Gould Crescent Outfall Christchurch

Dated: November 2011 Display all Projects
Principal: Christchurch City Council
Distributor: Humes Pipeline Systems
Contractor: Worthington Contracting
Product: Single corner and single parallel slide rail

Worthington Contracting chose to use single corner slide rail for the manhole and single parallel slide rail for laying pipe at Gould Crescent, immediately adjacent to the Heathcote Estuary in Christchurch. 

The site posed some challenges as the soils were poor and the water table high. The pipe was 900mm diameter PPS Frank PE in 6m and 14.5m lengths, forming an outfall into the Heathcote Estuary via an 1800mm diameter manhole. Trench depths were around 3.5 – 4m. 

The first step was to install the manhole. For this the contractor installed the single corner slide rail system, excavating as the shoring was progressively pushed in to the excavation. High water table and inflows required de-watering to enable the manhole to be installed in a dry excavation. 


Once installed the backfill was placed and compacted in layers as the shoring was progressively extracted. 

Next single parallel slide rail shoring with an inside width of 1.5m was installed linking an existing manhole to the new manhole. This was achieved using 4 modules of slide rail with a combination on 3m and 4m long panels to achieve the required length of shoring between the manholes. Once installed the transverse frame assemblies were raised in their slides to enable the pipe to be introduced into the trench in one length. 

The final 6m length of pipe was installed to the outfall, again using the single parallel slide rail. 

The single slide rail system enables safe and efficient excavation to an effective depth of 4m in almost all soil conditions.

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