GB2117079A - Outfall pipe - Google Patents

Abstract

The invention provides a land- drainage outfall pipe, preferably cast in glass-reinforced concrete. The lower profile (1) is laid in a trench and the flange (3) pressed into the seat- earth. Drainage water following the course of the trench in which pipe (4) lies, is prevented from eroding the seat-earth below the land drainage outfall pipe by flange (3). A lid (5) locates on the lower profile (1), sealing the inlet with flange (6). An interior vermin gate (7) prevents the infiltration of vermin, but swings on hinge (8), protected by flanges (9) to allow the passage of water and any debris. A spout (2) is provided to reduce bank scouring at the outfall. <IMAGE>

Description

SPECIFICATION Outfall pipe This invention relates to improvements in or means for the construction of land-drainage or similar liquid-flow systems.

It is customary in certain systems of landdrainage to have underground drainage pipes, which lie buried in trenches and emerge at an outfall into an open ditch or watercourse. One of the causes of failure of land-drainage sytems is the collapse of the outfall, as a result of the drainage water following the trench bottom and eroding the back below the outfall pipe, rather than flowing out of the outfall pipe. A further problem is in infiltration of vermin into the drainage system.

In accordance with the present invention there is provided a land-drainage outfall pipe, comprising a lower, "U"-shaped open topped profile incorporating an outwardly disposed flange on the inlet and a separate lid.

The lower "U"-shaped, open topped profile is laid in the trench at the outfall and the landdrainage pipe is laid inside it. The flange is pressed into the trench bottom and presents a barrier to drainage water, interrupting the erosion of the seat-earth. The separate lid is located on the top of the lower profile before back-filling.

Conveniently the lid comprises a planar part and a dependant flange with an arcuate, concave lower edge of the same outer radius as the land drainage pipe to be associated with the landdrainage outfall pipe, the upper edge of the flange being solid with one end of the planar part.

When a land-drainage pipe is placed within the lower profile and the lid located on top of the profile then the arcuate, concave lower edge of the flange meets the upper part of the pipe and prevents the entry of debris or of excavating vermin into the land-drainage outfall pipe.

Preferably the lid has a pair of dependent flanges being solid with the sides of the lid.

These dependent flanges prevent lateral movement of the lid. They may be generally continuous along the length of the edges, and lie external to the lower profile.

More preferably the land-drainage outfall pipe has a vermin gate within the lower "U"-shaped, open-topped profile.

The vermin gate will resist the infiltration of vermin into the drainage system. Being located within the drainage outfall pipe and not at the open end, it has the added advantage of being "tamperproof".

In the preferred embodiment the vermin gate is hinged at the upper edge and may only swing forward, towards the outfall. This allows the discharge of silt and organic debris from the landdrainage system without admitting vermin.

More preferably the land-drainage outfall pipe has a spout at the outlet end.

The provision of a spout at the outlet end ensures that drainage water falls directly into the open ditch or water-course or directly onto the drip-stone of a headwall support, this may also prevent water running back along the underside of the outfall pipe and scouring the bank.

More preferably the land-dainage outfall pipe is manufactured in a glass reinforced concrete.

The invention will be further described with reference to the accompanying drawings of which the sole figure is a perspective view of a preferred form of land-drainage outfall pipe according to the invention.

The drawing shows the lower profile and lid, both cast in glass reinforced concrete, however, it is envisaged that a suitable plastics material could be used.

The lower U-shaped open-topped profile (1) has a spout at the outlet (2) and a flange (3) at the inlet. The lower profile is laid in a trench and the flange (3) is pressed into the seat earth. A landdrainage pipe (4) enters the lower profile at the inlet carrying drainage water. Any drainage water following the course of the trench outside the land-drainage pipe (4) (usually is the seat earth below land-drainage pipe, or along its sides) will be prevented from following the course of the trench further by the flange (3). The flow of drainage water below the land-drainage outfall pipe will be reduced or prevented, obviating the erosion of the seat-earth below the land-drainage outfall pipe.

The lid (5) is located on the top of the lower profile, with the dependent flange (6) of the lid exterior to the flange (3). The lower, arcuate, convex edge of the dependent flange (6) meets the upper surface of the land-drainage pipe (4) ensuring a competent closure of the land-drainage outfall pipe. The flanges (9) locate exterior to the lower profile, and prevent laterial movement of the lid, relative to the lower profile. A slot (10) is provided between the flange (6) and the flanges (9). The flange (3) locates in this slot.

It may be acceptable in certain circumstances to replace the continuous flange (9) by a series of lugs, or to inwardly displace the flange (9) so as to locate internal to the lower profile (1) and depend from the lower surface of the lid (5).

The vermin gate (7! is secured by hinge means (8) within the lower profile, and is capable of swinging forward with the flow of water towards the spout (2). The vermin gate may be manufactured in a variety of materials, such as a glass reinforced concrete, cast alloy galvanized steel or a suitable plastics material. In this embodiment the flanges (9) of the lid, protect the hinge means (8), which comprises a slot cut into the upper edge of the lower profile (1).

It is intended that the land-drainage outfall pipe would be used in conjunction with a headwall assembly. The invention may be applied to the outfalls of land-drainage sytems which have already been installed and which require repair, due to erosion of the seat earth below the outfall and subsequent collapse.

Various modifications are envisaged within the scope of the invention.

Claims (7)

1. A land-drainage outfall pipe comprising a lower, "U"-shaped, open topped profile incorporating an outwardly disposed flange on the inlet and a separate lid.

2. A land-drainage outfall pipe as claimed in claim 1 in which the lid comprises a planar part and a dependent flange with an arcuate, concave lower edge of the same outer radius as the landdrainage pipe to be associated with the landdrainage outfall pipe, the upper edge of the flange being solid with one end of the planar part.

3. A land-drainage outfall pipe as claimed in claim 1 or 2, having a pair of dependent flanges being solid with the sides of the lid.

4. A land-drainage outfall pipe as claimed in claims 1, 2 or 3, having a vermin gate within the lower, U-shaped, open-topped profile.

5. A land-drainage outfall pipe as claimed in any previous claims having a spout at the outlet end.

6. A land-drainage outfall pipe as claimed in any previous claim manufactured in a glass reinforced concrete.

7. A land-drainage pipe as hereinbefore described with reference to the accompanying drawing.