2.1
The Department of Infrastructure, Transport, Regional Development and Communications seeks approval from the Committee to proceed with the proposed project, Christmas Island Stormwater, Landslide and Rockfall Mitigation Works Project.
2.2
The Department of Infrastructure, Transport, Regional Development and Communications (the Department) states that:
The Project aims to reduce the risk of injury or death, asset damage, and social and economic disruption from flooding, rockfall and landslides on Christmas Island by installing fit-for-purpose stormwater and landslide mitigation infrastructure.
2.3
The estimated cost of the project is $28.9 million (excluding GST).
2.4
The project was referred to the Committee on 12 May 2021.
Conduct of the inquiry
2.5
Following referral the inquiry was publicised on the Committee’s website and via media release.
2.6
The Committee received one submission, one supplementary submission, and two confidential supplementary submissions. A list of submissions can be found at Appendix A.
2.7
On 6 August 2021 the Committee conducted a virtual site inspection, private briefing, public and in-camera hearing via teleconference. A transcript of the public hearing is available on the Committee’s website.
Need for the works
2.8
A large portion of the population of Christmas Island lives in the five precincts surrounding Flying Fish Cove, a small sheltered bay on the northern tip of the island. Of these precincts, the Kampong, Flying Fish Cove and Smith Point Precincts are the most vulnerable due to the ‘almost continuous series of steep cliffs that descend from the island’s flat summit’. These areas include schools, multistorey apartments, houses, shops, community and port facilities, and critical infrastructure.
2.9
Measures to reduce the dangers posed by landslides include fencing and earthen beams, installed in six locations, in the late 1990s and early 2000s. These barriers were intended to reduce the risk of fatality through capturing fallen boulders and debris, however heavy rains have caused multiple landslides over the past five years and damaged barriers.
2.10
Due to age and deterioration, the current barriers are no longer fit-for-purpose and offer the community of Christmas Island little protection from the destruction of roads, and carparks, and the disruption of services. In addition, stormwater flooding remains an ongoing issue affecting local streets, properties, parks across both the island’s high and low lying areas, while the Christmas Island High School has recorded dangerously high flood water levels.
2.11
In their submission, the Department drew attention to the long-lasting impacts of landslides and flooding:
Loss of life and injury are the most severe potential outcomes of landslides and flooding at the Kampong and Flying Fish Cove. However, incidents can also undermine the area’s liveability and have economic impacts by restricting tourism activities, reducing access to economic hubs and employment areas, impeding suburban development and damaging business and community infrastructure.
2.12
Assessments of existing stormwater and landslide mitigation infrastructure were conducted in 2017 and 2018 respectively.
2.13
A technical assessment of stormwater infrastructure at the Drumsite Precinct was conducted in 2017, with remediation of high priority areas addressed through a $1.5 million works package.
2.14
A 2018 assessment of landslide mitigation fences and berms at the Kampong precinct identified four rockfall fences which posed ‘an unacceptable risk for loss of life’. Replacement of these fences as part of a $7 million medium works project, approved by this Committee in April 2020, is currently underway and due to be completed in late 2021.
2.15
The Department stated that as an administrator they have a responsibility to mitigate landslides.
Options considered
2.16
In developing the detailed business case for the works, the Department considered ‘Stormwater Remediation (Stage 2) Works’ and ‘Landslide Mitigation Works’ separately. Qualitative and quantitative assessments were used to determine the preferred options for both elements of the project.
2.17
In total, the Department considered 11 stormwater remediation options across the Drumsite Precinct’s three catchment areas (Northern Drumsite, Central Drumsite and Southern Drumsite). These approaches considered included doing nothing, upgrades to existing works, or more comprehensive overhauls and replacement of existing drainage systems. The Department noted that:
In general, preferred options connect to, or direct stormwater flow into existing drainage infrastructure to maximise its use. Some infrastructure must be upgraded so it can cope with new inflows.
Solutions focus on capturing and redirecting stormwater flows away from the escarpment above the Kampong and Port areas, particularly in the Central and Northern Drumsite catchment.
2.18
The Department’s preferred options for the Stormwater Remediation (Stage 2) Works were:
Northern Drumsite. Option 3 – Installation of additional pit and pipe drainage throughout the area along with creating compensation within the Northern Drumsite then directing stormwater flow down the George Fam Incline with further detention adjacent the George Fam Incline.
Central Drumsite. Option 3 – Installation of additional pit and pipe drainage to local roads and installation of a diversion bund adjacent Nursery Court.
Southern Drumsite. Option 4 – Combination of the installation of additional pit and pipe drainage on local roads, a new basin to the south of the Christmas Island school, installation of an on roadway speed hump diversion south of the school site, and reshaping of school entrance roads to redirect stormwater flows in this area.
2.19
The Department stated that all stormwater remediation infrastructure has a design life of 50 years or more.
2.20
In addressing landslide mitigation works across three sites at the Kampong Precinct both, six infrastructure interventions options were considered across three sites (Sites C, D and F as outlined in the Department’s submission). These included development of rockfall barrier fences, reinforced earthen berms, reinforced gabion walls, rigid concrete walls, supplemental baffles and channelised attenuation.
2.21
The Department stated that ‘rockfall barrier fences and reinforced earthen berms are the only geographically appropriate interventions’. The preferred option replaces existing 1,000-kilojoule-capacity fences and berms (which have an unknown capacity) with 3,800-kilijoule-capacity berms, which have a 100 year lifetime.
2.22
In evaluating the options, the Department stated that ‘the proposed project works represent the best value for money to the Commonwealth and will deliver multiple benefits … to the Christmas Island community’.
Scope of the works
2.23
The Department stated that the proposed scope of the project will ‘deliver works at the Drumsite Precinct, located on the central plateau 2.5 kilometres from the Christmas Island Airport, and the Kampong and Smith Point Precinct, located on the shoreline three kilometers north-west of the airport’.
2.24
The proposed scope for the Stormwater Remediation Works includes the ‘design and construction of new drainage infrastructure to better manage stormwater flows within, and discharge from, the Drumsite Precinct to reduce landslides and flooding at Flying Fish Cove, the port and Kampong’. Specific elements include ‘installing new lined basins, bunding, culverts, pits, extensive pipework, open drains, basins, and stormwater diversion structures’.
Works will be delivered at three distinct catchment sites and include:
Northern Drumsite – drainage upgrades on and adjacent to the George Fam incline to capture, slow and redirect stormwater flow;
Central Drumsite – drainage upgrades, installation of additional pipework and pit infrastructure on and adjacent to Murray Road to reduce road flooding and redirect water discharge; and
Southern Drumsite – installation of a new lined basin, drainage pipework, pit infrastructure and admendments to roadway design near the Christmas Island High School to improve drainage networks and redirect water.
2.25
The proposed scope for the Landslide Mitigation Works includes ‘the design and construction of new landslide and rockfall protection barriers across the bottom on the escarpment in the Kampong Precinct to reduce the impact of landslides’ and the associated dangers. The works will be delivered across three sites:
Site C – Two fences at Site C will be removed and a single berm will be demolished, with a new berm installed. Site C is located behind Block 413. Utilities such as a galvanised iron potable water main and a sewer main are buried beneath the berm;
Site D – The single fence at Site D will be removed and a single berm will be demolished. A new berm will then be installed. The berm also contains buried utilities; and
Site F – The fence at Site F (Christmas Island Club Fence) will be upgraded. The lower section of this fence is partially located in Site E and is being upgraded through the early works package.
Community consultation
2.26
The Department stated that since 2017 there has been significant community consultation through face-to-face public hearings, site inspections, bilateral discussions, and community forums. Further, since 2017 key stakeholders have been engaged with the project through monthly teleconferences, project workshops and review processes, with consultation ongoing.
2.27
The Department drew attention to the benefits of early consultation with key local groups including Christmas Island Phosphates (CIP), the Emergency Management Committee, and the Shire of Christmas Island. A representative of GHD reflected on discussions with CIP and noted:
They've highlighted a number of concerns that we weren't necessarily fully across at the start, and we've adjusted the design to better equip that area so that it remains fully accessible for them during their mine operations. That's been quite an intricate process, and it's been very positive.
2.28
Additional stakeholder and community consultation by the Department include:
provision of a dedicated informational webpage on the project hosted on the Department’s website; and
correspondence from the Assistant Minister for Regional Development and Territories, the Hon Nola Marino MP to the Member for Lingiari, Northern Territory, to the Hon Warren Snowdon MP.
Cost of the works
2.29
The proposed works have an estimated cost of $28.9 million (excluding GST) and is inclusive of management and design fees, construction costs, contingencies and escalation provisions.
Revenue
2.30
There will be no revenue generated by the project.
Heritage protection and environmental impact
2.31
The Department stated that the project will improve environmental sustainability on Christmas Island ‘by reducing the impacts of major rainfall events on infrastructure and natural areas’, which will ‘reduce the risk of landslides and erosion to avoid future degradation of natural areas and damage to developed areas’.
2.32
Environmental impacts of both stormwater remediation works and rockfall (project element 1) and landslide mitigation works (project element 2) were undertaken for the project.
2.33
Environmental risks for project element 1 were deemed suitable to be ‘managed through site-specific construction environmental plans’. The Department noted that project element 2 requires minimal vegetation clearance, and there are no anticipated impacts to protected flora or fauna, ‘however, migration paths for the red crab species (Gecarcoidea natalis) must be maintained as it is likely that crabs will move down the escarpment to the cove’.
2.34
The project’s impact on items of heritage value are minimal, and ‘can be managed through site-specific cultural heritage management plans’. The Department stated that elements of project will deliver increased protection to culturally significant sites from landslide hazards.
Committee comment
2.35
The Committee thanks the Department for their highly detailed presentation and briefing which was provided to the Committee in lieu of an in-person site inspection.
2.36
The Committee is pleased to note that the proposed works will result in a higher level of safety to the public and provide critical infrastructure required to mitigate key health and safety risks to the Christmas Island community and visitors.
2.37
The Committee did not identify any issues of concern with the proposal and is satisfied that the project has merit in terms of need, scope and cost.
2.38
Having regard to its role and responsibilities contained in the Public Works Committee Act 1969, the Committee is of the view that this project signifies value for money for the Commonwealth and constitutes a project which is fit for purpose, having regard to the established need.
2.39
The Committee recommends that the House of Representatives resolve, pursuant to section 18(7) of the Public Works Committee Act 1969, that it is expedient to carry out the following proposed works: Department of Infrastructure, Transport, Regional Development and Communications, Christmas Island Stormwater, Landslide and Rockfall Mitigation Works Project.
2.40
Proponent entities must notify the Committee of any changes to the project scope, time, cost, function or design. The Committee also requires that a post-implementation report be provided within three months of project completion. A report template can be found on the Committee’s website.