Project Overview
UDCS Consulting was engaged by Sovereign Energy and the Department of Defence, on behalf of John Holland, to undertake the detailed design, review, and optimisation of the earthing system for the 33/11kV bulk supply substation ISS-1 located within the Gallipoli Barracks precinct in Enoggera, Queensland.
The project involved both the development of a new compliant earth grid design and the optimisation of previously proposed solutions. The objective was to improve safety performance, reduce risk, and enhance constructability while supporting staged construction and energisation requirements.
Scope of Works
UDCS Consulting delivered a full earthing assessment, redesign, and validation package, including:
- Detailed ground resistivity testing across the site using the Wenner 4-Point Method and Fluke 1625 Geo Earth Ground Tester
- Development of a two-layer soil model and earthing system simulation using CymGrd™
- Engineering and optimisation of the earth grid layout to improve constructability and reduce installation complexity
- Simulation and assessment of Earth Potential Rise (EPR), step voltage, and touch voltage under fault conditions
- Refinement of the design to accommodate staged construction and partial energisation of the 11kV switchroom prior to full substation completion
The combined study provided both validation of safety performance and a practical, constructible solution for site delivery.
Design Approach
The earth grid was designed and optimised to meet stringent fault condition safety requirements while accommodating complex construction staging constraints.
Design parameters were based on Energex-specified fault levels of 6kA at 33kV for 2 seconds, with 11kV fault conditions considered secondary. A key focus of the design approach was the use of measured site-specific soil resistivity data, which significantly improved the accuracy of modelling outputs compared to standard assumptions.
All design and analysis were completed in accordance with:
- ENA EG-1 – Substation Earthing Guide
- AS/NZS 2067
- IEEE Std 80-2000
Project Outcomes
- Reduced metallic pipeline hazard zones from 1.3 km to 320 m
- Reduced telecommunications earthing hazard zones from 120 m to 30 m
- Delivered a significantly more efficient earth grid design with reduced copper usage
- Lowered overall construction cost through targeted optimisation
- Improved constructability and enabled staged construction and energisation
- Successfully delivered within required timeframes to meet the requirements of Sovereign Energy, John Holland, and the Australian Defence Force
