Twin Culverts

Project Location: Oaro, Kaikoura
Client: New Zealand Transport Authority

PROJECT DESCRIPTION

In early February 2018, Tropical Cyclone Gita, a category 4 storm with winds of more than 275 kilometres per hour, ravaged the Pacific. This caused thousands of cubic meters of debris to slip off the hills along the east coast of the South Island, New Zealand, causing road blockages requiring repair. The twin culverts located in Oaro could not handle the water inflow due to the small culvert intake and pipe diameters of 450mm and 625mm. This lead to rain accumulation at the culvert intake, which then flooded over the road and down the slope to the river below. Due to the ground being saturated and the
culvert pipes having water pressure on them, the pipes were thrust out of position, causing further erosion of the slope below the road. By the time the Cyclone had passed only one lane of the road was usable.