Collaboration key to developing MAR for open space irrigation

Right: Hartfield Park MAR infrastructure top view and Dan Nelson (middle)

As climate change and population growth continue to put pressure on Perth’s groundwater, interest is developing for small scale alternative irrigation schemes using recycled storm and wastewater.

In October 2019, the Western Australian Government released the Waterwise Perth Action Plan to transform Perth into a leading waterwise city by 2030. As part of this plan, recycled and alternative water supplies could make up to 45 per cent of the projected gap between future supply and demand by 2030.

When it comes to developing alternative water supplies, there is no single solution and there is a lot that can be learned along the way.

This message was recently re-enforced by Dan Nelson from the City of Kalamunda who shared his experience developing the city’s Managed Aquifer Recharge project at the Hartfield Park sporting precinct.

Dan with the support of his council has led the building of Perth’s first scaled local Managed Aquifer Recharge irrigation project to service the extensive sporting fields and recreation grounds at Hartfield Park.

Licensed by the Department of Water and Environmental Regulation (DWER), the project harvests and stores stormwater in winter for recovery and use as irrigation water in summer.

Lessons learned from the Hartfield Park trial and subsequent upscale of this project were shared locally and internationally in December.

The 19th International Small Water and Wastewater Systems Conference included a field tour of Hartfield Park giving policy directors, engineers and academics an opportunity to learn about the project.

The City of Kalamunda has put great effort into the project – from the trial to its full implementation – to meet operating and regulatory requirements for recharging and abstracting stormwater for public open space irrigation.

Given our extensive groundwater systems, managed aquifer recharge is an attractive option to store winter runoff.

It also enables runoff to be captured, including in areas that waterlog, to balance our seasonal demands in dry summers. Where feasible, managed aquifer recharge has the potential to make stormwater and treated wastewater an asset for communities - supplying water for industry, public open spaces and sporting fields.

It can also reduce the cost of managing the impact of stormwater on sensitive waterways, such as estuaries, and support groundwater levels.

Other local governments in growing metropolitan areas are looking at opportunities to develop alternative water supplies to supplement groundwater use.

The City of Swan is exploring a different approach to recycling by harvesting sub-surface drainage water for public open space irrigation.

The City of Mandurah is also looking to add to their existing wastewater reuse scheme utilising the Caddadup wastewater treatment plant. Planning is underway for a new non-potable scheme using treated wastewater, stored through managed aquifer recharge, to irrigate public open space within the northern sector of Mandurah.

The Shire of Serpentine-Jarrahdale is also planning for a range of alternative water sources to satisfy its future water needs. As one of the fastest growing communities in Australia, it is adopting an integrated water management strategy to respond to current and future water supply and infrastructure pressures, with this work winning an AWA WA water award along with industry partners Wallbridge Gilbert Aztec.

The best solution in each place depends on the scale and nature of the demand, the source and storage options, and how any risks to the environment and human health are managed. Hydrogeologists, engineers, economists, environmental scientists, microbiologists, urban planners and public servants all have a role in identifying solutions.

A key component of the Waterwise Perth Action Plan is to identify any barriers and work on any issues regarding policy, regulations and legislation to support waterwise outcomes. This means consolidating, streamlining and improving the suite of water policies, guidance and technical advice to drive waterwise outcomes as well as improving water-related State planning policy, guidelines and associated processes to strengthen waterwise outcomes at all levels of land use planning.

In preparation for increased use of this practice, DWER is currently reviewing the regulatory framework for using aquifers to store treated wastewater and stormwater.

Department of Water and Environmental Regulation Executive Director Science and Planning Nygarie Goyal said a scientific approach to understanding what actually happens when we pump source water into the deep aquifer will ensure environmentally responsible outcomes.

“As part of the Peel Integrated Water Initiative, DWER, in collaboration with CSIRO and the Peel Development Commission, has conducted a study to determine if recharging aquifers with stormwater could help secure long-term water supplies for intensive agriculture in the area,” Nygarie said.

“This study involved drilling a bore into the target aquifer and investigating potential interactions between the source water and the water already stored in that part of the aquifer. Results of the work will be published in 2020.”

DWER has also been helping proponents determine the feasibility of alternative water supplies for public open space in areas without available groundwater. “To this end, we have been working with local government, developers and planning consultants to take ideas and concepts through to viable, costed and well-understood alternative water supply solutions,” Nygarie said.

“For example, we have been collaborating on the investigation and mapping of planning and approval pathways for non-potable water supplies.

“This includes supplies for heavy industry in the Kwinana / Western Trade Coast areas, for irrigated agriculture on the Gnangara groundwater system, and in the Peel and South West regions, as well as irrigation of greenspaces in Perth’s North East corridor, Western Suburbs and in Greater Bunbury.” DWER is also working with the Water Corporation to identify future demand for treated wastewater and how infrastructure can be designed to deliver it.

To support water supply planning for the future, the two agencies are investigating locations in Perth where recycled wastewater, stormwater, surface and sub-soil drainage and sustainable water supply options are found to be suitable.

“As a department we are looking at the lessons of others, and also our own,” Nygarie said.

Until recently, water recycling and stormwater harvesting for public open space irrigation in Western Australia were led by regional areas.

Although substantially smaller populations, the lessons of our regional towns are useful. These regional areas have led the way in innovation because they have had to.

Water Corporation is involved with supplying treated wastewater to approximately 50 water recycling schemes in WA that irrigate parks, gardens, gold courses, sports grounds and other open spaces.

Where required DWER has worked to reduce red tape and unnecessary cost burdens for acting as non-potable water service providers.

It has also strategically supported development of nonscheme supplies to assist regional towns in some of the State’s driest areas build water security. This includes complementary non-potable water supplies for townscape irrigation, sports fields, and emergency firefighting needs.

These supplies leverage off existing local infrastructure, as well as the built and natural landscape, to harvest and re-use stormwater. This builds resilience and reduces the use of valuable and limited scheme water supplies.

The challenge as we move forward is to continue to innovate, collaborate, share and build upon our experiences. So whether in the regions or the city, our lessons learned become part of the tools in our water innovation toolbox for WA to keep our groundwater and public open space healthy and sustainable under climate change.

More information on Managed Aquifer Recharge is available from the Department of Water and Environmental Regulation at http://www.water.wa.gov.au/urban-water/water-recyclingefficiencies/managed-aquifer-recharge

Photos - Top Right: Hartfield Park MAR valve controller

Bottom Right: IAL on-site members' visit to Hartfield Park

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