Moore Construction was directly contracted by Horizons Regional Council for the construction of three secant pile retaining walls located both upstream and downstream of the Tremaine Avenue Bridge over the Mangaone Stream. The scope of works included the development of temporary works designs to facilitate access and establish stable working platforms suitable for continuous flight auger (CFA) piling operations.
Temporary erosion and sediment control systems were implemented in accordance with regulatory requirements. Sheet piling was installed within the stream channel to enable a temporary stream diversion and maintain a dry working environment.
The primary structural works comprised the installation of 340 no. CFA piles, each 750mm in diameter, forming the secant wall system. A total of 173 linear metres of cast in situ reinforced concrete capping beam was constructed to tie the pile walls together and provide structural continuity.
Additional works included the excavation and removal of deteriorated gabion basket structures and the bulk excavation of the streambed to facilitate placement of engineered rock riprap for long-term channel protection and scour resistance.
