Summary
- KiwiRail's $419 million Papakura to Pukekohe(P2P) Electrification Project extended Auckland's electric rail network 19 kilometres south, enabling direct electric train journeys from Pukekohe onwards from February 2025.
- Alongside the railway upgrade and redevelopment of Pukekohe Station, new drainage and water infrastructure was needed within the rail corridor.
- KiwiRail initially engaged Awa Environmental in November 2022 to provide monitoring, surveillance, and quality assurance (MSQA) support for drainage and associated civil works at Pukekohe and Drury stations.
- From 2023, our role progressively expanded to include engineering design, flood risk assessments, regulatory approvals, and construction monitoring.
- Working closely with KiwiRail, contractors, and other consultants, we helped resolve complex infrastructure challenges and respond to changing construction requirements, supporting progress on this major rail electrification programme.
Challenges
- New stormwater and wastewater infrastructure were needed to connect with existing public networks while meeting Auckland Council and Watercare requirements. Congested underground services, limited physical clearances, and construction already underway complicated design and regulatory approval processes.
- At Pukekohe, a new drainage swale near Franklin Road had to provide the required flood storage within a narrow corridor bounded by the railway and neighbouring properties. Existing vegetation, a bridge foundation, and restricted space for a drainage pipe beneath the bridge added further complexity.
- The northern swale design also needed to fit within the wider construction timetable, with approximately three months between our appointment and the planned start of construction.
Solutions
- We brought together our Engineering Design, Planning, and Catchment Dynamics services to help KiwiRail address these challenges.
- Our initial MSQA role (Management, Surveillance, and Quality Assurance) involved reviewing construction documentation, monitoring work quality, and supporting compliance with KiwiRail's technical and contractual requirements.
- In April 2023, we took over responsibility for progressing existing engineering plan approval applications for stormwater, wastewater, and water supply infrastructure at Pukekohe Station. This involved working closely with Auckland Council and Watercare, resolving complex technical and design issues, and adapting designs to accommodate existing underground services and construction requirements. We also addressed requirements for connections to public networks and approvals for work near existing water infrastructure.
- For the northern swale, we used three-dimensional modelling to carefully refine its alignment and side slopes, accommodating the required flood storage while minimising disturbance to existing vegetation. The design also needed to accommodate an existing bridge crossing the swale. We designed a drainage pipe to pass beneath the bridge, using connections that allowed changes in direction while maintaining safe clearances from the bridge foundations and railway tracks.
- We also undertook flood risk assessments for the Southern Power Feed and Ōpaheke Railway Crossing sites. During construction, we reviewed inspection and test plans, carried out site visits, and updated designs to reflect site conditions.
- Throughout the project, we prioritised urgent design queries and made our team available to respond directly to site teams, enabling rapid decisions and practical design adjustments as issues arose.
Benefits
- Our northern swale design avoided extensive vegetation clearance and reinstatement, reducing the associated construction work while meeting the required flood storage and clearance requirements. We also completed the design within budget.
- Our engineering and regulatory expertise helped secure Auckland Council's approvals for new water supply, wastewater, and stormwater infrastructure at Pukekohe Station, supporting construction progress. By resolving design challenges around existing underground services, we also helped KiwiRail accommodate new infrastructure within the constrained station environment.
- Our flood risk assessments provided KiwiRail with information to inform decisions about flood exposure at the Southern Power Feed and Ōpaheke Railway Crossing sites.
- Throughout construction, our MSQA services provided KiwiRail with ongoing quality oversight of drainage and civil works. Site visits, reviews of construction documentation, and timely design adjustments helped address issues as they emerged.
- Our responsiveness also helped avoid costly disruption. For example, when a contractor raised a catchpit location issue just two hours before an accessway concrete pour, we amended the design within 45 minutes of receiving the necessary information, avoiding additional delays on site.
- Together, Awa’s services supported KiwiRail's delivery of essential infrastructure for a major rail upgrade that now provides more convenient, quieter, and lower-emission train journeys for South Auckland communities.
