Optimising Water Treatment Plant Commissioning: Strategies for Successful Integration

Pearson, S (Beca) & Lewis, C (Marshall Projects Limited)

Tauranga’s water supply was under pressure and the construction and commissioning of the recently completed Waiāri Water Treatment Plant (WTP) needed to be brought forward prior to the 2022/2023 summer water demand peak.

The WTP, with a 30 ML/d capacity and a future design capacity of 60 ML/d using coagulation, clarification, membrane filtration and disinfection (sodium hypochlorite), and zero liquid discharge facility first produced water to supply in December 2022, made possible from an integrated commissioning approach. 

In June 2022 Tauranga City Council explored options to bring forward the production of water to supply through either:
• decoupling construction items from practical completion to allow commissioning to progress, or
• to integrate commissioning into the construction programme, with commissioning occurring prior to practical completion.

After careful consultation and engagement with the key stakeholders, including client, engineer to contact, principal contractor and sub-contractors, it was concluded and instructed to proceed with an integrated commissioning approach, where parts of the process / plant were commissioned in parallel with construction activities on less critical / non process related works.

The overall Waiari Project delivery team was fairly complex, including; TCC’s project team and wider stakeholders, the plant operations team, health and safety specialists, the intake construction contractor, the WTP construction contractor, the membrane design build contractor, the trunk main contractor, plant designers, software engineers, commissioning agents, the communications team, and multiple contract administration teams. This required a significant amount of collaboration and trust between all parties for the commissioning process to be successful.

This paper discusses / explores the key factors for the success of this integrated approach, including, but not limited to;
• Why the Integrated Commissioning Approach?
• The contractual considerations to manage change and reduce liabilities in the form of damages, extension of time and further potential project delay.
• Construction adaptation to manage health and safety for construction and commissioning occurring concurrently.
• The Health and Safety approach and protocols needed to allow works to progress safely.
• The requirements for commissioning to start, and effect on contractual elements.
• Being able to plan and then adapt that plan as things inevitably change.
• Still retaining some programme float.
• Clear communication pathways during commissioning.
• Creating a commissioning environment which allowed people to be their best and for the approach to succeed.

The result of this was a successfully commissioned plant, allowing water to enter supply in December 2022, in time to manage the summer peak without the need for significant water restrictions, while reducing the risks to the overall water supply scheme.

This paper also discusses elements of this approach that can be applied to other projects including sharing of knowledge, transfer of skills, and the ability to make changes quickly, efficiently and safely.