Manhole and sewer network

Abstract

A manhole (100) for subterranean installation is described. The manhole (100) comprises a first chamber (110) arranged to receive storm water and a second chamber (120) arranged to receive sewage water. The first chamber (110) comprises a first inlet (111) and a first outlet (112). The second chamber (120) comprises a second inlet (121) and a second outlet (122). The first chamber (110) comprises a first access port (113) opposed to a first base (114) and a first wall (115) arranged therebetween. The second chamber (120) comprises a second access port (123) opposed to a second base (124) and a second wall (125) arranged therebetween. A first normal N1 to the first base (114) extends through the first base (114) and the second base (124). A sewer network 1000 and a method of installing the sewer network are also described.

Claims

1. A manhole for subterranean installation, the manhole comprising: a first chamber arranged to transport storm water and comprising a first inlet and a first outlet, the storm water being received into the first chamber via the first inlet and being discharged from the first chamber via the first outlet; and a second chamber arranged to transport sewage water and comprising a second inlet and a second outlet, the sewage water being received into the second chamber via the second inlet and being discharged from the second chamber via the second outlet; wherein: the first chamber and the second chamber are separate chambers fluidly disconnected from one another, such that the storm water and the sewage water do not mix during transport through the first and second chambers, respectively; the first chamber comprises a first access port opposed to a first base and a first wall arranged therebetween; the second chamber comprises a second access port opposed to a second base and a second wall arranged therebetween; a first normal to the first base extends through the first base and the second base; the first normal extends through a first region defined by a first perimeter of the first base, the first perimeter being defined by an intersection of the first base and the first wall; and the first access port and the second access port each lie in a single plane, the single plane being substantially perpendicular to the first normal.

2. The manhole according to claim 1, wherein: a second normal to the second base extends through the second base and the first base, the second normal extends through a second region defined by a second perimeter of the second base, and the second perimeter is defined by an intersection of the second base and the second wall.

3. The manhole according to claim 1, wherein the single plane is further coplanar with a plane defined by a surface of the ground.

4. The manhole according to claim 1, wherein at least one of: the first chamber and the second chamber are superposed, or the first base and the second base are arranged in different planes.

5. The manhole according to claim 1, wherein the first chamber and the second chamber are arranged coaxially.

6. The manhole according to claim 5, wherein the first chamber surrounds the second chamber coaxially.

7. The manhole according to claim 1, wherein at least one of: the second chamber is arranged at least partly within the first chamber, or the second chamber extends at least partly through the first chamber.

8. The manhole according to claim 1, wherein at least one of: the first inlet is opposed to the first outlet, or the second inlet is opposed to the second outlet.

9. The manhole according to claim 1, wherein at least one of: the first wall comprises a cylindrical wall, or the second wall comprises a cylindrical wall.

10. The manhole according to claim 9, wherein the first chamber and the second chamber are arranged concentrically.

11. The manhole according to claim 10, wherein the first chamber is toroidal and the second chamber is cylindrical, the second chamber extending at least partly through a passageway defined by the toroidal first chamber.

12. The manhole according to claim 1, wherein the second wall of the second chamber separates the second chamber from the first chamber.

13. A sewer network for transporting storm water and sewage water separately, the network comprising: a first manhole and a second manhole, each according to claim 1; and a first pipe and a second pipe each extending between the first manhole and the second manhole; wherein: the first pipe is coupled to a first outlet of the first manhole and to a first inlet of the second manhole; the second pipe is coupled to a second outlet of the first manhole and to a second inlet of the second manhole; and the first pipe and the second pipe are superposed for at least a part of lengths of the first pipe and the second pipe, respectively.

14. A method of installing a sewer network according to claim 13, the method comprising the steps of: providing an excavation arranged to receive the first manhole, the second manhole, and the first pipe and the second pipe extending therebetween; arranging the first manhole, the second manhole and the first pipe and the second pipe extending therebetween in the excavation, wherein the first pipe and the second pipe are superposed for at least the part corresponding with the lengths of the first pipe and the second pipe, respectively; coupling the first pipe to the first outlet of the first manhole and to the first inlet of the second manhole; coupling the second pipe to the second outlet of the first manhole and to the second inlet of the second manhole; and backfilling the excavation.

15. The method according to claim 14, wherein: a first chamber of the first manhole is toroidal and a second chamber of the first manhole is cylindrical, the second chamber extending at least partly through a passageway defined by the first chamber; the second chamber of the first manhole is an existing second chamber in the excavation; and the step of arranging the first manhole in the excavation comprises arranging the first chamber of the first manhole around the existing second chamber.

16. The manhole according to claim 2, wherein: the first perimeter defines a first diameter of the first chamber; the second perimeter defines a second diameter of the second chamber; and the first diameter is greater than the second diameter such that the first chamber surrounds the second chamber.

17. The manhole according to claim 16, wherein the first chamber and the second chamber are arranged coaxially and the first chamber surrounds the second chamber coaxially.

18. The manhole according to claim 1, wherein: the second chamber is defined, in part, by a second diameter; and the first chamber is defined, in part, by a first diameter, the first diameter being greater than the second diameter such that the first chamber surrounds the second chamber coaxially.

19. The manhole according to claim 1, wherein: the first base lies in a second plane parallel with the first plane; the second base lies in a third plane parallel with the second plane; and the second plane is positioned intermediate the first and third planes.

20. The manhole according to claim 1, wherein: the first base lies in a second plane; the second base lies in a third plane parallel with the second plane; and the second plane is positioned closer to the first plane than the third plane is positioned relative to the first plane.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic figures, in which:

(2) FIG. 1A schematically depicts an orthographic projection of a manhole according to an exemplary embodiment of the invention;

(3) FIG. 1B schematically depicts a plan view of the manhole of FIG. 1A;

(4) FIG. 1C schematically depicts a longitudinal cross section of the manhole of FIG. 1A;

(5) FIG. 2 schematically depicts a cutaway orthographic projection of the manhole of FIG. 1A, in use;

(6) FIG. 3 schematically depicts a cross sectional view of conventional manholes, in use;

(7) FIG. 4 schematically depicts a cross sectional view of a conventional arrangement of pipes, in use;

(8) FIG. 5 schematically depicts a cross sectional view of the manhole of FIG. 1A, in use;

(9) FIG. 6 schematically depicts a cross sectional view of an arrangement of pipes for use with the manhole of FIG. 1A, in use;

(10) FIGS. 7A and 7B schematically depict transverse and longitudinal cross sections, respectively, of finite element analysis of a conventional manhole, in use;

(11) FIGS. 8A and 8B schematically depict transverse and longitudinal cross sections, respectively, of finite element analysis of the manhole of FIG. 1A, in use;

(12) FIG. 9 schematically depicts graphs of displacement of a conventional manhole and of a manhole according to an exemplary embodiment of the invention, in use;

(13) FIG. 10A schematically depicts graphs of displacement of the conventional manhole of FIGS. 7A and 7B, compared with displacement of the conventional manhole of FIG. 9, in use;

(14) FIG. 10B schematically depicts graphs of displacement of the manhole of FIGS. 8A and 8B, compared with displacement of the manhole of FIG. 9, in use;

(15) FIGS. 11A and 11B schematically depict finite element analysis of soil and of a pipe for use with the conventional manhole of FIG. 6, respectively, in use;

(16) FIGS. 12A and 12B schematically depict finite element analysis of soil and of an arrangement of pipes for use with the manhole of FIG. 1A, respectively, in use;

(17) FIG. 13 schematically depicts graphs of deformation of the pipe of FIG. 11B and the arrangement of pipes of FIG. 12B, respectively, in use;

(18) FIG. 14A schematically depicts graphs of deformation of the pipe of FIG. 11B and determined experimentally for a pipe for use with the conventional manhole, respectively, in use;

(19) FIG. 14B schematically depicts graphs of deformation of the pipe of FIG. 12B and determined experimentally for an arrangement of pipes for use with the manhole of FIG. 1A, respectively, in use;

(20) FIG. 15 schematically depicts computational fluid dynamics analysis of flow of water through the manhole of FIG. 1A, in use;

(21) FIG. 16 schematically depicts computational fluid dynamics analysis of flow of water through the manhole of FIG. 1A, in use;

(22) FIG. 17 schematically depicts a plan view of a manhole according to another exemplary embodiment of the invention, in use;

(23) FIG. 18 schematically depicts a side elevation view of the manhole of FIG. 3, in use;

(24) FIG. 19 schematically depicts a cutaway orthographic projection of a manhole according to yet another exemplary embodiment of the invention;

(25) FIG. 20 schematically depicts a cutaway orthographic projection of the manhole of FIG. 19, in use;

(26) FIG. 21 schematically depicts a cross section of a manhole according to still yet another exemplary embodiment of the invention;

(27) FIG. 22 schematically depicts a perspective view of a sewer network according to an exemplary embodiment of the invention;

(28) FIG. 23 schematically depicts a perspective view of another sewer network according to an exemplary embodiment of the invention; and

(29) FIG. 24 schematically depicts a method of installing a sewer network according to an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

(30) FIG. 1A schematically depicts an orthographic projection of a manhole 100 according to an exemplary embodiment of the invention. FIG. 1B schematically depicts a plan view of the manhole 100. FIG. 1C schematically depicts a longitudinal cross section of the manhole 100. The manhole 100 is for subterranean installation.

(31) The manhole 100 comprises a first chamber 110 arranged to receive storm water and a second chamber 120 arranged to receive sewage water. The first chamber 110 comprises a first inlet 111 and a first outlet 112. The second chamber 120 comprises a second inlet 121 and a second outlet 122. The first chamber 110 comprises a first access port 113 opposed to a first base 114 and a first wall 115 arranged therebetween. The second chamber 120 comprises a second access port 123 opposed to a second base 124 and a second wall 125 arranged therebetween. A first normal N1 to the first base 114 extends through the first base 114 and the second base 124.

(32) The second chamber 120 is cylindrical, having a length of 2.69 m, an outer diameter of 1.00 m and a wall thickness of 0.10 m. The second base 124 is flat, having a thickness of 0.15 m, and the second access port 123 is provided by an open end of the second chamber 120. The first chamber 110 is toroidal, having a length of 2.00 m, an outer diameter of 2.50 m, an inner diameter of 1.00 m and a wall thickness of 0.15 m. The first base 114 is flat, having a thickness of 0.15 m, and the first access port 113 is provided by an open end of the first chamber 110. The open ends of the first chamber 110 and the second chamber 120 (i.e. the first access port 113 and the second access port 123) are coplanar. The first chamber 110 surrounds the second chamber 120 coaxially. The second wall 125 of the second chamber 120 separates the second chamber 120 from the first chamber 110. The manhole 100 is formed from concrete, or/and GRP or/and HDPE or/and PVC or/and any other material can use in constructing manholes. As would be understood by the person skilled in the art, dimensions of the manhole 100 may be changed, for example according to the material, design circumstances of each case in the field, and/or depth of a sewer network.

(33) A second normal N2 to the second base 124 extends through the second base 124 and the first base 114. The first chamber 110 and the second chamber 120 are superposed. The first chamber 110 and the second chamber 120 are arranged coaxially. The second chamber 120 is arranged at least partly within the first chamber 110. The second chamber 120 extends at least partly through the first chamber 110. The first inlet 111 and the second inlet 121 are aligned about the first normal N1. The first outlet 112 and the second outlet 122 are aligned about the first normal N2. The first inlet 111 is opposed to the first outlet 112. The first wall 115 comprises a cylindrical wall. The second wall 125 comprises a cylindrical wall. The first chamber 110 and the second chamber 120 are arranged concentrically. The first inlet 111 and the first outlet 112 are arranged through the first wall 115. The second inlet 121 and the second outlet 122 are arranged through the second wall 125.

(34) Also shown are a first inlet pipe 11 coupled to the first inlet 111 and a first outlet pipe 12 coupled to the first outlet 112. Also shown are a second inlet pipe 21 coupled to the second inlet 121 and a second outlet pipe 22 coupled to the second outlet 122. The first inlet pipe 11 and the second inlet pipe 21 are superposed for their respective lengths, the first inlet pipe 11 being arranged above the second inlet pipe 21. The first outlet pipe 12 and the second outlet pipe 22 are superposed for their respective lengths, the first outlet pipe 12 being arranged above the second outlet pipe 22.

(35) FIG. 2 schematically depicts a cutaway orthographic projection of the manhole of FIG. 1, in use.

(36) In use, the storm water flows from the first inlet 111 to the first outlet 112 via the first chamber 110, across or over the first base 114. In use, the sewage water flows from the second inlet 121 to the second outlet 122 via the second chamber 120, across or over the second base 124.

(37) FIG. 3 schematically depicts a cross sectional view of conventional manholes, in use. Particularly, FIG. 3 shows two conventional manholes Ma and Mb spaced apart laterally under a street, according to a conventional arrangement. The manholes Ma and Mb are for storm water and for sewage water, respectively. In this cross section, the manholes Ma and Mb require for installation an excavation having a cross sectional area of about 17.5 m.sup.2, for open-cut installation without use of side supports, for a given depth.

(38) FIG. 4 schematically depicts a cross sectional view of a conventional arrangement of pipes, in use. Particularly, FIG. 4 shows two pipes Pa and Pb spaced apart laterally under a street, according to a conventional arrangement. The pipes Pa and Pb are for storm water and for sewage water, respectively. In this cross section, the pipes Pa and Pb require for installation an excavation or trench having a cross sectional area of about 12 m.sup.2, for open-cut installation without use of side supports, fora given depth.

(39) FIG. 5 schematically depicts a cross sectional view of the manhole 100 of FIG. 1, in use. Particularly, FIG. 5 shows the manhole 100 under a street. In this cross section, the manhole 100 requires for installation an excavation having a cross sectional area of about 12 m.sup.2, for open-cut installation without use of side supports, for a given depth.

(40) FIG. 6 schematically depicts a cross sectional view of an arrangement of pipes for use with the manhole of FIG. 1, in use. Particularly, FIG. 6 shows the superposed first inlet pipe 11 and the second inlet pipe 21 spaced apart vertically under a street, according to an exemplary embodiment of the invention. The first inlet pipe 11 and the second inlet pipe 21 are for storm water and for sewage water, respectively. In this cross section, the first inlet pipe 11 and the second inlet pipe 21 require for installation an excavation or trench having a cross sectional area of about 8 m.sup.2, for open-cut installation without use of side supports, for a given depth.

(41) In this way, installation of the manhole 100 requires less excavation compared with installation of the conventional manholes Ma and Mb. In this way, installation of the superposed first inlet pipe 11 and the second inlet pipe 21 requires less excavation compared with installation of the laterally spaced apart conventional pipes Pa and Pb. In this way, cost and/or construction time may be decreased. In this way, the manhole 100 and the superposed first inlet pipe 11 and the second inlet pipe 21 occupy a smaller footprint in and/or under the street, providing more space for other infrastructure services in and/or under the street.

Analysis of Soil-Manhole Interactions

(42) Finite element analysis (FEA) allows modelling of soil S and a prototype of manhole arrangements mathematically and test them over a variety of load conditions or boundary conditions, and to test the shape of the manhole 100 over a variety of load conditions or boundary conditions.

(43) FIGS. 7A and 7B schematically depict transverse and longitudinal cross sections, respectively, of FEA of a conventional manhole M, in use. Particularly, FIGS. 7A and 7B show FEA, performed using ABAQUS (®) FEA software (available from Dassault Systèmes Simulia Corp, R.I., USA), of soil S surrounding the conventional manhole M, according to a 3 dimensional (3D) model. As an example, displacement or settlement of the soil S and hence of the manhole M is due to a weight of the manhole M and an applied load of 20 kN, to simulate usage, displacement of the soil S of approximately 4.5 mm is observed. Different loadings, such as 10 kN, 15, kN and 20 kN were applied, to simulate different usage. At higher loadings, displacement of the conventional manhole M exceeded limits of the FEA.

(44) FIGS. 8A and 8B schematically depict transverse and longitudinal cross sections, respectively, of finite element analysis of the manhole 100, in use Particularly, FIGS. 8A and 8B show FEA, performed using ABAQUS, of soil S surrounding the manhole 100, according to a 3 dimensional (3D) model. As an example, displacement or settlement of the soil S and hence of the manhole 100 is due to a weight of the manhole 100 and an applied load of 50 kN, to simulate usage, displacement of the soil S of approximately 2.1 cm is observed. Different loadings, such as 10 kN, 15, kN, 20 kN and 50 kN were applied, to simulate different usage.

(45) In this way, displacement or settlement of the soil S and hence of the manhole 100 is approximately half of that determined for the conventional manhole M, fora given load.

(46) FIG. 9 schematically depicts graphs of displacement of a conventional manhole M and of a manhole 200 according to an exemplary embodiment of the invention, in use. Particularly, the data shown in the graphs was obtained for a scale model of the conventional manhole M and the manhole 200, which is a scale model of the manhole 100. The conventional manhole M was fabricated from a steel tube having an endplate, of length 0.30 m and of external diameter 0.10 m. The manhole 200 was fabricated from two steel tubes having end plates, providing a first chamber 210 and a second chamber 220 respectively, according to the design of the manhole 100. The first chamber 210 was of length 0.25 m and of external diameter 0.25 m. The second chamber 220 was of length 0.30 m and of external diameter 0.10 m.

(47) Normal live load on a manhole from traffic is about 16 tons (160 kN). When scaling this load to the surface area of the manhole 200, it will be 14 kN.

(48) The resistance of the manhole 200 to live loads has shown superiority of this shape with regards to loading from the traditional design of the conventional manhole M. Results showed that under 50KN which is 3.5 times of the normal load, the manhole 200 can still resist the load and remain stable.

(49) The conventional manhole M has a higher displacement than the manhole 200 in low compacted soil by less than 2 times. The conventional manhole M sank under a 20 kN load.

(50) When the soil has a high compacted value, the conventional manhole M has a similar displacement compared with the manhole 100 in low compacted soil at load 35 kN which is about 2 times higher normal load value. However, the conventional manhole M sank under 35 kN load while manhole 200 remains stable even under a 50 kN load.

(51) The manhole 200 has a higher capacity to carry live loads compared with the conventional manhole M. This improvement can mitigate collapse risk that many sewer networks have and make the sewer system more stable against a shock live load in addition of other advantages such as decrease the initial construction cost of sewer system and environment protection by separate storm water flow from sewage water flow.

(52) FIG. 10A schematically depicts graphs of displacement of the conventional manhole M of FIGS. 7A and 7B, compared with displacement of the conventional manhole M of FIG. 9, in use. That is, the results of the FEA and the experimental analysis are compared, with good correlation.

(53) FIG. 10B schematically depicts graphs of displacement of the manhole 100 of FIGS. 8A and 8B, compared with displacement of the manhole 100 of FIG. 9, in use. That is, the results of the FEA and the experimental analysis are compared, with good correlation.

Analysis of Soil-Pipe Interactions

(54) Soil is a texture (i.e. a material) in which sewer system appurtenances such as manholes, pump stations and pipelines, are embedded. The ability to simulate the interactive behaviour of the materials in these objects with soil is considered one of the more complicated challenges due to the complex media of soil. This can include different types of solid matter peppered with voids which can be filled by air or water or other liquids, creating a variety of soil stiffness, subject to a variety of loading and unloading conditions. Sewer system structure performance is a function of both soil type (soil shear strength properties) and pipe stiffness. Mathematical analyses use soil property criteria, in parallel with pipe material properties, to model the soil and pipe structure properties mathematically. FEA is a tool suitable for testing pipes in soils over a variety of load conditions and boundary conditions as well as the system in its entirety.

(55) Two PVC pipes were used in this study to establish the behaviour of buried pipe in two different situations. The first was the traditional case where a sanitary pipe is laid alone in soil, this representing the normal combined sewer system, or separate sewer system (i.e. conventional), where pipes are buried in soil according to standard design criteria (FIGS. 11A and 11B). The second case is the according to an embodiment of the invention, two pipes in the trench, the storm pipe on the top and the sanitary pipe below. They are approximately 15 cm apart, separated vertically by filling soil and the bedding layer for the storm pipe (FIGS. 12A and 12B). The traffic load applied in this test, H-20 loading, simulated a highway load of a 20-ton truck.

(56) FIGS. 11A and 11B schematically depict FEA of soil S and a pipe P for use with the conventional manhole M of FIG. 6, respectively, in use. Particularly, FIGS. 11A and 11B show FEA, performed using ABAQUS, of soil S surrounding the pipe P for use with the conventional manhole M, according to a 3 dimensional (3D) model. Displacement or settlement of the soil S and hence deformation of the pipe P is due to an applied load of 0.108 N/mm.sup.2, to simulate usage. A maximum deformation of the pipe P and soil S underneath of approximately 4.4 mm is observed.

(57) FIGS. 12A and 12B schematically depict FEA of soil S and of an arrangement of pipes 11 and 12 for use with the manhole 100 of FIG. 1, in use. Particularly, FIGS. 12A and 12B show FEA, performed using ABAQUS, of soil S surrounding the superposed first inlet pipe 11 and the second inlet pipe 21 for use with the manhole 100, according to a 3 dimensional (3D) model. Displacement or settlement of the soil S and hence deformation of the first inlet pipe 11 and the second inlet pipe 21 is due to an applied load of 0.108 N/mm.sup.2 (MPa) to simulate usage. A maximum displacement of the first inlet pipe 11 and soil S underneath and the second inlet pipe 21 and soil underneath of approximately 5.5 mm and 3.2 mm m are observed, respectively.

(58) FIG. 13 schematically depicts graphs of deformation of the pipe P of FIG. 11B and the arrangement of pipes of FIG. 12B, respectively, in use. Particularly, FIG. 13 compares deformation of the pipe P of FIG. 11B and the second inlet pipe 21 of the arrangement of pipes of FIG. 12B. Loading of the pipes included a consolidation stage of the soil, followed by H20 cycled loading and then H25 cycled loading. As shown in FIG. 13, deformation of the second inlet pipe 21 is approximately half that of the pipe P, during H25 cycled loading.

(59) FIG. 14A schematically depicts graphs of deformation of the pipe P of FIG. 11B and determined experimentally for a pipe P for use with the conventional manhole, respectively, in use. That is, the results of the FEA and the experimental analysis are compared, with good correlation.

(60) FIG. 14B schematically depicts graphs of deformation of the pipe of FIG. 12B and of determined experimentally for arrangement of pipes for use with the manhole of FIG. 1, respectively, in use. That is, the results of the FEA and the experimental analysis are compared, with good correlation. Furthermore, the deformation of the second inlet pipe 21 of the arrangement of pipes of FIG. 12B is significantly lower than for the pipe P for the same loading.

(61) In other words, there are no significant differences between the experimental results and mathematical results regarding deformation of the pipes. The new method (two pipes) has facilitated a reduction in strain from 1.4 mm in the first case (FIG. 14A), to 1 mm in the second case (FIG. 14B). In both cases, the deformation is still within the design criteria limitation, approximately 3% from the diameter of the pipe. The composite structure of the system improved the capacity of this unit to adsorb dynamic loads for example, traffic loads thus protecting the pipe system from failure.

(62) In this way, arranging the first inlet pipe 11 and the second inlet pipe 21 superposed in one trench mitigates deformation and settlement when compared with the pipe P buried under the same conditions. Particularly, deformation in the lower second inlet pipe 21 is about 2 times less under the same load. In other words, setting two pipes in one trench seems to mitigate deformation and settlement when compared with one pipe buried under the same conditions. These results were validated through the physical model in the lab after identifying the correct properties for the soil and pipe material.

(63) FIGS. 15 and 16 schematically depict computational fluid dynamics (CFD) analysis of flow of water through the manhole 100 of FIG. 1, in use.

(64) Particularly, hydraulic properties (capacity, flow, velocity, depth and head losses, retention time) of the manhole 100 were simulated by CFD using SOLIDWORKS®. The results of velocity, as an example, showed that an area inside the storm manhole (i.e. the first chamber 110) has a small velocity of flow, and it is expected that some settling will happen in this area unless the design and slope of the basic ground is modified. The physical model helps to figure out the dead velocity zone inside the storm manhole and design criteria and gradient of storm manhole base will be determined to get the optimum slope for the storm manhole base to prevent any settlement within the manhole zone.

(65) FIG. 17 schematically depicts a plan view of a manhole 300 according to another exemplary embodiment of the invention, in use. FIG. 18 schematically depicts a side elevation view of the manhole 300 of FIG. 18, in use. Like numerals of the manhole 300 denote like features of the manhole 100. Generally, the manhole 300 is as described with respect to the manhole 100. The manhole 300 includes additional inlets, as described below.

(66) The manhole 300 comprises a first chamber 310 arranged to receive storm water and a second chamber 320 arranged to receive sewage water. The first chamber 310 comprises a first inlet 311 and a first outlet 312. The second chamber 320 comprises a second inlet 321 and a second outlet 322. The first chamber 310 comprises a first access port 313 opposed to a first base 314 and a first wall 315 arranged therebetween. The second chamber 320 comprises a second access port 323 opposed to a second base 324 and a second wall 325 arranged therebetween. A first normal N1 to the first base 314 extends through the first base 314 and the second base 324.

(67) A second normal N2 to the second base 324 extends through the second base 324 and the first base 314. The first chamber 310 and the second chamber 320 are superposed. The first chamber 310 and the second chamber 320 are arranged coaxially. The second chamber 320 is arranged at least partly within the first chamber 310. The second chamber 320 extends at least partly through the first chamber 310. The first inlet 311 and the second inlet 321 are aligned about the first normal N1. The first outlet 312 and the second outlet 322 are aligned about the first normal N2. The first inlet 311 is opposed to the first outlet 312. The first wall 315 comprises a cylindrical wall. The second wall 325 comprises a cylindrical wall. The first chamber 310 and the second chamber 320 are arranged concentrically. The first inlet 311 and the first outlet 312 are arranged through the first wall 315. The second inlet 321 and the second outlet 322 are arranged through the second wall 325.

(68) The first chamber 310 comprises another first inlet 317. The second chamber 320 comprises another second inlet 327. The another first inlet 317 and the another second inlet 327 are aligned about the first normal N1. The another first inlet 317 is arranged through the first wall 315. The another second inlet is arranged through the second wall 325. The another first inlet 317 is arranged transverse to the first inlet 311 and the first outlet 312. The another second inlet 327 is arranged transverse to the first inlet 321 and the first outlet 322.

(69) FIG. 19 schematically depicts a cutaway orthographic projection of a manhole 400 according to yet another exemplary embodiment of the invention. Like numerals of the manhole 400 denote like features of the manhole 100. Generally, the manhole 400 is as described with respect to the manhole 100. However, in contrast to the manhole 100, a second access port 423 is accessed via a first chamber 410.

(70) The manhole 400 comprises the first chamber 410 arranged to receive storm water and a second chamber 420 arranged to receive sewage water. The first chamber 410 comprises a first inlet 411 and a first outlet 412. The second chamber 420 comprises a second inlet 421 and a second outlet 422. The first chamber 410 comprises a first access port 413 opposed to a first base 414 and a first wall 415 arranged therebetween. The second chamber 420 comprises the second access port 423 opposed to a second base 424 and a second wall 425 arranged therebetween. A first normal N1 to the first base 414 extends through the first base 414 and the second base 424.

(71) A second normal N2 to the second base 424 extends through the second base 424 and the first base 414. The first chamber 410 and the second chamber 420 are superposed. The first chamber 410 and the second chamber 420 are arranged coaxially. The second chamber 420 is arranged at least partly within the first chamber 410. The second chamber 420 does not extend at least partly through the first chamber 410. The first inlet 411 and the second inlet 421 are aligned about the first normal N1. The first outlet 412 and the second outlet 422 are aligned about the first normal N2. The first inlet 411 is opposed to the first outlet 412. The second access port 423 is accessed via the first chamber 410. The second access port 423 is arranged in the first base 414. The first wall 415 comprises a cylindrical wall. The second wall 425 comprises a cylindrical wall. The first chamber 410 and the second chamber 420 are arranged concentrically. The first inlet 411 and the first outlet 412 are arranged through the first wall 415. The second inlet 421 and the second outlet 422 are arranged through the second wall 425. The second chamber 420 comprises a second cover 426, arrangeable to close the second access port 423.

(72) FIG. 20 schematically depicts a cutaway orthographic projection of the manhole of FIG. 20, in use. In use, the storm water flows from the first inlet 411 to the first outlet 412 via the first chamber 410, across or over the first base 414 and the second cover 416 arranged in the first base 414. In use, the sewage water flows from the second inlet 421 to the second outlet 422 via the second chamber 420, across or over the second base 424.

(73) FIG. 21 schematically depicts a cross section of a manhole 500 according to still yet another exemplary embodiment of the invention. Like numerals of the manhole 500 denote like features of the manhole 100. Generally, the manhole 500 is as described with respect to the manhole 100. The manhole 500 includes a second sensor 528, a transmitter 530 and a vent 540, as described below.

(74) The manhole 500 comprises a first chamber 510 arranged to receive storm water and a second chamber 520 arranged to receive sewage water. The first chamber 510 comprises a first inlet 511 and a first outlet. The second chamber 520 comprises a second inlet 521 and a second outlet. The first chamber 510 comprises a first access port 513 opposed to a first base 514 and a first wall 515 arranged therebetween. The second chamber 520 comprises a second access port 523 opposed to a second base 524 and a second wall 525 arranged therebetween. A first normal N1 to the first base 514 extends through the first base 514 and the second base 524.

(75) A second normal N2 to the second base 524 extends through the second base 524 and the first base 514. The first chamber 510 and the second chamber 520 are superposed. The first chamber 510 and the second chamber 520 are arranged coaxially. The second chamber 520 is arranged at least partly within the first chamber 510. The second chamber 520 does not extend at least partly through the first chamber 510. The first inlet 511 and the second inlet 521 are aligned about the first normal N1. The first outlet 512 and the second outlet 522 are aligned about the first normal N2. The first inlet 511 is opposed to the first outlet 512. The second access port 523 is accessed via the first chamber 510. The second access port 523 is arranged in the first base 514. The first wall 515 comprises a cylindrical wall. The second wall 525 comprises a cylindrical wall. The first chamber 510 and the second chamber 520 are arranged concentrically. The first inlet 511 and the first outlet 512 are arranged through the first wall 515. The second inlet 521 and the second outlet 522 are arranged through the second wall 525. The first chamber 510 comprises a first cover 516, arrangeable to close the first access port 513. The second chamber 520 comprises a second cover 526, arrangeable to close the second access port 523.

(76) The manhole comprises the second sensor 528 arranged to measure a level of the sewage water in the second chamber 520. In this way, the level of the sewage water in the second chamber 520 may be sensed. The manhole 500 comprises the transmitter 530 arranged to transmit a signal, for example an overflow signal, a warning signal or an alarm signal, according to the sensed water level. In this way, the sensed water level may be received remotely and appropriate action may be taken, for example inspection and/or maintenance.

(77) The manhole 500 comprises the vent 540, for example, a passageway or a conduit arranged between the second chamber 520 and the surface of the ground G. The vent 540 comprises a 2 inch PVC pipe provided within the first wall 515, the first base 514 and through the second wall 525 into the second chamber 520. The second sensor 528 is arranged in the vent 540. The transmitter 530 is arranged in the vent 540 proximal the surface of the ground G.

(78) FIG. 22 schematically depicts a perspective cutaway view of a sewer network 1000 according to an exemplary embodiment of the invention. Particularly, the sewer network 1000 is installed under an existing street. The UK and most other European countries usually have narrow streets, occupied by a complex network of infrastructure services such as potable water, electricity, communication and gas lines. Finding a space in which to place another two sets of pipes (in a conventional separate sewer system) is a challenge, but the sewer network 1000 is capable of overcoming this challenge.

(79) The network comprises a first manhole 1100 according to the first aspect, a second manhole 1200 according to the first aspect, and a first pipe 1011 and a second pipe 1012 (not shown) extending therebetween. The first pipe 1011 is coupled to the first outlet 1112 (not shown) of the first manhole 1100 and to the first inlet 1211 (not shown) of the second manhole 1200. The second pipe 1012 (not shown) is coupled to the second outlet 1122 (not shown) of the first manhole 1100 and to the second inlet 1221 (not shown) of the second manhole 1200. The first pipe 1011 and the second pipe 1012 (not shown) are superposed for at least a part of their respective lengths. The first pipe 1011 and the second pipe 1012 (not shown) are superposed for their respective lengths, the first pipe 1011 being arranged above the second pipe 1012 (not shown).

(80) FIG. 23 schematically depicts a perspective cutaway view of another sewer network 2000 according to an exemplary embodiment of the invention. Particularly, the sewer network 2000 is installed under a new street.

(81) The network comprises a first manhole 2100 according to the first aspect, a second manhole 2200 according to the first aspect, and a first pipe 2011 and a second pipe 2012 extending therebetween. The first pipe 2011 is coupled to the first outlet 2112 (not shown) of the first manhole 2100 and to the first inlet 2211 (not shown) of the second manhole 2200. The second pipe 2012 is coupled to the second outlet 2122 (not shown) of the first manhole 2100 and to the second inlet 2221 (not shown) of the second manhole 2200. The first pipe 2011 and the second pipe 2012 are superposed for at least a part of their respective lengths. The first pipe 2011 and the second pipe 2012 are superposed for their respective lengths, the first pipe 2011 being arranged above the second pipe 2012.

(82) FIG. 24 schematically depicts a method of installing a sewer network according to an exemplary embodiment of the invention, wherein the sewer network is according the first aspect.

(83) At S2401, an excavation arranged to receive the first manhole, the second manhole and the first pipe and the second pipe extending therebetween is provided.

(84) At S2402, the first manhole, the second manhole and the first pipe and the second pipe extending therebetween are arranged in the excavation.

(85) At S2403, the first pipe is coupled to the first outlet of the first manhole and to the first inlet of the second manhole.

(86) At S2404, the second pipe is coupled to the second outlet of the first manhole and to the second inlet of the second manhole, wherein the first pipe and the second pipe are superposed for at least the part of their respective lengths.

(87) At S2405, the excavation is backfilled.

(88) In summary, the invention provides a manhole, a sewer network and a method of installing a sewer network. The manhole may maintain sewage water and storm water separately, thereby better avoid mixing of the sewage water and storm water. In this way, the capacity requirements of the treatments plants may be reduced compared with conventional combined sewer networks while diversion of sewage water by CSOs is avoided. In this way, contamination of the watercourses is avoided. Since the sewage water and the storm water may be maintained separate in the same manhole, the manhole and/networks comprising the manhole be associated with lower costs and/or reduced installation requirements compared with conventional separate sewer networks, allowing installation in narrow streets, for example. By superposing first and second pipes in the sewer network, deformation of the pipes may be reduced, thereby reducing failure of the pipes.

(89) A comparison between using the sewer network as described herein and a conventional sewer network shows that the sewer network as described herein may be expected to decrease an initial cost by about 10% to 20% and may reduce a construction time by 40%. In addition, using the sewer network as described herein, a reduction in earthworks by about 40% as a result of using one trench for the two separate pipes (storm pipe and sanitary pipe) is estimated. The sewer network as described herein is expected to decrease an installation footprint by about 15% to 20% and may give a margin of space for other utilities, especially in narrow streets. The sewer network as described herein may improve an hydraulic integrity of storm networks significantly. The sewer network as described herein is expected to increase storage capacity by 250% compared with conventional sewer networks and increase a retention time for storm water flow inside the storm network by 200% compared with a storm flow retention time of conventional networks. Improving the hydraulic properties of the storm networks increase the safety factor of the design against flooding.

(90) Furthermore, the sewer network as described herein may be used to improve existing combined sewer networks by adding the external chamber (i.e. the first chamber for example a storm chamber) to the existing manholes used in the existing combined networks, and installing pipes for storm water above the combined pipe which will use only for the sewage flow. This method is promising to solve the combined sewer system in the narrow streets prevalent in UK and EU cities.

(91) This sewer network as described herein may be used for installation of a separate sewer network in all new developments.

(92) Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

(93) All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

(94) Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

(95) The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.