The Greater Metropolitan Cemeteries Trust (GMCT) manages 18 Melbourne cemeteries and is a significant water user. The GMCT engaged W&G to undertake an alternate water supply options investigation covering nine cemetery sites across Greater Melbourne, to determine the potential to utilise alternate water sources which are fit-for-purpose.
The GMCT recognises the potential to achieve positive social, environmental and financial outcomes by better managing its water use and reducing its reliance on potable water.
Increasing supply from alternate water sources is an opportunity for the GMCT to optimise its on-site water management. A supplementary water source will assist the GMCT in maintaining these important public parks in times of drought and water restrictions.
The investigation covered a range of different sites in various phases of operation including active, transitional and establishing sites. Each site has different priorities for water use, water demands and opportunities and drivers to improve water use.
Key Stages of the Investigation
• Data Acquisition and Analysis
• Preliminary Options Assessment
• Comparative Assessment and Ranking
• Preliminary Design
Data Acquisition and Analysis
Data acquisition stage determined the current and future non-potable water usage at each site. This was determined from a combination of review of historical water bills, consultation with ground staff, review of planting plans and species, and other site specific demands such as water feature and fountains. The assessment also considered seasonality of demands including review of rainfall and evaporation data for each site. This data formed the basis for assumed alternate water demands for each site.
Typical Non-Potable Demands: • Irrigation • Water features • Vehicle wash-down • Monument wash-down
Future Water Demand
The analysis also considered future demands, as many of the sites are in a transitional phase which could impact future water use. Potential influences to demand considered include;
• Site expansion and development
• Changes to planting types (i.e. native or exotics).
• The status of site (i.e. establishing, transitional or active)
• Water efficiency audits
• The age of the site
• Site specification location and objectives.
Two-way Knowledge Transfer (Consultation)
A key ingredient in the success of the project was the two-way knowledge transfer through real consultation with the GMCT staff. This allowed the site specific details and operational requirement to be understood and accommodated in design, and also sharing of the real value of improved water management strategies at each site with the operational staff.
Preliminary options Assessment
A preliminary options assessment of alternate water supply at each site was undertaken using our detailed knowledge of each site and an understanding of the available alternative water sources. Further data was compiled from a desktop review of site conditions, available infrastructure and consultation with key authorities to shortlist the options for each site. Potential sources and opportunities investigated include:
• Rainwater tanks
Reuse Stormwater Harvesting
• Stormwater extraction from watercourses
• Onsite stormwater harvesting
• Availability and quality of available recycled water supply
• Desktop assessment of optential aquifiers
• Existing bore data
• Ground water quality (i.e. salinity)
Each option was then reviewed in respect to:
• Site constraints
• Water demand
• Operational risk
• Preliminary costs
• Security of supply
• Economic assessment
• Southern Rural Water
• Water Authorities
• Department of Health
• Melbourne Water
A comparative assessment allowed the GMCT to consider each option against a Triple Bottom Line (TBL) assessment with respect to social, economic and environmental factors. The GMCT have key strategic values that guided the determination of weighting of the factors, and were specific for each site location.
A financial assessment was undertaken to support the TBL assessment and provide the GMCT with an understanding of the cost-benefit of these options against a base-case of potable supply.
While some schemes did not have a positive benefit cost ratio this was only one element of the PBL assessment, where many of the schemes were shown to rank positively against other strategic, environmental and social outcomes.
Unique Nature of the GMCT Site
The GMCT has a particularly strong social commitment and as a place of respect and remembrance.
Due to the unique and sensitive nature of their sites, there is often an emotional attachment to the landscapes, and key site features such as a fountain or gardens, which can represent a connection to loved ones.
For this reason security of water supply is often ranked very highly by the GMCT as it enables landscapes to be maintained to the high standard expected by the public.
Shortlisted Options & Preliminary Designs
The shortlisted options for each site were ranked against the key drivers of the GMCT. In most cases an alternate source of water was considered viable, and while no source could yield all the non-potable demand reliably, there were options to supplement potable water and provide the GMCT with additional water security.
Preliminary designs were completed for the highest ranked option at each site. Final options included stormwater harvesting, rainwater tanks and connection to nearby recycled water supplies.
Aquifer (balanced) storage and groundwater extraction was considered at a number of sites but was typically ruled out on the basis of cost per ML and land take for required infrastructure, including water quality treatment requirements.
The availability of land and aesthetic quality of landscapes are very important issues for the GMCT.
• Up to 22ML/a of alternate water could be sourced for non-potable demand across the nine sites with the implementation of these projects.
• This will provide the following benefits to the GMCT and community:
• Reduce demand for potable water supply
• Maintain high quality landscapes and key features
• Increased water security
• Lower potential operating costs
• Public open space
• Contribute to GMCT social environmental values
• Showcase awareness on sustainable water practices
The investigation provides the GMCT with the information required to implement alternate water use at many of the existing and future sites across greater Melbourne. The GMCT are excited by the outcomes of the project and are actively seeking to implement a number of projects in the next 2-3 years, as budgets allow. The outcomes will also be used to guide future works and budget planning.
The finding of the investigation will be revisited over time particularly with the development of new sites to ensure alternate water is considered as a viable source of supply and accommodated in master-planning and design. The investigation forms part of the GMCT’s overall water strategy which also includes review of irrigation practices, irrigation infrastructure, planting plans and water efficiency audits. The report is therefore a living document which will form part of the greater water management vision for the GMCT.
The study has determined a number of viable options to reduce potable water demand and contribute to better environmental and social outcomes at GMCT sites. The GMCT are currently planning for future implementation of these and other similar initiatives and to help maintain some of Melbourne’s most important public spaces.