Flovac Australia installed in 2015 a vacuum pump station in Christchurch, the largest city in the South Island of New Zeland. Specifically, it was installed in the Prestons residential development, located in Marshlands, which has continued to grow and house sales in the area ahead of schedule. Every effort has been made by the developer Ngai Tahu to ensure that this medium priced housing development for 8,000 residents is world class.
Right next to the vacuum station, a school for children aged 5-13 has been completed: the Marshland School. When master planning a vacuum sewer system it is always important to consider that any flows from schools will be interrupted during school holidays and weekends. So to ensure that plenty of air is entering the system, everything needs to be tuned correctly. One option is having an automatic air inlet system that can be programmed to take the change into account.
The vacuum sewerage system is the ideal technology for a development like this. It can be very flexible with new additions over time, and is resilient to damage from earthquakes. Unlike low pressure pump systems, the only power requirement is at the vacuum station. If an earthquake interrupted power supply, the vacuum sewerage network at Prestons would continue to work as there is a back up generator located at the station.
Another resilient feature of the Flovac system is that if any of the vacuum mains break or rupture during an earthquake, the negative pressure in the pipe will ensure that no sewage will leak out. A low pressure pump system operates on positive pressure, so if a pipeline breaks, sewage will surcharge from the pipe into the surrounding area. In an environmentally sensitive area like Prestons, that could be a disaster.
Another benefit of the vacuum sewer system is its ability to handle high flows into the collection system. A large supermarket complex is being planned in the neighborhood complete with a Foodstuffs supermarket, cafe’s and restaurants. There is also a large BP service station already built in the area, which houses a cafe and a Jetwash. The Flovac system can handle all the commercial premises and any flows from the car washing facility.
On the right side of the BP Jetwash there are three of the Flovac pillars. They house the air vents that are required to admit air into the vacuum sewer. These are connected to three separate valve pits which are served via a splitter to handle the high flows. The pillars will also house the wireless monitoring system that is being rolled out. This monitoring system will alert operators to any valve faults or potential overflows from the pit.
The operators looking after the system have been very content with the operational benefits and have had very few callouts. As the operators have little to no contact with sewage and have no requirements to enter the property of the residents, they see real benefits relative to how the low pressure pumps have performed. Many low pressure pumps are located on the property of the resident and any maintenance often leaves residual sewage on the lawns of the residents. Prestons residents have been very pleased with this innovative vacuum system and want to keep relying on it in the future.