Rag resulted in spill
A USED nappy or rag shoved down a toilet brought on a sewerage spill that resulted in between 100 and 200 kilolitres of raw sewage getting into the Clarence River at Maclean, according to the Clarence Valley Council.
The council's water manager, Greg Mashiah, said people regularly put inappropriate material into toilets - including a beach towel that blocked a pump a couple of years ago.
But the Maclean incident last week resulted in untreated sewage getting into the river on the South Arm near the Maclean Showground.
He said the blockage occurred in the main pump at the showground, which was installed about two years ago.
The rag blocked the pump's impeller, which is designed to cater for solid objects up to 50mm in diameter.
He said council officers believed the pump had been installed so a back-up pump would kick in as soon as there was a blockage, but the system had not been programed the way they believed.
"When our guys got to work, the pump hadn't run," he said.
They flushed effluent in a nearby drain and tested water quality and initial tests showed bacteria counts were below acceptable levels.
Later tests showed bacteria counts had fallen further and were about equal to normal background levels in the river.
Council officers have now spoken with the system's installers to overcome the computer programing issues that resulted in the spill.
A second pump, near the Maclean hospital, will also be checked.
He said it was the first spill they had experienced with the new system.
Council workers have to dismantle the pumps and remove blockages by hand when they occur.
Mr Mashiah said it was not expected there would be any long term impacts on water quality as a result of the sewage overflow.