GB2150953A

GB2150953A - Manholes and catch-pits

Info

Publication number: GB2150953A
Application number: GB08429990A
Authority: GB
Inventors: Ian Thomas Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-11-28
Filing date: 1984-11-28
Publication date: 1985-07-10
Also published as: GB2150953B; GB8429990D0

Abstract

A modular construction system for a circular or other manhole shaft or catch-pit comprises a sump and drain connection pan member 10, extension members 20 of different heights and a cover member 30 (shown as a grating). The members are fabricated from uPVC or high density polyethylene by hot-air welding. The cover and extension members have collars 36, 24 receivable in adjacent members when stacked together to a desired height, the stacked members being secured by solvent cement or self-tapping screws. The floor 16 of the sump member 10 is apertured to prevent flotation where the water table is high. An alternative cover member, which may be solid or apertured and/or include an optional lid, is shown in Figure 3. It has a skirt 44 which depends into the manhole shaft, and is supported by a shallow top flange 50. This cover is particularly advantageous when used in a railway drainage scheme because it minimises the tendency for loose ballast to fall into the manhole or catch-pit when the cover is removed. <IMAGE>

Description

SPECIFICATION Manholes and catch-pits The present invention relates to manholes and catch-pits, for examples ones which are used in railway drainage schemes.

The invention provides a modular manhole or catch-pit system for construction of a manhole or catch-pit structure, comprising a connection pan member having an upstanding tubular wall portion with at least one pipe-connection aperture therein, a cover member for the top of the manhole structure, and, optionally, at least one tubular extension member for fitting between the connection pan member and the cover member, the members having means which allow interengagement of the members when stacked to form a manhole structure.

The interengagement means preferably comprises a collar protruding from the end of one member and shaped for interengagement with an adjacent member of the structure, the extent of interengagement being determined by abutment of a shoulder on the one member with the end surface of the other member.

The tubular extension member(s) can be selected from a plurality of extension members of predetermined height and the invention also provides a method of construction of a manhole or catch-pit structure, comprising the steps of providing a sump member of the structure, stacking upon the sump member one or more extension members and fitting a cover member to the or the uppermost extension member, each member of the structure being in engagement with its adjacent member(s) and the height of the extension member(s) being selected from a plurality of extension members of predetermined heights whereby a structure of a desired height is constructed. In this way, a manhole of a desired depth can be constructed quickly and easily and by use of a small number of component parts.

For use in either the system described above or otherwise the invention also provides a sump member for use in a manhole or catch-pit structure and having an apertured base portion. Preferably, the member is a sump and connection pan member and includes a tubular wall portion which has at least one pipe-connection aperture and which extends upwardly from the apertured base portion.

The apertured base portion allows ingress of water to the sump during construction of the manhole structure and prevents flotation of the member at locations where the water table is high.

Further, there is also provided a sump and connection pan member for use in a manhole or catch-pit structure, the member having a base portion and an upstanding tubular wall portion having at least one pipe-connection aperture therein. Such a member provides a combined sump and connection pan which simplifies the construction of manhole and catch-pit structures.

In yet another aspect, the present invention provides a cover member for a manhole or catch-pit structure, comprising a cover portion and a skirt portion extending from the cover portion, the cover portion having a peripheral flange extending outwardly of the skirt portion such that, when the cover member is used to close the upper end of a manhole or catch-pin structure with the skirt portion fitted within an upstanding tubular part of the structure, the flange abuts the upper edge of the structure.

In use of such a cover member, the member extends above the top of the manhole or catch-pit structure by only the thickness of the cover portion which can be small compared with the depth of the skirt portion. This is of particular advantage in railway drainage systems where, after construction of the manhole or catch-pit (for example using components described above), and fitting of a cover member, it is usual to place loose ballast around the structure and to level the ballast to the upper surface of the cover member. When the cover is subsequently removed, the loose ballast around the perimeter of the manhole or catch-pin is unsupported and tends to fall into the manhole or catch-pit where it tends to cause blockages.

With known covers, this unsupported depth is often quite considerable: for example 150mm or more. With a cover member according to the present invention, when the ballast or other material is levelled to the upper surface of the cover member, little or no ballast falls into the manhole or catchpit because a depth of ballast equal only to the thickness of the cover portion becomes unsupported around the periphery of the manhole or catch-pit when the cover member is removed.

The depth of the skirt portion is preferably at least five times, and more preferably at least eight times, the thickness of the cover portion. The lower edge of the skirt preferably tapers inwardly for ease of fitting to a manhole or catch-pit structure.

The cover members according to any aspect of this invention may include a removable lid which may be solid with suitable hand holes for ease of removal or may be apertured, for example in the form of a grating.

Preferably, the manhole or catch-pit structure members of the present invention are formed from a plastics material which is advantageously unplasticised polyvinyl chloride (uPVC) or high density polyethylene. When formed from plastics material, the tubular wall portion and apertured base portion of the sump and connection pan member are preferably welded together, for example by hot air welding, to form a unitary structure. The cover portion and skirt portion of the cover member described are also preferably separately fabricated and then united by welding, for example by hot air. The tubular and collar parts of the extension member may be similarly formed.

The members of the modular system, when formed from plastics material, can, after construction of the manhole structure, be secured together by, for example, self-tapping screws or a suitable solvent cement.

A plastics manhole structure constructed from components according to the present invention can weigh as little as 10% of the weight of an equivalent structure of concrete or brickwork. Moreover, the structure of the invention is installed much more quickly and easily than concrete or brick structures, is more readily transported to the location of installation, and can be manufactured at less expense. Structures according to the invention can be of compact dimensions compared with concrete and brickwork structures and are particularly advantageous for use at locations where limited space is available and a concrete or brickwork structure would be difficult to install.

The invention will now be described further by way of example with reference to the drawings in which: Figure 1 shows the parts of a modular manhole system, partly in elevation, partly in section and partly in plan, Figure 2 is a plan view of a manhole cover, and Figure 3 is a side elevation of the cover of Figure 2.

The system shown in Figure 1 of the drawings consists of a sump and connection pan 10, an extension ring 20 and a top cover 30. The members are each fabricated from component parts by hot air welding of uPVC material. In a modified embodiment the material is high density polyethylene.

The sump and connection pan 10 is approx. 610 mm in internai diameter and includes a cylindrical wall 12 having four circular apertures 14 of 200 mm diameter for connection to drainage pipes.

The centres of the aperture 14 are 400 mm above a circular fioor 16 which has an array of apertures 18 for ingress of water to the pan 10. The sump depth is thus 300 mm. In this embodiment, the wall 12 and floor 16 are each of uPVC material and are secured together by hot-air welding.

The extension ring 20 shown in the drawing is 250 mm in height. Alternative heights may be, for example, 115 mm, 150 mm and 450 mm. The ring 20 has a main cylindrical wall portion 22 and a circular collar 24 received within one end of the wall portion 22 and secured by hot-air welding. The collar 24 has a height of 100 mm and protrudes by one-half of this distance from the main wall portion 22 so as to form a peripheral shoulder 26 on the extension ring. The shoulder 26 abuts the upper end on the sump and connection pan 10 when the extension ring 20 is fitted to the pan 10. In a similar manner, further extension rings of desired heights may be fitted to the upper end of the illustrated ring 20.

The upper end of the manhole structure is closed by a top cover 30 which is formed from uPVC material and has a frame portion 32 which provides a seating for a removal lid 34 having apertures 36 therein. Alternatively, the lid 34 may be solid and have hand holes to facilitate its removal. A collar 36 is secured in the frame 32 by hot-air welding and protrudes downwardly in a similar manner to the collar 24 of the extension ring 20 and forms a peripheral shoulder 38 for abutment with the upper end of an extension ring, such as the ring 30, or a sump and connection pan, such as the pan 10.

To build a manhole structure, the sump and connection pan 10 is first placed at the bottom of a suitable hole in the ground and any pipes to be connected are fitted to the aperture 14. One or more extension rings such as the ring 20 are then fitted to the pan 10 to bring the upper end of the structure to the desired height. The structure is then completed by fitting the cover 30 to the uppermost extension ring. If the height of the structure is appropriate, the structure can of course be built without any extension rings. The cover 30 is then fitted directly to the pan 10.

During construction, the parts of the structure can be secured to each other with self-tapping screws or a suitable solvent cement.

The dimensions of the components of the modular system are given as examples only. Components of different heights, diameters, etc. may of course also be used within the scope of the invention.

The cover shown in Figures 2 and 3 of the drawings consists of a circular top portion 42, a tubular skirt portion 44 and a reinforcing bar 46. The top portion 42 has two kidney-shaped hand holes 48 for ease of removal of the cover from a manhole or catch pit structure. In modified versions, the cover is apertured to form a grating or includes a removable lid.

The diameter of the top portion 42 is greater than that of the skirt portion 44 so that, when the parts are united, a peripheral flange 50 protruding beyond the skirt portion 44 is formed. The lower edge of the skirt portion 44 is chamfered at an angle of about 45% for ease of fitting into an upstanding part of a manhole or catch-pit structure.

The parts of the cover are formed from uPVC or high density polyethylene material and then united by hot-air welding.

When the cover is fitted to a manhole or catchpit structure, the skirt portion 44 is received within the upstanding part and the flange 50 rests on its upper rim. Only the top portion 42 extends above the top of the manhole or catch-pit structure. After fitting of the cover, ballast is placed around the cover and levelled to the top of the cover. When it is necessary to remove the cover, little or no ballast falls into the hole or pit because only ballast to the depth of the thickness of the top portion 42 is unsupported by the walls of the manhole or catchpit structure.

The dimensions of the top cover may, for example, be: diameter of top portion: 640mm; external diameter of skirt portion: 60mm; depth of skirt: 98mm; thickness of top portion: 12mm.

It will be appreciated that manholes and catch-pit members of the invention may be shaped for the construction of circular, rectangular, or any other shape of manhole or catch-pit.

It will be appreciated that the advantages of the aspect of the invention described with reference to Figures 2 and 3 will also be obtained when a manhole or catch-pit is surrounded by any loose material. Further, a reduction in the tendency for loose material to fall into the manhole or catch-pit will be obtained with the invention in comparison with the known, deep covers, even if the surrounding loose material is levelled to above the top surface of the cover. Moreover, that tendency can be avoided altogether with the cover of the invention by levelling the material to only a short distance below the top surface.

Claims

1. A modular manhole or catch-pit system for construction of a manhole or catch-pit structure, the system comprising a connection pan member having an upstanding tubular wall portion with at least one pipe-connection aperture therein and a cover member for the top of the manhole or catch pitft,ructure, the members having means which al low Interengagement of the members when they are stacked to form a manhole or catch-pit structure.

2. A sump member for use in a manhole or catch-pit structure, the member having an apertured base portion.

3. A sump member according to claim 2, including a tubular wall portion which has at least one pipe-connection aperture therein and which extends upwardly from the apertured base portion.

4. A sump and connection pan member for use in a manhole or catch-pit structure, the member having a base portion and an upstanding tubular wall portion having at least one pipe-connection aperture therein.

5. A system according to claim 1, in which the connection pan member is in accordance with claim 3 or 4.

6. A system according to claim 1 or 5, including at least one tubular extension member for fitting between the connection pan member and the cover member, the member having means which allow interengagement of the extension member(s) with adjacent connection pan, cover or extension member when the members are stacked to form a manhole or catch-pit structure.

7. A modular manhole system for construction of a manhole structure, the system comprising a sump member, a cover member for the top of the manhole structure and at least one tubular extension member for fitting between the sump member and the cover member, the member having means which allow interengagement of the members when they are stacked to form a manhole structure.

8. A system according to claim 7, in which the sump member is in accordance with claim 2.

9. A system according to any one of claims 1 and 5 to 8, in which the interengagement means comprise a collar protruding from one end of one member and shaped for interengagement with an adjacent member of the structure, the extent of interengagement being determined by abutment of a shoulder on the one member with the end surface of the other member.

10. A system according to any one of claims 1 and 5 to 9, in which the cover member comprises a removable lid.

11. A system according to claim 10, in which the lid is in the form of a grating.

12. A cover member for a manhole or catch-pit structure, comprising a cover portion and a skirt portion extending from the cover portion, the cover portion having a peripheral flange extending outwardly of the skirt portion such that, when the cover member is used to close the upper end of a manhole or catch-pit structure by insertion of the skirt portion within an upstanding tubular part of the structure, the flange abuts the upper edge of the structure.

13. A cover member according to claim 12, in which the length of the skirt portion is at least eight times the thickness of the cover portion.

14. A cover member according to claim 12, in which the length of the skirt portion is at least five times the thickness of the cover portion.

15. A system according to any one of claims 1 and 5 to 11, in which the cover member is in accordance with any one of claims 12 to 14.

16. A sump or cover member according to any one of claims 2, 3 and 4 or any one of claims 12 to 14 and being formed from plastics material.

17. A sump and connection pan member according to claim 3 or 4 and formed from plastics material.

18. A system according to any one of claims 1, 5 to 11 and 15, in which the members are formed from plastics material.

19. A sump, cover or sump and connection pan member according to claim 16 or 17, in which the plastics material is unplasticised PVC or high density polyethylene.

20. An extension member for use in a system according to claim 6, 7 or 8, the member being formed from plastics material and having interengagement means comprising a collar protruding from one end of the member and a shoulder for abutment with the end surface of an adjacent manhole or catch-pit structure member when the members are stacked to form a manhole or catch-pit structure.

21. An extension member according LO claim 20, in which the plastics material is unplasticised PVC or high density polyethylene.

22. A method of construction of a manhole or catch-pit structure, comprising the steps of providing a sump member of the structure, stacking upon the sump member one or more extension members and fitting a cover member to the or the uppermost extension member, each member of the structure being in engagement with its adjacent member(s) and the height of the extension member(s) being selected from a plurality of extension members of predetermined heights whereby a structure of a desired height is constructed.

23. A method according to claim 22, in which the members are of plastics material and are secured to one another by means cf a solvent cement or self-tapping screws.

24. A modular manhole or catch-pit system substantially as hereinbefore described with reference to Figure 1 of the drawings.

25. A manhole cover substantially as hereinbefore described with reference to Figures 2 and 3 of the drawings.

26. A method of construction of a manhole or catch-pit structure, the method being substantially as hereinbefore described with reference to the drawings.