GB2629754A

GB2629754A - Access chambers

Info

Publication number: GB2629754A
Application number: GB2303430.9A
Authority: GB
Inventors: Edwards Gary
Original assignee: Cygnet Fabrications Ltd
Current assignee: Cygnet Fabrications Ltd
Priority date: 2023-03-09
Filing date: 2023-03-09
Publication date: 2024-11-13
Also published as: GB202303430D0

Abstract

A device for constructing/use as an underground access chamber or inspection chamber for a drainage system i.e. a manhole shaft, having a planar base 10 , preformed concentric walls extending from, and attached to, the base, together defining a closed bottom annular space defined between respective inner wall or form 12, outer wall or form 14 and base 10, the outer wall being tubular in form, the inner wall and the base defining an inner access chamber, the annular space being open at an end opposing the base, the inner and outer walls including corresponding inlet 16 and outlet 18 apertures receiving a sealed pipe connector, bridging the annular space, for receiving a pipe of a drainage system to which the access chamber is connected to, and connecting it to the inner access chamber, in use. Cement is poured into the annual space between the walls which sets as a annular concrete chamber wall within the forms which remain in situ. A method of use and a manhole formed using the device is also claimed. The device may be recycled plastic material.

Description

ACCESS CHAMBERS

Field of the Invention

This invention relates generally to a method of constructing an access chamber or inspection chamber in a drainage system, and to a device for use in a method of constructing an access chamber, as well as an access chamber constructed by such a method, using such a device.

Background of the invention

All underground pipework systems, including utilities and drainage, require the installation of access points for cleaning and maintenance purposes. They are especially crucial in drainage systems where blockages can occur, and play an important role in keeping domestic and commercial drains in good working order.

An inspection chamber or man access chamber is one of the options available when it comes to installing access points, allowing drainage professionals to inspect, clean and repair underground pipework.

Man access chambers are best, although not exclusively, suited to installations where workers will need access to carry out CCTV drain surveys, drain rodding and water jetting to inspect and clean the pipework without having to physically enter the chamber. Inspection chambers are most useful when installed anytime there is a bend, intersection, or other significant change in the system. The more access points you have, the easier it will be to maintain the pipeline and clear any blockages that Occur.

There are a few different options available for constructing a man access chamber in a sewage drainage system, but the traditional method is a modular method using a pre-cast recessed concrete base (into which the system pipes are fed), multiple pre-cast concrete tubes mounted one on top of the other over the recessed portion of the base to create the surround of man access chamber, and a pre-cast concrete cover slab.

More recently, pre-formed chambers such as catchpits, benched manholes and inspection chambers formed of High Density Polyethylene (HDPE) or Polypropylene have become available, which are quicker and easier to instal, and less prone to leakage.

Whilst there are a few variations, the most common way of securing these (concrete or plastic) access chambers in place is to construct temporary formwork around the PE chamber or preformed concrete tubes in such a way as to create an annular surround then into which perform a concrete pour after one or 2 units are placed. As a result, the process of constructing a man access chamber of this type can several days, to allow time for each layer of concrete to set.

The process is complex and labour intensive, and not very ecologically sound.

Furthermore, the pre-case concrete elements can erode over time, and if they are required to be replaced, the whole complex, labour-intensive process has to be repeated.

There is, therefore, a desire to provide an improved method of constructing a man access or inspection chamber that addresses at least one or more of these issues.

Statements of Invention

In accordance with a first aspect of the present invention, there is provided a device for use in constructing an access chamber in a drainage system, the device comprising a planar base, a pre-formed inner access chamber joined or integrated at a first end edge thereof on the base such that an annular portion of the base extends beyond and around said first end edge of said inner access chamber, the inner access chamber comprising at least one inlet aperture and at least one outlet aperture, the device further comprising a tubular outer former that is joined or integrated at a first end edge thereof to the base, concentric with the inner access chamber such that it extends around the outer wall of the inner access chamber with an annular space between an inner wall of the outer former and said outer wall of said inner access chamber, said annular space being open at a second, opposing end of said outer former, the outer former including at least a first through-hole corresponding to said at least one inlet of said inner access chamber and at least a second through-hole corresponding to said at least one outlet of said inner access chamber, wherein a sealed pipe connector is fluidly coupled or couplable to each of said at least one inlet and at least one outlet of said inner access chamber, each said pipe connector extending from a said inlet or outlet of said inner access chamber and through a respective through-hole in said outer former, and being configured to receive, at a distal end thereof, a pipe of a drainage system, in use.

Beneficially, the inner access chamber, the outer former and the base may be formed of plastics material, such as recycled/recyclable plastics material, for example, high density thermoplastic polymers such as high density polyethylene or polypropylene.

In an exemplary embodiment, the height of the outer former is such that it extends beyond a second, opposing end edge of said inner access chamber, such that there is a vertical space, when the device is oriented for use, between the second end edge of said inner access chamber and a second, opposing end edge of said outer former.

Beneficially, the device may comprise one or more planar spacer members, joined or integrated between the outer wall of the inner access chamber and the inner wall of the outer former such that the or each spacer member extends radially across said 15 annular space therebetween.

An exemplary embodiment of the device may comprise at least a first plurality of spacer members equi-angularly spaced around said annular space between the outer wall of the inner access chamber and the inner wall of the outer former. Optionally, the first plurality of spacer members may be located at said first end edges of said inner access chamber and said outer former, adjacent said base. Optionally, each of said spacer members may have a wedge-shaped end, and wherein said spacer members of said first plurality of spacer members are oriented such that the apex of said wedge-shaped end abuts said first end edge of said inner access chamber.

An exemplary embodiment of the device, may further comprise at least a second plurality of spacer members equi-angularly spaced around the annular space between the outer wall of the inner access chamber and the inner wall of the outer former, wherein the spacer members of said second plurality of spacer members are located at a second, opposing end edge of said inner access chamber, and each spacer member of said second plurality of spacer members is oriented such that the apex of its respective wedge-shaped end is substantially adjacent to, and radially spaced apart from, the second end edge of said inner access chamber.

In an embodiment, the device may, optionally, further comprise a cover slab former arranged and configured, in use, to be removably mounted over a second, opposing end edge of said inner access chamber.

The cover slab former may comprise a lid shaped and configured to fit over said 5 second end edge of said inner access chamber and having a generally central opening therein and a wall that extends at substantially 90o from the edges of said opening to a height, in use, at or near said second end edge of said outer former.

In accordance with another aspect of the present invention, there is provided a method of constructing an access chamber in a drainage system, the method comprising creating an excavation at a site at which a said access chamber is to be constructed, securing a device substantially as described above into said excavation, and pouring concrete into said annular space between said inner access chamber and said outer former, via said open end thereof, until said concrete fills said annular space up to a level at or near said second end edge of said inner access chamber.

The method may, optionally, further comprise connecting pipes of said drainage system to each said pipe connector extending through said outer former.

The method may, optionally, further comprise placing a cover slab former over said second end edge of said inner access chamber and pouring concrete thereover to form a cover slab of said access chamber.

According to yet another aspect of the invention, there is provided an access chamber constructed by a method substantially as described above.

These and other aspects of the invention will be apparent from the following specific description.

Brief Description of the Drawings

Embodiments of the present invention will now be described, by way of examples only, and with reference to the accompanying drawings, in which: Figure 1 is a simplified schematic longitudinal cross-sectional view of a device according to an exemplary embodiment of the invention; Figure 2 is a simplified schematic front perspective view of the base, inner chamber 30 and spacer/reinforcing members of the device of Figure 1; Figure 3 is a simplified front perspective view of the device of Figure 1, illustrating placement of the inlet and outlet pipes; Figure 4A is a simplified schematic front perspective view of a device according to an exemplary embodiment of the invention, illustrating the placement of a cover slab former; Figure 4B is a simplified schematic front perspective view of the device of Figure 4A, with the cover slab former in situ; Figures 5, 6 and 7 are simplified schematic longitudinal cross-sectional views of the device of Figure 4B, in use and at various respective stages of the concrete pour; Figure 8 is a simplified schematic longitudinal cross-sectional view of the device of Figures 5, 6, and 7 with a concrete cover slab applied or formed over the cover slab former; and Figure 9 is a schematic illustration showing the manner of forming through-holes in a device according to an exemplary embodiment of the invention.

Detailed Description

Referring to Figure 1 of the drawings, there is provided, in cross-section, a simplified illustration of an example device for constructing an access chamber in a drainage system. The device comprises a base 10, an inner chamber 12, an outer former 14, at least one inlet pipe 16 and outlet pipe 18 and a cover plate 20.

Referring additionally to Figure 2 of the drawings, the base comprises a planar sheet of, for example, High Density Polyethylene or Polypropylene, which may be recycled and/or recyclable. A tubular inner chamber 12 is located centrally on the base 10 with its longitudinal axis at 90° to the plane of the base 10. In the example illustrated, the base 10 and the cross-section of the inner chamber 12 are generally circular, with the diameter of the base 10 being greater than that of the inner chamber 12 such that an outer annular portion of the base 10 forms a lip 10a that extends beyond and around the outer wall of the inner chamber 12. The inner chamber 12 may also be formed of, for example, High Density Polyethylene or Polypropylene, which may be recycled and/or recyclable. The inner chamber 12 is formed integrally with the base 10, or permanently affixed to the base 10 by, for example, sheet butt fusion, which will be familiar to a person skilled in the ad, although other methods of permanently affixing the inner chamber to the base will be known to the skilled person, and could, alternatively, be used. In a typical example, the diameter of the inner chamber might be of the order of 1200mm and the diameter of the base 10 might be of the order of 1600mm, such that the width of the annular portion 10a of the base extending beyond and round the outer wall of the inner chamber would be of the order of 200mm. However, it will be understood that the invention is by no means intended to be limited in this regard, and the dimensions of the inner chamber and the base will be very site and application dependent.

The device of the invention can be pre-formed to suit any specific site requirements. Thus, the inner chamber 12 can be any type of pre-formed inspection or catchpit chamber required for the specific purpose of the access chamber, as will be familiar to a person skilled in the art. Pre-formed polyethylene inspection and catchpit chambers are known. Such chambers are formed by extrusion and comprise a twin-walled pipe with a section through the middle to give it strength. As such chambers still require several concrete pours to secure them in place, the total thickness of the chamber wall is, of necessity, very large and the resultant chamber is, therefore, expensive to make and also heavy and cumbersome to transport. Although this type of chamber could be utilised in some embodiments of the invention, one of the major zo benefits of the invention is that the thickness of the chamber wall can be of an order of magnitude thinner than that of known inspection and catchpit chambers. Indeed, in some embodiments, the inner chamber can be formed of sheet plastic bent into a generally cylindrical shape. As a result, the cost of creating an access chamber using embodiments of the invention can be significantly reduced, in addition to the reduction in time (and resources) required to install a man access chamber.

In an example, the inner chamber 12 could be a catchpit chamber, which is an empty chamber built into a drainage system to catch silt and other debris that is carried (with water) along the drainage system, and plays a significant part in preventing the build up of materials that could otherwise block the underground drainage system. A catchpit chamber comprises a base and a tubular chamber having an inlet pipe and an outlet pipe. In a catchpit chamber, the inlet pipe is usually raised relative to the outlet pipe, such that when water flows through the chamber, silt and debris will fall to the bottom of the chamber. Alternatively, the inner chamber 12 could, for example, comprise a pre-formed benched inspection chamber or, indeed, any other access or inspection chamber required for the purpose. It will be appreciated that the number and location of the inlet pipe(s) 16 and the outlet pipe(s) 18 of the device will vary according to the construction and purpose of the access chamber, and this will be understood by a person skilled in the art. Thus, the inlet and outlet pipes 16, 18 illustrated in Figure 1 are simply intended to be a representative and simplified example for the purposes of explaining the invention, and it is to be understood that the location and number of inlet and outlet pipes in real embodiments of the invention will vary according to user requirements.

Referring back to Figure 2 of the drawings, a plurality of spacer or reinforcing members 24 are permanently affixed to the outer wall of the inner chamber 12. In the example shown, each spacer/reinforcing member 24 comprises a planar element, which may again be formed from a sheet of High Density Polyethylene or Polypropylene, having a first end edge 24a, a pair of parallel side edges that extend at right angles to from the first end edge 24a, one of said side edges 24b being longer than the other 24c, and a second end edge 24d that extends between the ends of the side edges 24b, 24c, at the opposite end, to form a wedge'-like shape. One or more apertures 24e are provided in the planar spacer/reinforcing member 24.

In an exemplary embodiment, a first plurality of spacer/reinforcing members 24 is provided, that are arranged in equi-spaced configuration around the outer wall of the inner chamber 12 adjacent the end nearest the base 10, and at least a second plurality of spacer/reinforcing members 24 is provided that are arranged in equispaced configuration around the outer wall of the inner chamber 12, adjacent its opposite end. Each spacer/reinforcing member 24 in the first plurality of spacer/reinforcing members 24 is, at its longer side edge 24b, integrally formed with, or permanently affixed to (e.g. by extrusion welding, or other, similar technique which will be familiar to a person skilled in the art), the outer wall of the inner chamber 12 such that the apex of the wedged end abuts the adjacent end edge of the inner chamber 12 (nearest the base 10). Each spacer/reinforcing member 24 of the second plurality of spacer/reinforcing members 24 is similarly, this time at its shorter side edge 24c, integrally formed with, or permanently affixed to, the outer wall of the inner chamber 12 such that the apex of the wedged end thereof is substantially diametrically in-line (and spaced apart from) the adjacent opposite end of the inner chamber 12 (furthest from the base 10). Each spacer/reinforcing member 24 extends diametrically from the outer wall of the inner chamber 12 with the outer side edge thereof (i.e. the side edge not directly affixed to the outer wall of the inner chamber 12) being substantially parallel to the longitudinal axis of the inner chamber 12, and the width of each spacer/reinforcing member 24 (between the side edges 24b, 24c) is substantially equal to the width of the annular lip 10a of the base 10 extending beyond and around the inner chamber 12. It will be understood that one or more further sets of spacer/reinforcing members could be provided around the outer wall of the inner chamber 12, as required and depending on dimensions and io other site-specific variables.

Through holes 15 are provided in the wall of the inner chamber 12, as required, to accommodate the inlet and outlet pipe(s) of the access chamber being constructed.

Referring back to Figure 1 and also to Figure 3 of the drawings, an example device further comprises a tubular outer former 14, which may again be formed of recycled/recyclable plastic, such as High Density Polyethylene or Polypropylene.

The outer former 14 has a cross-section of substantially the same shape and dimensions as the base 10. An end edge of the outer former 14 'sits' around the circumferential edge of the base 10, and is permanently affixed thereto by means of, for example, sheet butt fusion, such that it extends around the inner chamber 12 with the spacer/reinforcing member 24 extending radially between the outer wall of the inner chamber 12 and the inner wall of the outer former 14. Through-holes 17 are provided in the outer former 14 to match the through-holes 15 in the inner chamber 12, such that two or more pairs of aligned through-holes 15, 17 is provided in the inner chamber and outer former walls.

At each such pair of aligned through-holes 15, 17, a pipe (an inlet pipe 16 or an outlet pipe 18) extends from the through-hole 15 in the wall of the inner chamber 12 and through the aligned through-hole 17 in the wall of the outer former 14, the free end of the pipe extending beyond the outer wall of the outer former 14 and having thereon connector means (e.g. a screw thread or seal member 22) that allows a pipe of the drainage system to be connected thereto, thereby fluidly coupling the inner chamber 12 to the pipe of the drainage system and allowing fluid to flow from the inner chamber into the drainage pipe or to flow from the drainage pipe into the inner chamber 12, depending on whether it is an inlet or an outlet pipe. The pipe 16, 18 is integrally formed with, or affixed to, the circumferential edge of the through-hole 15 in the inner chamber 12, the connection or joint between the pipe 16, 18 and the inner chamber 12 forming a fluid-tight seal. In an embodiment, each pipe 16, 18 may be welded (and thus sealed) at the respective through-hole in the inner chamber. However, in some embodiments, especially if the apparatus is to be retrofitted, it may be desirable to provide separate pipe connectors that include, at one end, means for sealing coupling it to a respective through-hole in the inner chamber.

Referring back to Figure 1 of the drawings and also Figures 4A and 4B, a cover slab former 20 is optionally provided, which can also be formed of, for example, High Density Polyethylene or Polypropylene. The cover slab former 20 comprises a circular lid section 20a of diameter substantially similar to that of the top edge of the inner chamber 12, and having a circumferential lip 20b that extends at right angles (downwardly, when the device is oriented for us) from the circumferential edge of the lid section 20a. A central opening 20c is provided in the lid section 20a, which may be square or rectangular in shape, and an open box-like frame 20d is provided around the opening 20c, the walls of which extend (upwardly) at right angles from the edges of the opening 20c. The lid section, lip 20b and frame 20d may be formed integrally and/or fused or joined by any known method, that will be familiar to a person skilled in the art. The cover slab former 20 is, however, provided separately to the device, and is affixed over the inner chamber 12 after the device has been placed in position for construction of an access chamber. The cover slab former 20 may then be held in place over the inner chamber 12 by, for example, wing nuts (not shown) or other suitable releasable connection means. When so secured so for use, the top of the box-like frame 20d extends to just below the top edge of the outer former 14.

Referring now to Figure 5 of the drawings, in use, an excavation is prepared as required, and the device including the base 10, inner chamber 12, outer former 14 and any inlet/outlet pipes 16, 18 is positioned and placed within the excavation. The cover slab former 20 (if being used) is secured over the top opening of the inner chamber 12, and the pipes of the drainage system connected and sealed, as required, to the inlet/outlet pipes 16, 18.

Next, concrete 26 is poured into the space between the outer former 14 and the inner chamber 12. As the concrete is being poured, steel reinforcing frame members 28 are (optionally) inserted into the space between the outer former and the 14 and the inner chamber 12. When the concrete 26 reaches the top of the inner chamber 12, a steel support frame 30 may be placed over the cover slab former 20, and further concrete can be poured over the cover slab former 20 to form a cover slab 32. However, in other embodiments, the contractor may prefer to utilise a preformed concrete cover slab (or other covering), and the cover slab former 20 could then be omitted.

A method of constructing a man access chamber has been described above in terms of a fully prefabricated device, including all inlet and outlet pipes (and associated through-holes), as required for a specific application. However, and referring to Figure 9 of the drawings, in some embodiments of the method, the contractor can drill their own through holes 15, 17 in a prefabricated device comprising the base 10, inner chamber 12 and outer former 14, using an adjustable circle hole saw cutter drill bit 34, and a prefabricated pipe connector (not shown in Figure) can be inserted through the through-hole 17 thus formed in the outer former 14 and sealed against the through-hole 15 formed in the inner chamber wall. This would mean that users can place their inlet/outlet pipes at whatever position and/or height that suits their specific circumstances.

Thus the inventors have developed a system that alleviates the above-referenced issues, and allows a man access chamber to be reliably placed and secured in one day. The innovation comprises a pre-fabricated chamber comprising integrated recessed base, surround (the outer former) and, optionally, cover slab former.

Furthermore, the recessed base portion of the chamber can be prefabricated with pipes already secured so that connectors thereto protrude from the outer wall of the device, and to which the pipes of a sewage system can be secured and sealed. Once the chamber is in place, and the pipes secured as required, a single concrete pour can be performed to secure the chamber in place. The whole process can be performed in less than a day. The chamber can be manufactured from recycled plastics, and can be recycled again, when the chamber is eventually removed and replaced.

The chamber can be used to construct a new man access or inspection chamber or it can be retrofitted to replace an old concrete version.

It will be appreciated by a person skilled in the art, from the foregoing description, that modifications and variations can be made to the described embodiments without departing from the scope of the invention as defined by the appended claims.

For example, whilst it is perfectly feasible to fabricate a device having precisely the dimensions required by the site in which the man access chamber will be constructed, in some embodiments, the 'upper' end of the inner chamber and/or former may include means for adjusting the height of the device on-site to meet specific requirements (especially if the device is being retrofitted). As an example, a telescopic height adjustment section may be provided at the upper end of the inner chamber and/or former to allow the height thereof to be adjusted by raising or lowering the telescopic section.

Claims

CLAIMS1. A device for use in constructing an access chamber in a drainage system, the device comprising a planar base, a pre-formed inner access chamber joined or integrated at a first end edge thereof on the base such that an annular portion of the base extends beyond and around said first end edge of said inner access chamber, the inner access chamber comprising at least one inlet aperture and at least one outlet aperture, the device further comprising a tubular outer former that is joined or integrated at a first end edge thereof to the base, concentric with the inner access chamber such that it extends around the outer wall of the inner access chamber with an annular space between an inner wall of the outer former and said outer wall of said inner access chamber, said annular space being open at a second, opposing end of said outer former, the outer former including at least a first through-hole corresponding to said at least one inlet of said inner access chamber and at least a second through-hole corresponding to said at least one outlet of said inner access chamber, wherein a sealed pipe connector is fluidly coupled or couplable to each of said at least one inlet and at least one outlet of said inner access chamber, each said pipe connector being configured to extend from a said inlet or outlet of said inner access chamber and through a respective through-hole in said outer former, and being configured to receive, at a distal end thereof, a pipe of a drainage system, in use.
2. A device according to claim 1, wherein said inner access chamber, said outer former and said base are formed of plastics material.
3. A device according to claim 2, wherein said inner access chamber, said outer former and said base are formed of recycled and/or recyclable plastics material.
4. A device according to claim 2 or claim 3, wherein said inner access chamber, said outer former and aid base are formed of a high density thermoplastic polymer, such as polyethylene or polypropylene.
5. A device according to any of the preceding claims, wherein the outer former extends beyond a second, opposing end edge of said inner access chamber, such that there is a vertical space, when the device is oriented for use, between the second end edge of said inner access chamber and a second, opposing end edge of said outer former.
6. A device according to any of the preceding claims, further comprising one or more planar spacer members, joined or integrated between the outer wall of the inner access chamber and the inner wall of the outer former such that the or each spacer member extends radially across said annular space therebetween.
7. A device according to claim 6, comprising at least a first plurality of spacer members equi-angularly spaced around said annular space between the outer wall of the inner access chamber and the inner wall of the outer former.
8. A device according to claim 7, wherein said first plurality of spacer members are located at said first end edges of said inner access chamber and said outer former, adjacent said base.
9. A device according to claim 8, wherein each of said spacer member has a wedge-shaped end, and wherein said spacer members of said first plurality of spacer members are oriented such that the apex of said wedge-shaped end abuts said first end edge of said inner access chamber.
10. A device according to claim 8 or claim 9, further comprising at least a second plurality of spacer members equi-angularly spaced around the annular space between the outer wall of the inner access chamber and the inner wall of the outer former, wherein the spacer members of said second plurality of spacer members are located at a second, opposing end edge of said inner access chamber, and each spacer member of said second plurality of spacer members is oriented such that the apex of its respective wedge-shaped end is substantially adjacent to, and radially spaced apart from, the second end edge of said inner access chamber.
11. A device according to any of the preceding claims, further comprising a cover slab former arranged and configured, in use, to be removably mounted over a second, opposing end edge of said inner access chamber.
12.A device according to claim 11, when dependent on claim 2, wherein said cover slab former comprises a lid shaped and configured to fit over said second end edge of said inner access chamber and having a generally central opening therein and a wall that extends at substantially 90° from the edges of said opening to a height, in use, at or near said second end edge of said outer former.
13. A device according to any of the preceding claims, further comprising means for adjusting the height of the device in situ.
14.A device according to claim 13, wherein said height adjustment means comprises an additional pipe section, telescopically mounted at the distal end of the inner chamber and/or the former, such that the height of the outer wall of the inner chamber and/or former can be adjusted by raising or lowering said additional pipe section as required, in use.
15.A method of constructing an access chamber in a drainage system, the method comprising creating an excavation at a site at which a said access chamber is to be constructed, securing a device according to any of the preceding claims into said excavation, and pouring concrete into said annular space between said inner access chamber and said outer former, via said open end thereof, until said concrete fills said annular space up to a level at or near said second end edge of said inner access chamber.
16.A method according to claim 15, further comprising connecting pipes of said drainage system to each said pipe connector extending through said outer former.
17.A method according to claim 15 or claim 16, further comprising placing a cover slab former over said second end edge of said inner access chamber and pouring concrete thereover to form a cover slab of said access chamber.
18. A method according to any of claims 15 to 17, utilising a device according to claim 13 or 14, further comprising adjusting the height of the device in situ prior to pouring said concrete.
19. An access chamber constructed by a method according to any of claims 13 to 17.