Extreme Weather Flood Relief:
Morningside Stormwater Upgrade

Ongoing flooding in Whangarei's CBD was the driver behind the construction of a one kilometre long flood relief channel, to protect not only the residents in a central city suburb, but the foundations for the city's rail infrastructure.

United Civil Construction were awarded the contract, known as the Morningside Flood Relief Drain, to reduce the risk of flooding in Whangarei during extreme weather events. Over a four month period, a 1000m flood relief channel was constructed between the Morningside Basin and Limeburner’s Creek and within the existing Kiwi Rail corridor, including a Rail Possession to facilitate culvert construction under rail infrastructure.

The works comprised of site clearance, service diversions, bulk earthworks and construction of twin box culverts underneath the railway lines during a rail possession over the Christmas holiday period.

Key features:

  • United Civil Construction liaised closely with Kiwi Rail to ensure there was no unplanned disruption to the rail service and completed construction of the twin box culvert structure ahead of schedule to Kiwi Rail standards.
  • The scope of works included manufacture of the precast box culvert units weighing 13 tonne each, precast concrete wall panels and in-situ concrete works to form the culvert crossing and inlet/outlet structures in the Kiwi Rail Yard.
  • Service diversions were required to facilitate construction of the new flood channel. All traffic management and erosion and sediment control measures were planned and managed by United Civil personnel.

This was a challenging project with all works undertaken in close proximity to existing Kiwi Rail infrastructure together with erosion and sediment control measures to facilitate substantial widening of the existing channel. Works also included drainage, gabion wall construction, fencing, bespoke guardrail and anti-access covers, reinstatement and landscaping.