Concrete removal key in wharf upgrades

​Work commenced at Whakatane Wharf mid-August 2020 as well as on the Ohope Wharf September 2020 to remove existing concrete from the structural piles and beams via hydro-demolition and is planned for completion in 2021.

The project, run by infrastructure and industrial services speciality InterGroup, is a’ measure and value’ contract to remove approximately 70m3 of damaged concrete from Whakatane and 27m3 from Ohope wharves.

Each site was first established within a defined compound, and surrounded by noise attenuation panels to mitigate plant noise from the jetting and compressor machinery.

Concrete has then been removed in progressive stages from each element – typically a 360mmx360mm pile has been reduced to a 180mmx180mm core, with all reinforcing steel exposed and jetted clean. Given that no support props were to be placed adjacent to the demolished elements, a structural core was required to be left intact ahead of any refurbishment.

A 20,000 psi jetting plant was used at between 96-116 l/min-1, with staff wearing air-fed blasting helmets, Kevlar protection, and separated by Kevlar curtains to allow active work fronts while in close proximity to each other.

Both sites are greatly affected by tides, and this requires the team to also use steel-capped safety waders while standing on mesh platforms.

Planning for all works has been collaborative with client BBR throughout the project – with works delivered within client expectations, and a strong focus on HSE. Daily safety audits remain ongoing for both sites, with each area running a 5-person crew to manage fatigue, safety watch, equipment management, and staff rotation on a 6-day per week operation.

“Contractor management has been a key factor, with concrete formers, steel workers, and concrete supply companies all working adjacent to each other to deliver the works within a defined period. Attention to house-keeping and establishment of clear demarcation zones has allowed multiple activities to continue unimpeded and without compromise to safety,” says InterGroup.

“Public safety, management and engagement has remained paramount from the outset, with part of each site remaining open to public throughout the project.”

Key stakeholders have been engaged including adjacent businesses that have continued trading while in close proximity to the works, and Intergroup have maintained active noise mitigation throughout the project without fail or public complaint.

The general delivery has been managed by Graeme McNamara for both sites, including liaison with BBR and engineering consultant company Beca, delivery of all works, HSE management, fuel management, QC for finished work, and measurement confirmation for invoicing.