air transfer between adjacent modules by way of the air pipe 89 shown more clearly in Figure 11. 10 The side walls are provided with a sloped region 74 at the join between the side walls and the top panel 75 and a bottom panel 76 closes off the reservoir module. Parallel recessed ribs 77 and 78 are provided on the top panel. These provide 15 structural strength to the top panel. Four hollow columns 92, shown more clearly in Figure 14 extend between the top and bottom panels and further increase the structural strength. The hollow columns may be formed integrally with the reservoir module during the plastics moulding operation used to produce it or they may be added separately afterward. 20 The hollow columns are located at the intersection of the parallel pairs of recessed ribs 77 and 78 and may be covered with a cap 80. Referring to Figures 10 to 13, there is shown a number of views detailing the manner 25 in which a number of reservoir modules may be joined together to form a liquid storage reservoir under a cast concrete floor. A plurality of modules are located next to each other on a prepared area of ground 82 and are joined together with clips 90. 30 Pipes 70 between adjacent modules are connected to allow free transfer of liquid between the modules. The pump module 9 which sits outside the brick wall 88 of a WO 2007/016721 PCT/AU2006/001025 13 house is also connected prior to casting of the concrete. The brick wall sits on the perimeter beam 85 as is known in the art. A sand layer 83 surrounding the modules to a depth slightly higher than the step 65 is 5 laid so that it covers the connecting pipes 70 and the bottom of the air pipe 89 joining adjacent modules. Additional form work 86 in the form of expanded polystyrene pods are positioned in the normal manner as is the steel reinforcement 13. Where the pipes 70 do not lead to 10 an adjacent module, they are closed by plugs 87 prior to the sand layer being put in place. Although the pipes may be separate items which are inserted into a hole drilled in the wall of the module. In such instances where there is no adjacent module there is no hole drilled and no pipe inserted. 15 The steps 65 of adjacent modules abut each other and are joined by U-clips 90. This leaves a void or mould form between the upper sides of adjacent modules and/or pods allowing for the casting of intermediate beams 93. The offtake pipe 45 and supply pipe 39 are connected to one of the modules. This 20 module acts as a distribution point for the other reservoir modules. It is noted that there will be open regions 91 between adjacent modules, these may also be filled with sand to the same level as the sand layer 83. 25 Finally, concrete 84 is poured over the top and sides of the assembly of reservoir modules to form a composite liquid storage reservoir under the floor of the building. The various pipes 70, 39 and 45 lie in the sand layer so that they will be protected from damage by the concrete layer should there be any cracking or movement of the concrete. 30 Whilst the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously WO 2007/016721 PCT/AU2006/001025 14 described without departing from the essential features or the spirit or ambit of the invention. It will be also understood that where the word "comprise", and variations such as 5 "comprises" and "comprising", are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features. The reference to any prior art in this specification is not, and should not be taken as, 10 an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge in Australia.

Claims (19)

1. A method of creating a liquid storage reservoir under a floor cast from a settable material comprising the steps of, 5 creating a mould form for casting of the settable material, the mould form having a shape including an area for casting of flooring, and a trough for moulding a beam extending under the flooring, disposing a void forming material in the mould form in the sub-floor space to create a liquid storage cavity for the liquid storage reservoir, 10 disposing the liquid storage reservoir in the cavity before or after casting of the settable material, and connecting a pump module to the liquid storage reservoir, the pump module being adapted to direct liquid into the liquid storage reservoir and to pump liquid from the liquid storage reservoir. 15

2. The method according to claim 1 wherein the settable material comprises concrete reinforced with steel.

3. The method according to claim 1 or claim 2 wherein the void forming 20 material comprises the liquid storage reservoir.

4. The method according to any one of claims 1 to 3 comprising using a plurality of reservoir modules to form the storage reservoir and interconnecting the reservoir modules so as to allow the liquid to flow between the reservoir modules. 25

5. The method according to any one of the preceding claims wherein the mould form is shaped so as to provide a perimeter beam under and around the flooring and one or more intermediate beams within sub-flooring space surrounded by the perimeter beam, and the liquid storage reservoir is located between intermediate 30 beams or an intermediate beam and the perimeter beam. WO 2007/016721 PCT/AU2006/001025 16

6. The method according to claim 5 comprising locating a pump module external to the sub-flooring space and connecting it to the liquid storage reservoir by a supply pipe extending through or beneath the perimeter beam. 5

7. The method according to claim 4 comprising disposing a layer of fine granular material between adjacent reservoir modules and below the cast settable material and interconnecting the reservoir modules by a liquid transfer pipe passing through the fine granular material. 10

8. The method according to claim 7 wherein the granular material comprises sand and air bleed pipes are connected between the modules at a level higher than the liquid transfer pipes.

9. The method according to claim 8 wherein the air bleed pipes are arranged to 15 pass through the sand.

10. A reservoir module having a generally square shape, the reservoir module being suitable for carrying out the method of claim 4 comprising, four ribbed side walls, 20 a bottom panel, a ribbed top panel, and at least one support member extending between the top and bottom panel.

11. The reservoir module according to claim 10 comprising a step formed on each 25 of the four ribbed side walls.

12. The reservoir module according to claim 10 or 11 comprising four tubular support members extending between the top and bottom panel. 30

13. The reservoir module according to any one of claims 10 to 12 wherein the reservoir module has a holding capacity of between 400 and 900 litres and the reservoir module has been formed as an integral unit by a plastics rotational moulding process. WO 2007/016721 PCT/AU2006/001025 17

14. The reservoir module according to any one of claims 10 to 13 comprising three ribs in each side wall and two pairs of parallel ribs extending across the top panel, each of the pair of parallel ribs running generally perpendicular to the ribs of 5 the other pair of parallel ribs, wherein one of the support members is located at each intersection of the ribs.

15. A pump module suitable for use with a liquid storage reservoir, created according to the method of claim 1 comprising, 10 a housing, an inlet for connecting the pump module to a source of the liquid, a filter, a supply pipe for delivery of the liquid after passing through the filter to the liquid storage reservoir, 15 an overflow pipe for discharge of the liquid when the liquid storage reservoir is full, and a pump for pumping liquid from the liquid storage reservoir through a distribution pipe. 20

16. A pump module according to claim 15 wherein the filter is provided with a removable cap accessible from outside the housing to give access to the filter.

17. A cast concrete floor comprising a liquid storage reservoir created according to the method of claim 1. 25

18. A reservoir module substantially as hereinbefore described.

19. A pump module substantially as hereinbefore described.