Northlink Central Section

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Environmental planning and management during the tender phases and the delivery of the Northlink Central Section

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Team members worked closely with the Contractors to develop Environmental Management Plans and sub-plans to comply with: Main Roads requirement that ‘Delivery contractors be required to manage the IS Rating process and to achieve a minimum of an ‘Excellent’ rating’; strict Environmental Approvals under the Environmental Protection and Biodiversity Conservation Act 1999, Environmental Protection Act 1986 and the Aboriginal Heritage Act 1972 and associated ministerial conditions and permits.
This central section project will construct a free-flowing link from Reid Highway to Ellenbrook, improving access to Ellenbrook and the surrounding precincts.
It includes nearly 20 km of highway with four interchanges, including 14 road bridges and three footbridges. The Project required up to 152 ha of native vegetation to be cleared for the works.
Our Enveng team members were directly involved in the environmental planning and management during the tender phases and the delivery of the Northlink Central Section.
Team members worked closely with the Contractors to develop Environmental Management Plans and sub-plans to comply with the strict Environmental Approvals under the Environmental Protection and Biodiversity Conservation Act 1999, Environmental Protection Act 1986 and the Aboriginal Heritage Act 1972 and associated ministerial conditions and permits.
This Main Roads Project also required sustainability management during tender, procurement and delivery phases as the Project was obligated to achieve an IS rating under the Infrastructure Sustainability Council of Australia (ISCA).
It was a Main Roads requirement that ‘Delivery contractors be required to manage the IS Rating process and to achieve a minimum of an ‘Excellent’ rating’; Henceforth early engagement to plan, establish sustainability objectives and ensure these could be met throughout the Project execution played a large role within the overall Project.
Our team was able to assist the Main Contractors (Laing O’Rourke and BGC) in their commitment to the delivery of the Central Section, which has striven to enhance economic and social development, while minimising negative impacts on the natural, built and social environment between Reid Highway and Ellenbrook.
During the tender phase the Enveng team identified opportunities to reduce the volume of fill required to be imported by the project by lowering the project alignment and improving the project cut to fill ratio. The lowering of the alignment resulted in the installing of eight fauna passes to be unfeasible. The fauna underpasses were originally proposed to maintain a degree of fauna connectivity between two bush forever sites.
The 18 km alignment requiring investigation and management was mostly in areas of cut and included the consideration of Bassendean Sands associated with drainage basins. The project required approximately 2 cubic metres of fill material, consequently in order to reduce the strain on the local materials market, opportunities within the construction footprint were identified by the engineering team to increase the depth and size of the drainage basins. Two challenges were associated with the solution identified, the first was an increase in clearing of native vegetation and the second was associated with the presence of shallow coffee rock and Bassendean sands.
Water demand assessments conducted during the environmental approvals estimated a total 2.2 Gigalitres was required during the construction of the project.
No available groundwater allocation in the superficial formations.
Contractor was required to find “other sources” of water for construction. This included negotiating with land owners with bores.
To facilitate the construction of footings and services, 13 structures required dewatering spears.
Assessments, approvals and 5 C licenses were required under the Rights in Water and Irrigation Act 1914.
The monitoring of groundwater abstraction impacts for construction water and dewatering across the Northlink Central alignment situated on the GUWPCA with emphasis on the priority one drinking allocation areas, Threatened Ecological Communities and Conservation Category Wetlands.