Located in the Clarence River near Yamba in Northern NSW, Harwood Marine own and operate one of the largest privately owned commercial slipways in the Southern Hemisphere.
As part of proposed repairs, upgrades and improvements to the Slipway and surrounding infrastructure, a watertight temporary sheet piled cofferdam was required to seal off the Clarence River from the construction site to allow these works to happen ‘in the dry’.
J Steel was approached by Harwood Marine to redesign and replace a poorly designed cold formed sheet piled cofferdam that had failed during a king tide.
Using J Steel’s extensive stock of long, high strength, hot rolled AZ sheet and tubular piling, a propped wall was designed by the J Steel Engineering department to support up to 8m of water head from the Clarence when fully dewatered in the alluvial soil conditions.
The sheet pile cofferdam performed very well and remained serviceable during the severe storm events that struck the area in March 2017. The cofferdam also remained effectively watertight throughout.
The sustainable sheet pile option allowed the complete removal of the cofferdam when no longer required and these will be reused on other projects.
For the Harwood Marine Permanent works, refer to separate Case Study here.