An unparalleled level of collaboration, communication and commitment underscored Allied Concrete’s experience during the extremely-challenging restoration of Kaikoura’s earthquake-devastated infrastructure.
Allied Concrete oversaw the manufacture and delivery of about 90,000 cubic metres of concrete and cement-stabilised materials in late 2017 along State Highway 1 between Picton and Christchurch.
The story of concrete and Kaikoura is really a story about people. It is about the ability of client and supply teams to pull together quickly, with a common purpose, and work through very difficult conditions to deliver on commitments.
People often talk about ‘once-in-a-lifetime’ experiences and it is highly unlikely that the circumstances and operating environments experienced in Kaikoura will be replicated. The scale and complexity of the project will provide stories for those who participated in it for years to come.
Following an enormous amount of work by the North Canterbury Transport Infrastructure Recovery (NCTIR) design teams from May to July in 2017, concept studies were presented in August that year.
Given the magnitude of the job, it was apparent that Allied Concrete would need to work closely alongside aggregate and cement partners, Fulton Hogan and Holcim (New Zealand) Ltd, to overcome numerous challenges.
These were identified as crushing and screening enough materials, storage capacity, the cement tanker fleet to service the operations via the inland route to Kaikoura, and getting enough people on the ground at a time when national concrete outputs were already at historic highs.
preliminary step was to establish a ‘project purpose’ for onboarding new team members quickly. Although a simple step, it galvanised different parent organisations quickly around prioritising actions and providing the ‘why’ for people involved in the project.
Having collectively readied for the task within little over a month, changing circumstances then saw the team need to undertake a second phase of mobilisation.
One of the main challenges for the client was the close time proximity between design and construction. Survey information in this environment is a huge undertaking and as a result of the site geometry, quantities changed.
This increased programme pressures, and it quickly became apparent that more production capacity was required.
Ensuring the quality of the concrete and cement-stabilised materials to be deployed was another key priority, as evidenced by measures undertaken to adapt design requirements, trial methodologies and complete sample testing.
Largely finishing the second round of mobilisation by the end of September 2017, the team’s focus then turned to how to maintain production on a consistent basis. Facing a wide range of weather, geographic, timing and human resource challenges - some within control, but many not - production duly advanced on a “sprint and stop, sprint, repeat” basis.
Production conditions were certainly not ‘business as usual’ for the construction teams.
One of the most challenging areas of the project - the stretch of road located between Hapuku and the Clarence River (north of Kaikoura) – necessitated relocating the road alignment towards the sea to avoid the path of potential slips on the coastal slope faces after clearing.
This involved the construction of a large retaining wall on the newly-uplifted land. 30 MPa concrete was required for the mass foundation footings, and 50 MPa concrete for the precast seawall blocks. Backfill behind the retaining wall required a nominal 2 MPa no-fines concrete that was capped off by 4 percent cement stabilised 65.
The size of the task was enormous, with three key retaining structures to be constructed. These had the non-descript names of Wall 2 (between Hapuku and Nins Bin), Wall 6 (south of Ohau Point) and Wall 7 (around and to the north of Ohau Point). This was nearly two kilometres of wall and roading up to nine-metres-high.
Some of the unique operational experiences included:
- As the Hapuku site was situated in an area where an upland dam had formed due to a large landslip, teams had to suddenly vacate when a flood warning was issued as it was deemed the dam could burst - “luckily it didn’t!”.
- Floods on the Hapuku formed quickly due to the terrain and short response time of the river to heavy rain, which duly sent teams scrambling to relocate equipment that, through necessity, was located within the wider floodplain.
- Drivers timed their runs to avoid waves going over the top of the freeboard on the seawalls.
- Teams frequently picked their way through boulders that came across the road and, when they were sizeable, needed to co-ordinate with digger drivers to be able to get through the slip areas.
- Skilled and experienced drivers reversed up to 300 metres at night down slopes in all weathers.
However, despite the uniquely-challenging environment, the operation stayed true to its induction statement to “provide concrete and cementitious stabilised fill to NCTIR as fast as we can”, while ensuring:
- No injuries to team members or others,
- no impact on other road users or NCTIR members; and
- minimal damage to the environment.
Safety was built into the plant facilities and logistics through the identification of key controls and the use of behavioural coaching programmes; which ultimately resulted in nil lost time incidents. This was despite the high-pressure operating environment and numerous risks.
Initially engaged by the NCTIR to provide 10,000 cubic metres of concrete over a 40-week period, the project evolved to being 90,000 cubic metres of material largely delivered over three-and-a-half months between September-December 2017.
This was achieved by establishing one concrete plant, three pugmills and supporting infrastructure for production of aggregates and cement delivery and storage that, at times, were working 24 hours per day, six days per week.
Ultimately, the project is an example of what construction and supply teams can achieve when aligned. Design and construction took place virtually simultaneously without compromise to quality.
Allied Concrete are extremely grateful to have been given the opportunity to contribute to this project. It involved collaboration, communication and a partnering approach that they have not seen on any other project. This speaks largely for NCTIR management and supervisors, along with Allied Concrete and its partners.
Article based on - To, Wade (October 2018). Kaikoura concrete supply. Paper presented at the Concrete NZ Conference 2018, Hamilton, New Zealand.
Taken from Concrete magazine.