AU2004100956A4

AU2004100956A4 - Gross Pollutant Trap

Info

Publication number: AU2004100956A4
Application number: AU2004100956A
Authority: AU
Inventors: Randall John Crisp
Original assignee: KYLO PROPERTIES Pty Ltd
Current assignee: KYLO PROPERTIES Pty Ltd
Priority date: 2004-11-10
Filing date: 2004-11-10
Publication date: 2004-12-09
Anticipated expiration: 2012-11-10

Description

GROSS POLLUTANT TRAP Z The present invention relates to water treatment, in particular the present 0 invention relates to the removal of gross pollutants from a stormwater system.

Stonuwater systems collect water from a variety of sources such as frm

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5 roads, driveways, car parks, roofs as well as many other sources. The water collected from these sources is often contaminated with gross pollutants. Gross pollutants generally 0 include organic mailer such as plant material leaves, bark, branches and the like), soil, o refuse such as plastic bags, wrappers, cigarette bulls and the like as well as hydrocarbon 0 products such as kerosene that may leach from a roadway and oils that may be deposited on a roadway by a vehicle.

The contamination of water in a stormwater system by these gross pollutants results in a concentration of these gross pollutants at the outflows of the stormwater system, for example into a dam, an ocean, a river or a lake. The contamination of the environment surrounding the outlet of a stormwater system results in a degradation of the environment or requires costly decontamination or filtering.

Gross pollutant traps have been produced for local installation such that gross pollutants are not accumulated in the stormwater system but are removed at or adjacent the source, In this way, the removal of gross pollutants can be efficiently achieved.

Gross pollutant traps generally comprise a collection chamber into which stormnwater is accumulated through a grate and/or other filters. Immediately below the grate is a collection tray for accumulating large gross pollutants. The collection trays also retain silt and dry out, leaving a dry misc of larger and small gross pollutants that may be blown out of the trap to repollute the surrounding environment.

The difficulty with pollutant traps of this design includes the potential for many gross pollutants to be blown from the trap out through the grate. The maintenance of such traps is intensive as in order to ensure minimal redispersion of pollutants frequent clearing of the collection trays is required. Also, in order for the traps to operate efficiently the frequent cleaning of the collection tray is required to prevent blocking.

We have now found a gross pollutant trap that enables the collection of a wide range of gross pollutants and provides reduced maintenance costs.

-2- According to one broad form of the invention there is provided a gross Z pollutant trap comprising a collector, a first chamber, and a second chamber, wherein the O collector comprises a first aperture in fluid communication with the first chamber and a plurality of second chambers in fluid communication with the second chamber wherein the ND 5 first aperture is disposed to drain the collector of fluid into the first chamber and wherein the plurality of second apertures are disposed around the first aperture to divert a portion of the 0 O fluid substantially free of gross pollutants into the second chamber, and wherein the first chamber is in fluid communication with the second chamber whereby fluid flowing from the 0 O first chamber to the second chamber is substantially free of gross pollutants and wherein the second chamber comprises an outlet for fluids substantially free of debris, said outlet being disposed above the base of the first chamber whereby gross pollutants retained in the first chamber are retained in a substantially wet state.

In use, water that may be contaminated with gross pollutants flows into the collector from a drainage system. As the water drains towards the first aperture, the water passes over the second apertures whereby water that is substantially free of gross pollutants can be collected in the second chamber. The majority of the gross pollutants are washed into the first chamber through the first aperture and the larger particles of gross pollutants are retained in the first chamber whilst the water is able to flow into the second chamber.

The filtered water, substantially free of gross pollutants is then able to be discharged from the second chamber into the stormwater system. The retention of gross pollutants in the first chamber is facilitated by the retention of water in the chamber such that the pollutants may be maintained in a wet state thereby reducing the likelihood of the pollutants being blown from the trap. The maintenance of the gross pollutant trap is simplified by merely requiring the insertion of a suction hose through the first aperture to remove gross pollutants from the first chamber as well as smaller gross pollutants that have flown through to the second chamber, such as hydrocarbons or silt.

It will be appreciated that by reference to the gross pollutants retained in the first chamber being "retained in a substantially wet state" it is meant that the first chamber or at least a substantial portion of the first chamber is disposed below the water level of the gross pollutant trap. This can be readily achieved by positioning the outlet from the second chamber to the stormwater system above a substantial portion of the first chamber. In a 0-3- 0 preferred configuration, the first chamber does extend above the outlet from the second Z chamber as this is necessary as the first chamber extends upwards to the collector. As a 0 result, whilst a proportion of the first chamber may extend above the water level, any silt or gross pollutants that are susceptible to being blown out of a gross pollutant trap will generally be retained in the bottom of the first chamber and below the water level. In this Oway the likelihood of gross pollutants being dislodged from the gross pollutant trap is o lessoned.

oWhilst the gross pollutant trap of the present invention may be manufactured in any convenient shape, we have found a particularly convenient gross pollutant trap to be of cylindrical construction. Accordingly, in a preferred form of the invention there is provided a gross pollutant trap in which the second chamber is formed in a cylindrical housing and wherein the first chamber is also a cylindrical chamber centrally disposed within the second chamber. The present invention will be further described with respect to this preferred embodiment although it will be appreciated that the respective chambers may be disposed adjacent to each other or connected by a suitable conduit as well as being concentric as described with reference to the first embodiment.

The collector may preferably be in the form of a tray that fits into the housing that forms the second chamber. The tray may be formed with the collector and first chamber as a single piece with the tray supported by the base of the first chamber resting on the base of the housing and the sides of the tray resting on cooperating lugs on the inner wall of the housing. The second chamber is thereby defined by the position of the tray within the housing.

The collector preferably includes a centrally disposed circular aperture, the first aperture, that opens into the first chamber. The first aperture is preferably unencumbered by a grate or grill such that larger particles of gross pollutants can freely flow into the first chamber for collection. The unencumbered opening of the first aperture makes it easy to insert a suitable hose for removal of the gross pollutants.

The collector includes a plurality of second apertures. The second apertures may be disposed in an array around the first aperture such that the maximum possible volume of water that is substantially free of gross pollutants can flow directly into the -4second chamber. The second apertures may be in any convenient form although we have 0 Z found that it is desirable to employ slots in the collector approximately 2mm wide, which o slots extend from the periphery of the collector chordally and spaced symmetrically about the centre of the collector. The slots partially extend along the length of the cord and preferably terminate so as to leave an unperforated section of the collector around the first aperture. Preferably the slots are relatively small in dimension such that water flowing 0 O through the slots into the second chamber is at a relatively low velocity and promotes the rapid settlement of sediment in chamber 2.

0 OPreferably the collector includes a shallow drainage grade that causes water held into the collector to flow towards the first aperture. Employing cordal slots in the collector results in water flowing from the periphery of the collector towards the first aperture to have to flow over at least one of the slots thereby permitting a proportion of the water that is substantially free of larger gross pollutants to flow directly into the second chamber.

In use a grate may be positioned above the collection. The first chamber is in fluid communication with the second chamber. Suitable slots or apertures may be included in the outer wall of the first chamber to enable the flow of water substantially free of larger gross pollutants to flow into the second chamber. We have found that vertical slots extending down the first chamber may conveniently be used to provide fluid communication between the respective chambers. The slots in the outer wall of the first chamber are preferably small in dimension whereby water flowing between the first chamber and the second chamber is restricted such that a low velocity of water flows between the chambers and separation and settlement of any gross pollutants is promoted. It is desirable that the slots or apertures introduced the water substantially free of larger gross pollutants into the top of the second chamber so as not to disturb any settled gross pollutants or settlements in the second chamber.

In a preferred form of the invention the first chamber also includes a series of clearance orifices at the base of the first chamber such that upon insertion of a hose into the first chamber to remove gross pollutants can readily vacuum or suck gross pollutants from the base of the second chamber into the first chamber and through the hose.

0 The outlet from the second chamber preferably includes a baffle that extends Z below the outlet from the second chamber. The baffle prevents the majority of o hydrocarbons floating in the second chamber from flowing to the outlet. We have found it preferable when using a baffle to have the vertical slots extending between the first and second chambers to terminate at the height of the opening of the baffle.

It is preferred that the baffle be tapered such that it has a large inlet allowing 0 0for a relatively low velocity of water flow through the baffle and into the stormwater. It is odesired that a low velocity of water flow be maintained such that turbulence in the sediment 0retention zone, the lower part, of the second chamber is reduced.

The outlet baffle may preferably include an overflow inlet that can permit the flow of water directly into the stormwater system. The use of an overflow inlet reduces the likelihood of flooding resulting from any blockage of the gross pollutant trap.

It is preferred that the overflow inlet be covered by a stainless steel gauze so as to minimise the flow of gross pollutants into the stormwater and to also exclude mosquitos and the like from accessing the chambers to lay eggs and breed. The unencumbered opening of the first chamber is not generally a problem with respect to the breeding of mosquitos as the top of the water retained in the gross pollutant trap generally includes a layer of hydrocarbon which will effectively prevent the mosquitos from breeding.

The present invention will now be described with reference to the accompanying drawings that serve to illustrate the present invention and are not intended to limit the scope of the invention disclosed.

Figure 1 is a cross-sectional view of a gross pollutant trap according to the present invention. Figure 2 is a top plan view of the gross pollutant trap of the present invention. Figure 3 is a cross-sectional view of the outlet baffle and Figure 4 is a top plan view of the outlet baffle.

Figures 1 and 2 show a gross pollutant trap according to one embodiment of the present invention. Figures 3 and 4 show the outlet baffle employed in the gross pollutant trap shown in Figure 1. The gross pollutant trap 1 is formed from a housing 2 which defines a second chamber 3. The housing 2 has a ledge 4 extending into the housing. A tray 5 rests on the ledge and includes both the collector 6 and the first chamber 7. The collector 6 t-6includes a series of cordal slots 8 as well as fins 9. Water caught in the collector 6 flows to

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Z the first chamber 7. Water substantially free of large debris can flow through the cordal o slots 8 into the second chamber 3. The remaining water in the collector 6 can flow into the primary chamber 7.

The primary chamber 7 includes vertical slots 10 that allow water to flow to the second chamber from the first chamber. Large debris is retained within the first chamber. The first chamber includes a series of cleaning holes 11 at its base that allows silt o and other gross pollutants to be sucked through a hose (not shown) inserted into the first 0chamber 7.

The second chamber 3 includes a baffle outlet 12. The baffle outlet 12 has an outlet 13 allowing filtered water to flow into the stormwater. A baffle 14 prevents a large proportion of any hydrocarbon from flowing to the outlet 13 as the baffle 14 extends below the depth to which the hydrocarbon is likely to float. The outlet baffle 12 includes an overflow inlet 15 that is covered by a stainless steel mesh (not shown).

Persons skilled in the art will appreciate that the invention described above may be subject to improvements and modifications that will be apparent without departing from the spirit and scope of the invention described herein.

Claims

2. A gross pollutant trap according to claim 1 wherein the collector is in the form of a tray removably disposed within a housing that forms the second chamber, said tray further including the first chamber extending downwardly from the collection.
3. A gross pollutant trap according to claim 2 wherein the tray is supported by the base of the first chamber resting on the base of the housing and the sides of the tray resting on cooperating lugs on the inner wall of the housing.
4. A gross pollutant trap according to either claim 2 or claim 3 wherein the outlet from the second chamber includes a baffle that extends below the outlet from the second chamber wherein the baffle is tapered such that it has a large inlet allowing for a relatively low velocity of water flow through the baffle and smaller outlet into the stormwater. A gross pollutant trap substantially as hereinabove defined with reference to the accompanying drawings. DATED this 10 h day of November 2004 RANDALL JOHN CRISP and KYLO PROPERTIES PTY LTD By their Patent Attorneys CULLEN CO.