Advantages of Engaging a Trenchless Specialist as Principal Contractor for a Significant Sewerage Project

Abstract

Unitywater used a non-traditional procurement approach when contracting two major sewerage upgrades in growth hotspots on the Sunshine Coast. Community and environmental concerns were forefront in the planning process, and river and major road crossings meant some trenchless construction would always be necessary. However, instead of taking the traditional path of selecting a civil contractor who would sub-contract the trenchless works, they chose a trenchless specialist to act as the principal contractor. This approach was driven by knowing the biggest project risks lay in the trenchless sections and would be best understood and managed by a trenchless specialist. Unitywater’s early engagement of a specialist trenchless consultant meant that the market was informed with an advanced design and ground condition data prior to evaluating the risks and tendering for 5.7 kilometres of 900mm diameter pipelines. The initial 3.3 kilometres proposed for the trenchless sections was increased to 4.6 kilometres by the trenchless contractor. This included a 1.6 kilometre section that was the longest horizontal directional drill of this size in Australia. Unitywater’s procurement approach resulted in a reduced impact on the environment and urban amenity, while delivering the sewerage upgrades for the same cost and time as selecting a civil contractor.