Seawater Quality Monitoring

Seawater quality is continuously monitored from the moment it enters the plant and moves through the desalination process to where it becomes potabilised water. The seawater concentrate is also continuously monitored as it is returned to the marine environment.

Seawater concentrate is only returned to the marine environment when the plant is producing potable water.  Therefore monitoring is only applicable when the plant is producing water.

Process Monitoring

The seawater and subsequent potable water quality is continuously monitored within the plant for parameters such as pH, turbidity, residual chlorine and temperature to ensure that it meets both the operational and the contractual requirements.

The plant is equipped with automated control systems which provide an early warning of any unexpected changes in water quality at the plant, and automatically correct the process to bring water quality levels back to the required target range.

Should the control system fail to correct the deviation the process will be automatically stopped until the issue has been resolved.

The continuous in-plant monitoring and automated control systems are critical safety features that ensure corrective actions can be taken before potential issues even reach the marine environment.

Seawater Concentrate Monitoring

The seawater concentrate (which is the seawater not used in the desalination process) contains salt and other elements that already occur naturally in seawater. Chemicals used in the desalination process are removed from the seawater concentrate, or neutralised, before the seawater concentrate is discharged.

A key Performance Requirement and EPA Discharge Licence condition for the operation of the plant and marine outlet structures is that only seawater concentrate that meets the requirements of the EPA Licence conditions can be discharged to the marine environment. To obtain a copy of AquaSure’s EPA Discharge Licence (No. 8693), see https://www.epa.vic.gov.au/for-business/permissions/search-for-licence

Continuous monitoring of the seawater concentrate quality in the outfall chamber is undertaken before it reaches the outlet tunnel and structures to ensure discharge limits are met (see monitoring results below). Should an issue be detected the plant will automatically stop production to prevent out of specification water from entering the marine environment.  The EPA Licence also requires the seawater concentrate to be diluted back to appropriate levels within a specified area called the mixing zone. The VDP mixing zone has been approved by the EPA and extends 180 metre from each of the two outlet structures.

The mixing zone is a defined area where some changes to the marine environment are permitted, although effects must still be minimised. Within this area changes such as an increase in salt tolerant species can be expected. Outside the mixing zone no changes to the marine environment in relation to the plant operation are permitted.

Seawater Concentrate Monitoring Results

Seawater concentrate monitoring results are published on a monthly basis when the plant is producing water.

Annual summary results are provided in our Annual Report.

Any non-compliance with EPA requirements is reported to EPA Victoria.