Overseeing design and construction of a 132 kV transmission line
Client: Power and Water Corporation
Location: Northern Territory, Australia
Date: September 2014 –September 2016
Providing owner’s engineer services for optimum design and construction of a category-4-cyclone-rated transmission line across a river, for secure and climate-resilient power transmission.
Background
The 132 kV transmission line from Channel Island Power Station (the largest power station in the Northern Territory and the main source of electricity for the city of Darwin) to the Hudson Creek 132 kV Terminal Station required augmenting to ensure that the new section of the transmission line crossing the 700 m span of the Elizabeth River would be able to withstand a Category 4 cyclone.
Solution
Entura acted as the owner’s engineer for the Northern Territory Government’s Power and Water Corporation, supporting it throughout the procurement, design and construction phases of this transmission line project.
The project’s challenges included provision of a 700 m span across the Elizabeth River using 70m-tall towers while ensuring that this section would survive a Category 4 cyclone (280 km/hr). Program timing was critical so as to be able to construct the line in the dry season, between April and September 2016.
Entura explored various solutions (use of high-temperature low-sag conductors, HV cable, and lattice steel towers or steel poles) with the tenderers and the client to determine the optimum solution by comparing and contrasting the technical advantages and disadvantages, the operation and maintenance requirements and associated costs, and the reliability of proposed materials and arrangements, as well as reviewing tenderers’ experience and capability to execute the design and construction.
Entura prepared the technical specification for the overhead line including technical specifications for various alternative options; responded to technical queries from all tenderers; prepared the tender assessment report; provided expert advice for design and procurement; reviewed the contractor’s design; and supervised the works on site on behalf of the client during construction.
Outcome
Working closely with Power and Water Corporation and the construction contractor, Entura’s project team was successful in scoping and executing the project to meet all project requirements. Entura’s involvement during the tender stage assisted Power and Water Corporation to adequately assess the suitability and practicality of each of the proposed solutions. Entura’s flexibility in conducting a progressive review of the design assisted the contractor to minimise re-work by providing them the opportunity to address identified concerns with the submitted designs early in the design process, saving time and costs.
The in-depth technical review of the contractor’s designs provided reasonable investigations and crosschecks to steer the design towards achieving the project goals, helping the client achieve an effective, successful and safe solution. As part of the owner’s engineer role and in coordination with Power and Water Corporation, Entura is set to deploy expert staff to supervise construction. The project is on-track to be completed by the end of September 2016 as planned.
