Stormwater flow control

Abstract

 The invention relates to apparatus for controlling flow of stormwater in a stormwater handling system, comprising a chamber (7) having an inlet (8) and an outlet (9) for water flow into and out of the chamber, a means (10) to control flow between the inlet (8) and outlet (9), and means (11) providing a bypass of the flow control means (10).
The bypass means (11) is in the form of a pipe, tube or conduit which passes through, and is supported at its inlet or mouth end, by a wall (14), and at its outlet end by a wall of the chamber (7), through which it passes.

Description

[0001] The invention relates to stormwater flow control, particularly to apparatus including a chamber for control of stormwater flow, a system including such apparatus, and a development served by the system.

[0002] The term stormwater will be understood to include water such as rainwater or water from melting snow, ice, or hail.

[0003] Normally any stormwater will be discharged to a sewage system or to a water course.

[0004] The control of stormwater discharged to water courses is a restraint placed on builders and developers for many new redevelopment projects. This occurs where there is a concern that additional areas of impermeable surfaces (roof, carriageway, pavement or parking) will overwhelm the capacity of the current system.

[0005] This can affect domestic, retail, commercial and industrial developments and particularly residential developments.

[0006] It is an object of the invention to seek to mitigate these disadvantages.

[0007] According to the invention there is provided apparatus for controlling flow of stormwater in a stormwater handling system, comprising a chamber having an inlet and an outlet for water flow into and out of the chamber, a means to control flow of water between the inlet and outlet, and means providing a bypass of the flow control means.

[0008] The apparatus may comprise an additional outlet which is both inoperative to provide for water flow therethrough and selectively operable to provide fluid flow to bypass flow through the outlet.

[0009] The additional outlet may be obturated when inoperative, suitably by a movable valve, preferably being manually movable.

[0010] The valve may comprise a slidable plate which in the inoperative mode of the additional outlet obturates an inlet end of the additional outlet.

[0011] The slidable plate may be connected with an elongate device for moving the valve, suitably the elongate device comprising a chain, rope, pull cord or the like device.

[0012] The plate may suitably be slidable vertically. This provides for return to the obturating position under gravity.

[0013] The chamber may have an internal wall which supports an inlet end of the respective outlet and additional outlet.

[0014] The outlet and additional outlet may be at the same height from a floor of the chamber, and may also preferable be substantially parallel.

[0015] Alternatively the bypass means may comprise an upstanding pipe, conduit, tube or the like. Preferably the bypass means may be upstanding from and connected with the outlet for flow of bypass water into the outlet.

[0016] The inlet end of the bypass means may be open, or may have a flow control device.

[0017] Such a flow control device may comprise a restrictor plate, which may comprise a plate with an aperture therethrough for passage of bypass water into the bypass means.

[0018] The pipe, tube, conduit or the like may be removably mounted in the outlet.

[0019] The outlet suitably comprises a pipe, conduit, tube or the like,

[0020] The flow control means may comprise an inlet of the pipe, conduit, tube or the like of less diameter than the diameter of the said inlet.

[0021] The inlet may comprise a plate with a through hole, which plate is secured to the pipe, conduit or tube, suitably at substantially 90° across an inlet orifice of the outlet.

[0022] The respective inlet, outlet and additional outlet may comprise a plastic pipe, preferably a plastic pipe comprising a twin-walled corrugated pipe.

[0023] The means to control flow of water into the outlet may be a vortex flow control device.

[0024] According to another aspect of the invention there is provided a stormwater handling system, including apparatus as hereinbefore defined.

[0025] The system may comprise a holding container for receiving stormwater via the apparatus. Suitably the holding container may be connected in line with the apparatus.

[0026] The container may comprise a generally rectangular box having perforated walls, suitably with a geotextile outer covering or a geomembrane outer covering.

[0027] The system suitable comprises a silt trap which is suitably mounted between the apparatus and the holding container.

[0028] According to a third aspect of the invention there is provided a building development connected with a system as hereinbefore defined.

[0029] The development may comprise a plurality of separate items, each connected with a respective system, or with a common system.

[0030] The item(s) suitably comprise a building, or a car park.

[0031] Apparatus and a system embodying the invention are hereinafter described, by way of example, with reference to the accompanying drawings.

Fig. 1 is a schematic perspective view of a first embodiment of apparatus according to the invention;

Figs. 2 and 3 are, to an enlarged scale, plan and longitudinal sectional views of the embodiment of Fig. 1, Fig. 3 being taken on the line C-C of Fig. 2;

Figs. 4 to 8 are respective schematic perspective, plan, longitudinal sectional, perspective top view and elevational views of a second embodiment of apparatus according to the invention, Fig. 6 being taken on the line A-A of Fig. 5;

Figs. 9 and 10 are respective plan and longitudinal sectional views of a third embodiment of apparatus according to the invention; Fig. 10 being taken on the line B-B of Fig. 9; and

Figs. 11 to 13 are respective schematic views of a stormwater control system including apparatus as shown in Figs. 1 to 10.

[0032] Referring to the drawings, in which like parts are indicated by like reference numerals, there is shown apparatus 1, 2 or 3, for controlling flow of stormwater in a stormwater handling system 4, 5, 6 (Figs. 11 - 13), comprising a chamber 7 having an inlet 8 and an outlet 9 for water flow into and out of the chamber, a means 10 to control flow between the inlet 8 and outlet 9, and means 11 providing a bypass of the flow control means 10.

[0033] In all the embodiments, the chamber 7 is a plastic body of right cylindrical form being made of a double-walled corrugated plastic with a base or bottom 12.Piercing the wall of the chamber 7 are the inlet 8 and outlets 9 in the form of pipes, tubes or conduits. The inlet 8 could be at any desired height other than that shown, and the outlet 9 is arranged to discharge water to a suitable location (not shown) which in practice will be a water course such as a stream or river.

[0034] Internally of the chamber 7 there is a wall 14, or head wall, which is secured to the interior surface of the chamber 7 as by plastic welding, and forms a support for an inner end of the outlet pipe 9. The inlet to the outlet pipe 9, on the inlet side of the wall 14, has the means 10 to control flow of the stormwater from the interior of the chamber 7 to the outlet pipe 9. This means 10 is in the embodiments, a plate secured to the inlet or mouth of the outlet pipe at 90° to the longitudinal axis thereof, and has a through hole, suitably centrally located, of less diameter than that of the outlet pipe, thereby restricting, and hence controlling flow of stormwater from the inlet 8 via the chamber 7 and thence the outlet pipe 9 to the water course. The means 10 is of such a size as to provide a vortex flow control device.

[0035] Also, in all the embodiments, the chamber 7 is located below ground, accessed from the surface via a manhole (not shown).

[0036] The means 11 providing a bypass in Figs. 1 to 3 is an additional outlet which is in the form of a pipe, tube or conduit which passes through, and is support at its inlet or mouth end, by the wall 14, and at its outlet end by the wall of the chamber 7, through which it passes.

[0037] The outlet pipe 9 and the additional outlet pipe 11 are substantially parallel, and at the same height or level in the chamber 7. In order to provide a bypass, the inlet or mouth of the additional pipe 11, which is on the inlet 8 side of the wall 14, is obturated against water flow into the outlet pipe by a movable valve or plate 15. The plate 15 is connected with the surface by means of an elongate lifting member (not shown) such as a rope, chain, pull cord or cable, hereinafter pull cord. The pull cord passes through guides in the form of eyes 16 on the wall 14 and chamber 7 inner surface.

[0038] To activate the bypass system 11, 15, 16, the pull cord is pulled to slide the plate 15 out of the way of the mouth of the additional pipe 11. Water in the chamber 7 then flows into the additional, or bypass, pipe 11, thus diverting water around or away from the flow control means 10 (also known as a vortex control means), through the additional outlet 11 and back to the outlet pipe 9 at a position outside the chamber 7, there being a "dog leg" connection between the additional outlet or bypass pipe 11 to the outlet pipe 9.

[0039] Desired discharge rate will not be exceeded unless by an authorised person (e.g. authorised by a Water Authority or Environment Agency) gaining access to the chamber 7 through the manhole. Thus the authorised person has control of over the time and frequency of providing the bypass flow. Thus the apparatus 1 is not operated continuously, but any problem in back-up can be readily observed and dealt with on an ad hoc basis when necessary.

[0040] The plate 15 will usually be slidable vertically by lifting, lateral edges of the plate being guided in guides on the wall. On release of the pull cord, the plate 15 returns under gravity, to its position covering the mouth of the bypass pipe 11.

[0041] Thus the first embodiment has several benefits:-

1. Will not automatically exceed the discharge rate;

2. Provides a way of bypassing the flow controller in emergencies;

3. Provides a way of draining down the upstream system to the level of the outlets invert;

4. Operative entry is not required to operate the bypass flap;

5. Blockages easily spotted as the chamber will flood; and

6. All fastenings at a minimum of A2 (304) Stainless steel.

[0042] Referring now to the second embodiment 2 of Figs. 4 to 8, the bypass means 11 comprises an automatic bypass of the flow control means or vortex flow control device. In the event of a blockage in the vortex flow control device, the level of the stormwater in the chamber 7 rises so that it passes into the upstanding pipe which acts as a bypass means and as an overflow weir, thus avoiding any flooding upstream of the chamber 7. This action also promotes back flushing of the system 4, 5 or 6 which can prevent blockage of the flow control means 10.

[0043] If the automatic backwashing is not effective, any blockage is readily observed by authorised inspecting personnel as the water level in the chamber 7 will not fall below the level of the top of the pipe, which is connected into the outlet pipe 9 as shown.

[0044] The pipe 11 may be movably mounted in the outlet pipe 9 to aid in the drain down of the system, thus in the event of a blockage the overflow weir can be disconnected where it joints the soffit of the outlet pipe allowing the water level to fall right down to the level of the wall. This provides a quick alternative to pumping out the chamber, but a pump may still be required depending on the height of the wall.

[0045] The second embodiment has benefits, as set out below:-

1. Avoids flooding upstream of the flow controller or chamber;

2. Provides a quick way of lowering the level of water in the chamber;

3. Promotes a backflush of the system when the bypass flow is excessive;

4. Blockages easily spotted during maintenance inspections; and

5. All fastening used are corrosion resistant.

[0046] In Figs. 4 - 8, the upper as viewed end of the bypass pipe 11 or weir is open. In the third embodiment, Figs. 9 and 10, the upper end of the bypass pipe 11 or weir has a flow control device 16 in the form of a plate 17 with a through hole 18.

[0047] The flow control device 11 thus is a secondary flow control device, the primary control device being the plate 10 on the mouth of the outlet pipe 9.

[0048] The primary flow control means or device 10 is a vortex flow control device. This is a most efficient flow controller, its outlet being made bigger than the equivalent orifice plate, making it more efficient at low flows and less prone to blocking. The reason for this is that under a set head of water a vortex is initiated within the outlet pipe, which, when fully formed with an air core running down the centre of it, provides an artificial choking effect thus reducing the allowable flow through the outlet.

[0049] The secondary flow controller is an orifice plate and will only be utilised in the event of a blockage or a storm that is so excessive that it will cause flooding upstream of the primary flow controller. The location of this secondary flow controller is within the flow control chamber but above the primary flow control device and above the highest point of an attenuation tank, thus allowing attenuation tanks to fill up before the secondary flow controller becomes active.

[0050] Orifice plates are as their name suggests, a plate with a hole in them. In simple terms the diameter of the hole and the head of water (pressure) behind it dictate the flow through the orifice and it is this relationship which dictates the maximum flow rate allowable at the maximum head of water. It is for this reason that the orifice plate is placed high in the chamber and not the vortex flow controller as the higher in the chamber the orifice plate is, the less the head of water behind it will be. This allows the orifice to be larger and more efficient.

[0051] Providing two forms of flow control device within the chamber allows there to be a backup flow controller or a way of doubling the allowable flow through the outlet in emergencies, in a controlled way.

[0052] The apparatus 1, 2, 3 described hereinbefore can be used in stormwater control systems e.g. 4, 5, 6 which include an attenuation tank 19 or tanks, generally comprising a rectangular box or crate of injection moulded plastic with perforated walls, and a geotextile or geomembrane cover over the outer surface. Such systems usually include a silt trap 20, for separating solids through settlement.

[0053] The system 4, 5 or 6 is used to prevent flooding in a development 22 such as dwellings, car parks etc.

[0054] In Fig. 11 the apparatus 1, 2 or 3 is connected by piping with the silt trap 20 and tank or tanks 19, the outlet 9 from the chamber being directed to a water course.

[0055] With this system the water flows from the drainage source to the silt trap and then in to the control chamber where it is released to the outlet pipe at a controlled rate. Stormwater flow into this system exceeding the allowed flow through the outlet will cause the stormwater to be held resulting in the water backing up into the silt trap and then into the container.

[0056] Fig. 12 shows another system, in which the container or tank 19 is connected directly to the chamber 7, rather than via the silt trap 20.

[0057] In this system the water flows from the drainage source to the silt trap and then into the control chamber where it is released to the outlet pipe at a controlled rate. Stormwater flow into this system exceeding the allowed flow through the outlet will cause the stormwater to divert into the container.

[0058] Fig. 13 shows an in-line system, in which the water flows from the drainage source to the silt trap, to the container or tank and then into the control chamber where it is released to the outlet pipe at a controlled rate. Stormwater flow into this system exceeding the allowed flow through the outlet will case the stormwater to be held resulting in the water backing up. The stormwater does not flow backwards, the point at which the water comes to a halt gets closer to the drained area.

Claims

1. Apparatus for controlling flow of stormwater in a stormwater handling system, comprising a chamber having an inlet and an outlet for water flow into and out of the chamber, a means to control flow of water between the inlet and outlet, and means providing a bypass of the flow control means.

2. Apparatus according to Claim 1, comprising an additional outlet which is both inoperative to provide for water flow therethrough and selectively operable to provide a fluid flow to bypass flow through the outlet.

3. Apparatus according to Claim 2, the additional outlet being obturated when inoperative.

4. Apparatus according to Claim 2, the additional outlet being obturated by a movable valve.

5. Apparatus according to Claim 4, the valve being manually movable.

6. Apparatus according to Claim 5, the valve comprising a slidable plate which in the inoperative mode of the additional outlet obturates an inlet end of the additional outlet.

7. Apparatus according to Claim 6, the slidable plate being connected with an elongate device for moving the valve.

8. Apparatus according to Claim 8, the elongate device being a chain, rope or the like device.

9. Apparatus according to any of Claims 6 to 8, the plate being slidable vertically.

10. Apparatus according to any of Claims 2 to 9, the chamber having an internal wall which supports an inlet end of the respective outlet and additional outlet.

11. Apparatus according to Claim 10, the outlet and additional outlet being at the same height from a floor of the chamber.

12. Apparatus according to Claim 11, the two outlets being substantially parallel.

13. Apparatus according to Claim 1, the bypass means comprising an upstanding pipe, conduit, tube or the like.

14. Apparatus according to Claim 13, the bypass means being upstanding from and connected with the outlet for flow of bypass water into the outlet.

15. Apparatus according to Claim 14, the inlet end of the bypass means being open.

16. Apparatus according to Claim 14, the inlet end of the bypass means having a flow control device.

17. Apparatus according to Claim 16, the flow control device comprising a restrictor plate.

18. Apparatus according to Claim 17, the restrictor plate comprising a plate with an aperture therethrough for passage of bypass water into the bypass means.

19. Apparatus according to any of Claims 13 to 19, the pipe, tube, conduit or the like being removably mounted in the outlet.

20. Apparatus according to any preceding claim, the outlet comprising a pipe, conduit, tube or the like.

21. Apparatus according to Claim 20, the flow control means comprising an inlet of the pipe, conduit, tube or the like of less diameter than the diameter of the said inlet.

22. Apparatus according to Claim 21, the inlet comprising a plate with a through hole, which plate is secured to the pipe, conduit or tube.

23. Apparatus according to Claim 22, the plate being secured at substantially 90° across an inlet orifice of the outlet.

24. Apparatus according to any of Claims 2 to 23, the respective inlet, outlet and additional outlet comprising a plastic pipe.

25. Apparatus according to Claim 24, the plastic pipe comprising a twin-walled corrugated pipe.

26. Apparatus according to any preceding claim, the means to control flow of water into the outlet comprising a vortex flow control device.

27. A stormwater handling system, including apparatus according to any preceding claim.

28. A system according to Claim 27, comprising a holding container for receiving stormwater via the apparatus.

29. A system according to Claim 28, the holding container being connected in line with the apparatus.

30. Apparatus according to Claim 28, or Claim 29, the container comprising a generally rectangular box having perforated walls.

31. A system according to Claim 30, the box having a geotextile outer covering.

32. A system according to Claim 30, the box having a geomembrane outer covering.

33. A system according to any of Claims 28 to 32, comprising a silt trap.

34. A system according to Claim 33, the silt trap being mounted between the apparatus and the holding container.

35. A building development connected with a system according to any of Claims 27 to 34.

36. A development according to Claim 35, comprising a plurality of separate items, each connected with a respective system.

37. A development according to Claim 36, each item being connected with a common system.

38. A development according to any of Claims 35 to 37, the item(s) comprising a building.

39. A development according to any of Claims 35 to 38, the item(s) comprising a car park.

Drawing