When the people of King Island needed a sewerage treatment plant, Syrinx Environmental proposed a passive treatment wetland system to solve the problem. Instead of unsightly and smelly engineered tanks, and pumping effluent into the sea, the wetlands treat sewerage naturally. Capturing the shape of the dunal landscape, these wetlands use native vegetation to treat the effluent. The result is a natural system with minimum embodied energy and high habitat values.
Design Strategies
A combination of mechanical filters for pre-treatment, followed by a series of
slow flow vegetated wetlands, open water zones and a subsurface bio-filter were
designed to integrate with the site to provide additional benefits such as habitat
and landscape values.
The project captures the essence of the dunal landscape of the Reserve and worked
within this theme to build an appropriate and site-specific wetland treatment system.
'Sustainable Industry' was proposed as an interpretive theme to highlight the
IslandÛs commitment to the pursuit of environmental sustainability within a
strong export industry backdrop. Where possible, materials local to King Island such
as the grey granite 'shingle' rocks havebeen chosen as the key defining feature of
the site to reinforce a local identity.
Environmental Outcomes
1) First application of constructed wetlands for secondary sewage treatment in
Australia
2) Low energy requirement system, integrating primary treatment with gravity fed constructed wetlands
3) High quality effluent discharge via an ocean outfall
4) Potential for reuse at minimal cost
5) Selection of native vegetation proven to be suitable for passive systems with high
organic loading
6) Wetland performance exceeding expectations
Social Outcomes
1) Local community participation
2) Educational awareness
3) Protection and enhancement of the 'green' image of the island
4) Enhancement of ecotourism values of the island
Economic Outcomes
1) Capital cost <30% of equivalent mechanical systems
2) 70% wind energy from central hybrid wind/diesel plant
3) Very low operating costs, due to native vegetated landscape and predominantly
passive technologies
4) Capitalisation of potential ecotourism opportunity
5) Provision of employment opportunities for local residents
6) Potential for reuse at minimal cost
Syrinx identified the skills of local industries and businesses as being significant to the
success of the project. The local community was therefore utilised as a source of
sustained employment in the construction, implementation and ongoing management
and monitoring of the wetland.
