Pipe scouring underway to take salt out of water main

23 August 2017, 12.30pm:

Council has begun scouring the mains pipe from the Bray Park Water Treatment Plant to King Street, Murwillumbah, to remove the likely highest salt concentrations from the top end of the Tweed water reticulation system.

A dredge is expected to arrive on site at Bray Park Weir late this afternoon to begin pumping out the heavier salty water from the bottom of the weir as a continual release from Clarrie Hall Dam refreshes with good water at the top of the pool.

Intake baffles at the weir have been closed at deeper depths and the main pump has been set to run at minimal capacity to reduce – as much as possible – the draw of salty water from the bottom of the pool. A smaller floating surface pump has been installed and is running at maximum capacity to draw good water from the top of the pool into the treatment plant.

“With these actions in place to reduce the salty water within the reticulation system and draw in as much ‘good’ water as possible, we have started to dump about one-fifth of the poorer quality water ready for release into the reticulation system in anticipation of producing better quality water tonight,” Manager Water and Wastewater Anthony Burnham said.

“Still, all going well, it is going to be at least three to four days before we get the salty taste out of the water and at least a week before we will be able to produce our normal high-quality drinking water.”

Further investigation into the climatic conditions leading up to the overtopping of the weir wall on Monday night confirms a perfect storm of events.

Bureau of Meteorology and tide data confirms a run of higher-than-expected tides up to 420mm above predicted levels; higher salinity levels offshore; and, warmer ocean temperatures.

Mr Burnham thanked Tweed residents for assisting by minimising their use of water.

“Hospital Hill reservoir is holding relatively steady at this stage which shows people are responding to our request to minimise water use. This effectively buys us time to rid the system of salt before the demand for water forces us to release more poorer-quality water into the system.”

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.