AU8930698A - Stormwater treatment apparatus and method - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

'-I

Name of Applicant: Actual Inventor: Address for Service: Invention Title: Swinburne University of Technology of John Street, Hawthorn, Victoria 3122, Australia Donald lan PHILLIPS DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne 3000, Victoria, Australia Stormwater Treatment Apparatus and Method Details of Associated Provisional Application No: P09877/97 Filed 17 October, 1997 The following statement is a full description of this invention, including the best method of performing it known to us: -1 p OPERGGCSe'; CAP 1!.S6 -2- STORMWATER TREATIMNENT APPARATUS AND METHOD This invention relates to stormwater treatment apparatus and method.

In WO 97/05338 there are disclosed various litter separators for removing buoyant and/or non-buoyant materials from stormwater. The litter separators include a boom orother means for deflecting buoyant and non-buoyant foreign bodies laterally towards a holding chamber so that they are effectively removed from the stormwater which flows through the separator. Whilst these litter separators have many advantages over known arrangements, it is an object of the present invention to provide a novel form of litter separator or fluid treatment apparatus which is more N effective in removing particular types of material from the fluid.

Accordingly, an object of the invention is to provide a method and apparatus for removing material such as oil, scum and/or sediments from fluid such as stormwater.

According to the present invention there is provided a method of treating stormwater flowing in a pipeline: said method including the steps of diverting the stormwater at an upstream Slocation under relatively low flow conditions thereof, to a processing chamber; processing the stormwater in the chamber; Sreturning processed stormwater at a downstream location to the pipeline; and under relative high flow conditions of the stormwater, permitting the stormwater to flow directly from the upstream location to the downstream location without passing through the processing chamber.

The invention also provides apparatus for removing material from a fluid, said apparatus including an inlet for receiving fluid with material entrained therein or carried thereby, an outlet for flow of fluid from the apparatus, a processing chamber in which at least some of the material is removed from the fluid to remain in the chamber, a bypass chamber, and flow control means for permitting said flow into the bypass -3chamber when the flow rate thereof is above a predetermined value to enable some of the fluid to flow directly through the bypass chamber to the outlet.

The invention also provides apparatus for removing foreign material from liquid flowing in a conduit including: an inlet pit which, in use, is located at an upstream location in the conduit; an outlet pit which, in use, is located at a downstream location in the conduit; a processing chamber which, in use, extends between the inlet and outlet pits; the inlet pit being arranged to divert said liquid to the processing chamber under S 10 relatively low flow conditions but to permit the liquid to pass from the inlet pit to the outlet pit through said conduit under relatively high flow conditions.

The invention also provides an inlet pit for use in a stormwater processing system, said pit including: a hollow body having inlet and outlet chambers having inlet and outlet ports respectively; a platform forming, at least in part, a barrier between the inlet and outlet chambers; an opening in said platform; the arrangement being such that, under conditions of low flow of stormwater flowing through said inlet port, the stormwater passes through said opening into said outlet chamber but, on conditions of high flow of stormwater flowing through said inlet port, the stormwater passes through the inlet chamber to a bypass outlet located opposite to said inlet port.

Normally the apparatus of the invention would be installed in stormwater pipelines to prevent undesirable materials being carried into waterways. The undesirable materials include floating litter, oil, scum, grease, emulsions and particulate material of various sizes.

Preferably, the processing chamber enables separation of the material to take place by sedimentation andor trapping floating materials. At higher flow rates, the -4excess of fluid is permitted to pass directly through the bypass chamber so that materials which have been separated in the processing chamber are not substantially re-entrained in the fluid which passes to the outlet.

S 5 Preferably, the apparatus includes first transfer means to transfer fluid from the inlet to the processing chamber and second transfer means to transfer fluid from the processing chamber to the outlet.

Preferably further, the processing chamber is located beneath the level of the §10 inlet and outlet.

Preferably further, fluid flowing through the inlet falls under gravity through the first transfer means into the processing chamber.

Preferably further, the first transfer means is arranged to distribute the flow within the processing chamber and more preferably induces turbulence in the fluid to t -thereby increase the likelihood of emulsification of oils and scums, Preferably further, the control means includes a boom located adjacent to the :l.l "20 inlet. Preferably the boom acts to collect highly buoyant materials and prevent them l entering the bypass chamber. Normally the boom will direct all flow of fluid from the inlet into the first transfer means. When, however, the flow of fluid to the inlet is relatively high the boom will lift enabling direct flow of fluid from the inlet through the bypass chamber to the outlet. For the fluid flowing through the bypass chamber, separation does not occur in the processing chamber but the highly buoyant materials are retained in a collection chamber adjacent to the inlet.

Preferably further, the control means includes a weir to control fluid flowing from f, the inlet into the bypass chamber.

T 30 f Preferably further, the apparatus further includes cleaning ducts for allowing removal of material accumulated in the processing chamber andior the inlet chamber.

The invention will now be further described with reference to the accompanying drawings, in which: FIGURE 1 is a fragmentary perspective view of stormwater treatment apparatus of the invention; FIGURE 2 is a longitudinal cross-section through the apparatus; FIGURE 3 is a plan view of the apparatus; FIGURE 4 is a schematic sectional view along the line 4-4; FIGURE 5 is a schematic sectional view along the line FIGURE 6 is a schematic diagram illustrating determination of transit times 10 through the processing chamber; FIGURE 7 is a schematic plan view of an existing pipe to which can be -retrofitted stormwater treatment apparatus constructed in accordance with a second embodiment of the invention: FIGURE 8 is a schematic plan view of a second embodiment of the invention; FIGURE 9 is a schematic sectional view along the line 9-9; FIGURE 10 is a cross-section through an inlet pit; Sl". FIGURE 11 is a plan view of the inlet pit; FIGURE 12 is a schematic sectional view along the line 12-12; FIGURE 13 is a perspective view of a pipe segment which makes up the settling chamber; FIGURE 14 is a schematic sectional view through the outlet pit taken along the line 14-14; FIGURE 15 is a section through the outlet pit taken along the line 15-15; FIGURE 16 is a schematic plan view of the outlet pit; and FIGURE 17 is a schematic sectional view taken along the line 17-17.

Figures 1 to 5 show schematically stormwater treatment apparatus 2 for removing material from stormwater. These Figures are not to scale.

Figure 1 is a partly broken away view whicn shows the apparatus 2 having a generally elongate housing 4 provided with a rebate 6 at its upper edge for receipt of a lid 8. Preferably the housing 4 and lid 8 are moulded from concrete, although other CPER GCP£ 2- -6materials could be used if desired. The lid 8 may be formed in a number of segments.

The housing 4 includes an inlet end wall 10 and outlet end wall 12 within which are formed inlet and outlet ports 14 and 16 respectively. In use the ports 14 and 16 receive the ends of upstream and downstream pipes 18 and 20 which normally carry stormwater or other fluids from which floating and/or suspended materials are to be removed.

Located in the housing 4 is a horizontally extending platform 22 which divides 10 the interior of the housing 4 into a lower settling chamber 24, an upper bypass chamber 26 and a dry material storage chamber 40. As best seen in Figure 2, the arrangement is such that the invert of the downstream pipe 20 is at the same level as the upper surface 28 of the platform 22. Because there is normally a fall in the pipeline, the invert of the upstream pipe 18 will be above the level of the upper surface 28 so that there will be some initial fall of fluid entering the housing 4, as will be 14", described in more detail below. The upper surface 28 of the platform 22 includes a transverse weir 30, the top of which is at about the same level or below as the invert of the inlet pipe 18. A boom 32 is seated on top of the weir 30 as shown. The boom i" 32 preferably has an average density less than water so that it will float when a predetermined level of water is present in the bypass chamber 26. The boom 32 is pivotally connected by means of hanger arms 34 and 36 relative to the housing 4 for rotation about a horizontal axis 38. Preferably the boom 32 is hollow and is formed from stainless steel sheet. The boom 32 will still operate to trap buoyant materials in the chamber 40. The boom 32 preferably extends fully across the chamber 26 (or to the sidewalls of chamber 26), has a height in the range 0.1 to 0.5 of the inlet pipe diameter and has an average density in the range 0.1 to .4 relative to water.

The region between the inlet port 14 and the weir 30 constitutes the dry material storage chamber 40. When buoyant material is carried into the housing 4 through the port 14 it will be engaged by the weir 30 andlor boom 32 and tend to remain in the chamber 40. A transfer duct 42 is provided in the platform 22 to enable passage of fluid and other materials entrained therein into the settling chamber 24. In the -7illustrated embodiment, the floor 43 of the chamber 40 slopes somewhat towards the duct 42 so that the fluid and material entrained therein or thereon will tend to drop into the duct 42. If the flow rate becomes excessive or above a predetermined rate, the level of water in the chamber 40 will rise to a point marked by line 45 in Figure 2 at which the boom 32 will float thereby enabling stormwater to flow through the bypass chamber 26 to the outlet port 16. This prevents excessive flows through the chamber 24 which could disturb or stir up the materials collected therein and cause inadvertent flow of these materials to the outlet port 16.

In the illustrated arrangement, the duct 42 opens into an inlet baffle structure 44 which includes a hollow channel member 46, the ends of which are open so that the material entering the settling chamber 24 will have substantial horizontal components of velocity as indicated by arrows 48. During low flow conditions, any oils, grease or fat or the like which is present in the stormwater will tend to be somewhat emulsified when passing through the baffle structure 44. It is more likely that these materials when emulsified will enter the settling chamber 24.

The platform 22 includes a pair of outlet openings 54 and 56 located adjacent to.the outlet end wall 12. Inwardly adjacent to the openings 54 and 56 are L-shaped baffles 60 and 62 which extend downwardly from the underside of the platform 22.

The baffles 60 and 62 ensure that the fluid flowing from the chamber 24 through the openings 54 and 56 is located near the sides of the chamber 24. The baffles 60 and 62 extend at least 300mm below the platform 22.

In use of the apparatus, stormwater enters the inlet port 14 and falls through the duct 42 into the settling chamber 24. The settling chamber 24 will normally be full of water and other materials collected in layers 70 and 72 at the top and bottom thereof.

Larger pieces of buoyant materials will tend to be collected in the dry litter collection chamber 40. When there are relatively low flows, oils, scums and other similar materials will tend to be slightly emulsified and it is quite likely that a high proportion of these will be carried through the duct 42 into the interior of the chamber 24. These materials will generally be lighter than water and will tend to collect adjacent to the -3underside of the platform 22 as indicated by the iayer 70 of floating material in the settling chamber 24, as seen in Figure 2. The layer 70 is prevented from escaping through the outlet openings 54 and 56 by means of the L-shaped baffles 60 and 62, which project downwardly from the underside of the platform 22.

Solid materials which are heavier than water will tend also to pass through the duct 42 into the interior of the chamber 24. Relatively larger components of the solid material such as stones, coarse gravel, coarse sand and the like will tend to fall quickly to the bottom of the chamber 24 where they accumulate as the layer 72 of sediment.

Finer materials will of course take longer to fall to the bottom of the chamber 24 by sedimentation.

In preferred embodiments of the invention, the dimensions of the device are chosen so that the transit time of fluid passing through the chamber 24 is sufficiently long to enable sedimentation of particles of a predetermined minimum size.

Figure 6 shows a diagrammatic representation of the flow of fluid through the settling chamber 24. Figure 6 shows the chamber 24 (not to scale) having a flow rate Q, width W and length L. The depth D is the settling depth and thus does not include the parts of the chamber occupied by the floating layer 70 or the sediment layer 72.

Assuming that there is uniform flow through the chamber 24, a sediment particle will follow the dashed line with a horizontal velocity component of Q/WD and a vertical velocity, V. The time, for the particle to traverse the length of the chamber 24 is TO (1) The time, for the particle to fall to the sediment layer 72 is TV=- (2) Vs In an efficiently designed chamber, the particle will fall to the sediment layer 72 just as the outlet zone is reached, i.e. TQ=T,.

"G

-9- Thus L D (3) QIWD Vs Simplification of Equation yields WL=- (4) Vs S' This represents the necessary surface area of the chamber for removal of particles of fall velocity Vs.

It will be appreciated that an ideal sedimentation chamber cannot be constructed. Such factors as short circuiting leading to uneven flow distribution, turbulence, scour, shape of the baffles 60 and 62, and temperature will all tend to reduce the efficiency. These effects suggest the incorporation of a surface area adjustment factor into Equation The magnitude of this factor would normally be dependent on site conditions but generally a value of 1.2 is preferred. Thus:

Q

WL =A =.2Z where A. is the appropriate area for trapping particles of fall velocity V.

Equation defines the preferred relation between the size of particle to be captured and the area required for the chamber 24. Application of this equation in conjunction with known sedimentation rates of various size particles enables the surface area requirements to be calculated. Table 1 below sets out the relationship between particle size, settling velocity and surface area requirements.

i! :8 TABLE 1 Particle Size Settling Velocity Surface Area Requirements (mm) (mrsec) (m 2 im 3 /sec) (coarse sand) 0.058 20.7 0.2 (medium sand) 0.020 58.7 0.1 (fine sand) 0-0070 171.0 0.05 (coarse silt) 0.0019 635.0 0.02 (medium silt) 0.00029 4,101.0 0.01 (fine silt) 0.000073 16,404.0 0.005 (clay) 0.000018 65,617.0 This table shows that the required surface area increases very rapidly as particle size decreases. Thus for domestic applications a minimum design particle size of 0.02mm would normally be the minimum size of particles to be separated in the chamber 24. In practice where flows are low smaller particles will be removed- -C 20 Equation does not give any indication of the most appropriate processing 1" chamber depth. If the chamber is too shallow, water flowing rapidly through it may resuspend settled particles and decrease capture efficiency. By application of sediment transport principles, the evaluation of the critical velocity at the inception of particle motion, and noting that the horizontal velocity in the chamber should not be greater than this critical velocity, leads to an evaluation of a preferred ratio of length to settling zone depth. A conservative design criterion is

L

200 (6)

D

It is preferred that the overall minimum depth of the chamber 24 is in the range 2-3m and that the depth of the settling zone is at least 1-2m.

It is desirable to have the processing chamber length to width ratio as large as is practicable. Often, however, particular site conditions may have a strong bearing on this. A primary reason for a large length to width ratio is to ensure that shortcircuiting does not occur with the accompanying formation of large dead zones in the H PAOPEinGCPa8? 7 .CAP -11- Schamber. To avoid this possibility the inlet baffle structure 44 is provided to direct inlet flows generally away from the bottom of the chamber and the layers 70 and 72, especially where the length to width ratio is less than 10:1.

The volume of the chamber 24 can be regarded as consisting of two portions: a settling volume and a storage volume (which in the embodiment illustrated in Figures S1 to 5 includes the two layers 70 and 72). The settling volume requirement is preferably at least 0.6m multiplied by the required surface area.

10 The storage volume should be large enough to contain sediment deposits without decreasing the settling volume. The depth required for storage is determined by considering the estimated sediment yield between maintenance clean-outs and the i surface area of the chamber.

15 In order to clean out material collected in the chamber 24, the device preferably includes a number of hollow shafts 74 which extend from just below the lid 8 through 'it i the platform 22. The shafts 74 enable a vacuum cleaning device to be used to remove materials accumulated in the chamber 24. Access to the shafts 74 can be provided i by covers (not shown) in the lid 8. Similarly, buoyant litter collected in the dry litter %I t 20 chamber 40 can also be removed by vacuuming the chamber 40 after removal of covers (not shown) in the lid 8. The vacuum cleaning device may also remove material from the chamber 24 through the opening 54 and 56 and possibly through the duct 42.

The device of the invention can be made in various sizes according to requirements and the dimensions are such that the time stormwater takes to pass through the chamber 24 is at least 16 minutes. Preferably the chamber 24 is at least three times as long as it is wide.

It will be appreciated by those skilled in the art that the preferred embodiment of the invention has a number of significant advantages. These include the fact that the chamber 24 is located beneath the bypass chamber 26 which facilitates installation I \because the unit is generally narrow and there is less likelihood that it will interfere with m a SpOpEiRGCP?7.CAPI o 15110 -12other services.

The housing 4 may be constituted by a concrete pipe with an appropriately shaped platform 22 mounted therein. In this arrangement a number of pipe lengths with platforms 22 therein may be coupled together to make up an apparatus of the required size. This would be particularly convenient from the point of view of ease of manufacture, transport and installation.

Figures 7 to 17 illustrate an alternative embodiment of the invention. This embodiment can be retrofitted to an existing pipeline 81 in order to provide a settling chamber for removal of litter and particulate material etc. The particular advantage of this embodiment is that the ex:sting pipeline remains substantially in place and the settling chamber can be constructed using a number of components which can be easily moulded from concrete and assembled in situ to provide the necessary separating function.

Figure 7 shows the existing stormwater pipeline 81 which would be cut at cut Slines 82 and 84 to allow removal of pipeline portions 86 and 88. Removal of the i r portions 86 and 88 leaves an upstream pipeline portion 83, intermediate pipeline portion 85 and downstream pipeline portion 87. After removal of the portions 86 and 88, an inlet pit 90 is inserted in place of the portion 86 and an outlet pit 92 is inserted in place of the pipeline portion 88, as diagrammatically shown in Figure 8. The inlet and outlet pits 90 and 92 are then interconnected by means of a plurality of pipe segments 94 which together form the settling chamber 24. This arrangement is particularly advantageous because the installation can be easily retrofitted by digging an appropriately sized trench next to the existing pipeline 81 to accommodate the pits I: 90 and 92 and the pipe segments 94 which make up the settling chamber.

As best seen in Figure 8, the segments 94 which define the chamber 24 are g: 30 located laterally of the existing pipeline, as shown in Figure 8, and beneath the level of the existing pipeline, as shown in Figure 9. The structure of the inlet and outlet pits and 92 can-be generally the same as the structure of the embodiment shown in -F P.\OPERGCP,7B?7.CAP -t511098 -13- Figures 1 to 5 so that the device functions in the same way as that shown in the previous drawings. it will be appreciated, however, that the technique of construction and installation is very much simpler than that of the previous embodiment.

The structure of the inlet pit is illustrated in more detail in Figures 10, 11 and 12.

It will be seen that the inlet pit essentially comprises a hollow cuboidal body 96 which is open at the top and is provided with a removable pit cover 98. The body 96 has sidewalls 104 and 106, bottom 108 and a platform 110. The sidewall 104 is formed with an inlet port 100 which registers with the upstream portion 83 of the pipeline. The sidewall 106 is formed with an outlet port 102 which registers with the intermediate portion 85 of the pipeline, as shown in Figure 10. The ports 100 and 102 are located I near upper parts of the sidewalls 104 and 106. The sidewall 106 is also provided with a port 112 which registers with the adjacent pipe segment 94, as shown in Figures 11 and 12. The inlet pit 90 includes a barrier wall 114 which projects upwardly from the Si "15 platform 110, the wall 114 defining an inlet chamber 116 in which a boom 32 is located. The boom functions in the same way as in the previous embodiment and will f i be operable at higher flow conditions to deflect buoyant litter over the top of the barrier wall 114 into a litter collection chamber 118. An outlet chamber 119 is located beneath the platform 110.

The platform 110 is provided with an opening 120 which has a circular or semioval shape as shown in Figure 11. The opening 120 is bounded by a downwardly depending skirt 122. The depth of the skirt 122 is chosen such that it is below the water level 124, as shown in Figure 10. This therefore defines a trap which prevents escape of floating material such as oil, scum, grease and the like through the opening 120 into the inlet chamber. The skirt will also serve to stop odours escaping in the J same way. The water level 124 of liquid in the outlet chamber 119 is determined by the level of the downstream portion 87 of the pipe, as will be explained below. 30 In the preferred embodiment of the invention, the upper surface of the platform 110 is basin shaped so as to facilitate flow of water into the opening 120 in low flow conditions. Alternatively, the upper surface of the platform can be flat and downwardly p, poPER\GCP\a987.CAP- 15110J18 -14inclined towards sidewall 104. Under higher flow conditions, however, the water entering the inlet chamber 116 from upstream pipe segment 83 will tend to have sufficient velocity so that it will clear the opening 120. Higher flow conditions do not occur for long periods and the majority of the stormwater will, however, still pass through the opening 120. When, however, there are full pipe flow conditions, the flow will occur from the upstream pipe segment 83 through the inlet chamber 116 and into the intermediate portion 85 through the port 102. This can occur without any significant head loss across the inlet pit 90. The avoidance of head loss is of course important in ensuring satisfactory performance of the device at full flow conditions.

3* 1 In normal operation where there is less than full flow conditions in the pipeline 81, the stormwater will pass into the lower chamber 119 of the inlet pit and from there through the port 112 into the settling chamber 24. The stormwater passes through the I chamber 24 to the outlet pit 92 over a relatively protracted period enabling settling of suspended foreign materials to occur, as described above.

i The boom 32 will tend to hold floating material in the inlet chamber 116 during relatively high flow conditions in which there are less than full pipe conditions. These S'"materials will be retained in the inlet chamber 116 by the boom until either the flow is high enough, whereupon they will pass over the barrier 114 into the chamber 118, or the flow is low enough so that buoyant materials will eventually pass through the outlet 120 into the lower chamber 119.

It will also be appreciated from Figures 9 and 10 that there is a vertical drop between the invert of upstream pipe segment 83 and the level 120. This typically may be of the order of 150mm to 300mm or more. The impact of water falling this distance tends to emulsify oils and the like so that it is carried beneath the skirt 122 and then into the settling chamber 24. Similarly, any smaller floating bodies will tend to be Si:entrained in the turbulent flow created by the impact of the water falling from the upstream pipe segment and carried into the settling chamber 24. w P-\OPER\GCPS8?77CAP-1510B19 The outlet pit 92 is shown in more detail in Figures 14 to 17. It is generally similar in construction to the inlet pit except that it does not include the boom 32.

The outlet pit 92 is again a hollow cuboidal concrete body 126 having an open top which is normally closed by means of a cover 128. The body 126 has a bottom 130, sidewalls 132 and 134 and a platform 136. The platform 136 is formed with an opening 138 which is bounded by a downwardly extending skirt 140. The opening 138 can be circular or semi-oval in shape, as shown in Figure 16.

|10 The sidewall 132 is formed with a port 142 which receives the intermediate portion 85 of the pipeline. The sidewall 132 is formed with a port 144 which receives the adjacent pipe segment 94. The sidewall 134 includes an outlet port 146 which receives the downstream portion 87 of the pipeline. A barrier wall 148 extends upwardly from the platform 136 so as to define an outlet chamber 150. A screen 152 extends downwardly from the platform to the bottom 130, as shown in Figures 15 and 17, the screen thereby defining an inlet chamber 154 which receives stormwater from the settling chamber 24. The stormwater can then pass laterally through the screen 152 into a transfer chamber 156 located on the other side of the screen. The S" stormwater can then pass through the opening 138 into an outlet chamber 150 defined 20 in part by the platform 136 and the barrierwall 148. From the outlet chamber 150, the treated stormwater can then enter the downstream portion 87 of the pipeline. The Sscreen 152 serves to stop buoyant materials and the like which may have passed through the settling chamber 24 from entering the transfer chamber 156 and then into the downstream portion 87 of the pipeline. The screen 152 may comprise a number of vertical metal bars, say 3mm steel wire, mounted in a framework having a clear spacing of about 12mm therebetween. The screen 152 is preferably located in such J.

Sa way that it can be easily removed for cleaning. Alternatively, they may be fixed in position and cleaned by hosing. As best seen in Figures 1 to 4, the outlet pit 92 will normally be filled with stormwater to the level 124, which is determined by the level of the invert of the downstream portion 87 of the pipeline. The downwardly depending skirt 140 extends beneath the level 124 and thus again prevents any floating materials i: from passing through the opening 138.

i ^Y p \OPER\GCP877.CAP- 15f'10° -16- One of the pipe segments 94 is shown in more detail in Figure 13. It may comprise a reinforced concrete pipe of standard construction, except that it is provided with a cleaning shaft 74. Typically the pipe segment may comprise a 1950mm diameter reinforced concrete pipe having a nominal length of about 2.4 metres. A predetermined number of such pipe segments can be utilised to give the necessary settling time in the chamber 24. In the illustrated arrangement, there are eight pipe segments 94 giving a total length for the chamber 24 of about 16 metres. The overall length of the device including the inlet and outlet pits would be about 18.8 metres.

The preferred embodiments also have the following additional advantages: relatively high oil and sediment removal and retention rates; bed-load material removed at all flows; suitable for installation in new pipelines or for retrofitting to existing pipelines; simple boom internal arrangement; fail-safe, even if not maintained; suitable for land sub-divisions up to 50 hectares in area; the settling chamber can be extended to cover a wide range of applications, particularly end of line applications; constructed in pre-cast concrete as a single unit for smaller applications; 20 constructed in pre-cast pits and pipe segments for larger applications thereby making design, manufacture, transport and installation easier; containment of odour and gas emissions within the chamber 24; easy to install; can be cleaned by a truck mounted induction pump through access shafts; insect breeding prevented by elimination of a free water surface in the chamber 24; well suited to steeper pipelines; and same difference in water levels between ends of unit at all flows maintains 30 constant flow-rate through separation/holding chamber.

Many modifications will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

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Claims (20)

1. A method of treating stormwater flowing in a pipeline: said method including the steps of diverting the stormwater at an upstream location under relatively low flow conditions thereof, to a processing chamber; processing the stormwater in the chamber; returning processed stormwater at a downstream location to the pipeline; and under relative high flow conditions of the stormwater, permitting the stormwater to flow directly from the upstream location to the downstream location without passing H 10 through the processing chamber.

2. A method as claimed in claim 1 wherein the processing chamber comprises a settling chamber and wherein the stormwater is retained therein for a sufficient time to permit a substantial portion of materials suspended in the stormwater to settle out. 0

3. A method as claimed in claim 2 wherein heavier than water materials are collected at the bottom of the settling chamber and lighter than water materials are collected at the top of the settling chamber.

4. A method as claimed in claim 1, 2 or 3 including wherein said pipeline is an existing pipeline and the method includes the steps of inserting inlet and outlet pits in the pipeline at said upstream and downstream locations respectively and providing the processing chamber which extends between the inlet and outlet pits.

5. A method as claimed in claim 4 including the step of digging a trench beside the existing pipeline and locating the processing chamber downwardly adjacent to the pipeline.

6. A method as claimed in claim 5 wherein a number of chamber segments are coupled together to form said processing chamber. ^1 m pOPER'.GCP7 .CA-ilIC's i -18-

7. A method as claimed in claim 4, 5 or 6 wherein the existing pipeline has a predetermined fall distance, between said upstream and downstream locations whereby stormwater entering the inlet pit drops from a height approximately equal to said fall distance the impact thereof with stormwater in the pit tending to cause buoyant material to be submerged and/or oils, grease and the like to be emulsified.

8. A method as claimed in any one of claims 4 to 7 including the step of providing a boom in an inlet chamber of the inlet pit and wherein the boom floats on stormwater in the inlet chamber and serves to retain buoyant material in the inlet pit or to deflect it to a collection chamber.

9. Apparatus for removing material from a fluid, said apparatus including an inlet for receiving fluid with material entrained therein or carried thereby, an outlet for flow of fluid from the apparatus, a processing chamber in which at least some of the material is removed from the fluid to remain in the chamber, a bypass chamber, and flow control means for permitting said flow into the bypass chamber when the flow rate V' thereof is above a predetermined value to enable some of the fluid to flow directly through the bypass chamber to the outlet. i 20 10. Apparatus for removing foreign material from liquid flowing in a conduit including: an inlet pit which, in use, is located at an upstream location in the conduit; an outlet pit which, in use, is located at a downstream location in the conduit; a processing chamber which, in use, extends between the inlet and outlet pits; the inlet pit being arranged to divert said liquid to the processing chamber under relatively low flow conditions but to permit the liquid to pass from the inlet pit to the outlet pit through said conduit under relatively high flow conditions.

11. Apparatus as claimed in claim 10 wherein the inlet pit includes an inlet and outlet I:i: 30 chamber, the inlet chamber receiving liquid from the conduit and the outlet chamber passing liquid to the processing chamber. s~o~D~a~Pee~e~Pe~ F} -19- K

12. Apparatus as claimed in claim 11 wherein the inlet chamber includes an inlet port which communicates with the conduit and a bottom which has an opening which is located adjacent to said inlet port so that under sai l relatively low flow conditions, the liquid flows from the inlet port, through the opening to said outlet chamber.

13. Apparatus as claimed in claim 12 wherein the inlet pit comprises a hollow body having first and second opposed sidewalls and wherein the inlet port is located in the first sidewall and wherein the inlet chamber includes an outlet port located in said second sidewall, the arrangement being such that under relatively high flow conditions, the liquid flows from the inlet port, through the inlet chamber to the outlet port. o°14. Apparatus as claimed in claim 13 wherein a barrier wall extends upwardly from said bottom to define a litter collecting chamber and wherein the inlet chamber includes transfer means to deflect litter over the barrier wall into the litter collecting chamber.

15. Apparatus as claimed in claim 14 wherein said transfer means comprises a boom and means for mounting the boom in the inlet chamber for pivotal movement Srelative thereto.

16. Apparatus as claimed in claim 10 wherein the outlet pit includes an inlet and outlet chamber, the inlet chamber receiving liquid from the processing chamber and :H the outlet chamber passing liquid to the conduit.

17. Apparatus as claimed in claim 16 wherein the outlet pit comprises a hollow body having first and second opposed sidewalls and wherein the inlet port is located in the first sidewall and wherein the outlet chamber includes inlet and outlet ports located in said first and second sidewalls respectively, the arrangement being such that under relatively high flow conditions, the liquid flows from the inlet port of the outlet chamber through the outlet chamber to the outlet port of the outlet chamber. 1 15 chamber i

18. Apparatus as claimed in claim 17 wherein the outlet chamber includes a bottom which separates having an opening therein which communicates with the inlet chamber.

19. Apparatus as claimed in claim 18 wherein the inlet chamber includes a screen which is interposed between the inlet port of the inlet chamber and said opening. Apparatus as claimed in claim 19 wherein the screen extends vertically downwardly from said bottom.

21. Apparatus as claimed in claim 18 wherein said opening is bounded by a Sdownwardly depending skirt, the lower edge of which is at a level lower than the outlet port of the outlet chamber. S 15 22. Apparatus as claimed in claim 12 wherein said opening is bounded by a .downwardly extending skirt, the lower edge of which is below said outlet chamber.

23. Apparatus as claimed in any one of claims 10 to 22 wherein the processing chamber is made up from a plurality of pipe segments. S- -g

24. Apparatus as claimed in claim 23 wherein at least some of said pipe segments are provided with access shafts. An inlet pit for use in a stormwater processing system, said pit including: a hollow body having inlet and outlet chambers having inlet and outlet ports respectively; a platform forming, at least in part, a barrier between the inlet and outlet chambers; San opening in said platform; the arrangement being such that, under conditions of low flow of stormwater flowing through said inlet port, the stormwater passes through said opening into said outlet chamber but, on conditions of high flow of stormwater flowing through said inlet Om ~L. P OPERGCP'S7 CAP 1s1s8 -21- port, the stormwater passes through the inlet chamber to a bypass outlet located opposite to said inlet port. DATED this 15th day of October, 1998 SWINBURNE UNIVERSITY OF TECHNOLOGY By its Patent Attorneys DAVIES COLLISON CAVE _a8 i.. 4~