AU2921202A - Method and apparatus for disposing of wastewater - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): DEAN RODNEY SCANLEN Invention Title: METHOD AND APPARATUS FOR DISPOSING OF WASTEWATER The following statement is a full description of this invention, including the best method of performing it known to me/us: METHOD AND APPARATUS FOR DISPOSING OF WASTEWATER TECHNICAL FIELD This invention relates to a method and apparatus for disposing of wastewater.

Specifically the present invention may be adapted to dispose of wastewater via filtration of the water using sloping terrain or surfaces.

BACKGROUND ART All, cities and public bodies responsible for the administration of a region's infrastructure need to deal with the disposal of wastewater. Wastewater can include storm water and road water runoff, normal household wastewater, and also sewage from industry. Care and attention needs to be taken with the disposal of such materials as they can create pollution within the environment.

One existing method of disposing of wastewater relies on treating the water to ensure .o that it is of a high enough quality to allow it to be discharged directly into natural waterways or the ocean. However, the degree of treatment required for wastewater is significant and therefore requires a substantial investment in the resources to complete such processes. Residents of a region may also have health concerns with regard to the safety of the flows discharged and the quality and effectiveness of the treatments carried out. Furthermore in New Zealand the Maori people have cultural reservations and concerns relating to the discharge of wastewater directly into the environment.

Other methods of disposing of wastewater can be described as infiltration systems, which allow wastewater to filter through top and sub-soils into the local groundwater.

With these systems special care and attention needs to be taken to ensure that the discharged wastewater is sufficiently treated before it reaches localities in which the groundwater has other uses (eg as a water supply source) or emerges above the ground.

Our Ref: 27320/16CL Some types of infiltration systems rely on sprinklers that spray wastewater directly on to an area of land. The wastewater is sprayed and distributed widely to ensure that it is able to all be absorbed by the ground surface without flowing over it.

However, there are some problems associated with the spraying of wastewater directly on to land. Care needs to be taken to ensure that the public or any other unprotected persons cannot obtain access to the area being sprayed. A person within such an area may faces significant health risks due to their exposure to wastewater (even when it has been subject to substantial previous treatment). Furthermore, such systems are also relatively expensive to implement due to the need for large areas of land to properly distribute the wastewater. The spraying systems and distribution lines required to transport the wastewater to each of many spraying sites also increase the costs of these systems.

Spraying systems are also ineffective in areas that experience significant and frequent rainfalls. If the ground area to be sprayed is already saturated with rainwater it cannot 15 effectively absorb and filter wastewater. In some instances this will result in the wastewater running off the surface of the spray area, or alternatively may require the use of a reservoir that will store the wastewater until the soil to be sprayed is no longer saturated.

Other types of infiltration systems used to dispose of wastewater employs soak holes 20 or mounds. These are subterranean systems that discharge wastewater directly into a mound of material and/or a deep pit with natural and/or imported soil walls that allow the wastewater to permeate out through into the surrounding soil and into the local groundwater.

However, these types of infiltration systems again need substantial pipework and are also relatively complicated and costly to construct due to the large amount material that needs to be imported. There are also limitations on the regions in which such Our Ref: 27320/16CL systems may be installed due to local soil and groundwater conditions. Such infiltration systems are also still affected by local rainfalls and again will not operate efficiently if the surrounding soil and subsoil are saturated with rainwater.

A method and apparatus used for the disposal of wastewater that solved any or all of the above problems would be of advantage. A system that could be implemented inexpensively and in a wide variety of terrains and regions, and which did not experience significant adverse effects from rainfall at its location would be of advantage.

It would be advantageous if at least preferred embodiments of the present invention addressed the foregoing problems or at least provided the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the S"ensuing description that is given by way of example only.

:e••i DISCLOSURE OF INVENTION According to one aspect of the present invention there is provided a wastewater 15 disposal apparatus, said apparatus in use being located on a sloping surface, the apparatus including, o at least one layer of permeable material, and at least one impermeable cover adapted to at least partially cover one or more of said at least one permeable layer, and at least one baffle positioned along a contour line of said sloping surface, wherein said at least one permeable layer is located on the sloping surface above said at least one baffle.

Our Ref: 27320/16CL According to a further aspect of the present invention there is provided a wastewater disposal apparatus substantially as described above wherein said at least one baffle is adapted to impede the movement of wastewater down the sloping surface.

According to a further aspect of the present invention there is provided a wastewater disposal apparatus substantially as described above wherein- said at least one baffle is adapted to distribute wastewater within said at least one permeable layer.

According to yet another aspect of the present invention there is provided a method of manufacturing of wastewater disposal system, characterised by the steps of: locating at least one baffle along a contour line of a sloping surface, and (ii) applying at least one layer of permeable material above said at least one baffle, and (iii) applying at least one impermeable cover above said layer of permeable .i S' material wastewater using an apparatus substantially as described above, characterised by the steps of: supplying wastewater to a permeable layer located on the sloping surface, and (ii) distributing wastewater within said permeable layer using said at least one baffle, and (iii) allowing the wastewater within said permeable layer to permeate through the permeable layer and down into the sloped surface underneath the permeable layer.

The present invention may be adapted to provide a method and apparatus by which wastewater may be disposed of. Wastewater may consist of or include a number or Our Ref: 27320/16CL range of waste liquids, ranging from mildly polluted to heavily contaminated.

Preferably the present invention may be adapted to dispose of mildly contaminated water flows or alternatively wastewater which has been pre-treated to allow the method and apparatus of the present invention to cope with its disposal. Preferably the present invention may act to both dispose of and also further treat wastewater before it reaches a waterway or locality in which groundwater is used as a water supply source.

Preferably the present invention may use or be located on sloping land such as a hillside. The disposal apparatus of the present invention may be located on a sloping hillside and may harness the effects of gravity to help distribute and further treat wastewater. Gravitational forces can be employed to distribute wastew~ter down the sloping surface.

.o o Reference throughout this specification will also be made to the present invention being located on a hillside that is used to form the sloping surface discussed above. In 15 some instances the gradients or locations of particular hillsides make them uneconomic to commercialise through horticulture and difficult to manage for agricultural purposes. Reference throughout this specification will also be made to the disposal apparatus being located on a hillside but those skilled in the art should appreciate that any type of sloping surface may also be used in conjunction with the present invention.

S"Preferably the present invention includes at least one permeable layer which is located above a baffle running along a contour line of the hill used. A permeable layer may be formed from any material that allows wastewater to permeate through the layer within the disposal apparatus. The material used to form such a permeable layer may vary in different embodiments of the invention depending on the particular characteristics of the wastewater to be disposed of. However, the material used may normally allow Our Ref: 27320/16CL settlement, filtration, precipitation, microbiological transformations, and/or volatilisation of the contaminants in the wastewater as it travels through the permeable layer. Further processes or reactions may also be promoted by a permeable layer in other embodiments depending on the material used to form same.

Reference throughout this specification will also be made to a permeable layer being formed by material introduced or imported onto the sloping surface used. However, those skilled in the art should appreciate that this feature of the invention need not necessarily be considered essential. For example, in one alternative embodiment a permeable layer may simply be formed by the material already present in or making up the sloping surface such as existing soil or subsoil already present on the site of the disposal apparatus. Those skilled in the art should appreciate that the reference to importing a material to form a permeable layer throughout this specification should in no way be seen as limiting.

In a preferred embodiment the present invention may include at least one impermeable 15 cover that is adapted to at least partially cover a permeable layer or layers. The exact configuration, size and dimensions of the impermeable cover or covers provided may "obe dictated by the size and capacity of the wastewater disposal apparatus implemented, and also characteristics of the hillside on which it is located. An impermeable cover used in conjunction with the present invention may act to primarily prevent rainwater from reaching the permeable layer and filtering down into the soil of the hillside used.

A secondary or additional use for an impermeable cover is to protect the health of any persons in the vicinity of the disposal apparatus. An impermeable cover will form an effective barrier between the wastewater and anyone close to the disposal apparatus.

In a preferred embodiment the present invention includes at least one baffle located along a contour line of the hillside on which the apparatus is located. A baffle may be formed from any material that is substantially impermeable to wastewater or rainwater OurRef: 27320/16CL and will also not be degraded or damaged by wastewater. Those skilled in the art should appreciate that a large range of materials may be used to form a baffle, such as for example, sheets of wooden or plastic material pegged in place along a contour line of a hillside. Those skilled in the art should appreciate that a baffle or baffles formed and used within the disposal apparatus need not necessarily filly encircle and cover a single contour line of a hillside if the entire hillside is not to be used by the disposal apparatus. In such instances the sides or ends of each baffle running along a contour line may be met at right angles by a second baffle which seals the sides of the disposal apparatus.

Preferably a permeable layer formed within the disposal apparatus may be located above a baffle on the hillside used. The baffle in this situation will prevent or impede the flow of wastewater directly down the slope, creating a dam or blockage at the end of the impermeable layer. As wastewater is prevented from flowing past the baffle it will then be forced to distribute itself within the permeable layer and to permeate 15 through this surface into the surrounding soil and subsoil of the hillside. A baffle may o S"trap wastewater within a permeable layer that will further filter and treat the :wastewater as it is disposed of through permeation into the surrounding hillside.

o* Those skilled in the art should appreciate that the soils and materials present in hillside used will also have a further filtering effect on the disposed wastewater. The 20 body of the hillside will continue to filter the wastewater disposed of until it reaches a S. local waterway. The baffles discussed above allow wastewater to be disposed of on a sloping hillside and also for the wastewater to be banked up and distributed within the permeable layer or layers provided. In addition the use of a naturalhillside minimises the amount of material to be imported for use as a filtering and treatment medium for the wastewater.

OurRef: 27320/16CL Once it enters the soil, the wastewater flows downwards by gravity. It flows virtually vertically downwards through unsaturated soil until it joins the groundwater. It then flows both horizontally and vertically until it emerges back above ground, usually via springs lower down the slope.

Once the wastewater enters the soil, it continues to receive treatment until it emerges above ground again. The treatment processes may be substantially the same as those present with an imported permeable layer (although they are likely to have completely different relative efficiencies) plus plant uptake (if the slope below is vegetated) and dilution (by existing groundwater and rainfall infiltration below the site of the apparatus).

The extent of treatment depends on the following factors: the permeability and chemical composition of the soil,

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:the depth of the groundwater at the site, the length of slope available before the groundwater (and treated wastewater) 15 emerges above the ground, I.. o• the extent of vegetation of the slope, and V. C oo• oo the degree of rainwater surcharge of the slope below the apparatus (which influences the extent of dilution and the speed at which the groundwater flows), g.

0. and 9 the width of the apparatus across the slope. The wider the system, the more soil and groundwater that is available for treatment and dilution.

In a preferred embodiment a disposal apparatus may be constructed with a plurality of baffles running down a portion of the hillside. At least one permeable layer may be Our Ref: 27320/16CL located above each baffle and baffles may run parallel to each other so that the disposal apparatus will occupy a continuous area on the hillside.

To form the apparatus in accordance with such an embodiment may initially require the removal of topsoil from the hillside in some instances. At this stage locating pegs for each of the baffles may be driven into the correct positions along the contour lines of the hillside. Sheet materials used to form the body of the baffles may then be put in place using each of the locating pegs, and then at least one imported permeable layer may be laid down above each baffle provided. Once the permeable layer or layers are introduced one or more impermeable covers may be made to the top of the apparatus.

In some embodiments a single impermeable cover may be sufficient for the apparatus whereas in other embodiments several impermeable covers may be required.

Reference throughout this specification will also be made to the disposal apparatus including a plurality of baffles running down the length of a hillside. However those skilled in the art should appreciate that other configurations of the present invention 15 are envisioned such as for example the use of a single baffle only and reference to the above only throughout this specification should in no way be seen as limiting.

Preferably wastewater may be introduced to the disposal apparatus through one or more inlet pipes or associated with the permeable layer and baffle at the highest point of the hillside. One or more inlet pipes can be provided adjacent to a baffle nearest 20 the top of the sloping surface °oi* In such an embodiment where the apparatus may include multiple baffles running down the hillside and an air gap, spillway or overflow channel provided above the top of each baffle and below the associated impermeable cover. Such a spillway will allow excess wastewater that cannot be blocked or restrained by the uppermost baffle to flow down into the lower baffles on the hillside. A trickle down effect may be used Our Ref: 27320/16CL to charge each of the permeable layers provided through a single inlet system at the top of the hillside.

In a further preferred embodiment a wastewater inlet system of the present invention may be formed by a single inlet pipe that includes a number of perforations or ports.

The inlet pipe and the perforations or ports it contains may run substantially along the length of the baffle provided uppermost on the hillside to evenly distribute the wastewater to be disposed of along the entire width of the apparatus.

However an alternative embodiment is a single inlet pipe only may not be provided.

For example, an alternative embodiment an inlet pipe may be provided above each of the baffles of the apparatus with such inlet pipes including a plurality of perforations or ports.

Reference throughout this specification will also be made to the present invention including a single inlet pipe only adjacent to the uppermost baffle on the hillside.

However, those skilled in the art should appreciate that other configurations of the 15 present invention are also envisioned and reference to the above only throughout this S• specification should in no way be seen as limiting. For example, in other alternative embodiments an inlet port or pipe may be provided to charge each baffle if required.

In a preferred embodiment the disposal apparatus may include a single permeable layer only for each baffle. The permeable layer may be applied directly onto the surface of the hillside above each baffle. This will allow wastewater when introduced into the apparatus to filter through the single permeable layer and then directly into the surrounding hillside.

Reference throughout this specification will also be made to the disposal apparatus including a single permeable layer for each baffle provided. However, those skilled in the art should appreciate that other configurations of the present invention are also Our Ref: 27320/16CL envisioned and reference to the above only throughout this specification should in no way be seen as limiting.

For example, in one alternative embodiment a plurality of permeable layers may be provided for each baffle. Layers of permeable materials may be applied one on top of each other above a single baffle if required by the particular characteristics of the wastewater to be disposed of or of the hillside on which the apparatus is used.

Different types of material used to form each permeable layer may be used in such embodiments if required.

Those skilled in the art should also appreciate that numerous different types of imported materials may also be used to form a permeable layer in conjunction with the present invention. For example, the materials listed below may be used in some embodiments depending on the characteristics of the hillside and the wastewater to be o disposed of. Those skilled in the art should also appreciate that the examples provided below are in no way a definitive or final list of permeable materials that may be used 15 and are given by way of example only.

Stone aggregate: This can be uniform graded stone such as 40-60mm drainage aggregate, in which the main treatment process is settlement. The aggregate can be graded if necessary to increase the filtration of solids and increase the surface area available for microbiological activity.

20 Stone aggregate is a virtually inert, permanent material with minimal to nil maintenance requirements. However, it has several disadvantages because of its weight including transport difficulties, virtual inaccessibility of the permeable soil surfaces and incompatibility with other, lighter, permeable materials that have higher treatment capability.

Our Ref: 27320/16CL Waste or recycled plastic: As for stone aggregate, this could be uniformly aggregated or graded. It is much lighter than stone, but likely to be less-readily available in a suitable form.

Bark or wood chips: As for stone aggregate, this could be uniformly aggregated or graded. It is also carbon-rich and nitrogen-poor and, as a result, will remove nitrogen from the wastewater while in contact with it. The extent of such removal depends on the grading of the material.

Bark or wood chips has the advantage of being extremely light it is possible to carry up to 60 cubic metres in a single truck/trailer load. The main disadvantage of these materials is that they are biodegradable and will require ongoing replacement. The finer the material, the more readily it will break down. Coarse bark is readily available and relatively stable.

Peat: This is fine and highly acidic. It will significantly increase the filtration of solids and the precipitation of phosphorus. It will also significantly reduce the oo S 15 proportion of exchangeable sodium cations (which, in turn, will minimise damage to the underlying soil structure and maximise the permeability of the soil). Peat is .o readily available from most locations.

*o"r Limestone and/or waste steel: These materials will provide calcium and iron cations respectively. Those cations have a key role maintaining good soil structure, especially 20 in acidic conditions.

Various combinations of these materials can be used to provide optimum levels of treatment in conjunction with the treatment also received in the ground. Additionally, the system allows for materials to be changed relatively readily if found not to be suitable.

Our Ref: 27320/16CL Some of these materials listed are degradable and, thus, will involve higher ongoing replacement and maintenance costs. However, the degradable materials generally have higher treatment capability, the advantages of which need to be weighed against the additional cost.

In a preferred embodiment an impermeable cover used in conjunction with the present invention may be constructed from several components or layers of material. In one further preferred embodiment an impermeable cover may be provided over the entire top surface of the apparatus.

For example, this can be achieved by applying a layer of plastic film, such as flexible polythene material over each of the permeable surfaces and baffles. A comparatively heavy topping material may then be layered on top of the plastic film to protect same from sunlight and prevent it from being blown or washed away by high winds or heavy rainfall. The impermeable plastic layer provided is substantially impermeable to local rainwater and will prevent rainwater from reaching each of the apparatus' 15 permeable layers. Preferably an appropriate topping material may also be used to hold eeeei down, anchor and protect the plastic or polythene sheet and may form a second component or layer of the cover. For example, in some embodiments an appropriate topping cover used in conjunction with an additional layer of impermeable material used to form a cover may consist of soil, bark, stone, hay, or loose vegetative material.

However, in other embodiments an impermeable cover may not be provided through multiple components or multiple layers of material, or exactly as described above. For example in one alternative embodiment a cover may simply be provided by or through a rigid, solid sheet of material such as, for example, wood or plastic materials which are simply laid over the top of the baffles and permeable layers provided. Those skilled in the art should appreciate that any number and range of configurations of impermeable cover may be used in conjunction with the present invention.

Our Ref: 27320/16CL In a preferred embodiment the disposal apparatus may also include an aeration system.

Such a system may be adapted to blow or supply air into the apparatus above the top level of the baffles and below the impermeable cover or covers provided. The supply of air through such an aeration system may be carefully controlled depending on which chemical and microbiological processes are to be promoted within the disposal apparatus.

In a further preferred embodiment such an aeration system may be implemented through a series of flexible perforated pipes run above the top of the baffles. These flexible pipes may be used to supply air into the apparatus from, for example, an inlet port on the exterior of the apparatus or alternatively a mechanical blower system which forces air into the perforated pipes.

The present invention provides many potential advantages over existing wastewater disposal systems.

A disposal apparatus formed in accordance with the present invention may be 15 constructed easily using readily available low cost materials. There is no need for significant earth works or earth moving operations to be completed during the manufacture or installation of the disposal apparatus.

The present invention may also be operated as a low maintenance system as it does •go not require or use any moving parts nor does it need any ongoing supply of treatment chemicals or frequent monitoring of the treatment and disposal processes.

By enclosing or covering the apparatus with an impermeable cover or covers this eliminates complications caused by rainwater which are experienced with existing systems. Furthermore, such covers also protect anyone in the vicinity of the apparatus from the health risks presented by the wastewater's presence.

Our Ref: 27320/16CL Furthermore, many different variants and arrangements of such wastewater treatment apparatus are also envisioned by the applicant. For example, in one instance crop or wetland plants may be placed on the upper layers of the apparatus with an appropriate water switching system. Wastewater may be fed to such plantings in dry weather (where wastewater run-off is unlikely) or alternatively supplied to the apparatus of the present invention in wet weather.

BRIEF DESCRIPTION OF DRAWINGS Further aspects of the present invention will become apparent from the following description that is given by way of example only and with reference to the accompanying drawings in which: Figure la,lb,lc,ld show a series of steps used to form a wastewater disposal apparatus in accordance with a preferred embodiment; and Figure 2- 4 show wastewater disposal apparatus configured in accordance 0: 15 with alternative embodiments to that shown with respect to Figure 1.

S"BEST MODES FOR CARRYING OUT THE INVENTION Figures la to ld show a series of steps used to form a wastewater disposal apparatus in accordance with a preferred embodiment of the present invention.

Figure la shows the initial state of a hillside on which a disposal apparatus formed in accordance with the present invention is to be installed. The hillside includes existing soil surface 1 including topsoil 2 that forms the ground surface 3.

The next step of the installation process is shown with respect to Figure lb where a number of locating timber pegs are placed along five contour lines of the hillside.

Our Ref: 27320/16CL These pegs mark out lines along the hillside of equal height and are also used to hold and lock in place a series of baffles 5. As a consequence of the arrangement of the locating pegs 4 the baffles will in turn run along contour lines of the hillside.

The next step of the installation process is shown with respect to Figure Ic. Once the baffles 5 are in place a fine substrate or sealant is applied along at the base of each baffle to seal spaces through which the wastewater could leak. Next a permeable layer 7 may be laid down within the apparatus and a perforated inlet supply pipe 8 is laid within the top of the permeable layer at the uppermost position on the hillside.

The permeable layer 7 supplied may be formed from any material which promotes the free flow of wastewater as it permeates down through the apparatus and into the original soil 1 of the hillside. The. permeable layer 7 also acts to support an impermeable cover. In the embodiment shown the material used to form the permeable layer may be uniformly aggregated scoria. However, those skilled in the art should appreciate that numerous different types of material may be used to form a 15 permeable layer in conjunction with the present invention and as such this example ooooo S. should in no way be seen as limiting.

In the embodiment shown a thick layer of scoria may be laid within the apparatus so

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that a permeable layer is supplied with the apparatus. The scoria may entirely cover •l the top of the baffles 5 and may therefore support a single impermeable cover 9, applied to the top surface of the apparatus.

In the embodiment shown, the scoria forming the permeable layer 7 are covered with a sheet of waterproof material such as polythene laid over the entire top surface of the *.i S"apparatus. The polythene sheet provided may then be covered by topping or anchoring material 10 such as for example surplus top soil.

Our Ref: 27320/16CL Figure ld shows the disposal apparatus when used. The perforated inlet pipe 8 may be used to introduce wastewater 11 above the top baffle on the hillside. The wastewater will permeate through the permeable layer 7 and pond behind the uppermost baffle When the level of the wastewater within the permeable layer exceeds the height of the baffle the excess water will then overflow 12 down towards the next baffle on the hillside. A trickle down effect from the uppermost baffle to the lowermost is used to charge each of the baffled areas within the apparatus. Each baffle may pond up in front of it a quantity of wastewater and distribute this wastewater throughout the permeable layer. As each baffle restrains or impedes the movement of wastewater down the surface, the wastewater is forced to permeate through the permeable layer and into the original soil 1. Once in the soil the wastewater will be further filtered and treated by materials present within the soil and also lower down in the hillside until it reaches a natural waterway or spring.

Figure ld shows a further possible addition to the apparatus in the form of perforated aeration pipes 13. Those skilled in the art should appreciate that any number of such pipes can be used to achieve the treatment objectives required of same.

Figures 2 to 4 show wastewater disposal apparatus' configured in accordance with alternative embodiments of the present invention.

S"The apparatus shown with respect to Figure 2 also makes use of the fine imported materials to further filter and dispose of wastewater. The apparatus also still includes a series of locating pegs 4 and baffles 5 located along the contour lines of the hillside.

However in the embodiment shown with respect to Figure 2, each baffle has a pair of imported permeable layers located above it on the hillside used. A first finely graded permeable layer may be supplied through a layer of material such as peat or pea gravel 7a. Over top of this material a second permeable layer 7b may be supplied through for example coarsely graded wood chips, bark, or stone aggregate.

Our Ref: 27320/16CL The wastewater disposal apparatus shown with respect to Figure 3 also employs a layer of polythene sheet 9 and anchoring material 10 to form an impermeable cover to the apparatus. The apparatus also includes the anchoring pegs and baffles discussed above. However, in the embodiment shown the apparatus is installed over a limiting horizon or layer 13 on the hillside which will prevent wastewater from filtering down further into lower depths. In this instance the apparatus may include a first permeable layer 7c formed in this embodiment from imported fine soil and a second permeable layer 7d formed in this embodiment from a coarse material such as stone aggregate.

The imported fine soil 7c may complete further filtering and treatment processes within the wastewater which would normally be completed by the subsoil of the hillside when present. Once the wastewater has filtered through the imported fine soil 7c it is then free to trickle or travel down the slope of the hillside below the level of each of the baffles.

Figure 4 shows a disposal apparatus configured in accordance with yet another alternative embodiment of the present invention.

S. In the embodiment shown the apparatus includes substantially the same elements as a.

that shown with respect to the apparatus of Figures la through Id. However, in this instance a different form of impermeable cover is used. Figure 4 shows an impermeable cover 14 formed from a single substantially rigid material such as

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plywood. The sheet of rigid material may be applied directly over the top of the apparatus' permeable layer or layers, and may also include brackets 15 which raise the S"lower surface of the impermeable cover 14 above each baffle and allow wastewater to overflow the top of each baffle and travel down to lower baffles on the slopes. In this embodiment, there is no imported layer of material, and the permeable layer is formed by the material already present in the sloping surface.

Our Ref: 27320/16CL Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

19 OurRef: 27320/16CL

Claims (25)

1. A waste water disposal apparatus said apparatus in use being located on a sloping surface, the apparatus including, at least one layer of permeable material, and at least one impermeable cover adapted to at least partially cover one or more of said at least one permeable layer, and at least one baffle positioned along a contour line of said sloping surface, wherein said at least one permeable layer is located on the sloping surface above said at least one baffle.

2. A waste water disposal apparatus as claimed in claiml wherein said at least one baffle is adapted to distribute waste water within said at least one •permeable layer.

3. A waste water disposal apparatus as claimed in any previous claim wherein gravitational forces are employed to distribute waste water down the sloping surface employed. o*

4. A waste water disposal apparatus as claimed in any previous claim wherein a layer of permeable material treats waste water through settlement, filtration, precipitation, microbiological transformations, and/or volatilisation of contaminants within said waste water.

A waste water disposal apparatus as claimed in any previous claim wherein a layer of permeable material is formed from stone aggregate, plastic, bark, wood chips, peat, limestone and/or steel. 3t Our Ref: 27320/16CL

6. A waste water disposal apparatus as claimed in any previous claim wherein said at least one baffle does not fully enclose a contour line of the sloping surface.

7. A waste water disposal apparatus as claimed in any previous claim wherein a baffle is impermeable to- water.

8. A waste water disposal apparatus as claimed in any previous claim which includes a plurality of baffles running down the sloping surface employed.

9. A waste water disposal apparatus as claimed in any previous claim wherein a single layer of permeable material only is provided above each baffle.

A waste water disposal apparatus as claimed in any previous claim wherein the impermeable cover prevents rain water from reaching the said at least one permeable layer.

11. A waste water disposal apparatus as claimed in claim 10 wherein the cover S•includes a layer of plastic film laid over at least one baffle and permeable layer.

12. A waste water disposal apparatus as claimed in claim 11 wherein the cover e*eS S e• includes a topping material applied over the plastic film.

13. A waste water disposal apparatus as claimed in claim 12 wherein the topping *e 5555 material is formed from soil, bark, stone, hay and/or loose vegetative material.

14. A waste water disposal apparatus as claimed in claim 10 wherein the cover is formed from a rigid sheet of material. A waste water disposal apparatus as claimed in any previous claim which includes one or more inlet pipes adjacent to a baffle nearest the top of the sloping surface.

Our Ref: 27320/16CL

16. A waste water disposal apparatus as claimed in claim 16 which includes a single inlet pipe only which includes a plurality of ports.

17. A vcwastewater disposal apparatus as claimed in claim 16 which includes an inlet pipe above each baffle said inlet pipes including a plurality of ports.

18. A waste water disposal apparatus as claimed in any previous claim which includes an aeration system which is adapted to supply air above said at least one baffle and below said at least one impermeable cover.

19. A waste water disposal apparatus as claimed in claim 18 wherein the aeration system includes a plurality of perforated pipes disposed above said at least one baffle.

A waste water disposal apparatus as claimed in any previous claim which includes a spillway between the top of said at least one baffle and said at least one impermeable cover adapted to allow waste water to flow onto lower baffles disposed on the sloping surface. •o

21. A method of manufacturing a waste water disposal system characterised by the steps of: o. locating at least one baffle along a contour line of a sloping surface, and (ii) applying at least one layer of permeable material above said at least one baffle, and (iii) applying at least one impermeable cover above said layer of permeable material.

22. A method of disposing of waste water using a waste water disposal apparatus, characterised by the steps of: Our Ref: 27320/16CL supplying waste water to a permeable layer located on a sloping surface said permeable layer being located underneath at least one impermeable cover, and (ii) distributing waste water within said permeable layer using at least one baffle, and (iii) allowing the waste water within said permeable layer to permeate through the permeable layer and down into the sloping surface underneath said permeable layer.

23. A wastewater disposal apparatus substantially as herein described with reference to and as illustrated by the accompanying drawings and/or examples.

24. A method of manufacturing a waste water disposal apparatus substantially as herein described with reference to and as illustrated by the accompanying drawings and/or examples.

25. A method of disposing of waste water substantially as herein described with reference to and as illustrated by the accompanying drawings and/or examples. Dated this 26 day of March 2002 S* Dean Rodney Scanlen By their Patent Attorneys GRIFFITH HACK Our Ref: 27320/16CL