Temporary Works
Sinking a Shoring Box for Underwater Pipe Works – Botany Bay
The Project
Shore Hire sunk steel shoring boxes 14 metres underwater in Botany Bay to provide safe diver access for subsea pipeline excavation works for a global oil and gas company.
Summary
Shore Hire worked with third-party hydro engineers to deploy two Shore 4m-60 Steel Trench Boxes fitted with Arch Spreaders over a bank of four underwater pipes, providing divers from SGS Diving Services with a safe, sand-free work zone for ultrasonic testing. The team navigated significant challenges including strong currents, low underwater visibility and strict weight limits to avoid destabilising the barge and crane during placement. Shore Hire also provided the client with full cost transparency upfront, including a replacement fee covering the risk of box damage, giving the client complete confidence before works commenced.
Challenge
One of our clients, a global oil and gas company, needed to perform subsea pipeline excavation works 14.6m underwater in Botany Bay.
The client wanted to place shoring boxes over a bank of four pipes running underwater and wanted Shore Hire to provide suitable and safe shoring boxes.
The boxes would be used to provide safe access below the pipeline so divers from SGS Diving Services could complete phased ultrasonic testing and so that when sand was being dredged, it wouldn’t blow back into their work zone and fill it back up with sand that had already been removed from the area.
The main challenge with this project was using shoring boxes that were heavy enough to sink to the required depth but not so heavy that they would cause the barge and crane to tip too far when placing the boxes under the sea.
Other challenges this project faced included strong currents pushing the shoring boxes away from the work zone, low underwater visibility, and working around incredibly high-cost assets.
Solution
To solve these problems, we worked with third-party hydro engineers to help with the complex requirements associated with sinking shoring boxes.
We decided to use two Shore 4m-60 Steel Trench Boxes with our Arch Spreaders for clearance over the pipes and also because these boxes and struts are a heavier option than some of our other shoring solutions.
Due to the risks involved in the potential destruction of the boxes, we were also able to provide the client with a replacement fee before hiring out the boxes, so they had full transparency on total project costs before going ahead.
The customer was extremely pleased with our solution; our shoring boxes were able to be sunk successfully, and the highly skilled and experienced divers were able to complete their underwater work with ease.
Overall, this project demonstrates Shore Hire’s ability to face difficult and unique projects head on, while providing our clients with safe and effective solutions.
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