Coliban Water experienced significant infrastructure impacts as a result of the 2022 floods in northern Victoria, but through an intense collaborative effort, maintained water services throughout. As the floods resided and the clean-up commenced a less visible risk emerged, a severe deterioration in and great variability of, raw water sources.
An exhausted treatment team turned their attention to the emerging threat and worked together to determine how to treat water that exceeded the treatment envelope of several water treatment plants, with raw water quality so poor, it was outside observed operational experience. This paper investigates the trials and tribulations of the team tackling a wave of challenges at the Cohuna Water Treatment Plant (WTP) to maintain a safe drinking water supply to the Cohuna community.
Highlights include:
- Implementation of enhanced coagulation to treat the high colour/low turbidity water
- An unsettled sludge blanket triggering poly trials and the return to service of decommissioned clarifiers
- 24/7 plant operation, resulting in break downs and rapid repairs
- Tri-daily cleaning program to manage weeds at the raw water inlet
- High concentrations of metals, requiring hypochlorite dosing to achieve pre-oxidation on the filters
- Taste and odour issues requiring a high powdered activated carbon (PAC) dose
- High concentrations of dissolved organics, requiring a maximum chlorine dose
- Demand exceeding supply, leading to the rural network isolation, a Boiled Water Advisory, and a major water carting operation
Author
- Angus Bowles, Manager Catchment & Water Treatment Operations, Coliban Water
- Cameron Kervin, Senior Water Treatment Operator Northern, Service Stream