Victorian Sites
Kubu River Hippos’ Exhibit, Werribee Open Range Zoo
introduction / overview / images / location /Projects
Landscape Architect: Urban Initiatives Pty
LOCATION: Werribee Open Range Zoo, K Road Werribee.
OVERVIEW
In 2004, Zoo’s Victoria and Werribee Open Range Zoo embarked on an innovative scheme for the Hippo Marsh Exhibit that delivers a unique experience of Hippos in a landscape thematically representing the Okavango Delta of Botswana.
The project reflects a new approach in the world of zoological design and includes a unique merging of constructed ecology, engineering and design with a key elements being the exhibit pools, filtration wetlands and hydraulic and treatment systems for Kubu River Hippos’.
This significant land management project not only challenged the traditional form of a Hippos exhibit, but the whole way it presents the critical issues to the public, engages with the visitor, cares for it’s constituents, and most importantly establishes a new approach to ‘sustainability’ within the exhibit.
BUDGET: $6.4 Million
THE CONSULTANT TEAM
Landscape, Exhibit & wetland design Urban Initiatives - Melbourne
Visitor Experience Design: Studio Hanson Roberts – Seattle
Architecture: Haskell Architects – Melbourne
Hydraulic Engineers: AHW
Structural Engineers: AHW
Biological Modelling & Water Treatment: Ecological Engineering
Captive Animal Management: Werribee Open Range Zoo
Head contractor: Kane Constructions
Wetland planting: Australian Ecosystems
Exhibit landscaping: Zoos Victoria staff
Urban Initiatives role in the development of ‘Kubu River Hippo’s’, Werribee Open Range Zoo, was to translate a biological model for the filtration system into a design than could be implemented on the Werribee site, linked to the existing site hydrology and integrated with the exhibit.
This role required understanding of the interpretive objective, and the landscape character and habitat of the featured ‘Okavango Delta’ to enable the integration of the technical and land management parameters into the design process.
The problem: Traditional re-circulating aquatic exhibits within Zoo environments are vast consumers of energy, chemicals, water and management resources.
The answer: To implement a land management solution and construct an exhibit that uses natural processes and biological systems to provide an ecologically based filtration and purification system that is sustainable and provides a healthy living environment.
Prior to this project the Hippos were resided in several couple of static farm dams and viewing was entirely via the Safari Bus, a guided bus tour that circulated through the Zoo’s remaining ‘open range’ paddocks. The dams were of such turbidity, with regular algal blooms, that when the hippos chose to be under water they were completely invisible. The Zoo’s existing Hippos, 3 females and one male, remained in their paddock and ponds day and night, since it was difficult to yard them.
The Zoo’s brief included a broad requirement for a ‘naturally filtered’ riverine exhibit, which did not depend on continuous ozone chemical water treatment, around the clock maintenance or significant energy consumption. They wanted a different looking exhibit that could be implemented on the heavy soils of the Werribee western plains and maintain a water quality that could be viewed into and was high quality (similar in appearance to ‘weak green tea’), rather than perfectly clear.
The wetland treatment system implemented in the project includes open, interconnected waterbodies that, as much as possible within performance parameters have been manipulated to resemble the flood plain of the Okavango delta of Botswana. The exhibit design incorporates a reticulated natural filtration system or a wetland treatment system, to resolve water quality issues within the three exhibit ponds.
The total capacity of the system including the wetlands is approximately 4.5-5 million litres. The use of such a system is not known to have been applied in a Zoo environment previously.
How the system operates
The aim of the project was to naturally filter the water from the three Hippo pools (approximately 2 million litres) through an extensive wetland cell system to deliver the sort of water quality that would be acceptable for an up-close viewing, and the beneficial health of the Zoo’s four Hippos.
Based on advice from Ecological Engineering, a 23-litre/sec-flow rate through the wetland was optimum to achieve a 30 hour effective detention time and the best balance between pond water quality, clarity and wetland treatment
The pond water from the lower pool is collected and pumped to the top of the wetlands. The heavily planted wetlands remove of suspended solids, trap and physically remove organisms and decrease nutrient levels. Treated water from the wetland system passes through a UV sterilisation system before entering hippo pool three before flowing onto the lower two pools. It is ultimately collected by the spillway and skimmer in front of the barge.
A sophisticated, manually operated hydraulic system has been designed to provide the Zoo with a high level of flexibilty of operation, to take into account various potential management scenarios, such as life-cycle events (off-spring), ageing, breeding and health issues. Isolation, flow splitting, flushing, drainage or maintenance of the ponds can be carried out remotely, through a system of valves interconnecting pools, inlet chambers and supply channels.
The design makes it appear that the paddocks, pools, visitor wetlands and treatment wetland marshes are linked. In fact only the paddocks are linked to the pools and the pools are connected to the wetlands. The Visitor wetlands capture all of the site and roof stormwater and itself can be biologically manipulated.
Special Factors
- Total plants – 71,936 units
- Wetland plants total – 69,312
- Oldest plants – 120 year old Ficus macrophylla
- Phragmities australis – common reed- 49,569 units This plant is indigenous to southern Australia- is also indigenous to Botswana.
- Water volume – static volume of wetlands and pools between 4.5 and 5 Million litres
- Hippo Poo – 30-40kg per Adult Hippo per day (fibre and cellulose in the water)
- Hippos will graze for 5-6 hours a night
- The Hippos do not inhabit the filtration wetlands themselves – the turbidity, apart from the damage to the plant based filtration of nutrient, would prevent the UV form working.
- There is a direct correlation between recirculation/recycle rate and energy use. As an example a relatively small exhibit pool (such as San Diego Zoo) with a 757 000 litres recirculating pump and filtration system typically consumes 2000 KwHr/day. The 2.25 MgL Hippo pools recirculate typically using only 90KwHr/day (our system consumes less than 1/20th of the energy but is three times larger).
Relevance to the profession and future land management practices
The ability of the wetland to reduce pathogen concentrations is expected to improve over time as the vegetation establishes resulting in increased biofilms which can trap and physically remove organisms.
In a carbon sensitive world, who more than Zoos and conservation organisations should be seen as leading the effort to reduce their ecological footprint? The application of low energy solutions to is the most obvious benchmark and achievement of this project.
A lot of the base references for effluent treatment for this scenario came not specifically from Hippos in captivity, but from dairy equivalent. The further use of this type of wetland and UV treatment system we hope will be applied to other applications in intensive agriculture such as dairy and aquaculture.
Success of the system and the project
Water for the initial filling and top up of the ponds is sourced from the Weribbee River. The next phase of it’s establishment will see this replaced with 90% recycled class A water from the adjacent sewerage treatment facility. This source water contains higher levels of dissolved nitrogen and phosphorus and will be a further test for the wetland system.
Although the system is not entirely maintenance free, but it is not the sort of around the clock, intensive maintenance such as is required at the Bronx Zoo, Disney’s Animal Kingdom, or San Diego Zoo.
Early testing of the old Hippo farm dams, revealed levels of E.coli in the magnitude of 4,000-40,000 organism per 100/ml. Bacteria soup!
The concentrations in the new exhibit are far lower with the concentrations at the outlet of the UV disinfection system being on most occasions less than 100 organisms/100mL.
The project is considered to be one of the most successful ever-implemented by Zoos Victoria. It won a major exhibit award at the recent Australasian Regional Association of Zoological Parks and Aquaria (ARAZPA) Awards and an Australian Zookeepers Association Award
introduction / overview / images / location /Projects
2008
