Set amidst one of Hobart’s busiest shopping precincts is the newly constructed Rosny Park zone substation. As one of three new substations commissioned by TasNetworks to cater for future electrical load increases, the Rosny substation has been a design and construction project defined by community engagement, tight project management and logistical coordination.
Rosny Park zone substation is an integral part of TasNetworks’ overall Hobart Eastern Shore future supply arrangement. Installing a new zone substation at Rosny will support the Lindisfarne and Geilston Bay substations to meet the required capacity for the area.
TasNetworks sought a contractor to provide a turnkey solution for the project.
Zinfra was chosen for the job and is responsible for delivering the overall project management and electrical construction components, while managing subcontractors for the design and civil construction elements.
In order to allow for future capacity, the 33/11kV zone substation design includes allowance for three 25MVA transformers, associated circuits and auxiliary equipment.
The construction scope is for the infrastructure to house two transformers and associated equipment and switchgear, as well as an additional 25MVA transformer, which will be installed initially.
To round out TasNetworks’ turnkey requirements, Zinfra is responsible for delivering the installation of the associated sub-transmission and distribution cables (under a separate contract), as well as commissioning management.
The urban environment in which the site is nestled has required delicate and careful community engagement and liaison.
Zinfra Project Manager, Andrew Hadley, has had his finger on the pulse.
“We’re located near this major shopping centre [Eastland], so pedestrians and traffic are a big consideration for us while we are managing this project,” Mr Hadley said.
“We’re sandwiched between residential properties, Cambridge road – a busy four-lane thoroughfare – and retail stores.”
Open and thorough communication throughout the process meant the local community were kept informed and were considered throughout the construction period, despite heavy excavation, noise and increased traffic to the site.
“We even created a temporary driveway for the next door [resident] neighbour while we were working near their own driveway,” Mr Hadley said.
A cable trench located below the switchgear required a five metre deep shear excavation. The trench runs along the boundary line to the adjacent neighbour’s driveway, so the driveway had to be closed and temporary parking made available on the substation site.
The shear excavation also required shotcrete application and geotechnical sign off for access to the cable trench.
Being constrained to a standard size residential block required careful consideration in terms of construction methodology for both current activities and future development.
The challenges presented by the small site are compounded by a single point of entry, so coordination and sequencing of construction has been critical to the successful delivery of the project, not to mention its safety.
“Having one access point means we have to coordinate what activity is occurring and where on the site at any point in time. If we’ve got an excavator working at the front of the site, like today for example, it means we can’t have access to the back of the site during this period.”
The project currently has no LTIs or MTIs and is scheduled to finish at the end of October.
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