NZ568879A - Sectional manhole pollution trap - Google Patents

Abstract

Disclosed is a device adapted to trap pollutants inside a storm-water manhole. The device comprises a multi-section removable grille and removable absorption material co-operating with the grille to trap and absorb pollutants from storm-water passing through the manhole. Also disclosed is a method of removing suspended solids and hydrocarbons from storm-water.

Description

Received IPONZ 28 May 2009 NZ 568879 1 TITLE: SECTIONAL MANHOLE POLLUTION TRAP INTRODUCTION This invention relates to a method for improving the effectiveness of pollution control in or relating to drains and especially relating to an improved pollution control system for storm water conduits and in particular, storm water manholes.

BACKGROUND: An urban environment consists of many hard stand surfaces like roofs, parking areas, streets and footpaths. During a rain event the water cannot be absorbed by these surfaces and thus runs off to the lowest point, generally via drains into 15 underground pipes or conduits washing down with it litter, organic materials, sediment and debris, and other pollutants.

Storm water drains can be accessed through storm water manholes. The principle purpose of a storm water manhole is to provide access via a secure 20 manhole opening lid to the storm water conduits for the clearing/cleaning of blockages and sediment removal. Storm water usually drains into lakes, rivers, streams and the sea (waterways).

To prevent the as above described polluted storm water from entering the 25 waterways it is important to trap the pollutants before they reach the waterways, without hindrance of the primary purpose of conveying storm water run off. It is important to regularly remove the trapped pollutants efficiently and cost effectively from the storm water system via the opened lid of a storm water manhole.

This invention has been brought about to resolve these issues.

Received IPONZ 28 May 2009 2 NZ 568879 SUMMARY OF THE INVENTION In accordance with the present invention there is provided a sectional manhole 5 pollution trap and method for improving pollution control of storm water before it enters the lakes, rivers, streams and the sea (waterways).

The trap provided is a multi-section removable grille. In a manhole each grille section comprises sides and divider means, connected to each other as well as 10 to the sides of the manhole, spaced apart by gaps to collect passing pollutants and let water flow by allowing for an overflow space between the combined grille sections and the top of the manhole when the grille is completely blocked.

Provided on the trap is a removable prong hanging on the downstream side of 15 the multi-section removable grille and holding (or suspending) a material for absorbing oil or hydro-carbon substances or matter from the polluted water which is easily reachable from the opened manhole lid hanging downstream.

In accordance with a further aspect of the present invention there is a method of 20 clearing the pollutants. The method requires the prong to be firstly removed from a manhole after every rain event and then using a rake means to rake the solid trapped pollutants from the bottom of the grille to the top into a basket (supplied separately) placed downstream of the grille.

The basket is lifted out when filled and the contents placed into a suitable receptacle means. This procedure is repeated until all pollutants have been cleared and taken to a waste disposal site for sorting and recycling where possible.

After every rain season the multi-section removable grille and the prong is completely removed from the manhole to clean out the collected sediment from the upstream conduit.

After inspection for serviceability the multi-section removable grille and the prong is replaced.

Received IPONZ 28 May 2009 3 NZ 568879 DESCRIPTION OF DRAWINGS: Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a frontal view looking downstream of a multi-section removable grille for a manhole, deployed and assembled inside the manhole taken of Figure 2; Figure 2 is a side sectional view taken along the lines A-A in Figure 1; Figure 3 is a plan sectional view taken along the lies B-B of Figure 2.

DETAILED DESCRIPTION OF THE APPARATUS AND PREFERRED EMBODIMENT: To assemble the apparatus the lid 1 of the manhole 10 described in Figures 1 15 and 2 is removed.

The multi-section removable grille with outer sections 5 and inner section 8 described with reference to Figure 1 and 2 is specifically for use in the manhole and is constructed from suitable non-corrosive durable material with gaps 20 (including gaps between the sides and the bottom of the manhole to which it is fitted) to define a substantially rectangular grille.

The outer sections 5 are hinged on two hooks 4 embedded into opposite sides of the manhole 10 directly across the normal flow path of the water. The inner 25 section 8 is then hooked into the outer sections 5 by hooks 3, causing a complete multi-section removable grille across the normal water flow obstructing and trapping street litter/debris such as leaves, polystyrene, plastic wrappings, bottles, silt, containers, cigarette butts, sticks, paper or any other foreign matter which has entered the storm water system, letting cleared water pass. Enough 30 space is provided for overflow if completely blocked, over the multi-section removable grille and out via the outlet 6.

The multi-section removable grille containing the trapped pollutants causes the water coming from the inlet pipe 15 to reduce velocity and in doing so lets the Received IPONZ 28 May 2009 4 NZ 568879 suspended silt and heavier items transported by the water drop down in the upstream side of the multi-section removable grille with the cleared water passing through the multi-section removable grille via the outlet pipe 6.

The prong 9 with absorbent material 7 securely fixed to it is hooked over the inner grille section 8 by hook 13 and spaced away from the grille by spacer 14 on the downstream side of the multi-section removable grille.

The prong 9 holds the absorbent material 7 in place on the downstream side 10 towards the outlet pipe 6 to collect any hydrocarbons available for absorption. The lid 1 can now be replaced and the invention is ready to function.

To clean/clear the grille manually, the lid 1 is opened and the prong 9 with absorbent means 7 is removed from the manhole 10 (the absorbent is replaced 15 according to suppliers guide). A removable basket (supplied separately) is then placed hanging from the top of the inner section 8 facing down stream towards the outlet pipe 6.

A rake is used to rake up all the obstructing litter caught on the upstream side of the outer sections 5 and the inner section 8 from the bottom of the manhole up 20 into the removable basket hanging downstream from the top of the inner section 8 (easy to grab hold of when lid 1 is open, no access required). The basket is then emptied into a collecting container and the process repeated as many times as needed to clear all polluted debris from the grille means, then to be disposed off site.

To clean/clear the multi-section removable grille mechanically by suction device, the lid 1 is opened the suction device is used to suck out all trapped debris on the upstream side of the outer sections 5 and the inner section 8. A rake can be used to loosen any debris sticking onto the grille and then be sucked out.

Silt and heavier items are removed only when visible. The silt removal process will require the lid 1 along with the prong 9 with absorbent material 7 to be removed from the manhole and then the unhooking and removal of inner section 8. A person is then required to enter the manhole 10 via the opened lid 1 (the health and safety of workers and the public must at all times be paramount and Received IPONZ 28 May 2009 NZ 568879 all requirements for entering a confined space must be adhered to) to scoop up the silt and heavier items with a shovel to be disposed off.

The basket can be lowered into the manhole once entry has been gained to be 5 used for cleaning/clearing purposes with an additional liner placed into it. When all silt and heavier items have been cleared, the inner section 8 is hooked in place as above, the prong 9 with absorbent material 7 is hooked onto inner section 8, the lid 1 replaced and the invention is again ready to function.

Silt can also be removed by any other means to suit for example suction via a suction means connected to a suction device.

• Received IPONZ 28 May 2009 6 NZ 568879

Claims (7)

CLAIMS:

1. A device adapted to trap pollutants inside a storm water manhole, the said device comprising a multi-section removable grille and removable absorption material co-operating with said grille to trap and absorb 5 pollutants from storm water passing through the manhole.

2. The said grille further comprising projections adapted to secure the said grille by way of hooks affixed into the manhole walls, the grille further comprising projections adapted to hook the said grille together.

3. The said grille further comprising projections adapted to suspend a prong 10 to which the said removable absorption material fixed.

4. A method of removing suspended solids and hydro carbons from storm water comprising a multi-section removable grille with overflow capacity, integrally formed with or adapted to be retained in a storm water manhole and a removable absorption material held in place by a prong for 15 absorption of hydro carbons for pollutant collection and removal from the said manhole.

5. The method of removing suspended solids and hydro carbons from storm water wherein the said multi-section removable grille has clearance between the side walls of the said manhole and the grill. 20

6. A pollution trap device as substantially described and with reference to the accompanying drawings.

7. A method of removing suspended solids and hydro carbons from storm water manhole substantially as herein described and with reference to the accompanying drawings.