Wivenhoe Dam Improvement Project

Client: Flagstaff Consulting Group
Asset Owner: Seqwater
Location: Wivenhoe Dam, South East Queensland
ECS Role: Specialist cost consultant within the advisory team
Services: Cost estimating, options cost comparison, basis of estimate
Project stage: Options analysis and business case
Year: 2025

Project Description

Wivenhoe Dam is the largest water supply and flood mitigation asset in South East Queensland, completed in 1984. It is one of several dams being upgraded under Seqwater’s Dam Improvement Program, which is bringing the region’s dams into line with modern engineering and design standards and with the requirements of the Queensland Dam Safety Regulator. The Wivenhoe Dam Improvement Project is in the options analysis phase, with a preliminary business case being prepared for the Queensland Government. While planning continues, the dam operates at a reduced full supply level of 90 per cent.

ECS Scope of Work

ECS was engaged by Flagstaff Consulting Group as specialist cost consultant within the wider advisory team, supporting Seqwater’s early planning and business case preparation for dam safety upgrade options.

ECS prepared early-stage cost estimates for the upgrade options under consideration, together with the associated works beyond the dam itself. The estimates were prepared as AACE Class 5 and Class 4 estimates and aligned to Seqwater’s cost estimating guideline, with construction cost built up from its individual elements — the plant, labour, materials and specialist subcontractors involved — rather than from benchmark rates alone. ECS contributed to the supporting documentation setting out how each estimate was reached, and every estimate was independently reviewed within ECS and then with the wider team before issue.

Key Deliverables

• AACE Class 5 and Class 4 cost estimates for three upgrade options
• Cost estimates for associated upstream works
• Basis of estimate documentation
• Like-for-like options cost comparison