AU2004201818B2

AU2004201818B2 - Stormwater Pit

Info

Publication number: AU2004201818B2
Application number: AU2004201818A
Authority: AU
Inventors: Phillip Thomas
Original assignee: Precast Civil Industries Pty Ltd
Current assignee: Precast Civil Industries Pty Ltd
Priority date: 2003-05-01
Filing date: 2004-05-01
Publication date: 2010-06-24
Anticipated expiration: 2024-05-01
Also published as: AU2004201818A1

Description

STORMWATER PIT FIELD OF INVENTION The present invention relates to stormwater pits and stormwater drainage 5 systems. The present Invention has particular but not exclusive application for the collection of water from roads, kerbs and gutters, and footpaths; commercial and domestic areas; and industrial sites. BACKGROUND 10 ConventIonal stormwater pits have side walls with square inner and outer wall surfaces. Each side wall is usually only 40mm thick. When the pits are subjected to a point load of 3 tons or greater, the side walls are often crushed under the weight and the pit consequently requires repair or replacement. Large point loads such as those generated by the weight of a forklift regularly damage side walls of pits on 15 roadways, footpaths, driveways, car parks, parks and Industrial sites. In addition the Internal cavity of the conventional stormwater pit is square shaped In cross section with square side walls. As a consequence the Internal cavity of the conventional stormwater pit has poor hydraulic efficiency because of the creation of turbulence and eddies. 20 As an alternative, steel reinforced cylindrical pipes have been adapted on site to form stormwater pits. These pipes are relatively thin and rely on the steel reinforcement to provide integral strength. On site one or more holes for positioning connecting pipes are made by marking an outline on the pipe and punching out the marked section with a hammer or cutting the section with an abrasive disc. After the 25 concrete of the marked section has been removed, the steel reinforcement is then cut out. The modified cylindrical pipe Is then positioned over a base slab which is -2 either formed on site or pro-cast and positioned on site. The connecting pipes are located and mortared in position. The pit is then backfilled and covers or surrounds and metal grates are then placed on top. While the cylindrical pipe can be adapted to form the shaft section of the pit, the walls are relatively thin and can not withstand 5 point loads of large weight on the wall ends. In addition the construction of the pit is labour Intensive, time consuming and prone to costly mistakes with miscalculation of position and size of the hole needed for the Installation of the connecting pipe. OBJECT OF THE INVENTION 10 It Is an object of the present Invention to provide an alternative stormwater pit. STATEMENT OF THE INVENTION in a first aspect the present invention broadly resides in a preformed unitary stormwater pit Including 15 a base wall, a square or circular shaped junction portion with a cylindrical shaped cavity open at a top end, and one or more removable portions for locating a pipe to the junction portion. The cylindrical shaped cavity provides comparatively good hydraulic efficiency 20 while the square shaped outer wall surface provides a substantially flat surface for the joining of pipes to the pit The walls of the pit may be of any suitable thickness. Preferably the walls of the pit are 80 mm or larger In thickness. The thickness of the walls preferably provide sufficient support for connecting drains, road gully units, grates and pipes.

-3 In a second aspect the present invention broadly resides in a preformed unitary stormwater pit including a base wall, a square or circular shaped junction portion with a cylindrical shaped cavity 5 open at a top end, one or more removable portions for locating a pipe to the junction portion, and support means for providing support to junction portion side walls adjacent the top end. In a further aspect the present invention broadly resides in a preformed 10 unitary stormwater pit including a base wall; a side wall with four outer side surfaces substantially at right angles to each other and a single inner surface forming a cylindrically shaped cavity; said one or more outer side surfaces with one or more removable portions for locating 15 a pipe form a junction portion; and an opening at a top end to provide access to the cylindrically shaped cavity. Preferably there is a reinforced top portion that extends outwardly from the side wall and substantially about the periphery of the side wall. The reinforced top portion preferably strengthens the side wall to withstand 20 comparatively large point loads. The reinforced top portion that extends outwardly from the side wall preferably has an upwardly extending peripheral flange and able to support a riser pipe, a grate assembly, a cover, a square surround with grate, V shaped grated surround, riser pipe or road gully unit.

-4 The junction portion preferably has substantially square shaped outer side wall surfaces. The junction portion preferably has substantially square shaped outer side wall surfaces with removable portions on one or more sides. Preferably the square shaped junction portion has a plurality of the removable portions. 5 The side walls are preferably 40 to 100 mm thick. The one or more removable portions preferably have recessed sections on the outer face of the side walls. The side walls at the recessed sections are comparatively thinner to allow relative easy removal of the removable portion. The recessed section preferably has an arched or circular peripheral shape. In one preferred embodiment the recessed 10 section has graduated marked areas corresponding to pipes with different diameters so that the appropriate sized area for the fitting of the connecting pipe can be removed. After the removable portion has been knocked out, the square ended connecting pipe is preferably fitted within the resultant opening to form a bell shaped mouth on the inner surface of the side wall. The formation of the bell shaped mouth 15 assists to lower the head loss in the pit. There may be one or more of the above described removable portions in the base wall. In one preferred embodiment there is a lower wall section adjacent the removable portion that can be removed to accommodate the positioning of 20 stormwater pipes within the storm water pit especially where the pipes have already been laid. The support means preferably includes a reinforced top portion that extends outwardly from the side walls and substantially about the periphery of the side walls. The design of the reinforced top portion preferably strengthens the side walls to 25 withstand comparatively large point loads. Said support means preferably supports -5 a drain means and surrounds the opening of the cavity. Said support means preferably includes a reinforced top portion that extends outwardly from the side walls with an upwardly extending peripheral flange and able to support a riser pipe, a grate assembly or a road gully unit. 5 There may also be lift points located on the inner surface of the side wall to allow installation and removal of the stormwater pit. Lift points located on the inner surface of the side wall avoid the need to provide an enlarged hole to position or remove the stormwater pit as is required by pits with externally located lifting points. The preformed stormwater pit is made of any suitable material but is 10 preferably a precast concrete stormwater pit. Where the cavity diameter of the pit is less than 900 mm, the stormwater pit of the second aspect with the reinforced top portion is preferably used. Where the cavity diameter of the pit is 900mm or larger, the stormwater pit of the first aspect without the reinforced top portion is preferably used. Where the sleeve or riser is 15 1050mm or larger the stormwater pit with a cavity diameter of 900mm or larger is preferably used. Where the diameter of the pit is 900mm or greater and the riser pipe diameter is within the range of 1050 and 1500mm, the stormwater pit without the reinforced top portion (or collar) is preferably used as the thickness of the pit walls is sufficient 20 to support the possible large point loads. Where the diameter of the pit is less than 900mm and the riser pipe diameter is less than 1050mm, the stormwater pit with the reinforced top portion (or collar) is preferably used as the additional support assists the pit walls in withstanding possible heavy point loads. In another aspect the invention broadly resides in a riser pipe for use with the 25 above mentioned stormwater pit, including a square or circular shaped pipe with a cylindrical shaped cavity open at both ends wherein the pipe has one or more removable portions. The riser pipe may have one or more of the features described in respect of the junction portion. The mould for the junction portion may be used to make precast riser pipes. 5 In a further aspect the invention broadly resides in a stormwater drainage system for directing the flow of stormwater from drains to stormwater pipes and including a stormwater pit as described above, one or more pipes connectable to the stormwater pit and drain means locatable above the stormwater pit. The drain means may include a cover, a grate, a square surround with grate, V shaped grated 10 surround, riser pipe or road gully unit. BRIEF DESCRIPTION OF THE DRAWINGS In order that the present invention be more readily understood and put into practical effect, reference will now be made to the accompanying drawings wherein: 15 Figure 1 shows a first preferred embodiment of the stormwater pit which has a reinforced top portion; Figure 2 is a photograph of the wall and inner bore of the stormwater pit with a riser pipe positioned on top: Figure 3 shows a second preferred embodiment of the stormwater pit; 20 Figure 4A and 4B are diagrammatic drawings of a variation of the second preferred embodiment of the stormwater pit; Figure 5 is a photograph of the installation of the stormwater pit of the first embodiment; and Figure 6 is another photograph of the installation of the stormwater pit of the 25 first embodiment.

-7 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the figure 1 and 2, there is shown a precast concrete stormwater pit 10 having a floor 11, a junction portion 12 and a reinforced top portion 5 (or collar) 13. The junction portion 12 is substantially square shaped with rounded corners 14, The rounded corners 14 assist in the placement of the stormwater pit 10 by reducing the size of the hole required for its installation. The rounded corners 14 also provide the pit 10 with integral strength. The junction portion 12 has four side walls 15 which are approximately 40 to 10 100 mm thick. The junction portion 12 offers a variety of sites for the connection of stormwater pipes. Each of the four side walls 15 have a recessed section 16 with graduated markings 17 that define the approximate outer diameter of different sized pipes. Some recessed sections 16 of some embodiments may not have graduated markings 17 corresponding to the diameter necessary for the fitting of pipes. The 15 knockout of the concrete in the area within the respective markings 17 provides an opening for the placement of the connecting pipe. With the additional strength in the side walls 15, larger diameter pipes may be fitted to the stormwater pit compared with conventional stormwater pits. For example, stormwater pits that have an internal bore diameter of 450mm can accept connecting pipes with a diameter of up 20 to 225mm, while stormwater pits that have an internal bore diameter of 600mm and 750mm can accept connecting pipes with a diameter of up to 375 and 600mm respectively. The thickness of the side wall 15 at the recessed section 16 is approximately 20mm. The thinner recessed section 16 and graduated markings 17 makes the 25 removal of the concrete area within a particular graduated marking 17 easier. The relatively flat outer faces of the side walls 15 assists the fitting of the stormwater pipes which protrudes partway through the side wall 15 in the newly made bore. The stormwater pipe is mortared into position to form a bell mouth shape so that there is comparatively lower head loss in the pit. 5 The floor 11 also has a recessed section (not shown) that is similar to the side wall recessed section16. The recessed section in the floor 11 allows the fitting of a pipe through the floor 11. The cylindrical shape of the chamber 18 within the junction portion 12 and the positioning of the connecting stormwater pipes provides hydraulic efficiency by 10 minimizing turbulence and eddy formation. The chamber 18 is also defined by the floor 11 at one end and open at the other end. Within the chamber 18 there is lifting points 19 to allow positioning and removal of the pit 10. Lifting points 19 within the chamber 18 provides an advantage that the size of the hole made for the installation or removal of the pit 10 is comparatively smaller than if the lifting points were on the 15 outside of the pit 10. The top portion 13 provides reinforcement to the top end of the pit 10 and includes an upwardly protruding lip 20 that surrounds a top surface 21. The height of the lip 20 is approximately 50 mm and is supported by a reinforcement section 22. The thickness of the side walls 15 at the reinforced section 22 is approximately 75 to 20 100mm. The lip 20 serves to locate a drain component and provide additional strength to the pit 10. The drain component is located on the top surface 21 The drain component may be a riser pipe 25 as shown in figure 2, a metal square grate with metal surrounds locatable within the peripheral lip 20, a metal square grate locatable 25 within a square surround or V shaped surround, or a road gully unit.

-9 The stormwater pit 10 with reinforced side walls 15 is able to withstand larger point loads than conventional stormwater pits and therefore avoid the problems of sidewalls being crushed when large point loads are applied such as those generated by the rear wheels of a forklift in an industrial site. Point load forces and downwardly 5 directed forces are able to be dissipated through the top surface 21 and the reinforced top portion 13. Conventional stormwater pits on the other hand rely on the integral strength of the thin walls to withstand these forces. However the focus of these forces in a small surface area causes damage to these walls. Conventional stormwater pits may withstand up to 3 tons of point load whereas the preferred 10 embodiment of the present invention is a stormwater pit that can withstand a point load of up to 21 tons, Installation of the stormwater pit is shown in Figures 5 and 6. Where stormwater pipes 27 are already laid, a section 28 below the recessed section 16 in the stormwater pit 10 is removed to allow the stormwater pipe 27 to fit and cemented 15 within the created bore 28. The cemented stormwater pipe 27 within the stormwater pit 10 forms a bell shaped mouth connection 29. After the pit 10 has been installed various drainage assemblies such as riser pipes, covers, grates and road gully units can be fitted so that stormwater can be diverted from the surface to stormwater pipes. 20 The stormwater pit 10 also forms part of a modular system where a variety of different drain components such as those mentioned above may be adaptably connected to the top portion 13 of the stormwater pit 10 while the junction portion 12 offers a variety of sites for the connection of in-ground stormwater pipes. The design of the preferred embodiment of the present invention also allows 25 the stormwater pit to be readily stacked for freight and storage purposes.

- 10 With reference to Figure 3, there is shown a precast concrete stormwater pit 50 having a floor 51 and a junction portion 52. Unlike the stormwater pit 10 shown in figure 1, the stormwater pit 50 has no reinforced top portion or collar but relies on the thickness of the pit walls 53 to support the riser pipes and drain assemblies. The 5 wall thickness is 80mm or larger. Where the bore diameter of the pit 50 is 900mm, the thickness of the wall 53 is 80mm and capable of supporting riser pipes or pipe sleeves of 1050mm diameter or larger. In one embodiment as shown in Figures 4A and 4B, the pit 60 has a rebate 61 around the periphery of the bore 62. The rebate 61 serves to allow the riser pipe to be fitted and positioned in the top wall 63. 10 ADVANTAGES The advantages of the present invention include providing a stormwater pit that has a hydraulically efficient cylindrical chamber and thicker side walls to withstand comparatively large point loads. The preferred embodiment of the 15 stormwater pit also has removable portions for the fitting of the connecting pipe. These removable portions are thinner sections in the side wall and are premarked for the fitting of different sized pipes. The preferred embodiment of the stormwater pit forms part of a drainage system where different drain components such as riser pipes, road gully units, grates and covers can be connected to the pit to divert 20 stormwater from the ground surface to the stormwater pipes. VARIATIONS It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations 25 thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is herein set forth.

- .11 Throughout the description and claims this specification the word "comprise" and variations of that word such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps.

Claims

1. A preformed unitary stormwater pit including 5 a base wall; a side wall with four outer side surfaces substantially at right angles to each other and a single inner surface forming a cylindrically shaped cavity; said one or more outer side surfaces with one or more removable portions for locating a pipe form a junction portion; and an opening at a top end to provide access to the 10 cylindrically shaped cavity.

2. A stormwater pit as claimed in claim 1, wherein there is a reinforced top portion that extends outwardly from the side wall and substantially about the periphery of the side wall. 15

3. A stormwater pit as claimed in claim 2, wherein the reinforced top portion strengthens the side wall to withstand comparatively large point loads.

4. A stormwater pit as claimed in claim 2, wherein the reinforced top portion that 20 extends outwardly from the side wall has an upwardly extending peripheral flange and able to support a riser pipe, a grate assembly, a cover, a square surround with grate, V shaped grated surround, riser pipe or road gully unit.

5. A stormwater pit as claimed in any one of the preceding claims, wherein the 25 wall of the pit Is 80 mm or larger in thickness. - 13

6. A stormwater pit as claimed in any one of the preceding claims, wherein the junction portion has substantially square shaped outer side surface with a removable portion. 5

7. A stormwater pit as claimed in claim 6, wherein the one or more removable portions have recessed sections on the outer face of the side wall, the recessed sections are comparatively thinner to allow easy removal of the removable portion, 10

8. A stormwater pit as claimed in claim 7, wherein the recessed section has an arched or circular peripheral shape.

9. A stormwater pit as claimed in claim 7or 8, wherein the recessed section has graduated marked areas corresponding to pipe diameters so that the 15 appropriate sized area for the fitting of the connecting pipe can be removed.

10. A stormwater pit as claimed in any one of the preceding claims, wherein the side wall is 40 to 100 mm thick, 20

11. A stormwater pit as claimed in any one of the preceding claims, wherein there are one or more lift points located on the inner surface of the side wall to allow installation and removal of the stormwater pit.

12. A stormwater pit as claimed in any one of the preceding claims, wherein 25 the preformed stormwater pit is a precast concrete stormwater pit. - 14

13. A stormwater pit as claimed in Claim 4, wherein the diameter of the pit is 900mm or greater and the riser pipe diameter is within the range of 1050 and 1 500mm. 5

14. A stormwater pit as claimed in claim 4, wherein the diameter of the pit is less than 900mm and the riser pipe diameter is less than 1050mm.

15. A stormwater drainage system for directing the flow of stormwater from 10 drains to stormwater pipes and including a stormwater pit as claimed in any one of the above mentioned claims, wherein one or more stormwater pipes are connectable to the stormwater pit and a riser pipe, a grate assembly, a cover, a square surround with grate, V shaped grated surround, riser pipe or road gully unit is locatable above the stormwater pit. 15

16. A stormwater pit as substantially described herein with reference to and as illustrated by the accompanying drawings.

17. A stormwater drainage system as substantially described herein with 20 reference to and as illustrated by the accompanying drawings.