In 2010 Urban Water Solutions was engaged by South East Water to build and calibrate an InfoWorks CS hydraulic model of the Blind Bight sewerage catchment.  The catchment includes the townships of Blind Bight, Tooradin, Cannons Creek and Warneet and is served by a mix of gravity and pressure sewers.  Constructed in 2001, Tooradin was the first pressure sewerage system constructed in Australia.

The objectives of the project were to:

• develop an understanding of how the pressure sewer component of the system was currently operating and assess its future performance as planned growth was achieved
• detail any system limitations
• compare Inflow/Infiltration rates between the gravity and pressure sewer components of the system
• use the model for master planning and operational purposes

An all-property hydraulic model was built which included over 780 pressure sewer pumps fully modelled with manufacturer’s curves and correct operating levels.  A flow and pressure monitoring programme was implemented with the data collected used for model verification.

Key findings of the project were:

• the pressure sewer component of the system was generally over-sized resulting in low velocities and associated maintenance issues
• the pressure sewer system had a negligible wet weather response
• the InfoWorks CS model was proven to be a robust platform for replicating the pressure sewer system performance, in particular the ability to include the actual wet well and pump type at each individual property.

Recommendations were made regarding real time control of pressure sewer pumps to improve the operation of the pressure sewer system and reduce the frequency of maintenance flushing.

The success of this project gave SEW confidence to use PSS for a major sewer backlog program servicing over 15,000 properties in the Southern Mornington Peninsula.