Survey work starts at East Coast’s Hikuwai River site for new bridge

Electro-seismic surveying techniques, including drilling, will be used to map out what lies under the surface of the Hikuwai River as part of planning for the new bridge.

Innovative electro-seismic surveying techniques will be used to map out what lies below the surface of the Hikuwai River, work that will bring the new Hikuwai Bridge a step closer to construction.

Gisborne-based companies Aquifer Mapping and Civil Assist will undertake part of the pre-construction investigations, which will provide design and engineering crews with insights into geological conditions and potential obstructions under the ground.

“This quick, non-invasive, non-destructive technique involves using a boat to send gentle seismic waves into the ground,” Transport Rebuild East Coast (TREC) project manager Richard Bayley said.

“These waves travel through the water and the ground, and when they hit different types of materials, they create electrical signals.”

The new Hikuwai No 1 bridge will replace the temporary Bailey bridge built after Cyclone Gabrielle. Consents are expected to be lodged later this year, ahead of construction in 2025.

Gisborne-based companies are involved in the testing programme, which will provide design and engineering crews with insights into geological conditions and potential obstructions under the ground.

“This work and other ground investigations to be carried out in the next few weeks will help highlight any issues early so they can be addressed during the design phase.

“The Hikuwai bridge project site is complex, and early investigations like these give our team critical information,” Bayley said.

“By measuring these signals, the team can create a detailed map of what’s below the surface.”

These early investigations also include some drilling work and are expected to take up to three weeks to complete.

“The team are working hard towards a construction start early next year and will share more information with the community before Christmas,” he said.

Blessings were held last week to mark the beginning of pre-construction investigations.

TREC will continue to work closely with iwi/hapū, landowners, the district council and local contractors as it designs and delivers the project.