Kalamunda – a local government’s passion for water reuse goes a long way (underground)!

Shire of Kalamunda's concept for water reuse at Hartfield Park (Source: Shire of Kalamunda)

Shire of Kalamunda’s concept for water reuse at Hartfield Park (Source: Shire of Kalamunda)

New WAter Ways  arranged a most excellent speaker for its Water Sensitive Cities Speakers Series event (try saying that three times quickly) earlier this year:  Dan Nelson, Coordinator Project Delivery from the Shire of Kalamunda.

Dan has been working for the Shire of Kalamunda for the past 6 years and has been recently working hard to get the Hartfield Park Managed Aquifer Recharge (MAR) project underway.

Hartfield Park Reserve is the largest sport and recreation reserve within the Shire of Kalamunda and is thus a very thirsty piece of public open space.  As you would expect with a growing population, the Shire has identified the need to increase the amount of active field space at the reserve, which means: more water. But given Perth’s notoriously depleting groundwater aquifers and dams, it became fairly obvious very quickly that an alternative water source would need to be found to maintain the field in the long term.

While sewer mining, or the diversion of sewage from a sewer main for treatment and use elsewhere, was first considered as an alternate source, it would cost a walloping $18/kL to undertake the required level of treatment (to put it in context, water generated from Perth’s seawater desalination plant in Kwinana costs $1.20/kL to produce).

After further consideration, Dan and his Shire officers came up with the brilliant idea of harvesting stormwater from Woodlupine main drain which happens to be located directly along one of Hartfield Park’s boundaries! This water runs off the Kalamunda hills and is normally channeled away into Perth’s urban drainage system and into the Swan River. The project was proposed to utilise Managed Aquifer Recharge (MAR), a process which involves the intentional recharge of an aquifer under controlled conditions in order to store water for later abstraction and indirect use. In the case of Hartfield Park, it will involve harvesting stormwater from the Water Corporation’s Woodlupine main drain in the winter months and re-injecting it into the local aquifer for later extraction in the summer months, when irrigation water is most needed. The advantage of this system is that the proposed aquifer would act to filter AND provide storage for an additional water source for free, as well as increase the Shire’s groundwater allocation under their existing licence under the Rights in Water and Irrigation Act 1914.  Essential Environmental has also been involved in the sidelines through our work undertaking a hydrological investigation for Woodlupine Brook in order to recommend upgrades to improve drainage function, amenity and (critically for this project) water quality in the main drain.

Managed aquifer recharge (Source: Department of Water, http://www.water.wa.gov.au/marBanner.jpg)

Managed aquifer recharge (Source: Department of Water, http://www.water.wa.gov.au/marBanner.jpg)

A detailed and rigorous hydrological feasibility study was required to prove that an adequate amount of water could be harvested from the stormwater system to meet Hartfield Park’s irrigation needs, without affecting downstream environments which would normally receive the stormwater. In addition, studies were required to determine whether a local aquifer (the shallow Superficial aquifer, or the deeper Leederville aquifer) had the capacity and permeability to store and recover stormwater without risking the water quality for other irrigators or nearby wetlands. These investigations showed that:

  • 25-50 kL/year could be harvested from the Woodlupine main drain for later aquifer storage and recovery;
  • the payback period for using MAR as a water supply scheme will be ~7 years, if compared to the cost of drinking water; and
  • water recover will not necessarily be 1:1 as there is still some uncertainty to the properties of the Superficial aquifer. However, given stormwater injected into the aquifer is expected to be recovered after 6 months it is considered likely to be close to this figure.

The most famous MAR project that has received a lot of press recently is the Water Corporation’s Groundwater replenishment scheme at Beenyup, the first major and most well known project in Perth.  Local scale projects, such as the City of Greater Geraldton’s stormwater harvesting and aquifer recharge project  and the Shire of Kalamunda’s Hartfield Park MAR project, are less well known but not any less important.  These projects provide evidence to demonstrate that MAR may be successfully utilised on a local scale given the proper investment of time and research in order to prove its feasibility. And given current groundwater allocations set by the Department of Water (see below!), more projects like these will have to be done sooner rather than later!

Dan has also shown that the key challenges to getting these projects under way include:

  • demonstrating that the aquifer is suitable for storage & recovery;
  • defining the ownership of future MAR infrastructure (the Woodlupine main drain is managed by the Water Corporation, aquifer and surface water allocations are managed by the Department of Water and Hartfield Park reserve is managed by the Shire of Kalamunda);
  • early engagement of multiple stakeholders & asset owners (such as the Water Corporation);
  • meeting the requirements of the Department of Water’s Managed Aquifer Recharge (MAR) policy;
  • meeting environmental & health regulatory requirements defined by state government agencies to gain approvals (Department of Environment Regulation, Department of Health and Environmental Protection Authority);
  • obtaining project funding (the Shire of Kalamunda received ~$500,000 for the Hartfield Park MAR project); and
  • overcoming local government fear of what is required of these projects!

Now that the appropriate approvals have been provided by the Water Corporation, Department of Water, Department of Health and Department of Environment regulation, the next phase of the project will involve selecting contractors for the proposed trial to ensure the system will work properly, and understanding what maintenance costs will be involved.  If it is proven that MAR works for the Superficial aquifer then further investigation into using the deeper Leederville aquifer for MAR projects will be undertaken, including the possibility of tying such projects to groundwater allocation trading. The project is also likely to require the development of a Memorandum of Understanding with the Water Corporation to secure stormwater from the main drain in the future.

Dan’s desire to work towards water saving solutions while continuing to provide green public open space, and ‘future water proofing’ our urban areas, is something we should be inspired by. This is especially critical as the Bureau of Meteorology indicates that we are heading towards El Nino hot and dry conditions this summer.

Learn how changes in ocean currents can affect weather conditions - El Nino and La Nina (Source: Science Channel)

Learn how changes in ocean currents can affect weather conditions – El Nino and La Nina (Source: Science Channel)

It is also a reminder to local government that they CAN influence change on the ground and that initiative combined with a bit of passion will go a long way.