Indigenous Environmental Health: Report of the Fifth National Conference 2004
Wastewater GardensTM Project at Emu Creek Community, Kununurra, Western Australia
Greer Ashby, Environmental Health Officer for Aboriginal Communities, Shire of Wyndham East Kimberley, Western Australia
Emu Creek (Gulgagulganeng) is a small Aboriginal community situated approximately 10 kilometres east of Kununurra in the East Kimberley region of Western Australia, within the Shire of Wyndham, East Kimberley, and the ATSIS Wunan Region. The population of Emu Creek varies throughout the year but generally maintains up to 30 residents, which increases during the Kimberley’s wet season when people from remote outstations come into town.
The community consists of four houses and two shelters that are connected to Kununurra’s town power supply by overhead powerlines, while an on-site bore supplies their water. Originally wastewater was disposed of with the traditional septic tanks and leach drains system. This caused many problems due to the area’s high water table and inadequately or poorly installed septic tanks and leach drains, particularly in areas that had highly saturated soil.
As a result of this type of wastewater treatment system not functioning properly at Emu Creek, engineer Kate West from ARUP - consulting engineers who act as program managers for the Western Australian Remote Area Essential Services Program - appointed Birdwood Downs Company to undertake a feasibility study of installing an alternative wastewater treatment system known as Wastewater GardensTM. ARUP is responsible for managing capital works projects for water, wastewater and power in remote Aboriginal communities funded by the Australian Government through its responsible agency, ATSIC or ATSIS. Funding provided for this Wastewater GardensTM project at Emu Creek Community allowed $124 000 for all works involved in installing through to commissioning the systems.
As the Birdwood Downs Company proposal confirmed that this type of system would suit the conditions at Emu Creek, the Executive Director of Public Health in the Department of Health approved the Wastewater GardensTM concept for installation. The project was approved as a pilot study for two years as this was the first time this system would be installed on an Aboriginal community. Suitability factors for installing the Wastewater GardensTM system at Emu Creek included:
- the community had a permanent population throughout the year
- the community was accessible at all times during the year including the wet season
- the community was connected to a reliable power supply to operate the pumps
- the system would work, even in a high water table area, according to the Birdwood Downs Company calculations.
Put simply, Wastewater GardensTM is an alternative wastewater treatment system that uses sub-surface flow of wastewater into a lined gravel wetland bed that is planted with a variety of water-loving plants as chosen by the household residents. Wastewater GardensTM still uses the traditional method of septic tanks and leach drains, but with the garden gravel bed located between them. However, in this instance it was a requirement that they be designed so the gardens could be bypassed at any stage, were they to fail.
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The project at Emu Creek involved a three-stage approach.
- Stage 1: Correctly position the septic tanks that were to be completely sealed and have trafficable lids.
- Stage 2: Install Wastewater GardensTM to treat the wastewater produced at each house.
- Stage 3: Install appropriately sized leach-drains into well-drained soil on the community.
During the initial stages of the proposal, Birdwood Downs Company, together with ARUP, Waringarri Aboriginal Corporation, environmental health officers and senior field support officers met with community members on numerous occasions to explain how the systems functioned, but also to decide on their locations. These agencies continued their involvement with the community right through the construction stage, commissioning of the systems and throughout the two-year maintenance period. Birdwood Downs Company also ran education workshops for residents at which they discussed water usage, water conservation and Wastewater GardenTM maintenance requirements. During construction, CDEP positions were also made available.
Wastewater GardensTM require minimal maintenance if they are functioning correctly. Maintenance is carried out on the filter located inside the secondary septic tank, which generally requires cleaning/rinsing every three months. Water levels in the garden (gravel bed) need to be checked periodically to ensure the garden doesn’t dry out, and the plants need to be pruned. A maintenance manual was prepared for environmental health workers and senior field support officers who would, on a weekly basis, monitor water levels within the gardens, any odours, rainfall in the area, any vandalism to the systems and the plants’ overall condition. Any serious plumbing issues identified during the weekly checks were reported and addressed by a registered plumber.
Another requirement of approval was that quarterly water samples be collected for the first two years of operation from the secondary septic tank and at the discharge point where the wastewater leaves the garden. Testing the water ensured treatment of the sewage was effective and that fairly purified water was entering the leach-drain area. The water samples were tested for:
- biochemical oxygen demand
- total suspended solids
- faecal coliform bacteria
- total nitrogen
- total phosphorus.
Some of the problems experienced with the Wastewater GardensTM system at Emu Creek have included:
- rock movement on the walls of the garden exposing the plastic liner
- vandalism to the gardens and plants
- children and dogs playing in the gardens
- if the systems did fail, there was severe pooling of wastewater in the garden wetland, potentially creating an area for mosquito breeding.
For further information
Environmental Health Officer for Aboriginal Communities,
Shire of Wyndham East Kimberley
PO Box 614,
Kununurra, Western Australia 6743
Phone: 08 9168 4100
Fax: 08 9168 1798