Licence conditions for pollution studies and reduction program


Licence conditions for pollution studies and reduction programs

Licence number: 2647
Title: Pollution Reduction Program 13 - Charmhaven STP Wet Weather Pond Remediation
Start date: 15 Oct 2021
Licence Condition
Background During the significant rainfall event of March 2021, the Charmhaven STP Wet Weather Storage Pond (CWWSP) overtopped due to the rate of inflow exceeding the capacity of the plant to store and pump to the outfall. The EPA note that the CWWSP has a dedicated spillway and the overtopping event resulted in a controlled discharge of treated effluent via the spillway to downstream waters and subsequently to Wallarah Creek. During reduction of the levels and operational monitoring in 2021, the licensee identified that over the course of the life of the pond, biosolids have accumulated at the base of the CWWSP which has created a reduction in depth and volume of capacity. The licensee is of the view that the removal of the accumulated biosolids will significantly increase the storage capacity for CWWSP during wet weather events. This, combined with ongoing effective pond and reticulation maintenance, will provide significant capacity to manage repeat occurrences of the significant inflows experienced during the 2021 rainfall event. Deliverables The licensee must engage a suitably qualified and experienced person to investigate and provide a report containing a full scope of works and actions recommended to safely maximise storage capacity of the CWWSP. The licensee must provide a copy of the report along with the a plan of upgrade and remediation works to the EPA's Director - Metropolitan North at by no later than 5pm Friday 31 March 2023. All works identified in the report must be completed by no later than 5pm Friday 28 June 2024.