Tight construction time, minimal site disturbance sees remote location get potable water.

Part of the Illawarra escarpment, Mt Keira is a 464 meter high landmark with a mixed vegetation of sclerophyll and rainforest. The Lookout on Mt Keira attracts many visitors each year for its sweeping views overlooking Wollongong.

After a period of community consultation, it became clear that the lookout would benefit greatly from having a kiosk to serve refreshments to locals and tourists visiting the area. However, being a remote site meant it didn’t have access to a potable water supply.

Potable water is water that is safe to drink and use in food preparation. Engineering a Potable Water Treatment plant depends on the quality of water of the specific site, whether the source is seawater, ground water or surface water. There are many factors that influence the quality of water including temperature, turbidity, flow rate requirements and the presence of minerals and bacteria which need to be removed.

Project engineers approached us to design a water treatment plant to produce potable water from a natural water source to service the pop-up kiosk.

The plant was designed to achieve both health and aesthetic Australian Drinking Water Guidelines (ADWG), through a multi-barrier approach. The aim of this approach was to reduce relying on one process to achieve the required health-based targets. The multi-barrier approach included screen pre-filter, UF (Ultrafiltration), chlorine (sodium hypochlorite) dosing, validated absolute rated polishing filters and ultra-violet (UV) disinfection.

We installed a JUDO pressure differential-controlled screen filter to remove coarse suspended solids from the raw water to protect the UF filters from mechanical and abrasion damage. Next the water flows through the UF plant to remove solids to approx. 0.01 micron in size, including removal of bacteria, protozoa and viruses to assist in meeting microbiological health targets. UF will also remove colour associated with solids to achieve targets for turbidity and ADWG compliance.

The UF treated water flows to a 10kL clear water storage tank to allow the dosing and recirculation of chlorine to provide microbiological disinfection of bacteria and viruses. This helps to achieve ADWG microbiological compliance and to provide a chlorine disinfection residual throughout the network to the kiosk outlets.

The chlorine dosing system incorporated analyser sampling to confirm adequate dosing of sodium hypochlorite to maintain a target residual of 0.5-1.5 mg/L. The treated water was then distributed throughout the network by a duplex variable speed drive pumpset via validated absolute rated filter cartridges. This formed part of the multi-barrier approach for the removal of cysts such as Cryptosporidium and Giardia with UV disinfection as a final barrier to inactivate protozoa microbiological contamination prior to use.

All equipment was controlled by a central programmable logic controller, incorporating fault monitoring with the provision for integration with site management and reporting system.

The complete water treatment plant of interconnecting pipework, valving and wiring was housed within a shipping container, significantly minimising site disturbance and interruption.

A tight construction program meant resource management was critical. To minimise time onsite and to speedup build time, the major plant items were skid-mounted in-house and delivered to site as complete packages. The plant was built, installed and commissioned inside 8 weeks.

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