To maintain a safe and reliable drinking water supply to the community, Power and Water commenced the annual McMinns water tanks maintenance program on Tuesday 28 January 2020. Works were complete by Friday 6 March 2020.
The McMinns water tanks, a 30ML and a 50ML tank, are located within the Power and Water compound at Coolalinga.
The process
Water from the 30ML tank will be drained, mostly via normal usage, leaving less than 4.5ML (15 per cent) in the tank when it is taken out of service. At this level chlorination of the water will stop, making it non-potable.
The clean non-potable water will be released into the Freds Pass irrigation dam via our onsite drainage network and stormwater drains. We will be monitoring the water flow to ensure the chlorine residual levels meet the Australian and New Zealand Environment and Conservation Council (ANZECC) Water Quality Guidelines for ecosystem protection.
When the tank water starts to register discolouration from the sediment buildup in the tank (turbidity reading of 5 NTU on sensors) release to the irrigation dam will stop. The remaining discoloured water (and sediment, approximately 1.2ML), and any water from the pressure cleaning, will be released into our onsite sediment retention basin. The water will flow through rocks and slowly seep through a large set of mulch bunds to filter and retain the sediment before reaching the natural bushland at our McMinns compound.
When cleaning and any repairs are complete we will refill the tank, test the water to ensure it meets all necessary health standards and bring it back into service.
This same process will then be followed for the 50ML tank.
When the cleaning program is complete and the sediment retention basin empty the mulch bunds, containing the filtered sediment, will be dismantled and transported to East Arm Biosolids Treatment Plant for disposal.
More information
If you have any queries about our tank cleaning program please contact us.
