A cofferdam has been built within Blackwattle Bay. It creates a dry space to safely carry out the work of the main structure of the new Sydney Fish Market.
The cofferdam is a swimming pool-type structure, built around the perimeter of the new building.
The cofferdam is around 20,000 square meters (the size of about 4 football fields) in area.
Over 1,000 interconnected steel sheets and tubular piles, driven up to 22 metres into the seabed, are used to build the cofferdam wall.
The cofferdam is installed using Giken Japanese technology. The Giken is often referred to as the ‘silent piler’. It is typically quieter than most of the regular construction activities occurring on site.
Sheets are installed using a press-in method. Silent pilers utilise their own weight and reaction against
The draining of the cofferdam is an engineering feat and a major milestone for the project. It is one of the most exciting, unique, and highly technical elements of its construction.
Over 100 million litres of water have been pumped out (equivalent to 40 Olympic swimming pools) to drain the cofferdam to a level around 4 metres below sea level.
De-watering took 14 days and was undertaken using 9 barge-mounted pumps.
A suitable base within the cofferdam will be set up to construct the basement and floors of the new building.