CA2166666C

CA2166666C - Sewer system

Info

Publication number: CA2166666C
Application number: CA002166666A
Authority: CA
Inventors: Richard W. Connelly
Original assignee: Richard W. Connelly; Innovative Sewage Systems Inc.; Clearford Industries Inc.
Current assignee: Clearford Industries Inc
Priority date: 1996-01-05
Filing date: 1996-01-05
Publication date: 2005-12-06
Anticipated expiration: 2016-01-05
Also published as: US5895569A; CA2166666A1

Abstract

There is provided in the present invention a small bore sewer system comprising a clarifier tank for receiving sewage, separating liquid and solid sewage and retaining the solid sewage; and collection means connected to the clarifier tank for receiving the liquid sewage and carrying it to a sewage treatment plant. The system may further include pumping stations and gravel and sand odour filters.

Description

SEHTBR SYSTEM
FIELD OF THE INVENTION
The present invention relates to the field of sewer systems for municipal developments.
BACKGROUND OF THE INVENTION
The cost of installing a conventional sewer system in a new parcel of land, whether its end use is residential, industrial or commercial, is one of the largest roadblocks to economic development for any community. Similarly, small or remote communities cannot afford the high price of adding a conventional sewer system even for residential usage and citizens continue to use private wells and inefficient septic systems. Septic systems have been shown to cause contamination of private wells, surface waters, and fresh water supplies, especially if this is the core servicing methodology for communities and commercial/industrial development. Septic systems are costly and have short life-spans in most development settings.
Conventional sewer system installations cause significant disruption to a community and require major reconstruction of roadways. Individual dwellings are connected to a conventional sewer system through the use of large diameter rigid piping consisting of a series of connected pieces of pipe. The connections of these pipes are often leaky allowing infiltration of ground water which can account for up to 50% of a conventional sewage system s capacity. Sewer leakage also results in exfiltration of sewage effluent into the environment. Moreover, the pipes must be deeply buried in areas of high frost penetration. Therefore, conventional sewer pipes require the excavation of large, straight trenches approximately 6 to 8 feet deep. As well, the preferred and normal location of conventional systems is the roadway centerline. Conventional sewers therefore are timely to install and the choice of overall layout is dictated by access for maintenance. Regular maintenance is required to ensure that system deterioration is controlled through the design life of the collection system.
Conventional systems are sensitive to gradient changes and require maintenance holes at each point of inflection change.
Pipe gradients are steeper than prevailing road gradient to allow for the required high cleansing velocities that are required to transport the solid component of the sewage in the piping. The pipes must be kept in a straight alignment between manholes to aid maintenance, the transport of solids, and regular cleaning of the system.
The inclusion of ground water and high peaking factors in the design of pipes, pump stations, and treatment plants results in an overall conventional sewer system which is a large, complex system. Conventional sewer systems transport sludge to the treatment plants which must be removed regularly. Due to the short time it is in the system, there is little degradation of sludge and therefore high sludge volumes result and additional stabilization is required before the sludge is removed for disposal. Lift pumps must be correspondingly large and complex in order to handle solids and high peak flows associated with historic systems.
Alternative communal sewer systems have been developed wherein an interceptor tank is employed to separate solids from the waste flow, and only the liquid portion of the sewage is then transported to a treatment center through small diameter pipes.
These small bore sewers, however, also suffer from problems related to the infiltration of ground water and exfiltration of sewage through leaks and joints in the system. There are also problems with tree root intrusion into pipe joints in small diameter collection systems, especially in shallow system applications.

2a Leakage problems can be resolved by making the system watertight, but a worker skilled in the art would appreciate that a watertight system will also suffer from problems relating to an inability of the liquid sewage to flow freely through the small bore piping. These problems occur as a result of the formation of a vacuum within the system which prevents the liquids from freely flowing through the sewer lines. There is therefore a need for systems having watertight connections which do not suffer from such flow problems.
There is also a need to provide an efficient sewer system which is inexpensive to install and maintain. It should utilize flexible piping which does not need to be laid in straight alignment and which prevents infiltration of ground water and exfiltration of sewage. There is a need to improve design-life of sewage collection/treatment systems and to simplify and streamline end-treatment technologies through the provision of early separation of solids and liquids. There is a need to provide a collection system that is simple to install, simple to operate, and to minimize costly mechanical components. There is also a need for a sewage system which is not dependent on roadways and existing infrastructures for layout design.
Summary of the Invention It is an object of the present invention to overcome the disadvantages of the prior art and to provide a sewer system which is easy and economical to install and can be easily adapted to circumvent existing roadways and infrastructures.
It is also an object of the present invention to provide a sewer system which does not allow excessive infiltration of ground water or exfiltration of sewage.

Therefore, the present invention provides a sewer system for the carrying of sanitary sewage from a source thereof for treatment at treatment centers, said sewer system comprising:
means for carrying sewage from a said source of the sewage;
a clarifier tank for receiving sewage from a said source of sewage via said means for carrying sewage, said clarifier tank comprising a first compartment for receiving sewage and retaining solid sewage, and a second compartment in fluid communication with said first compartment for receiving substantially liquid sewage from said first compartment, wherein liquid and solid components of the sewage are substantially separated and substantially all of the solid sewage is regained in said clarifier tank, said first compartment of said clarifier tank being provided with an inlet means and said second compartment of said clarifier tank being provided with an outlet means, and attachment means being provided for connecting said sewage carrying means to said inlet means and said collection means to said outlet means; collection means comprising a sewage carrying conduit connected to said clarifier tank and a collection main connected to said conduit for carrying sewage, for receiving the substantially liquid sewage from said second compartment of said clarifies tank and carrying it to a treatment center;
at least one pumping station substantially in-line with said collection means, said pumping station comprising a tank for receiving said substantially liquid sewage having an inlet means for receiving substantially liquid sewage from said collection means, outlet means for pumping substantially liquid sewage ou.t to said collection means, at least one submersible pump connected to said outlet means, and activating means for activating and deactivating said pump, said collection means further comprising a forcemain for receiving substantially liquid sewage from said pumping - 3 (a) -station; cleanout means comprising one or more openings spatially positioned along said collection means; and filter means connected t:o said clarifier tank, cleanout means or pumping station, for absorbing odour from and releasing sewer gases, said filter means comprising perforated pipe within a gravel and sand falter bed.
In another broad aspect, the present invention relates to a sewer system for the carrying of sewage from individual buildings for treatment at treatment centers comprising:a clarifier tank for receiving sewage having a first and second compartment with an overflow conduit therebetween from the first to the second compartment, inlet means into said first compartment, outlet means from said second compartment wherein solid sewage i:~ substantially retained in said first compartment; piping connected to the sewage system of a building and to said inlet means in said tank for carrying sewage from a building to said tank; collection means connected to said outlet means of said tank for receiving 2C substantially liquid sewage and carrying it to a treatment center, said collection means comprising: a flexible pipe connected to sa__d outlet means of said tank; a flexible collection main connected to said flexible pipe for carrying substantially liquid sewage to a treatment center; a filter 2~~ means connected to the system of absorbing odour from and releasing sewer gases; wherein said filter means comprises perforated pipe within a gravel and sand filter bed.
BRIEF DESCRIPTION OF DRAWINGS
30 Preferred embodiments of the present invention will now be described and may be better understood when read in conjunction with the following drawings in which:

- 3 (b) -Figure 1 is a perspective partial cross sectional overview of one embodiment of. the sewer system of the present invention.
Figure 2 is an end cross sectional view of the sewer pipe from Figure 1.
Figure 3 is a cross sectional view of the clarifier tank from Figure 1 in which Figure 3A is a top cross sectional view.

Figure 3B is a side cross sectional view, and Figure 3C is an end cross sectional view.
Figure 4 is a schematic diagram of the outlet connection from the clarifies tanl{ to the lateral sewer pipes from Figure 1.
Figure 5 is a schematic diagram of the inlet connection from the building sewer pipes to the clarifies tank from Figure 1.
Figure 6 is a schematic cross sectional view of the pump station connected to the collection main from Figure 1 in which Figure 6A is a schematic cross sectional top view of the pump station and Figure 6B is a side schematic cross sectional view of the pump station.
Figure 7 is a cro;~s sectional schematic view of the manhole and cleaning system for the sewer system of Figure 1 -whip Figure 7A is top schematic view of the manhole and ding system and Figure 7B is a side cross sectionalview of the manhole and cleaning system.
Figure 8 is a perspective view of the soil filter and vents for the sewer system of Figure 1 in which Figure 8A is a side perspective view of the filter and Figure 8B is a top perspective view.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Referring to Figures 1, there is depicted the Small Bore Sewer*
system 1 of the present invention. This system is designed to collect sewage i°rom commercial, industrial and residential housing and carry it to a central treatment centre for processing. It is designed to be used, in particular, in small communities which either do not have a common sewer * denotes trade-mark 2~sssss system or can not afford a conventional sewer system.
Preferably, it should be connected to no more than about 1400 dwellings to ensure efficiency. It is particularly well adapted to be installed in remote areas or areas with large amounts of rock near the ground surface which do not allow private sewage disposal systems to work well.
As shown in Figure 1, the sewer system 1 of the present invention comprises a clarifies tank 3, connected to and receiving sewage from a building 2, which tank separates solid 5 and liquid 7 sewage. The liquid sewage 7 is carried through sewer pipes to a collection main 25 where it flows to a central treatment centre.
The clarifies tanl~> 3, shown in detail in Figures 3A, B and C
is made preferably of concrete but may be made of any suitable material such as fibreglass or high density polyethylene (HDPE). It comprises two compartments 13, 15. The tank 3 is connected to a bui.lding~s sewage system through a sewer pipe 21 which receives sewage from the building 2 and empties it into the main compartment 13 of the tank 3. Each building 2 may have one or several clarifies tanks 3 or several buildings 2 may be connected to one tank 3, depending upon the sewer demand.
In the main compartment 13 of the tank 3, solid sewage 5 settles. Liquid sewage 7 flows from the main compartment into a separate side compartment 15 before flowing out of the clarifies tank 3 and into the rest of the sewer system 1.
This side compartment 15 allows remaining solid sewage 5 particles suspended in the liquid sewage 7 to settle out before the liquid sewage 7 passes into the remaining portions of the sewer system 1. The tank 3 has several openings 9, 17 and lids 11, 19 .in its top to enable easy access to the compartments 13, 15 of the tank 3 for maintenance and repairs .._~...._..~~.~..~..

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as well as remova7L of solid sewage 5. Tt will be understood, moreover, that the tank 3 may include additional settling compartments to receive the outflow from side compartment 15.
Provision of additional compartments will permit additional sludge solids to settle from the sewage liquid before discharge thereof into the system 1.
Solid sewage 5 settling to the bottom of the main compartment 13 of the tank :3 is reduced by the action of anaerobic digestion. The solid sewage 5 accumulates for a period of time and may then be pumped out of the tank 3 and removed on a regular basis. l3referably it is removed every five to seven years. The solid sewage 5 is removed through an opening 9 in the top of the tank 3. A lid 11 is removed to gain access to the main compartment 13 of the clarifier tank 3. By removing the solid sewage !5 at each dwelling 2, the sewage liquid in the system 1 is effectively pre-treated before it enters a treatment plant. Therefore, this sewer system 1 results in a reduction in size and complexity of the necessary municipal sewage treatment plants.
The liquid sewage '7 flows out of the clarifier tank 3 and into the lateral sewer pipe 23 which carries it to the collection main 25 shown in Figure 1. The piping 23, 25 (in Figure 2, pipe 23 is shown in more detail ) is flexible and substantially smaller in diameter than conventional sewer pipes . It is made of high density polyethylene and its joints are heat welded, virtually eliminating infiltration of groundwater and exfiltration of sewage. Moreover, all jointing in the sewer system 1 is preferably chemically or heat welded. Because the piping 23, 25 is flexible, it does not need to be placed in straight alignment as do conventional sewer pipes. It may deviate from a straight path to avoid obstacles or for ease of installation. Because of the smaller size and flexibility of the pipe 23, it is placed in a dug trench 27 which does not 21~6~~66 _ 7 _ need to be as wide or deep as in conventional sewer systems.
Typically, the trE~nch 27 is narrow and shallow, approximately one foot wide and three feet deep. Where necessary due to climatic or environmental conditions, the pipe 23 is surrounded by a sand bedding 29 and covered with insulation material 31 such as styrofaam insulation. The trench 27 is then backfilled as in conventional systems to restore the ground property 33 to its original condition.
Pipes 23 and 21 are connected to the clarifier tank 3 as shown in Figures 4 and 5, respectively. The inlet pipe 21 bringing sewage from a bui:Lding 2 enters the clarifier tank 3 at the opening 35. This opening is preferably 4" in diameter. This location deposits solid 5 and liquid 7 sewage in the main compartment 13 of the clarifier tank 3. As the solid sewage 5 settles out in the main compartment of the tank 3, the liquid sewage 7 f:Lows from the main compartment 13 into the side compartment 15. The outlet sewer pipe 23 takes the liquid sewage 7 out of the 3" opening 37 in the side compartment 15 and to the collection main 25. The pipes 23 and 21 are attached to the clarifier tank 3 through an attachment assemb:Ly. The attachment assembly comprises a female threaded bell 41, threaded HDPE lateral adaptor 47, gasket 43, and tee pipe 45. The bell 41 fits into the opening 37. Located on the inside of the clarifier tank 3 in the opening 37 is the tee portion 45 which connects to the bell 41. The opening 37 is made watertight by the utilization of a gasket 43 in the opening 37. Preferably an A-LOK gasket is used. The adapto:r 47, in the case of pipe 23, is a small section of pipe 47 which is connected to the bell 41 and fuse welded to the pipe 23. A similar connection system may be used, if necessary, for pipe 21 at the outlet opening 35 of the clarifier tank: 3. Preferably, the pipe 21 is attached directly to the bell 41. The ends of 41 and 21 have a threaded connection and are threaded together.

_8_ The pipe 23 brings liquid sewage 7 to the collection main 25.
The liquid sewage 7 flows through the collection main 25 to a central treatment centre. If the gradient differs substantially, pumping stations 50 may be provided, spaced along the collection main 25.
Detailed in Figure 6, a pumping station 50 is inserted in the collection main 25 to aid in the flow of the liquid sewage 7 to a treatment centre. The pumping station 50 includes submersible pumps 52 wired to a control panel 54 which is preferably located above ground. An inlet pipe 56 from the collection main 25 discharges liquid sewage 7 into the station 50. The submersible pumps 52 have a series of floats 58 which activate the pumps 52 when the level of the liquid sewage 7 in the pumping station reaches predetermined heights. The liquid sewage 7 is pumped out of the pumping station 50 and into a forcemain 60 which carries the liquid sewage 7 to a central sewage treatment centre. A-LOK gaskets are used to maintain watertight connections between the walls of the pumping station and the inlet pipe 56 and the forcemain 60.
Because only liquid sewage is pumped through the pumping station, submersible pumps 52 need only be effluent pumps rather than more complex and expensive sewage pumps required in conventional sewer systems.
The Small Bore Sewer* system 1 permits a low flow rate due to the absence of solid sewage passing through the system 1 and therefore fewer pumping stations 50 are required than in conventional sewer systems. The absence of solid sewage also allows for easier cleaning of the system 1. Access points 62 such as node cleanouts or manhole openings and covers are provided along the system 1 at spaced intervals. Because of the absence of solid sewage and the ease of cleaning the * denotes trade-mark system 1, the manhole access points 62 do not need to be placed as close together as in a conventional sewer system.
Stand pipes 64 below the manhole access covers 66 connect to the collection maim 25. The stand pipe 64 has a vent cap 68, flange and adaptor 67 at its upper end to connect to a hose such as a fire hose for easy flushing of the system 1.
Flushing is required less often than in conventional systems and may occur approximately every five years. Insulation 69 and clear stone 70 are provided to protect the piping 64 from damage, for example, due to the elements and frost.
A further feature of the present invention is a soil filter and vent 80. The soil filter 80 absorbs odours from septic gases created within the sewer and releases the gases through vents. The soil filter and vents 80 may be connected to the clarifier tank 3, manhole 62 or pumping station 50 using a gasket, for example, an A-LOK gasket. The soil filter 80 consists generally of perforated PVC piping 82 connected to the tank 3, station 50 or manhole 62 through a series of elbows 84. The elbows 84 and piping 86 ensures that groundwater does not infiltrate the sewer system 1. The perforated piping 82 is surrounded by a bed of gravel 88 covered with geote~aile fabric 90 and a layer of sand backfill 92. The gravel/sand filter media is located above the maximum high water table.
It is understood that variations may be made to the above description without departing from the spirit of the invention. The foregoing description is therefore not intended to limit ithe scope of the invention in any way.

Claims

1. A sewer system for carrying sanitary sewage effluent from a source of sewage for treatment at a treatment center, said sewer system comprising the following components:
an inlet pipe for carrying said sewage from the source of sewage;
a clarifier tank for receiving said sewage from said source of sewage via said inlet pipe, wherein said inlet pipe is attached to said clarifier tank via a watertight connection, said clarifier tank comprising a first compartment for receiving said sewage and retaining sewage solids, and a second compartment in fluid communication with said first compartment for receiving substantially liquid effluent from said first compartment, wherein liquid and solid components of the sewage are substantially separated and substantially all of the sewage solids are retained in said first compartment;
a conduit connected to said clarifier tank via a watertight connection for receiving the substantially liquid effluent from said second compartment of said clarifier tank, a collection main connected to said conduit via a watertight connection for receiving the substantially liquid effluent from said conduit, whereby said substantially liquid effluent is carried to said treatment center; and a vent for allowing the flow of air and sewage gases between the sewer system and external environment, wherein said vent comprises a pipe having one or more perforations within a gravel and sand filter bed located above the maximum high water table, and wherein said vent is incorporated into any of said foregoing components and is configured to prevent the infiltration of ground water or exfiltration of said sewage, wherein said sewer system is configured to prevent infiltration of ground water or exfiltration of said effluent.

2. The sewer system according to claim 1, wherein said vent is connected to said clarifier tank.

3. The sewer system according to claim 1, further comprising a pumping station substantially in-line with said collection main, said pumping station comprising a tank for receiving said substantially liquid effluent having an inlet for receiving said substantially liquid effluent from said collection main, an outlet, at least one submersible pump connected to said outlet, and an activator for activating and deactivating said pump, wherein said outlet comprises a forcemain for receiving substantially liquid effluent from said pumping station, and wherein said inlet pipe and said forcemain are each connected to said pumping station via a watertight connection.

4. The sewer system according to claim 3, wherein said vent is connected to said pumping station.

5. The sewer system according to claim 1, further comprising one or more access points spatially positioned along said collection main for flushing the system.

6. The sewer system according to claim 5, wherein said vent is connected to said one or more access points.

7. A sewer system for carrying sewage effluent from individual buildings for treatment at a treatment center, said sewer system comprising:
a clarifier tank for receiving sewage having a first and second compartment with a connecting conduit therebetween from the first compartment to the second compartment, an inlet pipe into said first compartment, and an outlet pipe from said second compartment, wherein sewage solids are substantially retained in said first compartment and liquid effluent passes into said second compartment via said connecting conduit;
piping connected to a sewage system of a building and to said inlet pipe in said tank via a watertight connection, wherein said piping is for carrying said sewage from said building to said tank;
a flexible pipe connected to said outlet pipe of said tank via a watertight connection;
a flexible collection main connected to said flexible pipe for carrying said liquid sewage to said treatment center; and a vent for allowing the flow of air and sewage gases between the sewer system and external environment, wherein said vent is configured to prevent the infiltration of ground water or exfiltration of said sewage, and wherein said vent is connected to said system, and wherein said vent comprises a perforated pipe within a gravel and sand filter bed located above the maximum high water table, wherein said sewer system is configured to prevent infiltration of ground water or exfiltration of said effluent.