The Oxley Creek sewage treatment plant in South East Queensland was impacted by severe flooding in 2011 causing $32 million worth of damage, forcing part of the treatment plant offline. This prompted a flood resilience upgrade to the facility to reduce the plant’s recovery time in case of future flood events.
Oxley Creek sewage treatment plant currently processes 65 million litres of sewage per day. It plays an important role in sewage treatment services provided by Queensland Urban Utilities. As one of the largest water distributor-retailers in Australia, Queensland Urban Utilities supplies drinking water, recycled water and sewage services to a population of more than 1.4m in south-east Queensland.
From the business case to completion, the plant upgrade project took three years with the help of Monadelphous Engineering, MPA, Voltex and NHP Electrical Engineering. A range of flood proofing measures were incorporated into the design of the upgrade, including an installation of a new high-voltage switchroom within a demountable building, which is where NHP’s help was enlisted.
The project included decommissioning the original high-voltage switchroom and the 11kV main switchboard for the site, and replacing it with a new main 11kV switchboard contained within a demountable building. The building was also raised 30cm above the 2011 peak flood line levels.
Within the switchroom, NHP specified the DF-2 air-insulated switchgear module with demountable vacuum circuit breakers and a remote operation functionality. Exclusive to NHP switchgear, the cubicles were specifically designed to minimise the consequences of an internal arc and forming a key component of this, is a built-in arc quenching system “arc killer”, which can extinguish an arc in less than 50ms.
Kim Kamat, from NHP business development, said, “With experts in this space, NHP were able to design, supply and install a solution for Queensland Urban Utilities that not only meets local requirements, but delivers an advanced technology which only NHP offers to the market”.
With the IEC 61850 GOOSE-based, arc-flash protection scheme recently implemented, the project requirements met these standards and assisted with minimising cut-over times and reduced installation time of the switchboard by minimising control wiring and testing. Provided for the complete protection, control and monitoring for this, agile protection relays were integrated into the solution.
As well as the high voltage equipment provided by NHP, there was a detailed design of the switchboard schematics that was undertaken by NHP staff in Melbourne who were familiar with the product capability and the design quality. Upon project completion, NHP delivered training sessions and provided training manuals to support Queensland urban utilities with ongoing maintenance requirements and operation.