Riverstone Wastewater System Second Pressure Main

UEA was engaged in 2025 by Confluence Water for the first time to deliver the HDD and minor civil scope of works for the Riverstone Wastewater System SP1154 Second Pressure Main project. UEA was contracted to install the section of the pipeline that crosses underneath Windsor Road and along Boundary Road.

Scope of Works

UEA negotiated mixed ground conditions with unexpected hard rock encountered throughout the bore. In response to the encountered ground conditions, UEA modified the tooling selection and reaming methodology from forward reaming to back reaming, facilitating the completion of the 20” ream. This adjustment required the deployment of additional resources to the exit side, including a drilling fluid recycling system and a high-pressure mud pump, to effectively manage the increased fluid returns at the exit side caused by the change in methodology. A breakout unit was also utilised on the pipe side of the project to safely manage the requirement for a tail string to ensure control of the borehole.

Due to the limited available room to string the product pipe and specification requirement regarding the removal of internal beads, the product pipe was strung out along O’Connell Street in 1 x 372m string and 4 x 36m strings. The configuration allowed the first string to be pulled in, with the subsequent strings welded, internally de-beaded and installed throughout the duration of the pipe installation.  

UEA’s scope of works on the Windsor Road HDD project involved the below: 

• Comprehensive design review 

• Hydrofracture analysis 

• Installation calculation for the product pipe 

• Construction of the HDD entry and exit pads 

• HDD installation 

• Post installation hydrostatic testing 

• Pipe welding and stringing 

• Minor civil scope of works involving pipe laydowns and 20 metres of trenching and concrete encasement on the western side of the bore 

Key Project Highlights

• Pipe installed in compliance with Sydney Water’s Civil Specification. 

• Negotiated mixed ground conditions without fluid loss. 

• Successfully managed community impacts. 

• Innovative methodology for managing the requirement to internally de-bead the product pipe with limited stringing room.