‘Good’ water produced overnight but not enough

Thursday 24 August, 8.30am:

Council last night managed to reduce the salt concentrations in the drinking water treated at the Bray Park Treatment Plant but has been unable to produce enough ‘good’ water to fully satisfy demand today.

Actions taken yesterday afternoon to bring in a small surface pump to draw the ‘good’ water from the top strata of the dam, avoiding as much as possible any draw of the heavier salty waters from the bottom levels, worked. The amount of total dissolved solids in the treated supply fell to within the ‘good’ range.

However, a number of reservoirs need to be recharged today and Council is again urging residents to use as little water as possible while it works to get more ‘good’ water into the system.

The treatment plant operated all night to treat the water intake but with inflow rates of ‘good’ surface water at just 128 litres per second, Council does not yet have the 20 megalitres of ‘good’ water it will need today to recharge the reservoirs.

Consequently it will start the main intake pump and run it at minimal capacity to limit the draw of salty water and, together, both pumps should draw a greater volume of a suitable ‘shandy’ of ‘good to fair’ quality water to boost production.

The dredge pumping the salty water from the bottom of the weir is now drawing very salty water from a depth of 8.5 metres at about 160 litres a second and releasing it downstream.

“If we can minimise the amount of water consumed and maintain a higher production level of ‘fair’ quality water, the situation will gradually improve from here on,” Manager Water and Wastewater Anthony Burnham said.

“But, if the demand for water is not contained, we will have to draw more salty water into the system to guarantee supply.”

The Australian Drinking Water Guidelines rule <600mg/litre of dissolved solids is ‘good’ quality; 600-900mg/litre is ‘fair quality; and, >1200mg/litre is of ‘unacceptable’ quality. Water produced last night had a dissolved solids concentration of 204mg/litre. By bringing the main pump online Council expects that to rise to about 500mg/litre today. Normally the water produced at the plant has a dissolved solids concentration of 160mg/litre.

The Australian Drinking Guidelines advise that the current salt levels are not harmful to human health. However, residents are advised to use bottled water for drinking if the taste of the water is too unpalatable.

The water at Uki and Tyalgum is not affected and no restrictions apply in those villages.