AU2003100895A4 - Trapper Litter Trap - Google Patents

Description

COMPLETE SPECIFICATION INNOVATION PATENT

TRAPPER

Stormwater Litter Trap The following statement is a full description of this invention, including the best method of performing it known to me: TRAPPER Stormwater Litter trap Pollution of stormwater and the adverse effects this have on receiving waters is of major concern in Australia and overseas.

Stormwater outfalls into receiving water bodies that are influenced by tidal movement are particularly difficult to manage. Existing end of pipe litter traps or inline devices often have problems operating when the stormwater outfall is submerged, resulting in re-suspension of trapped litter and/or risk of blockage of the pipe with an increased risk of flooding upstream as a result.

This device has been designed to overcome the problems currently encountered at stormwater outfalls in tidal influenced waters.

The invention may be better understood with reference to the illustration that accompanying this specification which: Figure 1shows a top view of the described litter trap Figure 2 shows a side view of the described litter trap Figure 3 shows a front view of the described litter trap Figure 4 shows the described litter trap from a top/side angle Detail 1 shows one specific detail of the described litter trap Please note that the net or mesh that surrounds the unit on all sides has been excluded in all figures except Figure 4 to allow an easier understanding of the unit.

A litter trap in accordance with this invention comprises a closed cylinder shaped body covered by mesh, grid or net, as shown in Figures 1-4, with a inlet situated at the top of the unit tangential to the centre of the unit. Top and bottom is covered of the same material as the sides, as shown in Figure 4. The size of the openings in the mesh, grid or net should be between 5-35mm, depending on what size of pollutants the unit is intended to capture.

The inlet is located at the upper end of the cylinder, tangential to the centre of the cylinder.

It can be horizontally or have a slight downward slope to ensure water to flow into the unit.

Figures 1-4 shows a unit with horizontal inlet.

The unit can be constructed of aluminium, galvanised steel or plastic material, with the recommended material being aluminium with regards to the salt water environment where the unit is intended to operate. The size of the unit itself is depending on the size and site specific parameters of the stormwater outfall where the unit is intended to be fitted. The distance between the invert of the pipe and the sea floor is of special importance, as this distance determines the litter storage area.

The inlet of the unit, which is to have a similar diameter as the stormwater pipe it is intended to be fitted on, has a solid bottom part[2], whereas the upper part are made of bars to allow water to escape if the pipe runs full under pressure or if the litter trap gets blocked The construction of the inlet is shown in Figures 2 and 4.

Inside the unit is two semi eclipse of grit, consisting of bars with a distance of 5- 50mm in between, as shown in Figures 1-4. The top grid is located on the opposite side of the inlet, in an angle, having a slope down towards the centre of the unit as shown in Figures 2-4. The lower grid is located on the same side as the inlet, opposite the upper grid as shown in Figures 2-4. The lower grid is attached to the same hight as the inlet, with a slope down towards the centre of the unit, with the edge of the grid located approximately 10-30 cm below the upper grid, as shown in Figures 2-4.

The upper grid is equipped with a number of pins on the lower end in the centre of the unit, attached so that they are allowed to move backwards or forwards, hanging freely down towards the lower grid and resting on the edge of the same as shown in Figure 4 and Detail 1.

This allows them to move freely in the same direction as incoming water, but they are prevented to move in the opposite direction. The lower grid is equipped with a strip at the edge where the pins rest, preventing litter and water currents from forcing the pins to open when the litter is trapped in the bottom of the unit, as shown in Detail 1.

When operating, stormwater is lead to the unit by the inlet that is fixed to an existing stormwater outfall.

In low tide and with a low flow of stormwater, the stormwater enters the unit through the inlet and passes down towards the bottom of the unit. As the water passes the two grids, litter is intercepted and flushed to the bottom of the unit. Water is allowed to escape through the sides and the bottom of the unit.

In low tide and with a high flow, the unit functions in the same way as for low flow, with the exception that some of the water is allowed to escape through the bars in the inlet, but leading all the litter into the unit.

As the tide rises, litter that has been captured in the bottom of the unit is prevented to escape by the angle of the grids and by the pins between the upper and the lower grids. Any litter that enters the unit during high tide will remain at the top of the unit. The inlet's location on the side of the unit will encourage a circular movement of captured litter, preventing the sides of the unit to be blocked. As the tide goes down the litter will settle down towards the bottom of the unit and will eventually be captured in the bottom.

There is no risk of re-suspension of captured litter, as any litter that has reached the bottom of the unit is prevented to move up towards the inlet by the grids and the pins attached to the upper one.

There is no risk of blockage, as litter is stored below the inlet, allowing a free flow. Under extreme conditions, if the unit is completely filled with litter and/ or there is high tide, water can escape through the bars in the inlet, preventing risk of blockage.

In order to allow allowing removal of litter and maintenance of the unit, the litter trap has to be fitted with an opening mechanism. This could be achieved, but are not limited to, by installing an opening flap on one side of the unit, or by making it possible, using henges, to open the unit in the middle.

The TRAPPER Stormwater Litter Trap is illustrated in Figures 1-4 and in Detail 1.

Claims (4)

1. A litter trap comprising a closed cylinder shaped body covered by grit, mash or net, with a inlet situated at the top of the unit tangential to the centre of the unit.

2. A litter trap as claimed in claim 1 with the inlet consisting partially of a solid surface and partially of bars.

3. A litter trap as claimed in claims 1 and 2, with two opposite directed semi eclipse shaped grids inside the unit, located at a different hight in relation to each other and inclining towards the centre of the unit.

4. A litter trap as claimed in claims 1, 2 and 3 with freely moving pins attached to the centre edge of the upper grid, hanging down towards the centre edge of the lower grid and be resting on the edge of the same, allowing the pins to move only in the opposite direction of the edge of the lower grid. A litter trap substantially as herein before described with reference to Figures 1-4 and Detail 1 of the accompanying drawings. Olof J. Jonasson 20 November 2003