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GRANITE ISLAND CAUSEWAY PROJECT
GRANITE ISLAND CAUSEWAY
GRANITE ISLAND
CAUSEWAY PROJECT WRITTEN BY ANTHONY O'BRIEN
The South Australian Government has committed $43 million for the Granite Island Causeway Project, which is being delivered by the Department for Infrastructure and Transport (DIT) and its contractor McConnell Dowell.
The landmark new Granite Island Causeway is now open and even the famous double-decker tramcars hauled by a magnificent team of Clydesdale horses are back.
The new 650-metre Causewayi opened to pedestrians on Wednesday, 22 December 2021, and further works are continuing in 2022, including the decommissioning of the old Causeway, the construction of a new boat landing facility, and minor finishing works. The Granite Island Causeway is located on the Fleurieu Peninsula, 83 kilometres south of South Australia's capital city, Adelaide. The project is supporting approximately 43 full time equivalent jobs per year over the life of the project. CONSIDERABLE HERITAGE VALUE
The Causeway is an iconic landmark with considerable heritage value. For locals and tourists, it is the only link between Granite Island and the mainland at Victor Harbor and it is also a site of cultural significance to the traditional owners of the area. The Causeway and its famous horsedrawn trams are also popular tourist attractions, important to the local, regional, and state economies.
CONDITION OF OLD CAUSEWAY
A condition assessment identified that the old Causeway was approaching the end of its useful life and a feasibility study into the potential upgrade options determined that retaining the old structure was not viable. A heritage impact statement found that only a very small proportion of the existing timber structure is original fabric. Existing timber elements have degraded to the point where they are no longer providing adequate support, resulting in the structure needing to be temporarily propped. The piles on the old Causeway have multiple issues including weathering /rot, marine borer attack, and white ant damage. The pile connections to the old Causeway headstocks in many instances have been compromised, where multiple bolts, plates and connections have been applied in the past which has weakened the structural integrity of these connections. Retaining the old Causeway in its current state would pose major safety, maintenance, cost and access issues, requiring ongoing monitoring, checking and propping to maintain safety, which is not sustainable. As part of the conditions associated with the Development Application approval, two substantial portions of the old Causeway will be retained at each end. These will be conserved and repaired for pedestrian access, to become viewing platforms with integrated signage to allow an appreciation of the history, original fabric and sightlines of the old Causeway.
UNINTERRUPTED, RELIABLE ACCESS TO THE ISLAND
The new structure provides a holistic, ‘like for like’ design solution with a 100-year design life that creates an elegant local landmark, respectful of heritage and place, meeting all relevant Disability Discrimination Act 1992 and standard requirements while also being a ‘whole-of-life’ solution that minimises maintenance costs over time.
The new Causeway will provide ongoing access to Granite Island with a modern structure that respects its historical significance. The new Causeway continues to deliver and enhance social and economic benefits to the region and provides a long-term solution that is environmentally sensitive. Other benefits of the reconstruction include the installation of a new and improved boat landing, to create better access for local tourism operators. The project will also enable more efficient and full access to and from Granite Island for emergency services. As mentioned earlier, the iconic Victor Harbor horse-drawn tram from the mainland to Granite Island Recreation Park is back. The tramway is one of the few remaining horse-drawn tram routes still operating around the worldii .
FAUNA SENSITIVITIES ADDRESSED
The protection of whales and other marine fauna sensitive to noise has been carefully considered throughout the planning, design and construction of the project. According to a spokesperson from DIT, the project is being managed in accordance with the Department’s Environment and Heritage Impact Assessment processes and Environmental approval conditions. “A number of control measures were implemented during construction works. The shallow water, combined with a modified piling gate with an air bubble curtain used during piling works limited any potential negative noise impacts to whales to within approximately 200 metres of piling works.
“Exclusion zones were also put in place to protect marine fauna while piling works were undertaken. Piling activities were required to stop if fauna entered these exclusion zones. The exclusion zones were 1 kilometre for whales, and 300 metres for dolphins, sea lions, seals and penguins. “Also, a marine observation zone of 1.25 kilometres was adopted prior to, and during, all piling works, with two or more specially trained marine fauna observers monitoring the exclusion zones. This approach was endorsed during assessment of the project under the Environment Protection and Biodiversity Conservation (EPBC) Act and was formalised in the Contractor’s Environmental Management Plan. “The Department also referred the project to the Commonwealth Department of Agriculture, Water and Environment (DAWE), which is the authority responsible for protecting whales (as well as other protected marine mammals). DAWE advised that the proposed mitigation measures were sufficient for the protection of whales within the area.”
GRANITE ISLAND – OLD AND NEW CAUSEWAY
PROTECTING THE PENGUIN POPULATION
The project team worked closely with the Department for Environment and Water, the Save Granite Island’s Penguins Group and Flinders University to ensure all possible mitigation measures were adopted to minimise impacts to the little penguin population on Granite Island. Several specific measures were adopted to mitigate negative impacts on the breeding patterns of the little penguin population. These measures included burrow surveys on Granite Island, phasing works outside of the breeding season, and conducting piling during daylight hours only to limit any disruption to penguins leaving/returning to Granite Island. In addition, if a penguin burrow was observed near the works,
cameras and noise monitoring were set up at the burrow and noise abatement enclosures were erected around the burrow.
As part of the project, a new fox gate will also be installed on the new Causeway, to protect local fauna.
WHAT FLORA WAS CONSIDERED AND HOW IT WAS PROTECTED
Vegetation present included a mix of native vegetation (including seagrass), regulated and significant trees and amenity vegetation. Throughout the design and construction process, impacts to vegetation were considered and avoided or minimised where practical. As an example, seagrass was protected by minimising the number of piles, minimising vessel movements in shallow water and controlling silt generation, while terrestrial vegetation (including a significant tree in the plaza area), was protected via establishment of tree protection zones. The design of the paved area near the significant tree was also changed from an impermeable concrete to permeable material to allow water to pass through and into the ground below for use by the tree. Overall, the project’s planning and design teams included environmental advisors and technical specialists, such as ecologists, heritage consultants and acoustic consultants. Similarly, the construction team includes an environmental management representative who is also supported by a technical specialist and construction staff, who all complete a site-specific induction that covers environmental management for the project and are provided with additional training for specific tasks as required. In addition to this, four marine fauna observers are employed during piling works.
DECOMMISSIONING OLD CAUSEWAY
The old Causeway closed on 31 January 2022 to commence preparation works for the decommissioning of the structure. Following the decommissioning, all timbers removed from the
structure will be stored off-site and will be inspected to determine the presence of any pests (termite/borer) and contamination (tar coatings, other) to decide whether the timber is suitable for re-useiii .
Timber will be sorted and where reusable will be prioritised for re-use as follows: ф replacement timber where required on the remaining old Causeway viewing platforms;
ф reuse throughout the project (seating, signage, art); ф stored for re-use on DIT marine jetty structures; ф allocated to council and the
Department for Environment and Water (for re-use on local community projects); and ф made available to registered interested parties. Until the timber structure is decommissioned the Department will not be able to determine the quantities of timber that may be available to interested parties. The Department cannot guarantee that timber will be available to those who register their interest. Interested parties can register their details by sending an email to DIT.GICauseway@sa.gov.au. All interested parties will be advised once more information on the condition of the timbers is known.
The decommissioning of the old Causeway is expected to be completed in the second half of 2022. To find out more about the Granite Island Causeway Project, provide feedback or register to receive project information as it becomes available, register your details or phone: 1300 049 048 email: dit.gicauseway@sa.gov.au
i https://www.environment.sa.gov.au/goodliving/posts/2019/07/granite-island-activities ii https://www.environment.sa.gov.au/goodliving/posts/2019/07/granite-island-activities iii https://dit.sa.gov.au/infrastructure/major_projects/granite_island_causeway
GRANITE ISLAND – NIGHT IMAGE OF NEW CAUSEWAY
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