Beechworth Sewerage Upgrade – North East Water

May 1, 2020

Gordon Gibson Nominees completed a Preliminary Design for North East Water for a new main Sewage Pump Station and Sewage Transfer Pipeline.

The former gravity outfall pipeline ran through the Beechworth Historic Park and lacked capacity resulting in regular overflows of untreated wastewater to the environment.

The project involved the design and documentation of a new main Sewage Pump Station, Transfer Pipeline, Energy Dissipation Structure and Treatment Plant inlet works.

North East Water awarded a Design and Construct Contract for the project to Longford Civil and Longford Civil appointed Gordon Gibson Nominees to carry out the detail design of the project.

The Beechworth Sewerage Upgrade Project involved a number of complex issues that required innovative solutions.

These issues included:

• Highly variable sewage inflows to the pump station due to ageing sewerage reticulation infrastructure suffering significant infiltration issues whereby wet weather flows are up to eight times the peak dry weather flow;
• Insufficient capacity in the existing transfer pipeline to the treatment plant resulting in regular overflows to the adjacent environmentally sensitive Beechworth Historic Park, and EPA infringement notices for North East Water;
• The originally proposed new pipeline route involved a long distance through a State Park, presenting environmental construction challenges;
• The pipeline route involved a relatively high lift, presenting pumping challenges;
• The pipeline route also involved a very large fall over the downstream end, resulting in very high static pressures at the outlet to the treatment plant;
• These complexities required:
  • A complex pumping system with two sets of pumps and intricate controls, depending on inflows to the pump station;
  • Detailed hydraulic design of the transfer main which incorporated both a pumped (pressure) section, and a gravity section;
  • Design of an Energy Dissipation structure at the outlet due to the 160m difference in elevation;
  • Boring of the transfer main under the State Park (500mm in diameter for approximately 1000m at 50m depth) through granite;
• We carried out detailed hydraulic analysis and modelling, particularly for the pumping system and the energy dissipation structure;
• The long bore required detailed calculations to confirm the practicality of the concept and the required pipe material details.