Pressure Sewerage Network
Pressure Sewerage Network
Pressure sewerage systems are different from the conventional gravity systems in that they don't need to be laid on a grade. Conventional sewerage systems rely on gravity for the flow from the house to pass to either a system pumping station or to a treatment plant, if there is sufficient natural slope.
Pumped sewerage systems replace this gravity component with the pressure head provided by the pump. Thus, these systems involve the installation of a specialized 'on property' pumping unit, connected into a pressurized reticulation system. This reticulation system is somewhat like conventional systems except that:
- these systems can be laid at the minimum depth, minimizing both cost and inconvenience to the existing residents, and
- the mains can all be laid in the footpath and do not need to go through private property.
A grinder on the inlet to the pump reduces all sewage to a watery slurry. This means that pipes smaller in diameter than conventional sewerage can be used, narrowing the width of the excavation trenches. The pump will automatically turn on when the sewage in the wet well reaches a set level, and will turn off when the pump lowers the sewage back to a minimum level.
Pressurised systems are now being widely adopted by Australian Water Authorities, as a way of being able to provide a sewerage service in areas which previously weren't economically viable. Typically these are areas with large blocks or a small developed centre, particularly in flat country, rocky areas, or high watertables. The pumped sewerage option is estimated to cost about 60% less to build than the equivalent conventional sewerage scheme.
Since 2002, Council has been connecting East Wagga and Gumly Gumly to a pressure sewerage scheme. The laying of reticulation is complete, while properties are still being connected. So far, the scheme has been very successful. Over the next 3 years, Council has plans to connect Collingullie, Oura, Mangoplah, San Isidore, Humula and Currawarna to the pressure sewerage scheme.
Frequently Asked Questions on Pressure Sewerage Systems
Will the Units overflow during a power failure? What should I do during the power failure?
The Wagga Wagga pumping units have been installed with sufficient capacity to not overflow during most power failures that might occur in the villages. When there is no power, there also isn't any contribution from dishwashers or washing machines. Baths should be taken used in preference to showers during an extended power failure, or showers be kept to a minimum. Other than that no extra care needs to be taken.
What do I do if the alarm goes off?
If the alarm goes off and there is no obvious reason why:
- Turn off the audible alarm.
- Contact Council on the numbers provided in the owner's manual.
- Stop any clothes washing until the pump unit is fixed.
- Minimise showers until the pump unit is fixed.
If the alarm goes off just after power is restored after a failure, the alarm is probably due to the level of sewage having exceeded the alarm point during the power failure:
- Turn off the audible alarm.
- Wait for up to two hours before contacting Council. It is possible that other units in your part of the system are trying to pump at the same time, and your pumping unit waiting for these pumps to finish before starting up.
- If, after two hours, the alarm light is still on, then you should contact Council and follow the instructions for situations where there hasn't been a power failure.
Are there limits on what I can put in the sewerage system?
Yes but what you can dispose off will be similar to conventional sewerage schemes. The owner's manual will clearly set out what can be disposed of into the sewerage system.
Can I connect my swimming pool or spa into the sewerage system?
Yes but it will require that a flow balance tank be installed in case the pool backwash sets off the high level alarm. These are standard and will be provided by Council, at additional cost, where necessary.
Can more than one property be connected to the same pumping unit?
No, for health reasons. The only exception is for strata title properties, on the common property, where this is economically viable.
Can I have the pumping station put in a different location?
Yes, but to minimise costs, the scheme assumes that the pumping unit will be located near the current septic tank. Any significant movement from that area will be at your cost, and of course the house still needs to be able to drain to the pumping unit under gravity.
If I later want to further develop the land can I build over a pressure sewer?
No, but unlike conventional gravity system the line could be moved inexpensively.
Do I have to connect to the pressure sewerage system?
- You will need to demonstrate that the on-site system isn't causing a problem in terms of health risks or damaging the environment.
- The reduced costs offered under this scheme will close within a defined period after the installation programme is completed, and anyone wanting to connect at a later date will have to pay the full cost. These dates and costs will be explained in detail in letters sent about each property as their closing dates could alter from village to village.
What if I cannot afford to pay for the new system now?
Contact Council and explore with them on a case by case basis on what can be done.
How much say do I get over where my connection is to go?
Plenty. The successful installer will make contact with the property owner and the owner will be required to sign off on the proposed household design. However if the changes wanted by you are significantly outside of the scope of the standard installation then you will have to pay the additional costs.