Field of the Invention

The present invention relates to a Sustainable urban Drainage system (SuDS), a Stormwater Attenuation System and Method of Manufacturing said systems and Method of Transporting said systems.

Background to the Invention

The present invention seeks to optimise stormwater attenuation tank construction particularly at shallow working depth. The present invention also provides a Sustainable urban Drainage system (SuDS).

Current methods of constructing stormwater attenuation devices in concrete include pipes, culverts, in-situ concrete and semi-precast concrete. The current methods suffer from a number of disadvantages including the following:

- pipes require a large area of excavation and then subsequent reinstatement of grounds; culverts are inherently heavy and require critical surface preparation for alignment and waterproofing;

- In-situ concrete pouring requires long installation periods whereas semi-precast

solutions in which the floor is poured in-situ and the vertical and upper elements are manufactured off-site have dominated the market for cost efficiency reasons;

Cellular methods (plastic crate and liner) are costed substantially by volume whereas concrete tank costs are primarily a function of the surface area of the walls roof and floor. Thus, the shallower that the tank becomes, the greater the surface area to volume ratio, thereby disproportionately increasing the cost per unit volume stored in conventional in-situ and semi-precast concrete installations

Conventional semi-precast approach solution to the challenges of low working height comprise reducing the dept of the standard vertical components whereby this solution eventually becomes uneconomical and other methods are then used instead. A particular disadvantage of current semi-precast solutions in shallow applications is that they can be adapted to a particular setting in one dimension only (that is, height) while the features of the two horizontal dimensions and component thicknesses remain constant and thus are inherently not suited to shallow working depth applications.

Summary

The present invention seeks to alleviate the disadvantages of known Sustainable urban Drainage systems (SuDS); and stormwater attenuation tank construction at shallow working depths.

Accordingly, the present invention provides an improved Sustainable urban Drainage systems (SuDS); including a stormwater attenuation system formed of a concrete construction system comprising a concrete slab on grade, modular unit elements which are of pre-determined generally- triangular shape and a concrete screed sealing the roof, vertical perimeter joints and a column between adjacent unit legs.

In an optional aspect, interfaces may or may not include a hydrophilic barrier.

In a separate aspect, the present invention also provides a method of manufacturing a concrete construction system comprising the steps of:

• Providing a concrete slab on grade,

• Providing modular unit elements which are of pre-determined generally- triangular shape and

• Pouring a concrete screed to seal the modular unit elements and to form the roof,

• forming vertical perimeter joints; and

• forming a column between adjacent unit legs.

Brief Description of the Drawings

The present invention will now be described more particularly, by reference to the accompanying drawings in which are shown, by way of example only, a number of embodiments of the present invention.

In the drawings:

Figure 1 is a perspective view of a Sustainable Urban Drainage Systems. (SUDS) and in one embodiment of the present invention, a stormwater attenuation system of the present invention showing section including base slab, a plurality of modular units and a roof; Figure 2 is a perspective view of an assembly of a plurality of modular units and a roof in accordance with an embodiment of the present invention;

Figure 3 is a perspective view of a first modular unit and a second modular unit in accordance with an embodiment of the present invention.

Figures 4 to 23 are perspective views showing details of the method of manufacturing the modular units in accordance with an embodiment of the present invention;

Figures 24 to 27 are perspective views showing details of the method of releasing the modular units in accordance with an embodiment of the present invention;

Figures 28 to 33 are perspective views showing details of the method for stacking the modular units for transportation in accordance with an embodiment of the present invention;

Figures 34 to 50 are perspective views showing details of the method of assembly the stormwater attenuation system in accordance with an embodiment of the present invention.

Description of the Embodiments

Referring now to Figure 1 there is shown a stormwater attenuation system 100 according to an embodiment of the present invention. The system 100 includes a base slab 130, an assembly of a plurality of modular unit elements 110 and 120. The system 100 may further include a roof 140. The roof 140 has a screed joint profile to cover the assembly of modular units 110 and 120 and fill in a plurality of apertures formed between the modular units as will be described in detail hereinbelow.

Figure 2 shows the underside view of the assembly and roof 140. The roof 140 has a hub 142 that fits into a corresponding aperture of the assembly of modular units.

Modular Units

Referring to Figure 3 there are shown a plurality of modular units comprising a first modular unit 110 and a second modular unit 120. The first modular unit 110 is an external wall modular unit while the second modular unit 120 is for use as an internal modular unit of the assembly.

The first modular unit 110 comprises a column leg 112, a wall leg 114 and a roof panel 116. The first modular unit may also comprise a through hole 111 in the roof panel 116. The second modular unit 120 comprises three column legs 122 and a roof panel 126. The second modular unit may also comprise a through hole 121 in the roof panel 126.

The triangular plan configuration of the first and the second modular units has the advantage of avoiding torsion when in use by uniformity of load transfer through the legs to the base slab 130. The triangular plan of the modular unit has the added advantage of providing the property of‘stackability’ in storage, transport and offloading to the workface using a novel combined lifting and load-securing device which will be described in details hereinbelow, and is another aspect of the present invention.

The modular units are relatively small and lightweight when compared with conventional concrete stormwater structures. For example, the second modular unit 120 weighs about 250kgs and the first modular unit 110 weighs about 600kgs. Since the modular units are relatively small and relatively lightweight, the modular units can be entirely produced in any precast concrete manufacturing plant with the capacity to lift and load a weight of 750kg. Additionally, the modular unit size eliminates the requirement for a mobile crane or other dedicated equipment for placement on site thereby reducing the spans of the floor and roof panels in bending, shear and deflection when compared to conventional solutions. Mobilising the phenomenon that structural behaviour is scalar, the base slab 130 and roof 140 (may therefore be thinner than those conventionally required at acceptable stress and strain levels. This brings cost, operational and carbon footprint advantages.

Each of the first and second modular units is integrally formed as a unitary piece of a stiff material, preferably reinforced concrete. In Figures 4 to 23 there is shown a method of manufacturing the first and the second modular units. Modular unit manufacturing is a two- step process. Wall leg 114 and legs 111 or 121 are manufactured to any precise required length with projecting reinforcement bars. Once manufactured they are slotted into position within the triangular mould 600 and the roof panel 116 or 126 is cast against them.

Method of Manufacturing Modular Units - Column Legs

Referring to Figure 4, each column leg of the modular unit comprises 3 F-shaped reinforcing bars. The reinforcing bars are steel bars used as a tension device in the reinforced concrete forming the leg of the modular unit to strengthen and aid the concrete under the tension produced. At Step 1, the bars are bundled in such a fashion that each of the ends which will form the reinforcement of the triangular roof panel of the modular unit can be angled relative to each other. In Figure 5 there in shown a mould 400. At Step 2, the mould is propped to form a deeper section as the closed end of the mould (the surface of the poured concrete is horizontal) is approached. The mould 400 forms a bevelled tray propped at the open end. As shown in Figure 3, the interface between the leg 112 or 114 and roof panel 116 is bevelled. This prevents any debris caught under the unit from unintentionally increasing the length of the column leg in its completed form.

As shown in Figure 6, at Step 3 the stop end 420 of the mould 400 is placed at one of the prefixed positions and secured in place using a peg/ pin 410 on either side which slots into a receiver 430 placed on the outside of the mould 400. There are a number of receivers on the mould 400. The length of the column leg is determined by which receivers are used. The receivers 430 ensure that all column legs lengths are the same.

In Figure 7 there in shown a mould 400 having the internal surface covered with a release agent 440. The agent is sprayed at Step 4 after the stop end 420 is in place. The release agent may be applied with the use of a sprayer. The release agent 440 enables to easily remove the formed column leg from the mould 400. After the release agent is applied, at Step 5 the reinforcing bars 118 is then placed in the mould on reinforcement chairs as shown in Figure

8.

With the reinforcement in place, at Step 6 a spacer unit 450 is slotted into a spacer unit receiver 460 placed at the base of the closed end of the mould as shown in Figure 9. The spacer unit 450 is configured to engage with the reinforcing bars 118 and maintains the reinforcing bars 118 spread apart at the selected angle. The spacer unit 450 also contributes to provide the correct cover to the reinforcing bars 118. To keep the reinforcing bars 118 and the spacer unit 450 in place while the concrete is being poured, two zip ties or tie wire are applied at Step 7. The first zip tie 472 laps around one diagonal reinforcing bar, the upright reinforcing bar and a post on the spacer component 450. The opposing zip tie 474 laps around the other diagonal bar, the upright bar and the post on the spacer component 450.

At Step 8 the mould 400 is filled with concrete. In Figure 11 there in shown a mould 400 filled with concrete as result of Step 8. At this point the reinforcing bars 118 can be checked to ensure that the reinforcing bars 118 are still spread apart at the selected angle.

Once the concrete has cured sufficiently, at Step 9 the zip ties are removed, the spacer unit 450 is lifted upwards as shown in Figure 12 and the pegs 410 for securing the stop end 420 are removed. This allows for subsequently extraction of the precast column leg of the modular unit. In the embodiment, the method of manufacturing the column legs of the first modular unit 110 and second modular unit 120 are shown as being carried on a single mould 400.

However, in alternative embodiments, a plurality of moulds 400 can be arranged to form a battery of moulds whereby pegs are used to align a plurality of mould 400 sideways as shown in Figure 13.

Method of Manufacturing Modular Units - Wall Leg

In Figure 14 there is shown a plurality of mould side rails 520. At Step 1, the mould side rails 520 are placed in parallel on a standard flatbed. At Step 2, unit dividers 510 are placed between the rails 520 at a defined length which determines the overall height of the first modular unit 110. Unit dividers 510 are locked in place by clamping to the rails 520 or using a magnet to fix them to the flatbed.

At Step 3 a plurality of reinforcing bars 119 are placed in the mould 500 as shown in Figure 16. The plurality of reinforcing bars is aligned parallel to each other. The ends of the reinforcing bars 119 are angled relative to each other to form the reinforcement of the triangular roof panel 116 of the modular unit 110. Additionally, other reinforcing material can be added to the reinforcing bars, such as additional steel bars and meshes of steel wires to strengthen and aid the concrete under tension.

At Step 4 the reinforcement 117 is held in place using a similar system used to the column leg as detailed above. The spacer unit 117 is configured to engage with the ends of the reinforcing bars 119 and maintain the ends of the reinforcing bars spread apart at the selected angle as shown in Figure 17.

At Step 5 the mould is filled with concrete as shown in Figure 18. Once the concrete has cured, the reinforced concrete wall 114 is released by releasing and removing the side forms of the mould.

Method of Manufacturing Modular Units - Assembly Mould

In Figure 19 there is shown a triangular mould 600 for manufacturing the modular unit.

At Step 1, the mould 600 is placed on a standard flatbed. The standard bed is preferably a flat steel surface. At Step 2 the mould is closed using two wedges 602 that interlock with a corresponding protruding portion of the mould 601 located at the opening comer of the mould to secure the triangular mould in a triangular configuration. Wedges 602 can have a trapezoidal profile similar to that used to secure scaffolding connections as shown in Figure 20. It is appreciated that when manufacturing a second modular unit 120, three legs are placed and secured in position using the locking wedges 602.

At Step 3 the one or more legs of the modular unit are inserted in the mould 600. A precast wall unit, or the two leg units, are positioned opposite the mould opening comer. The legs are stood in the mould with the protruding reinforcement situated in the area the roof panel will be formed. Figure 21 shows the formation of the first modular unit 110. It is appreciated that the formation of the second modular unit 120, is identical to that of the first modular unit but with a leg 122 placed in each comer of the triangular mould 600. While the wall leg 114 will geometrically lock into place, the column legs need to be secured to the triangular mould 600. At Step 4 a wedge 606 is inserted into a corresponding aperture 604 of the mould to ensure the column legs remain upright as shown in Figure 21.

In Figure 23 there is shown a close-up of the wedges 606 used to secure the column leg and the wedges 602 used to close the mould opening comer of the mould 600. The wedge used to hold a column leg 112 or 122 in place comprises a curve profile so that as the wedge is hammered in, it presses progressively harder against the leg. A 45-degree angle at the end of the parallel plates may be formed. This can be used to pry the plates apart with a chisel etc if the mould fails to release easily.

At Step 5 the roof panel 116 is formed by pouring a predetermined amount of concrete, this predefined volume ensures the roof panel is of defined thickness. Concrete is poured to the desired height in the mould. The amount of concrete may vary depending on the requirement of the project. Preferably, the produced modular unit roof panel has a thickness of 80mm.

The product is left to harden, typically 8 to 16 hours. It is appreciated that additional reinforcement bars may be placed in the mould before pouring the concrete. The correct working height of the reinforcement is ensured using proprietary reinforcement spacer devices.

Method of Releasing the Modular Units

On hardening of the concrete connecting plate the product may be de-moulded. Although the modular unit is assembled upside down, the modular unit is released in its final resting upright position. In order to achieve this, a Center Of Gravity (COG) device is used. The COG device comprises a plate 200 that is attached to the lifting device 700 at lifting points placed off the centre of gravity. Depending on the position of the centre of gravity of the modular unit being manufactured an appropriate aperture in the plate 200 is selected. The lifting frame cleats are inserted into the receivers on the moulding frame to lift and control the rotation of the mould and product assembly.

The COG device plate 200 is attached to the lifting device 700 at Step 6 before connecting to the mould 600. In Figures 24 and 25 there is shown a COG device plate 200 coupled to the mould 600 by means of a coupling portion of the COG device plate. The COG device plate is shown coupled to the mould 600 in isolation of the lifting device 700 for ease of

understanding. The COG device plate lifting points include square/ polygonal slots 202 on one side and circular openings 204 on the other. The openings are positioned just off the

COG device plate 200 for the second modular units and for the first modular units of varying heights.

In Figure 26 and 27 there is shown a lifting device 700 comprising a spreader beam, square section arms 706 that can rotate to make engaging the mould as easy as possible and on one side (the side with the square sockets) a rotational damper 708. With the lifting device 700, COG device plate 200, and mould 600 fully engaged, the entire assembly can be lifted. The lifting points being off the centre of gravity would cause an imbalance of the weight distribution when the mould is off the ground. In response to the modular unit being lifted off the ground, the modular unit will rotate. The speed of rotation is controlled by the l-way rotational damper 708 which will allow the unit to fully rotate 180 degrees under self-weight but at a controlled speed over. Preferably, the controlled rotation may be applied for a period of 10 seconds. The damper 708 is actuated such that the assembly comprising the mould 600 the modular unit and the plate 200 is free to rotate. Competition of the rotation may require manual input using a lever. The l-way damper is arranged to oppose rotation. Preferably, the damper 708 will provide less than 10% the resistance to the rotation. With the modular unit fully rotated to the upright position, the wall leg 114 and column leg 112 of the modular unit 110 can be placed on the floor. The wedges used to secure the column leg 606 and the wedges 602 used to secure the mould are then removed and the mould 600 can be lifted away from the modular unit 110. At this point, the mould 600 can be rotated back 180 degrees and returned to the flatbed for the next production cycle.

The lifting frame assembly is raised, lowered and positioned on plan using any appropriate lifting device capable of carrying the required total weight. This may be a gantry crane, teleporter, forklift of the like. The product and mould assembly is raised from the flatbed and taken to the approximate demoulding location.

Once upright, the rebated demoulding pin is inserted in the top of the modular unit and the retaining fork inserted. This prevents the product dropping out of the mould in an

uncontrolled manner once the mould opening clamps are released.

The main locking wedges to the frame assembly are released and the product will drop slightly to be supported by the pin and chain.

Timber protecting shims are placed on top of the preceding modular unit in the stack to maintain separation. Shims prevent contact damage, distribute load and facilitate the insertion of a lifting device on site for removal and placement.

The modular unit is progressively lowered to rest. The outer manufacturing mould piece will make first contact with the stacked modular unit below. Its travel will cease. The

manufactured modular unit will continue its travel until it rests on the shims on the preceding unit.

The fork device is pulled from the rebated pin and the mould and pin assembly withdrawn vertically.

The mould assembly is rotated by hand to the casting orientation and placed on the flatbed for subsequent production.

On completion of a stack, the transport pin is inserted through the units and secured. The completed stack is then taken to its storage location suspended by the transport pin, or resting on a pallet or trolley.

To secure the mould 600 to the lifting device 700, there is a rectangular receiver both on the mould and on the COG plate Lifter Connection. These are engaged by passing a rectangular bolt from the middle of the back of the mould out to the COG device. By engaging from the mould out, it allows moulds to be placed closer to each other on the flatbed. Method for Stacking The Modular Units For Transportation

The triangular configuration has the added advantage of providing the property of ‘stackability’ in storage.

As shown in Figure 3 each modular unit may comprise a through hole in its roof panel. The through hole can be located centrally on the roof panels of each unit so that when the modular units are stacked, each through hole is aligned with the holes of the remaining modular units of the stack. During production, units are extracted from their mould directly onto the floor or onto a stack of already formed modular units.

In Figure 31 there is shown a plurality of first and/or second modular units stacked together. Modular units stacks can be offloaded by a teleporter, such as a telescopic handler, and individual elements can be placed in final position by a digger bringing construction efficiency.

The modular unit stacks can be sized for transportation to site on curtain-side vehicles rather than flat-bed vehicles. This lowers transport cost, increases distribution opportunity (where flatbed backloads are not viable) and enables groupage for small and partial loads.

In another aspect of the present invention, a novel lifting/load anchoring device 200 is provided. The lifting/load anchoring device 200 is threaded through the holes of the stack of modular units and secured at the underside of the roof panel of the lowest modular unit in the stack. In handling, the lifting/load anchoring device 200 increases the number of modular units that can be anchored to the transport vehicle; and/or lifted in one lifting operation onto/off of a vehicle; thereby reducing time, cost and required storage area prior to distribution. The completed stack will typically hold 5 to 7 modular units.

Modular units stacks may also comprise a plurality of spacers 210 being arranged between the stacked modular units. Spacers facilitates the removal of the modular units from the stack for final placement

Spacers may be of such minimum area as not to crush under load and present an opportunity to repurpose mould timber offcuts. Spacers prevent contact damage, allow to distribute load and facilitate the insertion of a lifting device on site for removal and placement. This eliminates the requirement for cast-in lifters. Spacers 210 can be placed on the modular units using a waterproof mortar bed (in the manner of block drainage infrastructure). This bed seals the interface between the perimeter wall and the floor and prevents sliding of the unit under earth and water pressure. On assembly, the perimeter wall acts as a propped cantilever by its engagement with the roof panel.

A guide pin is used to align the units in the stack so that the lifting/transport pin may be easily inserted from the top without misalignment. To protect the unit surfaces and avoid damage in transport, a spacer (that can typically be ply offcut) is placed between each unit at the pin and at the leg position. There may be 4 spacers used or any number of spacers as appropriate. This prevents overload of top or bottom unit in transport.

Stack of units may comprise one first modular unit with a number of internal units stacked upon it. This is the most efficient transport configuration. Other load arrangements may occur to provide the correct number of external and internal wall units. In general, the stack of units will arrive on site on a curtain sider trailer. These units can be removed in the stacked configuration with a teleporter / mini digger. The stack of units can then be placed directly onto the work area. The units are stacked with a spacer between them as per the diagrams in the sections above. The bolt holding them together must first be removed and then a forklift like attachment is used to slide between the units and lift them off one by one. This lifting device is then used to place the unit in its final position.

In Figure 33 there is shown a system lifting tool.

Method of Assembly the Stormwater Attenuation System

In Figure 34, there is shown a base slab 130. The base slab 130 is integrally formed as a unitary piece of a stiff material, preferably reinforced concrete. The reinforced concrete may also including steel fibers to provide additional structural integrity to the base slab 130 when higher loads are applied. It is appreciated that the depth of this slab will vary depending on the application. The base slab 130 is formed at Step 1, once the site excavation is completed.

At Step 2 a layer of mortar 132 may be placed on the base slab 130 where the legs of the modular unit meet with the base slab 130. In Figure 35, there is shown a base slab 130 with a layer of mortar 132. The purpose of this mortar 132 is to ensure uniform bearing on the slab 130 and water-proofing integrity. Although Figure 35 shows the mortar placed in its entirety prior to the placement of the modular units, it will be appreciated that the placement of mortar 132 may occur alongside the placement of the precast modular units to provide additional efficiency to the method of assembly.

At Step 3 the first modular units are placed on the layer of mortar to form the external wall of the assembly. In Figure 36 there are shown a plurality of first modular units 110 placed on the layer of mortar.

At Step 4 the internal wall units can be placed once the external wall line has been started. The method of lifting and placement is the same for the internal walls as for the external walls. The placement of units should start in one comer and proceed diagonally across the tank, this allows for tolerance in placement.

At Step 5 there are two primary connections that will need to be made to the system 100. These connections are pipework 310 and manholes 320. Pipework connections are made by replacing a typical first modular unit 110 with a second modular unit 120 during assembly. This leaves an opening in the external wall face of the assembly 100. The pipe 310 is placed and the opening is shuttered and filled with mass concrete to seal the structure.

Access to the tank via manholes 320 can be done in either of two ways as shown in Figure 38. A manhole 320 may be constructed adjacent to the structure and a cleaning device can enter the tank via the inlet/outlet pipe 310. The open nature of the inside of the structure makes it easy to clean by means of jetting. Alternatively, manhole 320 access is possible through the roof of the assembly. In this instance, an second modular unit 120 is left out of the assembly. This leaves a triangular opening in the roof of the assembly. The manhole can placed on the roof panel of the modular unit to align with the roof hole of the assembly prior to the roof 140 of the system 100 is formed. This provides a waterproof connection between the manhole 320 and the assembly of modular units below.

In Figure 39 there is shown a complete assembly of modular units whereby all the modular units are in place.

The triangular plan configuration of the first modular unit 110 and the second modular unit 120 results in a configuration in which perimeter of each unit may interface with the perimeter of adjacent unit to form an assembly. The assembly of modular unit may result in a plurality of apertures 101, 102 and 103 having a profile corresponding to the profile of the edge profile of the modular units. Figure 3 shows details of the indentation on the side of the leg wall 114 of the modular unit 110 and on the edge of the leg. At Step 6 vertical shutters 800 is be applied to the structure as shown in Figure 41. The application of vertical shutters can occur in tandem with the placement of forming the perimeter of the system 100.

The in situ concrete around pipe penetrations etc may be poured at any stage but may be integrated into the roof and joint pour which follows next.

At Step 8, with the vertical joint shutters 800 and edge shutters for the roof 140 in place, the roof 140 can be formed. The roof 140 is formed by pouring a predetermined amount of concrete on the roof formed by the roof panels of the assembled modular units, the predefined volume ensures the roof is of defined thickness. In Figure 48 there is shown an assembly with a roof 140 formed on top of it. The roof 140 is preferably mesh reinforced to provide additional structural integrity to the assembly 100.

During pouring, the concrete will flow into the apertures 101, 102 and 103 and form vertical joints at the perimeter of the assembly and columns between the legs of the second modular units of the assembly.

At Step 9 the vertical joint shutters 800 are removed leaving the system 100 formed. The excavation can be backfilled to roof 140 level the day after the shutters have been removed. Depending on loading on the roof 140 of the stormwater attenuation system, the backfilling, if required, may commence between 1 day and 1 week after construction has been completed.

In an embodiment of the present invention, the invention provides a Sustainable urban Drainage System (SuDS) wherein the stormwater attenuation system comprises drainage means, preferably in the form of at least one aperture provided in the stormwater attenuation system configured for allowing stormwater which has accumulated in the stormwater attenuation system, in use, to drain out from the stormwater attenuation system. Ideally, the drainage means comprises a plurality of apertures in the stormwater attenuation system for allowing drainage of storm water into the ground by gradual exfiltration through the apertures. In a preferred embodiment, such apertures can be provided by not sealing the joints so that stormwater can drain from the stormwater attenuation system and preferably, flow into the ground.

Modular Wall Side Devices The triangular plan module results in three configurations in which perimeter wall units may interface angularly.

For waterproofing integrity, a rebate device is formed such as to ensure mechanical engagement of the concrete filler in all configurations and to form a trough for a hydrophilic strip should the particular application require.

A rebate may also be formed in the perimeter wall unit underside if necessary.

It is of course, to be understood that various modifications and alterations can be made to the system of the present invention within the scope of the present invention.