"This project faced a number of challenges, including very tight timeframes. Through effective coordination with our partners, the project team delivered an innovative stormwater design that was completed on time, while reducing overall costs and risks. The system is sustainable, future-ready, and already delivering benefits to the community." - Auckland Council Healthy Waters Project Manager - Gerhard van Rooyen.
Summary
- Part of the stormwater culvert under Greville Road in Pinehill, Auckland, collapsed after severe storms in early 2023.
- Greville Road is an important link to the Northern Motorway, carrying around 19,000 vehicles every day.
- After Awa discovered the collapse, emergency work started to safeguard the road and reinstate stormwater infrastructure.
- We delivered the design for a stormwater section that not only fixed the immediate problem but provided an enduring solution that reduced short- and long-term risks and costs for the council and community.
- After issuing the final design package, Awa provided expert advice and supported monitoring until construction on the $19.6 million project was completed by the contractor in April 2025.
- The project was a finalist in the Infrastructure Decarbonisation category of the Building Nations – 2025 Impact Awards.
Challenges
- The collapsed culvert presented a serious threat to roading that needed urgent attention.
- Damage to the road’s structural integrity and the Northern Busway from flooding would have caused major traffic disruption around a busy commercial area.
- Councils need to balance short-term risk reduction with the best use of public funds long-term and so require cost-effective, rapid solutions that are future ready.
- The old stormwater pipe ran deep under a landfill adjacent to the road and had a sharp curve halfway along its route making repair works difficult.
- As works were in the middle of a metropolitan area, there were many stakeholders involved, including:
- Auckland Transport
- NZ Transport Agency Waka Kotahi
- Members of the Northern Corridor Improvements (NCI) Alliance
- Other parts of Auckland Council
- Private landowners
- The construction contractor and specialist subconsultants.
- As this was emergency work, everyone on the project had to operate under time pressure whilst complying with relevant regulations and requirements.
Solutions
- A comprehensive design and risk management approach allowed the best solution to be developed rapidly.
- Awa engaged early with stakeholders to obtain their input and support, leading workshops focused on risk, options, and Safety in Design.
- We also conducted an options assessment, which considered multiple criteria to determine the optimal solution.
- Notably, Awa worked with the contractor earlier than is typical on a project of this sort.
- Rather than doing the design and then handing it to the contractor for construction, we collaborated from the start.
- This helped us develop a design that saved time and money by making the most of the contractor’s capabilities while allowing for practical project constraints.
- For example, the stormwater pipe was designed to fit a tunnel boring machine the contractor had just finished using on another project.
- The design features a new alignment that is more direct than the old section of the network, avoiding the landfill and other services on site.
- It allows for the growing needs of the Albany area and increased rainfall due to climate change.
- Awa worked with Auckland Council to follow the new emergency work declaration process.
- This enabled the works to take place before consent was granted – saving time and avoiding further damage.
- As retrospective consent is needed, Awa designed the solution according to best practice, relevant regulations, and consent requirements.
Benefits
Awa’s stormwater expertise, commitment to excellence, and flexible, collaborative working style was crucial to the success of this project.
