More robust wastewater system Halswell
A wastewater system new to Christchurch is currently being rolled out in part of Halswell. Pressure sewer pump systems are already used in many parts of New Zealand and in future will be used in several areas of Christchurch.
These systems provide reliable and robust wastewater management for residents, in relation to earthquake resilience.
City Care, as part of SCIRT, is currently working on a pressure sewer pump system for 36 properties in Halswell, the first permanent one of its type in the city.
The main reason for the installation of sewer pressure systems - which are located on private properties - is due to land levels dropping as a result of the earthquakes and the potential for future movements due to earthquakes. This means that in some instances, remaining on the old gravity wastewater system will only be possible by either raising the property’s ground level or increasing the depth of an already deep wastewater main. This would make earthquake repairs and on-going maintenance of the pipe a difficult, disruptive, time-consuming and expensive process.
Pressure sewer systems have been chosen for the following reasons:
• Shallower, more flexible pipes
• Can still operate even if the pipe moves
• More resilient and better able to cope with seismic events
• Do not rely on gravity to transport wastewater
• Can provide storage during a power loss
• An average maintenance call out of once every 10 years
• Nominal cost to run the (electric) pump of $25- $30 annually.
The graphic shows in simple terms how the pressure sewer system operates. Most city households will remain on their existing wastewater systems because they are able to be repaired cost effectively and gravity-based systems are still the best option for them.
City Care is well underway on the communication and consultation phase of its first pressure sewer pump project. Feedback has been positive, with residents understanding the necessity for a new way in which to manage wastewater in their neighbourhood. Read more detailed information on the works notice.
City Care’s Communication Team member Nicola Hunt and Project Manager Rashid Siddiqui with a pressure sewer pump lid and box used to assist with resident meetings.
