Alan Dickens, Brunswick Heads
As a long time Council worker, the majority spent managing Sewage Treatment Plants (STP), the fish kills in Tallow Creek surprise me. Council would open the Belongil and Tallow Creek once or twice a year through the eighties – no fish kills occurred.
I would like to offer what I consider could possibly be the cause of the fish kills in Tallow Creek.
In the mid-nineties, Water and Recycling did interim upgrades to West Byron and South Byron STPs (WB/SBSTP). Part of the upgrade at SBSTP was the introduction of a flow-based and rated dosing system of ferric oxide, this dosing was designed by Orica. Ferric oxide (FO) is a flocculent used in water and wastewater to assist in settling out solids so they can be removed. Ferric oxide is also a chemical that will remove oxygen out of a liquid.
The dosing regime at SBSTP was designed to dose at three points but for some reason this was changed, without consulting with Orica, to one point at the inflow point of the plant. The dosing rate was never reconfigured, so the plant was being tripled dosed with FO at one point rather than spread over three.
The result of this would have led to a substantial carryover of residual FO, which, over the years possibly has finished up in the bottom of Tallow Creek. Whenever the FO is stirred up it would remove the oxygen from the water and result in a fish kill.
It was pure negligence on behalf of the Water and Recycling management not to reduce the amount of FO being dosed into the plant for all those years. A test of the base of Tallow Creek would prove or disapprove that this may be the problem.