Byron Shire Council staffer Wayne Bertram has reported to the EPA that because the water level in Tallow Creek was lowered the water became deoxidized thus resulting in a significant fish kill.
Gavin Greenoak (Echo 16/3) is correct. BSC used to open Tallow Creek twice per year to the ocean in the nineties with an excavator. No fish kills occurred during this period.
The opening of Tallow Creek ceased by BSC in the late nineties.
This raises the question why fish kills now and not then?
In the mid nineties, part of the interim upgrade of South Byron Sewage Treatment Plant (SBSTP) included the introduction of a chemical called ferric sulphide as a flocculent i.e.used to mix with sewage to make the solids settle and control phosphorous levels.This chemical dosing program and quantities dosed was designed by Orica. The design provided for three dosing points through SBSTP.
The dosing system was changed by the operator in charge of SBSTP with BSC’s Sewer Operations Management’s knowledge. Ferric was to be dosed at one point and that was to be at the head of the plant. Orica was not consulted on the dosing change.
The volume of ferric being dosed was not reduced. This meant that the plant was being significantly overdosed with ferric sulphide. My concern is, where did the unused residual ferric, which would have flowed through the plant, finish up?
This practice continued until South Byron STP was taken off line in 2006.
Ferric sulphide will deoxidize water. Was the residual of the ferric sulphide from SBSTP sitting at the bottom of Tallow Creek creating a deoxidised zone in the water?
The EPA licence monitoring required to be carried out on effluent leaving SB STP did not include ferric sulphide and despite having a Nada registered laboratory owned by BSC in the Byron industrial estate, no testing was carried out for levels of ferric sulphide leaving South Byron STP into Tallow Creek.
I am left wondering if Mr Bertram or Mr Pugh were aware of the ferric sulphide dosing which had been carried out at South Byron (STP)?.
Alan Dickens, Brunswick Heads