Water is a precious resource, yet we have traditionally use it once and dispose of it through our sewage treatment plants. There are many activities that do not require drinking quality water and could use recycled water (e.g. irrigation and toilet flushing). Recycling means less water from the potable (drinking) system is needed. As part of an integrated water management solution, water recycling is an important way to help preserve our drinking water supplies.
Sewer mining provides a secure rainfall independent supply of water that is fit for a wide range of uses. The process normally involves the removal and treatment of sewage from sewer mains before it reaches the treatment plant where it is treated to produce high quality recycled water for use nearby. High reticulation costs, normally associated with conventional municipal sewerage, are avoided as product water is produced at point of use.
The Melbourne Cricket Club (MCC) with financial assistance from the State Government of Victoria completed the works at Yarra Park as part of a comprehensive Draft Yarra Park Masterplan, designed to greatly improve the parkland.
The project involved renewal and rejuvenation of Yarra Park through implementation of the Masterplan, based on the original design themes.
As part of the plan, an underground water recycling plant is installed to secure essential non-potable water for use in Yarra Park, the MCG and Punt Road Oval. The $24 million project, funded by the MCC ($18 million) and the Victorian Government ($6 million), treats sewage from the local sewerage network to Class A recycled water standards. This will ensure the park receives sufficient water regardless of drought or rainfall.
The purpose of the facility is to provide 140 to 180 million litres of Class A water annually, primarily as irrigation water, for municipal use in Yarra Park, Richmond Football Club and MCG. The water will also be used in a third pipe recycling scheme throughout the MCG toilets, amenities and for wash down (cleaning and maintenance). For comparison purposes, Class A water produced by the facility at Yarra Park will replace the volume of potable water sufficient to supply approximately 1150 households in Melbourne for every year of operation.
The water recycling facility is located underground in Yarra Park (adjacent to Gate 2 members entrance). The underground plant has a trafficable roof, architecturally designed entry, an egress with a box lift and chemical unloading area.
The MCG water recycling facility takes sewage from City West Water Wellington Parade South trunk route, where it is diverted and pumped via a dedicated underground supply pipe to the Yarra Park facility. Associated infrastructure on the inlet side includes the sewer connection, diversion structure/chamber, a 12-metre by 4.8-metre (diameter) pumping station and a rising main. Other infrastructure includes the connections to MCG and Punt Road storages as well as a pump station and sludge return gravity line downstream of the sewerage take-off.
Production capacity of the plant is 0.6 ML net of Class A water per day to the third pipe system, after allowances for backwash water and any other plant requirements have been met. Waste water flows and solids removed at the screening stage are combined, macerated and pumped back to City West Water sewer.
The design of the facility is strongly influenced by the requirements set down by VIC Department of Health and Australian Guidelines for Water Recycling in producing Class A water. It incorporates a combination of pre-validated equipment and best practices to reduce energy and minimise greenhouse gases whilst addressing those issues identified in the Environmental Risk Assessment.
The sewage diverted from the City West Water sewer is pumped to the water recycling facility where the following key stages of the treatment occur:
As part of the process the odorous air collected at source from the inlet works and other treatment processes within the facility are fed through a chemical scrubber and carbon unit prior to discharge into atmosphere via three stacks.
The treatment process selection is based on achieving desired water quality, reduced energy consumption and water use. The final process choice is determined via the triple bottom line assessment and the above options chosen to meet best practice energy consumption and carbon management.
Since its commissioning and validation in 2012 the water recycling facility at Yarra park has been producing class A recycled water of consistent quality at the rate of 200 kl to 600 kl per day with actual daily production depending on demand (e.g. events) and the sewage flows available in the Wellington Parade South City West Water sewer. The lowest sewage inflows are typically experienced during Christmas / New Year period as expected for the residential catchment.