Sewage is currently treated by a variety of mechanical and biological processes at Gisborne RWP. Watch the tour video (above) for more information.
Population growth impacts
Sewage volumes being treated at Gisborne have grown significantly in the past decade, driven by population growth. This has resulted in increased recycled water to manage.
In 2020, sewage from more than 14,000 customers is being treated at Gisborne RWP. By 2035, we expect the number of customers serviced by the plant to grow by another 46%.
Our master planning indicated that the Gisborne RWP may require an upgrade around 2023 to increase its treatment capacity and minimise harm to the environment from potential spills. The plant is now approaching capacity for treating inflows and interim measures have been developed to address this situation until the upgrade is complete.
We expect that with growth more discharges to Jacksons Creek may be required under our licence in future. However, to minimise this, we are investing in maintenance projects to reduce sewage inflows that come from infiltration of the sewerage network. We are also looking to sign up more users for recycled water – particularly for recreation spaces in new housing estates and new agricultural users.
Climate change impacts
Climate change has resulted in less predictable weather patterns, lower rainfall and longer dry periods, as well as more frequent storm events.
Lower rainfall and longer dry periods increase demand for recycled water for suitable purposes, increasing uptake. At the same time, Jacksons Creek can become stressed and experience low flows affecting its ecological health. During these times, recycled water can provide additional volumes to boost passing flows.
Improvements to the quality of recycled water will improve its value for environmental flows in Jacksons Creek. We are investigating this opportunity further as part of our integrated water management planning.
Less predictable weather - including storm events - can create significant surges in inflows to the plant. While works are underway to reduce infiltration of the network, an objective of the upgrade is to increase the plant’s storage capacity to manage these occasions and ensure the quality of the recycled water produced is not impacted.
At Gisborne, sewage is treated by a biological process which uses natural bacteria. The bacteria require a large amount of oxygen to break down the sewage. We currently use surface aerators for this process. However, these are not very energy efficient.
New aeration technologies are being considered for the upgrade that are far more efficient and could more than half the energy consumption and greenhouse gas emissions from the plant.
Environmental and cultural values
There are some notable biodiversity values at the Gisborne RWP site which Western Water preserves and enhances. Find out more.
While Jacksons Creek is indicated as an area of high archaeological potential, no evidence of Aboriginal sites have been discovered on the site of the treatment plant to date. Investigations are ongoing and new information will be shared on this page.
There are no European historical sites within the Gisborne RWP boundaries.