Barber Grove to Seaview Wastewater Treatment Plant Pipe Duplication
This project involved installing a new 1.2km-long, one metre diameter pressurised wastewater pipeline. This new pipeline will improve water quality to cater to the region’s growth and be resilient in the event of earthquakes.
The challenges
During the investigation phase, an area of geotechnically stable ground was identified as more resilient in a seismic event. Targeting this zone for the pipe installation resulted in the depth of the pipeline ranging from between 2.5 metres and nine metres below ground level. A high-water table across the site demanded extensive temporary works along
the alignment to ensure a safe and productive site. As one of the main arterial traffic routes in the region, the local council was involved early on in the Early Contractor Involvement (ECI) phase to ensure works could progress while maintaining traffic flow.
The solution
The ECI team reviewed a number of options and carried out multiple workshops with key stakeholders to develop a construction methodology that was
the most efficient while causing the least possible disruption to the road network, residents and businesses and minimising environmental impact.
The agreed solution was for a mixture of trenchless technology (55 per cent) and open trenches. This method was chosen because it is the most efficient and caused the least disruption to the road network, local residents and businesses.
how did we optimise, earlier?
Key to success
By working closely with key stakeholders early in the ECI phase, the contractor ensured all parties were well informed and the construction methodology was tailored to best accommodate the stakeholder needs.
During the ECI process, contributions were made to detailed design and optioneering. This resulted in a final design that was fit for purpose while being aligned with the construction methodology.
We were engaged early by McConnell Dowell to provide specialist technical support for all tunnelling operations. Our team worked closely with the contractor on a comprehensive Geotechnical Baseline Report, undertaking all temporary works design associated with the mTBM operations— including designs of the launch and retrieval shafts, settlement analysis, groundwater infiltration rate analysis and jointly developed the methodology to facilitate the smooth tie-in to the existing network.
The Andy O’Sullivan team developed the design for the temporary works as part of the Barber Grove ECI. This included aspects of geotechnical design from retaining structures to specialist considerations associated with TBM works. They provided practical and progressive solutions in a demanding geotechnical environment. Their well-considered designs brought real value to the project.
