Quinns Main Sewer Project: Challenges and Lessons Learned

Abstract

The Quinns Main Sewer (QMS) project consists of constructing approximately 1,900m of 1800mm internal diameter main sewer from Neerabup to Clarkson in Perth, Western Australia, including associated access chambers. The alignment starts in the Neerabup National Park, crosses the Mitchell Freeway and Transperth railway, proceeds through suburban streets and an easement through the Northern TAFE campus in Clarkson, and ends adjacent to a major distributor road where the sewer connects to the existing QMS. To minimise community impact during construction, trenchless construction by microtunnelling was adopted as a preferred technique versus open cut for most of the length. The project faced many challenges through the whole delivery process, including the hydraulic design, the community and stakeholder requirements, and the variable ground conditions for microtunnelling. The hydraulic design had to address a significant elevation difference of 25.7m over the first 700m of the sewer alignment. The selected design was a vortex drop chamber. The microtunnel crossing of the freeway and railway required extensive liaison with PTA and Mainroads WA through design and construction for approval of the proposed method. The variable ground conditions were extensively investigated during the development of the Geotechnical Baseline Report (GBR) and many challenging conditions were encountered during construction. The project was delivered for the Principal, Water Corporation, as a Design and Construct (D&C) Contract with the preliminary design undertaken by Jacobs, the Geotechnical Baseline Report (GBR) developed by Advisian, the head contractor was Rob Carr, with subconsultant detail design done by SMEC. 1 No-Dig Down Under 2023 Quinns Main Sewer Project: Challenges and Lessons Learned Richard Fourie, Nick Sarapunas, Steve Ilic, Paul Lee, Andrew Youngs