AU2017100650B4 - Improved Liquid Run-Off Disposal System - Google Patents

Abstract

Abstract An improved liquid run-off disposal system 10 comprises an infiltration chamber 12 having first and second sidewalls 14a and 14b. In cross-sectional view the first and second sidewalls 14 each include an inner surface 16 and outer surface 18. The first and second sidewalls 14 each include a plurality of louvre-shaped apertures 20 provided therein. In cross-sectional view each louvre-shaped aperture 20 includes an upper surface 22 and a lower surface 24 which are substantially parallel to each other and are angled upwards from the outer surface 18 to the inner surface 16. The upper and lower surfaces 22, 24 each comprise a plurality of angled sections, and the upper surface 22 includes a first substantially vertical section 26a. The angled sections of the upper and lower surfaces 22, 24 are arranged at an angle and of a length so as to substantially overlap when viewed in a horizontal direction. It is this overlap which ensures that the apertures 20 will admit the exit of water but substantially inhibit the entry of soil, hence obviating the need to wrap the infiltration chamber 10 in Geosynthetic cloths to prevent ingress of soils through the external apertures. In use, when liquid run-off is piped into the infiltration chamber 10 it can drain away by passing through the apertures 20 and infiltrating the surrounding soil. Drawings suggested to accompany the Abstract: Figure 2

Description

“IMPROVED LIQUID RUN-OFF DISPOSAL SYSTEM”

Field of the Invention

The present invention relates to an improved liquid run-off disposal system and relates particularly, though not exclusively, to such a disposal system for disposing of stormwater run-off and grey water effluent.

Background to the Invention

In Perth, Western Australia, because of the generally sandy soil, one of the most common methods for disposing of stormwater is to employ soakwells. A typical soakwell consists of a cylindrical section that is installed in a vertical orientation in the soil. It may have a plurality of apertures provided in the side wall, and it is open at the bottom to provide a maximum infiltration area, so that when water collects in the soakwell it can rapidly soak into the soil underneath. Downpipes connected to drains from roof guttering or road drains are plumbed into the side wall of the soakwell so that stormwater run-off is safely directed and disposed of away from building foundations and roadway surfaces. Soakwells may also collect rainwater run-off from car park areas.

Other types of infiltration devices/apparatus have been developed to provide liquid run-off disposal for various applications. An important factor in the design and installation of infiltration devices/apparatus relates to groundwater levels. For infiltration devices/apparatus to provide effective performance they need to have a measure of vertical separation for stormwater run-off or effluent to infiltrate into the soils below and then disperse into the groundwater table. The degree of separation can vary from location to location or Local Council to Local Council and can be as little as <0.5 metres or as high as >2.0 metres separation depending on the application such as rainwater or effluent grey water disposal.

Where there is a high groundwater table level the infiltration device/apparatus may not have the measure of separation required by engineering standards or policy levels such as Local, State or Federal Government levels (separation level nominated by law makers or Standards requirements or simply good design practices). Engineers may design for a level of separation, but there are instances where a storm event or higher than normal tides (tidal surges) may occur which raises the levels of ground water flow through the soils and the peak water levels may be greater or exceed the original design invert level (bottom) intent of the effluent storage/infiltration apparatus for short periods. Rising sea levels are also an issue.

Currently, the issue of ingress of soils in both water-affected and dry areas is mitigated by the use of Geosynthetic cloths wrapped around the external perimeter of the infiltration apparatus. The Geosynthetic material is designed to stop soils from entering after backfill and compaction, or suspended solids from the surrounding soil being carried in the groundwater back into the device/apparatus/chamber. Current devices/apparatus do not provide any protection against such groundwater backflow as the louvre design is ineffective to mitigate such backflow in its own right. However Geosynthetic cloths are proven to block-up over time from “fines” in the soils, which results in reduced infiltration from the apparatus into the surrounding soils and eventually renders the apparatus inoperable and not fit for purpose. Blocked Geosynthetic cloths cause the disposal system to retain effluent rather than infiltrate it into the soils, which in turn causes the system to back-up resulting in serious damage to property and surrounding locations. US 3,645,100 (La Monica) is an example of a prior art leaching chamber unit for a soil absorption system. La Monica describes a leaching chamber having a plurality of perforations molded into the sidewalls of the chamber through which effluent can flow from the interior of the chamber into the surrounding soil. Figure 8 of La Monica shows a preferred form of upwardly angled wall perforation 15’ wherein the lower edge 48 of the opening on the inside of the wall is higher than the upper edge 49 of the outer side of the opening to prevent the ingress of stone into the chamber interior. A problem with the perforations of La Monica is that the very small overlap of the lower edge 48 and upper edge 49 is insufficient to prevent the ingress of sand and other soil particles, particularly in the presence of groundwater. With this kind of system the use of Geosynthetic cloth is essential to inhibit backflow of soil into the interior of the leaching chamber.

Commonly-owned US 9,290,924 discloses a liquid run-off disposal system comprising an elongate tank structure having one or more culvert sections adapted to be arranged end to end in a substantially horizontal orientation below ground. Each culvert section includes a plurality of apertures provided in the sidewalls thereof wherein, in use, when liquid run-off is piped into the tank structure it can drain away by soaking into the surrounding soil. In several embodiments the louvre-shaped apertures are provided in the form of louvre-shaped inserts, which may be mass-produced from injection moulded plastics material as a separate component. The louvre-shaped inserts are of cylindrical shape and comprise an upper surface and a lower surface that are substantially parallel to each other and are angled downwards from the inside to the outside of the culvert section. Advantageously the upper and lower surfaces are angled at such an angle, and are of a length, so as to substantially overlap when viewed in a horizontal direction. In one embodiment about one half of the length of the respective upper and lower surfaces overlap, measured in a vertical direction. One problem with the culvert sections of US 9,290,924 is that the inserts are relatively expensive to manufacture and install as a separate component, compared to a product in which the apertures are formed integral to the sidewalls of the section.

The present invention was developed with a view to providing an improved liquid run-off disposal system that can be used in any situation without the use of Geosynthetic cloth, and that is particularly applicable where liquid runoff or effluent disposal by infiltration is applied in locations where there is the presence of groundwater.

References to prior art documents in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.

Summary of the Invention

According to one aspect of the present invention there is provided an improved liquid run-off disposal system comprising: an infiltration chamber having first and second sidewalls, in cross-sectional view the first and second sidewalls each include an inner surface and outer surface; the first and second sidewalls each include a plurality of louvre-shaped apertures provided therein, wherein in cross-sectional view each louvreshaped aperture includes an upper surface and a lower surface which are substantially parallel to each other and are angled upwards from the outer surface to the inner surface; and, the upper and lower surfaces each comprising a plurality of angled sections, the upper surface including a first substantially vertical section, the angled sections of the upper and lower surfaces being arranged at an angle and of a length so as to substantially overlap when viewed in a horizontal direction so that the apertures admit the exit of water but substantially inhibit the entry of soil wherein, in use, when liquid run-off is piped into the infiltration chamber it can drain away by passing through the apertures and infiltrating into the surrounding soil.

Preferably the first substantially vertical section of the upper surface is provided adjacent the outer surface of the sidewall. Preferably a second substantially vertical section of the lower surface is provided adjacent the inner surface of the sidewall so as to face the first substantially vertical section.

Advantageously two substantially vertical sections together form a dogleg bend in the cross-sectional view of the louvre-shaped aperture so that any backflow of groundwater, soil held in suspension in the water, or soil into the louvre-shaped aperture at the outer surface must flow substantially vertically upwards, for a distance of “Y”, providing a region where gravitational forces acting downwards will inhibit the ingress of soil particles up and through the aperture, preventing the soil from entering the chamber.

Preferably the distance “Y” is greater than or equal (>) to “X”, where “X” is the effective height of the opening of the aperture at the outer surface of the sidewall.

In one embodiment the sidewalls of the infiltration chamber are angled upwards at an angle of between 0° to 30° to the vertical. Typically the sidewalls are angled upwards at an angle of between 5° and 15° to the vertical.

In a preferred embodiment the louvre-shaped apertures are of rectangular shape when viewed facing the sidewalls. Preferably the louvre-shaped apertures are provided in a uniform rectangular array comprising a plurality of rows and columns in the side walls.

Typically for each aperture the distance between the upper surface and the lower surface at the outer surface is the same as the distance between the upper surface and the lower surface at the inner surface.

Throughout the specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Likewise the word “preferably” or variations such as “preferred”, will be understood to imply that a stated integer or group of integers is desirable but not essential to the working of the invention.

Brief Description of the Drawings

The nature of the invention will be better understood from the following detailed description of several specific embodiments of the improved liquid disposal system, given by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a side elevation view of part of a side wall of a preferred embodiment of the improved liquid run-off disposal system according to the present invention;

Figure 2 is a cross-section view of part of the side wall of Figure 1 through the line A-A;

Figure 3 is a top perspective view of part of the side wall of Figure 1;

Figure 4 is a top perspective view of a preferred embodiment of an infiltration chamber of the improved liquid run-off disposal system according to the present invention, in the form of a culvert section;

Figure 5 is a perspective view of the culvert section of Figure 4;

Figure 6 is a side elevation view of the culvert section of Figure 4;

Figure 7 is an enlargement of detail ‘B’ in Figure 6;

Figure 8 is an enlargement of detail ‘C’ in Figure 9; and,

Figure 9 is a section view along the line A-A through the culvert section of Figure 6.

Detailed Description of Preferred Embodiments A preferred embodiment of the improved liquid run-off disposal system 10 in accordance with the invention, as illustrated in Figures 1 to 9, comprises an infiltration chamber 12 having first and second sidewalls 14a and 14b. In cross-sectional view the first and second sidewalls 14 each include an inner surface 16 and outer surface 18 (see Figure 2). The first and second sidewalls 14 each include a plurality of louvre-shaped apertures 20 provided therein. In cross-sectional view each louvre-shaped aperture 20 includes an upper surface 22 and a lower surface 24 which are substantially parallel to each other and are angled upwards from the outer surface 18 to the inner surface 16.

The upper and lower surfaces 22, 24 each comprise a plurality of angled sections, and the upper surface 22 includes a first substantially vertical section 26a. The angled sections of the upper and lower surfaces 22, 24 are arranged at an angle and of a length so as to substantially overlap when viewed in a horizontal direction, as can be seen most clearly in Figure 2. The overlapping region is identified as “Y” in Figure 2. It is this overlap “Y” which ensures that the apertures 20 will admit the exit of water but substantially inhibit the entry of soil wherein, in use, when liquid run-off is piped into the infiltration chamber 10 it can drain away by passing through the apertures 20 and infiltrating into the surrounding soil.

Preferably the first substantially vertical section 26a of the upper surface 22 is provided adjacent the outer surface 18 of the sidewall 14. Preferably a second substantially vertical section 26b of the lower surface 24 is provided adjacent the inner surface 16 of the sidewall 14 so as to face the first substantially vertical section 26a. The two substantially vertical sections 26 together form a dogleg bend in the cross-sectional shape of the louvreshaped aperture 20. This dogleg means that any backflow of groundwater and/or soil into the opening of the louvre-shaped aperture 20 at the outer surface 18 must flow substantially vertically upwards, for a distance of Ύ”, in order to enter the interior of the chamber 12. Vertical sections 26a and 26b provide a region where gravitational forces acting downwards will inhibit the ingress of soil particles up and through the opening of the aperture 20 on the inner surface 16, preventing the soil from entering the chamber. The vertical sections 26a and 26b will also allow particles of soil large enough to drop back down due to gravitational forces, not allowing those particles to enter the chamber which may have a detrimental effect on the design performance of the chamber and cause silting within the chamber which would reduce the chamber capacity/storage over time.

Preferably the distance Ύ” is greater than or equal (>) to “X”, where “X” is the effective height of the opening of the aperture 20 at the outer surface 18 of the sidewall 14. Dimensions “X” and “y” will vary depending on the wall thickness of the chamber design. Dimension “Z” is the width of the louvreshaped apertures 20. As can be seen in Figure 1 and 3, in this embodiment louvre-shaped apertures 20 are of rectangular shape when viewed facing the sidewalls. Preferably the louvre-shaped apertures 20 are provided in a uniform rectangular array comprising a plurality of rows and columns in the side walls 14. Width dimension “Z” is preferably > “X”.

Dimensions “X”, Ύ” and “Z” can be any shape and any size desired depending on the wall thickness of the chamber design, but must follow the design performance criteria of the chamber 12, i.e. ratios relationships between “X” and “Y” only. If measurement Ύ” was to be increased to a minimum of 2 x ”X” or greater, it would negate the need for vertical wall sections 26a and 26b, i.e. it would allow a straight line louvre to perform in the same manner as if they were not removed.

In one embodiment the sidewalls of the infiltration chamber are angled upwards at an angle Θ0 of between 0° to 30° to the vertical. Typically the sidewalls are angled upwards at an angle 0° of between 5° and 15° to the vertical. Typically the louvre-shaped apertures 20 are angled at an angle a° of between 20° and 65° to the horizontal. More typically the louvre-shaped apertures 20 are angled at an angle a° of between 40° and 50° to the horizontal. Angles 0° and a° may vary from design to design, depending on the wall thickness of the infiltration chamber 12, so as to maintain the Ύ” dimension in line with the above functionality of the chamber design.

Typically for each aperture the distance between the upper surface 22 and the lower surface 24 at the outer surface 18 is the same as the distance between the upper surface 22 and the lower surface 24 at the inner surface 16, i.e. the height “X” of the opening of the louvre-shaped aperture 20 is the same at the inner surface 16 and outer surface 18. In the embodiment illustrated in Figures 1 to 3, the opening of the louvre-shaped aperture 20 at both the outer surface 18 and the inner surface 16 has a shallow step 28a and 28b respectively provided adjacent to it. The shallow step 28a at the outer surface 18 is formed on the rear of the first substantially vertical section 26a of an adjacent louvre-shaped aperture 20’ (the one below), whilst the shallow step 28b at the inner surface 16 is formed on the rear of the second substantially vertical section 26b of an adjacent louvre-shaped aperture 20” (the one above). This is an artefact of the molding technique used to manufacture the chamber. In fact, the upper surface 22 may continue in one plane from the first substantially vertical section 26a all the way to the inner surface 16 of the sidewall 14. The lower surface 24 may likewise continue in one plane from the second substantially vertical section 26b all the way to the outer surface 18 of the sidewall 14. A preferred embodiment of an infiltration chamber 12 of the improved liquid run-off disposal system 10 according to the present invention is illustrated in Figures 4 to 9. Typically the liquid run-off disposal system 10 comprises a plurality of the infiltration chambers 12 adapted to be arranged end to end in a substantially horizontal orientation so as to form an elongate tank structure below ground. Each infiltration chamber 12 has a plurality of louvre-shaped apertures 20 provided in the side walls 14 thereof wherein, in use, when runoff is piped into the chambers 12 it can drain away by infiltrating the surrounding soil through the apertures 20. In this embodiment each chamber is in the form of an arch-shaped culvert section 12 and is typically open at the base, as can be seen most clearly in Figure 9.

It can be seen how the culvert sections 12 thus perform a similar function to a prior art soakwell, in that stormwater run-off can infiltrate the surrounding soil through the open base and the apertures 20 in the sidewalls. However, unlike a soakwell, the liquid run-off disposal system 10 is scalable in that any number of the culvert sections 12 can be joined end to end to increase the capacity of the system longitudinally rather than horizontally, the latter being far more costly when installed. This scalability also overcomes the requirement of soakwells having to be a minimum of 1800mm apart, thereby saving space on site. Furthermore the height, length and width of the culvert sections 12 can be varied more readily to suit the application and achieve the required volume capacity.

Preferably each culvert section 12 is of elongate construction and has interlocking edges provided at each end adapted to interlock with an adjoining culvert section 12. Support for the culvert sections will be determined by the Civil Engineer to suit the subterranean soil conditions prior to site installation.

Each culvert section 12 of this embodiment has a plurality of rectangular louvre-shaped apertures 20 formed in side walls 14 thereof in a uniform array, as can be seen most clearly in Figures 6 and 7. Each culvert section 12 of this embodiment typically has an arch cross-sectional shape, as can be seen most clearly in Figure 9, and has an internal width of approximately 760mm and an internal height of approximately 490mm, and is about 1.2m in length. If the chamber capacity is increased or decreased by design, then these dimensions will vary significantly. The side walls 14 are of substantially constant thickness. The culvert section 12 has two substantially planar side walls 14 and an arc-shaped roof 19.

Preferably each culvert section 12 is formed with a plurality of reinforcing ribs 30, which extend from one side to the other of the section. The reinforcing ribs 30 are of isosceles trapezoid cross-sectional shape, and are integral to, and form part of, the sidewalls 14 and roof 19 of the culvert section 12. Each reinforcing rib 30 is of similar width to the spacing between the ribs, so that the effect is to create a corrugated cross-section for the sidewalls 14 and roof 19. The reinforcing ribs 30 are also formed with louvre-shaped apertures 20 in the sidewalls 14. The arch-shaped design and corrugated cross-section substantially increases the strength of the culvert section 12 so that it can withstand heavy vehicular traffic and earth loadings without necessarily requiring concrete or other support footings.

The louvre-shaped apertures 20 in the sidewalls 14 are similar to the apertures 20 illustrated in Figures 1 to 3, and will not be described again in detail (see detailed enlargements in Figures 7 and 8).

Preferably each culvert section 12 has interlocking edges provided at each end and adapted to interlock with an adjoining culvert section 12. A male edge is typically proved at one end, and is designed to interlock with a female edge provided at the other end of each culvert section 12.

The culvert sections 12 are preferably manufactured from Linear Low Density Polyethylene (LLDPE) material using a molding technique, and typically have a wall thickness of 11mm for heavy loads and a reducing wall thickness of 3mm for light loads. Wall thicknesses will vary depending on the size and the end-user application.

The infiltration chamber 12 need not be in the form of a culvert section, but may be of any suitable shape or configuration. It may be open or closed at the bottom and at each or one end. The sidewalls need not be planar, but may be, for example, of parabolic or semi-elliptical shape.

It will be understood that each of the above-described embodiments the infiltration chambers can be manufactured from any suitably rigid and strong material, including suitable plastics products such as HDPE, polypropylene, polyethylene, polyurethane filament additives and thermoplastics. Other suitable materials include various synthetic compounds, polymers, petrochemical derivatives, and fibreglass compounds.

Now that preferred embodiments of the improved liquid run-off disposal system have been described in detail, it will be apparent that it provides a number of advantages over the prior art, including the following: (i) Each of the embodiments is fully scalable in that the number of sections as well as the shape, height, length and width of the sections can be varied to suit the application. (ii) The scalability of the system can provide for greater land use by developers and local councils as it can do away with age old system designs such as compensating basins in subdivisions. (iii) The louvre-shaped apertures, in particular their downward angle together with the overlapping surfaces and vertical section(s), obviate the need for the use of Geosynthetic cloth to prevent the ingress of most soil types, even in locations with high groundwater levels and substantiality extend the life of infiltration into the soils. (iv) The culvert sections are simple and easy to install, and can be installed more quickly and inexpensively, compared to prior art soakwells to achieve equivalent volumetric capacities. (v) The excavated material from the installation of the present system is easily quantifiable for reuse by earthmovers. (vi) The sections may be readily mass-produced from various materials, thus reducing manufacturing costs.

It will be readily apparent to persons skilled in the relevant arts that various modifications and improvements may be made to the foregoing embodiments, in addition to those already described, without departing from the basic inventive concepts of the present invention. For example, in the illustrated embodiments the louvre-shaped apertures are of rectangular shape. However the apertures may be of any suitable shape, for example, circular or ovalshaped. Therefore, it will be appreciated that the scope of the invention is not limited to the specific embodiments described.

Claims (5)

1. The Claims defining the invention are as follows:

   1. An improved liquid run-off disposal system comprising: an infiltration chamber having first and second sidewalls, in cross-sectional view the first and second sidewalls each include an inner surface and outer surface; the first and second sidewalls each include a plurality of louvre-shaped apertures provided therein, wherein in cross-sectional view each louvreshaped aperture includes an upper surface and a lower surface which are substantially parallel to each other and are angled upwards from the outer surface to the inner surface; and, the upper and lower surfaces each comprising a plurality of angled sections, including a first substantially vertical section on the upper surface, the angled sections of the upper and lower surfaces being arranged at an angle and of a length so as to substantially overlap when viewed in a horizontal direction so that the apertures admit the exit of water but substantially inhibit the entry of soil wherein, in use, when liquid run-off is piped into the infiltration chamber it can drain away by passing through the apertures and infiltrating the surrounding soil.
2. 2. An improved liquid run-off disposal system as defined in claim 1, wherein the first substantially vertical section of the upper surface is provided adjacent the outer surface of the sidewall.
3. 3. An improved liquid run-off disposal system as defined in claim 2, wherein a second substantially vertical section is provided on the lower surface adjacent the inner surface of the sidewall.
4. 4. An improved liquid run-off disposal system as defined in claim 3, wherein the first and second substantially vertical sections together form a dogleg bend in the cross-sectional view of the louvre-shaped aperture, so that any backflow of groundwater, soil held in suspension in the water, or soil into the louvre-shaped aperture at the outer surface must flow substantially vertically upwards, providing a region where gravitational forces acting downwards will inhibit the ingress of soil particles up and through the aperture, preventing the soil from entering the chamber.
5. 5. An improved liquid run-off disposal system as defined in claim 4, wherein the distance “Y” is greater than or equal to (>) “X”, where “X” is the effective height of the opening of the aperture at the outer surface of the sidewall.