Engineering Safety at SA Water Desalination Plant Wednesday, 23 March 2016

Engineers Australia South Australia members recently visited SA Water’s desalination plant to learn about engineering safety features.

SA Water’s desalination plant can provide 100 gigalitres of fresh drinking water per year which is approximately half of Adelaide’s annual water requirement. The plant can run at 10% - 100% capacity in 10% increments ensuring it has the flexibility to respond to customer demand. The plant enables Adelaide to reduce its reliance on the river Murray and provides an insurance policy during times of drought or emergency.

The safety requirements are important to ensure the safety of people and the environment throughout the whole asset lifecycle. Continuous assessment of the environmental impact and licensing by the Environment Protection Authority (EPA) ensures that the marine environment is free from harm. Hazards within the plant have been removed and the safety concern of the plant’s ability to provide a safe and reliable water supply has been addressed. The plant removes up to 99% of the impurities and salt in the water which is then treated on-site to make sure it is safe to drink and palatable.

Safety features at the desalination plant include rails and floors made from a plastic or composite material to prevent premature ageing through oxidisation. Metal barriers are just above head height, at the end of some high-pressure vessels and at each end of the pressurised Reverse Osmosis (RO) filters. The plant’s air flow includes the deep working areas as a permanent design feature, to maintain a breathable atmosphere for workers at the bottom.

The project team considered the community and impact on the environment. The plant harvests rainwater on site for the irrigation of local species within, which in turn encourages revegetation, with local plants and animals returning to the site. SA Water also purchases all of its energy from renewable resources.

Significant marine and environmental studies were undertaken throughout the project, demonstrating compliance with strict licence conditions issued by the EPA. Approximately 70 salinity sensors are offshore surrounding the diffuser array however these only account for the permanent buoys.

The studies included thorough testing of the salinity levels, using additional sensors to test a far greater area of coastline. Multiple samples were taken and the water quality assessed, at different plant capacities, noting that the mixing from the diffuser array was generally rapid even at lower plant capacities. The results show that even at low plant capacity, dodge tide and low wind, the discharge is still sufficiently rapid to achieve the necessary levels of dilution.

The tests were conducted from Noarlunga to Hallet Cove, at numerous depths between 2mto 30m, extending from the shoreline up to 10km offshore. The saline concentrate that flows from the diffusers, when mixed with the sea water, will slightly increase the density of the sea water. This increase in density implies that the water will move to deeper areas of the gulf (i.e. out to sea) rather than down the coast to popular beaches.

Results from these studies were submitted to the EPA who concluded there was no evidence of environmental impact attributable to the construction or operation of the Adelaide Desalination Plant. On this basis, a revised EPA licence was issued in March 2015.

Do you want to tour the site? SA Water offer tours to schools, students and professional groups.

Contact:

Alison Wilson
Community Programs Coordinator
SA Water
T | 08 7424 1434
M | 0455 066 752

Article supplied by: Mark Peacock, a control systems engineer at Engineering.Systems.Management., working on engineering management, functional safety and systems safety for high-integrity control and power systems.